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Forest Entomology
@ &
he Gli ANDERS. PETS.
WOODS MANAGER TO HIS GRACE THE DUKE OF NORTHUMBERLAND, K.G.
WITH 351 ILLUSTRAZIONS
William Blackwood & Sons
Edinburgh and London
ee LIBRARY
FACULTY OF FORESTRY
UNIVERSITY OF TORONTO
.
' =e
CFLS WE ay
DEDICATED “BY PERMISSION
TO
HIS GRACE
THE DUKE OF NORTHUMBERLAND,
eG,
PREFACE,
In submitting a book on a branch of Natural Science which
has required any degree of research during its preparation, or
which otherwise is intended as a guide for research, perhaps
“no one realises its shortcomings more than the writer. At
least this is certainly the feeling of the author on the present
occasion.
The book was begun in a very humble way. Having
always had a strong inclination for Natural Science, and
further for studying subjects associated with the scientific
aspect of forest trees, I began as far back as 1887, while
residing in Cheshire, to write papers on Forest Insects for the
Warrington Field Club. To that district, with its Natural
History clubs or societies, and the many excellent men I met
in connection with them, I owe a very deep debt of gratitude.
I cannot in the present circumstances enumerate all to whom
I am indebted for assistance in the present book, but my first
teacher in Entomology was the late Mr Berry Kendrick of
Warrington, who gave me most ungrudgingly all the help any
one could possibly give to a beginner. Of the Warrington
Field Club itself it is impossible to speak too highly as a
Natural History society. Composed of some fifty members,
vill PREFACE.
original papers were given every fortnight during the winter
months, often accruing from investigation during the summer
months, and the members freely criticised the paper of the
evening. This, though perhaps not always appreciated at the
time, was in itself a most excellent school.
In a similar way I am indebted to the Manchester Micro-
scopical Society for a great deal of ready help from its
members. This Society, unlike the former, published the
papers of its members, and I have therefore to sincerely thank
it for publishing my papers on “ Forest Insects,” and, further,
for kindly giving me the blocks prepared from my own neg-
tives, some of which I have used for the present book.
I have also to thank the Chester Society of Natural Science
for many extended courtesies given from time to time. The
* material for this book has been collected in Cheshire and
Northumberland, but more especially the former county.
I am also indebted to the Country Gentlemen’s Association,
the Highland and Agricultural Society of Scotland, and the
Royal English Arboricultural Society for publishing papers on
Forest Entomology.
Turning from societies to individuals, it is almost impossible
to acknowledge without being invidious those who have
assisted me in the subject-matter of the volume. Two
names may be mentioned. Mr R. Newstead, author of ‘A
Monograph of British Coccide, gave me from time to time
much assistance on Scale Insects. Mr A. Flatters, Man-
chester, has given me great help in microscopical manipulation,
and has, in addition to the figures acknowledged with his
name, photographed several specimens from my own micro-
scopic slides, as, for example, the tiny Cecidomyia flies.
As regards the first works from which I derived consider-
able assistance, I may specially mention ‘A List of Insects on
PREFACE. 1X
Forest Trees, by Mr S. L. Mosley, Huddersfield, and the
splendid ‘Manual of Injurious Insects’ by the late Miss
Ormerod. Of the latter [ cannot speak too highly, more
especially as Miss Ormerod gave me very great encourage-
ment by correspondence.
As the period during which I have studied the subject has
extended over twenty years, it is obvious that much original
work has been done by many workers during that time.
I have tried, so far as means or leisure would afford, to keep
in touch with all original work. In order, therefore, that the
student may get the full advantage of that, I have, whenever
I found the work of others more suitable than my own,
quoted from those writers. In most cases this has been done
by direct permission of the author, but in all cases when
giving an extract I have endeavoured to duly acknowledge
the same. In this advanced age of ours, knowledge, more
especially Entomological knowledge, is no longer the prop-
erty of any one individual. Hence all quotations are freely
given as epitomised knowledge suitable for the student.
They are given to obviate at first the necessity of consulting
other works, and yet at the same time be a guide as to what
other works he may consult for fuller information. It will
be apparent that the majority of quotations are of a systematic
nature. Hence the great difficulty in preparing the book has
been to amalgamate the systematic with the economic, and so
maintain a due proportion. On the one hand, if too many
details of a systematic nature were given, the work would not
only have been very much overladen, but the practical man
would be impatient in reading it: on the other hand, if too
few systematic details were given, it would not act as a guide
to fuller inquiries, or form, as designed, a suitable text-book
for students at agricultural and other colleges. The main
x PREFACE.
feature which is attempted is recognition of the insect from
the damage, together with systematic characters and life-history
details,
In studying the subject from the economic point of view, I
have become convinced, from a prolonged study of the subject,
that the economic student must of necessity study the system-
atic side and associate himself with systematic men. Hence,
for example, I have added often, in extenso, extracts from
valuable works like Fowler’s ‘ British Coleoptera,’ &c. At the
same time, the matter is so arranged that the beginner, or the
practical man, may at first, if he chooses, skip them, and study
the nature of the injuries, the life-history of the insect, and
in some cases the remedies which may be adopted. If, how-
ever, the subject is to be thoroughly studied, the systematic
points must be ultimately mastered.
With a view of making the work more reliable, I have
submitted each chapter in proof to men who have specially
studied particular sections or families of insects, and in all
cases I am glad to count these specialists as personal friends.
As the work embraces nearly all families of insects, this was
considered all the more advisable, and though the changes
made in the proof form by these specialists were compara-
tively few, yet in every case they were most important from
the systematic point of view.
The following are the names of those who looked over the
respective chapters in proof form—viz., Mr E. T. Connold,
“ Gall-Mites””. and “ Oak Galls”; Mr R. 8. Bagnall, “ Cole-
optera’”; Mr A. C. Forbes, “ Scolytide”; Rev. F. D. Morice,
“Saw - flies”; Mr R. Newstead, “Scale- Insects”; Mr J.
Collins, “ Lepidoptera”; Mr F. V. Theobald, “ Aphidide ” and
“ Diptera.”
I have also to thank Mr J. F. Annand, Lecturer on Forestry,
PREFACE. Xl
Armstrong College, Neweastle, for kindly looking over the
MS. previous to sending it to the publishers, and also for
discussing many of the practical points with me.
Iam specially indebted to Commander J. J. Walker, R.N.,
Oxford, for kindly correcting the final proofs,
With reference to the illustrations, for the loan of blocks or
electros I am indebted to Messrs Sampson, Low, Marston,
& Co., Ltd., for figs. 14, 16, 20, and 21; to Professor Miall
for fig. 18; to Messrs L. Reeve & Co. for figs. 39, 415 and 42;
to the Ray Society for figs. 202 and 210, and also for
granting permission to photograph figs. 213, 214, 280, 282,
284, 287, and 311; to Messrs Headley Brothers for figs.
175, 221, and 270; to the Proprietors of ‘The Entomologist’s
Monthly Magazine’ for figs. 157, 158, and 159. Mr W. R.
Fisher has given me much encouragement from time to
time, and I have to thank him for receiving from Messrs
Bradbury, Agnew, & Co., Ltd., the large number of blocks—
mia es. 47,48, 49) 50, 60; Ole 8, 6 9e 92,1321, 126, 127,
163, 164, 238, 239, 240, and 241. I also owe thanks to
Messrs Blackwood for figs. 45, 46, 72, 73, 79, 101, 102, 104,
and 245, from ‘The Forester, by Dr J. Nisbet. With the
exception of the figures taken from the valuable German
works, and acknowledged under each figure respectively, all
the others are original.
Finally, I beg to say that I submit the knowledge con-
tained in the book with a feeling that I have just about the
necessary amount of knowledge to make a beginning rather
than a finish; and I trust that the student will take up the
subject with the object of making a study of it on his own
account, and verify each point by observation and rearing. In
other words, the student must consider the work as an intro-
duction only. Further, there is the most important point left
Xl _ PREFACE,
to the last—viz., the study of German literature. The
Germans are our great teachers in this branch of knowledge,
and I have added many points and illustrations from German
sources with the distinct object of showing their superiority,
and inducing students to study their most valuable works.
Park CoTTaGE, ALNWICK,
May 1908.
CHAP.
XII.
XIII.
XIV.
CONTENTS.
PREFACE
INTRODUCTION
ERIOPHYIDE (PHYTOPTIDE) OR GALL-MITES .
COLEOPTERA (BEETLES) . :
" —SCOLYTIDH (BARK-BEETLES)
HYMENOPTERA—OAK GALLS.
" —SAW-FLIES, ETC.
COCCIDEH (SCALE-INSECTS)
LEPIDOPTERA (MOTHS)
APHIDIDE (GREEN-FLY) .
DIPTERA (TWO-WINGED FLIES)
PART I.—PSYLLIDE
" II,—CICADIDA
HINTS ON COLLECTING, PREPARATION, AND MOUNTING
INSECTICIDES AND GENERAL REMEDIES
BENEFICIAL INSECTS : .
LIST OF TREES WITH INJURIOUS INSECTS
INDEX
FIG,
Ic
2.
3.
4,
5.
6.
LIST OF ILLUSTRATIONS.
INTRODUCTION.
Eggs of Arctia menthastri .
Eggs of Bombyx neustria on
birch c
Typical forms of larv: Wee ¢
Typical pupal form of an
insect
Pupal case of Vanes Sa Ur tiew
First emergence of Tor-
toiseshell Butterfly from
pupal case
7. Emergence of Tortoiseshell
Butterfly more fully ad-
vanced .
8,9. Fully developed Tortoise-
10.
We
16.
17.
18.
ade
20.
shell Butterfly
Typical mouth parts of in-
sects
Compound eye of insect as
seen under the micro-
scope
. Typical forms of antenne .
. Typical form of leg . c
. Diagram of longitudinal
section of an insect
. Horizontal section through
the head of a worker bee
Diagram of the chief trunks
of the tracheal a of
an insect : c
Trachea of butterfly .
Food canal of cockroach
Diagrams of the heart of
an insect
Female genital organs of
the cockchafer
oe
FIG, PAGE
21. Male genital organs of the
cockchafer . : 17
ERIOPHYID (Gatt-Mirss).
| 22, Eriophyes rudis : 21
23. Abortive swollen buds on
hazel caused by 1 eae
avellanc F 24
24, Abortive swollen bade on
birch . 25
25, Abortive Soiled Buda on
English yew - 26
26. ‘‘Nail-galls” on leaf of
lime-tree 4 Pail
27. Galls on leaves of field
maple caused by Zyi-
ophyes macrochelus A As}
28, Galls on leaf of field maple
caused by Ur rae
macrorhynchus. 29
29. Galls on leaves of common
alder caused by pe
levis . 29
30. Galls on midrib of the leav es
of common alder caused
by Eriophyes axillaris . 29
31. Galls on leaf of Wayfaring-
tree caused by Hriophyes
tetanothrix . 30
32. Malformation of the flower
of ash caused by Lri-
ophyes fraxinti. 5 OI
| 33. Edges of hawthorn leaf
| rolled inwards by H7i-
ophyes goniothorax all
Xvl1
34.
36.
37.
39,
THe OO
Or Or Or Or nr or OL
a
=
ale
OMAD
Surface of leaflets of moun-
tain-ash injured by Lri-
ophyes aucuparie .
. Edges of leaves of black-
thorn rolied inwards by
species of Hriophyes
Dorsal surface and side view
of Phyllocoptes carpini .
Galls on leaf of sycamore
caused by ae
acericola
COLEOPTERA (BEETLES).
. Typical larvee of beetles
Head of Cicindela ee
fied) . ; :
. True wings of beetle
. Typical beetle (upper side)
. Typical beetle (under side)
. Stag - beetles,
male and
remale :
. Portion. of ash fies in-
jured by larvz of stag-
beetle
. Young beech seedling, the
roots of which have been
destroyed by larve of
May beetle .
common
or May beetle:
chrysalis, &c.
. Melolontha hippocastani
49. Injury caused to beech
saplings by Agrilusviridis
. Agrilus viridis . :
. Portion of dead hawthorn
stem burrowed by larvee
of Priobium castaneum .
. Markings of larvee of Hr-
nobius mollis on spruce
pole
. Clytus arietis (Wasp beetle)
. Rhagium inquisitor
thagium bifasciatum
Acanthocinus cedilis .
. Saperda carcharias
. Larva of Saperda carcharias
. Injury caused to stem of
aspen poplar by larvee of
Saperda populnea . :
Melasoma populi: beetle,
larva, and pupa
cockchafer
feelers,
43
45
61.
62.
63.
64,
die
78.
79.
80.
81.
83.
LIST OF ILLUSTRATIONS.
Injuries done by JJelasoma
populi ,
Phyllodecta vitelline “(Wil-
low beetle) .
Willow leaf injured by
larvee of Willow beetle
Leaf of balsam poplar in-
jured by larvee of Willow
beetle .
. Oak leaves rolled by Atte-
labus curculionides . A
Attelabus curculionides
. Birch leaves rolled by De-
poraiis betule
. Deporaiis betule :
. Otiorrhynchus picipes
. Otiorrhynchus sulcatus (Vine
weevil) . .
. Foliage of mountain - ash
eaten by Phyllobius
maculicornis . : 1
Young. spruce — plants
gnawed by Hylobius
abietis . 5 :
Hylobius abietis (Pine
weevil), beetle, one
and pupa
. Cocoons of Pissodes aa on
stem of Scots pine
. Pissodes pin
. Young pine -stem barked
to show pupal-beds of
Pissodes notatus
Beech leaves showing in-
juries done by larva and
holes eaten by Orchestes
Sage :
Larval burrows of CH ypt-
orrhynchus lapathi in
alder stems .
Cryptorrhynchus lopathé
Balaninus nucum
Portion of beech timber in-
jured by Rhopalomesites
Tardyt : ;
COLEOPTERA (ScoLyTip#).
2. Typical workings of “ bark-
beetles ”
‘Antenna of Hylesinus cren-
atus
il
72
82
83
83
84
88
90
87.
LIST OF ILLUSTRATIONS.
. Markings of Scolytus de-
structor in bark of ee
lish elm
. Showing exit-holes of same
. Scolytus destructor .
Markings of Scolytus pruni
in branch of apple
. Markings of Scolytus multi-
striatus in bark of elm.
Markings of Scolytus intri-
catus on oak pole
. Scolyius intricatus
. Markingsof Hylastes palli-
CLUS) ‘
92. Hylastes palliatus
93. Markings of Hylesinus
crenatus
94. Hylesinus crenatus .
95. Markings of Hylesinus
Sraxini
96. Hylesinus fraxini
97. Markings of Hylesinus
oleiperda
98. Hylesinus oleiperda. .
AD.
. Markings
. Markings
. Cryphalus abietis
. Showing ‘exit-holes”
. Markings
of Aylesinus
vittatus : :
. Hylesinus vittatus
. Shoot of Scots pine show-
ing the entrance-hole
and boring of a pine
beetle .
. Showing mother and lar val
galleries in process of
formation
. Portion of bark of Séots
pine, showing two
mother - galleries and
larval workings of pine
beetle .
. Hylurgus piniper da, :
. Markingsof Phlwophthorus
rhododactylus on gorse.
. Markings of Phlwophthorus
rhododactylus on broom
. Phleophthorus rhododac-
tylus : : ¢
of Cryphalus
abietis - :
of
Cryphalus tilie
of C7 yphalus
tilie on lime
Markingsof Cr -yphalus fagi
94
94
95
96
96
97
97
100
100
102
103
104
105
105
106
106
107
108
108
109
110
113
113
114
117
Walz
118
118
118
113.
114.
115.
116.
Ze
118.
His).
120,
121.
122.
Xylocleptes bispinus . :
Mother-gallery of Dryo-
cetes villosus : ‘
Dryocetes villosus
Dryocetes alni
Tomicus sexdentatus
Markings of T'omicus acu-
minatus i :
Markings of Pztyogenes
bidentatus (initial stage)
Fully developed markings
of Pityogenes bidentatus
Pityogenes bidentatus
Block of wood shown in
perspective to illustrate
the workings of the
genus T'rypodendron
. Workings of Trypodendron
lineatum
. Trypodendron lineatum
. Markings of 7rypodendron
domesticum .
. Xyleborus dispar (male) .
127.
128.
Xyleborus dispar (female)
Burrows of Xyleborus
dispar ‘ :
HYMENOPTERA (0axk-GALLS).
129.
130.
131.
132.
133.
134.
135.
136.
137.
138.
139.
140.
141.
142.
143.
Gall-fly of ‘‘oak-apple”
and structural details .
Galls of Neuroterus lenti-
cularis
Neuroterus einen is
Galls of Spathegaster bac-
carum on male flowers
of oak
Galls of Spathegaster bac-
carum on leaves of oak
Spathegaster baccarum
Galls of Neuroterus fumi-
pennis
Galls of Spathegaster fri:
color F
Galls of Newroterus Te
usculus
Galls of Spathegaster al-
bipes :
Galls of Neur bier Us NUMIS-
matis .
Gall of Aphilothriz padlicis
Galls of A philothriz corticis
Galls of A plulothrix globuli
Gall of Andricus inflator .
138
140
141
142
142
143
144
144
XVill
Jalls of Andricus cwrv-
ator
5. Injury done ‘to leading
shoot by gall of Andrz-
cus curvator
. Galls of Aphilothrix quad-
rilineata
. Galls of Aphilothri« albo-
punctata
. Gall of Andricus Fee iE
(cotton gall)
. Galls of Aphilothriz Fe.
undatrix
. Gall of Dryophanta ‘seutel-
laris
. Galls of Dr Mj trie lege
ventris
2. Galls of Dryophanta divisa
3. Galls of Biorhiza aptera .
4. Gall of Teras terminalis .
. Galls of Biorhiza renum .
. Galls of Cynips Kollari
(marble gall)
LIST OF
ILLUSTRATIONS.
169. Galls of Pontania salicis .
150 | 170. Galls of Pontania bella
171. Galls of Pontania galli-
COldaue.
150 | 172. Galls of Panne Agi
cerus . :
151 | 173. Leaf of goat willow eaten
by larve of Pontania
152 salicis.
174. Larve of Cresus genlen: ‘
153 trionalis on alder
175. Cresus septentrionalis: in-
153 sect and larvee
176. Foliage of larch injured
154 by larve of Nematus
Hrichsonwi . : A
154 | 177. Nematus Erichsoni .
155 | 178..Larve of Nematus Erich-
155 sonit
156 | 179. Pupal. cases of Nematus
157 Brichsonii
180. Plank of silver fir injured
158 by Strex gigas
HYMENOPTERA (Saw-F igs).
166.
167.
. Thorax of a saw- fly:
dorsal surface
. Lateral or side view of
fig, 157 :
: Typical upper wing of
saw-fly 6 .
). Trichiosoma HTS
. Cocoon of
Trichiosoma
after escape of fly
2. Larve of V'richiosoma on
hawthorn leaf
. Lophyrus pini (Pine saw-
fly), male
. Lophyrus pini (Pine saw-
fly), female .
: Foliage of Scots pine eaten
by “larvee of Pine saw-
fly. Injury done by
first brood of the season
Pupal case of Long
pint
Foliage of Scots pine ented
by ‘larve of Pine saw-
fly. Injury done by
second brood of the
season
. Galls of Buura pentandre: e
184
167 | 185
186
167
187
168 | 188
173
174 | 189
175
190
176
176 | 191
192
177 | 193
177
17774 1948
181]
. ** Moss
. Sirew gigas (female)
. Sirex gigas (male) .
. Spruce timber injured by
Sirex juvencus
. Sirex juvencus (female)
. Strex juvencus (male)
. Injury done to ash stem
by hornet
. Hornet (Vespa Grae 0)
. Galls on under side of leaf
of dog-rose caused by
Rhodites eglanterice
or pin - cushion
gall,” caused by Rhod-
ites Tose
. Seeds of Douglas fir in-
jured by Megastigmus
spermotrophus
. Megastigmus spermotrophus
(female)
. Megastigmus spermotr ophus
(male)
. Seeds of silver fir injured
by Megastigmus strobi-
lobius . : : :
COCCIDA® (ScaLe-INsEcts).
Cerataphis latanic (fringed
aphis) on palm. :
182
182
183
184
184
185
186
187
187
188
188
189
190
190
191
OM
191
192
193
193
193
195
196
197
199
LIST OF
. Seale - like secretion of
Aleurodes on leaf of
tomato .
. Female scale of A spidiotus
. Male scale of Aspidiotus .
. Female scale of Diaspis .
. Male scale of Diaspis
. Female scale of Chionaspis
and Mytilaspis
. Male scale of Chionaspis .
202. Pygidium, or
anal seg-
ment, of Mytilaspis pom-
orum, showing dorsal
and ventral parts, &e. .
. Male scales of Chionaspis
salicis
. Female pales of Clon:
aspis salicis
. Life-history of Chionaspis
salicis .
. Seales of Aspidiotus on
leaf of Lapageria
. Scale of Aspidiotus on leaf
of Stephanotis
. Seale of Aulacaspis rose
on dog-rose
. Female scales of eran
caprece, ** brown scale,”
on sycamore
. Adult female Jie
after treatment with
potash x 20.
. Typical antenne of female
Lecanium
2. Male and female scales BE
Pulvinaria .
3. Male of Pulvinaria, species
found on currant.
. Male of Lecanium, species
found on sycamore
. Scales of Physokermes
abietis
. Depressions on twigs of
oak caused by Astero-
lecanium variolosum
. Pseudococcus acerisonbark
of hornbeam
. Antenna of Ereecceans
aceris .
. Leg of Pseudococeus aceris
. Rostrum of Pseudococeus
aceris .
. Cryptococcus fag gion eran
222. Apterococcus fraxini
ILLUSTRATIONS.
. Winter Moth:
LEPIDOPTERA (Morus).
. Smerinthus populi .
. Smerinthus ocellatus
. Timber of goat willow in-
jured by larvee of T’ro-
chilium bembeciformis .
26. Pupal case of V’rochilium
bembeciformis
. Trochilium hembeciformia
. Oak plank
injured by
larvee of goat moth
. Cossus ligniperda
. Larva of Goat Moth
. Pupa of Goat Moth
2. Zeuzera wesculi
. Orgyia antiqua
. Pupa of Puss Moth on
twig of birch
. Dicranura vinula
3. Pygera bucephala
7. Larve of Buff-tip Moth
on twig of oak .
. Larva of Bordered W hite
Moth
. Pupa of Bordered White
Moth .
. Fidonia piniaria (male) .
. Fidonia piniaria (female)
2. Foliage of lime-tree eaten
by larve of Winter Moth
. Leaf of wych elm eaten by
larve of Winter Moth.
. Foliage of sycamore eaten
by larve of Winter Moth
male, fe-
male, and caterpillar
. Trachea piniperda .
. Cone of silver fir parti-
ally eaten by larve of
Dioryctria abietella
. Dioryctria abietella .
. Foliage of oak destroyed
by larve of the Green
Tortrix Moth
. Foliage of hazel injured
by larve of Tortrix
ribeana
. Leading shoot of poplar
injured by larva of
Hedya ocellana
. Shoots of English yew
injured by larve of
_ Batodes angustiorana .
264
bo
(or)
or
LIST OF ILLUSTRATIONS.
. Shoot of holly injured
by Padisca gaat:
cane
. “Leading” bud of Scots
pine injured by larva
of Retina turionana
. ‘Leading shoot” of young
Scots pine injured by
larva of Retinia buoli-
ana
. Retinia wor aan. male ne
female :
. Gall of resin on "Scots
pine caused by Retinia
resinella
258. Retinia resinella
. Hyponomeuta evonymellus
260. Web and empty pupal
cases of Hyponomeuta
evonymellus .
. Leading bud of ash- tree
injured by larva of
Prays curtisellus .
. Young ash-tree ‘‘ forked”
by larva of Prays curtis-
ellus
263. Prays curtisellus : its life-
history after Judeich
and Nitsche :
. Leaves of osier drawn
together by larva of
Depressaria contermin-
ella. :
. Shoots of broom drawn
together by larve of
Depressaria assimilella .
. Tops of young larch-trees
injured by larve of
Argyresthia levigatella
. Leaf of lilac injured by
the mining larve of
Gracillaria syringella
. Normal foliage of larch
. Foliage of larch injured
by larvee of Coleophora
laricella C
). Coleophora laricella: pupal
case and moth
. Coleophora sp. on birch
2. Typical blotch of Litho-
colletis on oak leaf
. Injuries to foliage of holm
oak by larvee of Litho-
colletis messaniella
274. Foliage of laburnum in- -
jured by larvee of Cemi-
- ostoma laburnella
APHIDIDA (GREEN-FLY).
. Wing of Aphis sambuci
. Wing of Schizoneura ulmi
. Wing. of ee pal.
- lichig
278. Wing of Chermes abietis :
. Terminal shoot of wild
cherry i injured by ie s
CErUSt .
. Mi sejnoamerontve sors
. Eggs of ee Bs: on
thorn .
. Aphis-cr ieee ‘
. Aphis padi on bird- -cherry
. Aphis-sambuci
. Chaitophorus aceris (special
peculiar form)
. Eggs of Lachnus long ngipes
on oak
c Phyllaphis fagi
. Foliage of copper beech
(under side) covered
with Phyllaphis fagi .
. Leaves of wych elm rolled
by Schizoneura ulmi
. Gall on leaf-stalk of poplar
caused by Pemphigus
bursarius
. “Stem mother” of Pem-
phigqus bursarius .
Larval stage of Pemphigus
bursarius
. Pupal stage of Pemphigus
bursarius
Winged form of Pemphigus
bursarius
. ‘Corkscrew ” gall on leat
stalk of poplar caused
by Pemphigus spirothece
. Gall of Pemphigus pallidus
on midrib of leaf
. Galls of Vetraneura ulmi.
. Gall of Chermes abietis
. Early. stage of. gall of
Chermes abietis
. Winged forms of Chermes
abietis on spruce leaves
. Chermes laricis on bark of
larch .
302,
303.
304.
305.
306.
307.
308.
309.
310.
311.
312.
LIST OF
Foliage of larch injured
by attack of Chermes.
Chermes laricis on foliage
of larch :
Chermes pint on stem sf
young Scots pine
Ghermes pint on terminal
shoot of Scots pine
Terminal shoot of Scots
pine killed by Chermes
pint
Cherimes cor eal: on ‘branch
of Weymouth pine
Chermes picew on bark of
silver fir
Hibernating winter "forms
of four species of
Chermes
Under side of oak leaf in-
fested with ashe
punctata
Apterous female, eggs,
and larva of Phylloxera
punctata 5
Winged form of Phyllow-
era punctata .
ILLUSTRATIONS.
DIPTERA (Two-winceD FLtss).
313.
. Cecidomyia
. Cecidomyia
Leaves of Salix viminalis
rolled by Cecidomyia
marginemtorquens
marginem-
torquens (male)
marginem-
torquens (female)
. Shoot of hawthorn in-
jured
crategt
by Cecidomyia
. Twig of yew injured by
Cecidomyia taxi .
. Shoots of Salix caprea in-
jured | by Cecidomyia
rosaria
. Cecidomyia rosaria (male)
. Section of willow stem
showing injuries caused
by Cecidomyia salici-
perda .
. Portion of bane anal aed
cut off to show the
injuries of Cecidomyia
saliciperda .
343
322.
340,
341.
342,
. Leaves
Leading shoots of a species
of willow injured by
Cecidomyia heterobia
. Twig of Salix caprea in-
jured
salicis .
by Ce es a
. Cecidomyia salicis (male) .
. Leaf of lime-tree injured
by Cecidomyia tiliam
volens .
. Shoots of lime-tree injured
by Cecidomyia tiliam
volens .
. Foliage of ash injured by
Diplosis botularice
. Edges of oak leaves folded
by Diplosis dryobia
. Galls on leaf-stalks of
aspen poplar caused by
Diplosis tremule .
. Galls on upper surface of
beech leaves caused by
Hormomyia piliger
of goat willow
galled by Hormomyia
caprece
. Galls on broom caused by
Asphondylia sarothamni
. Asphondylia sarothamni .
4. Pupa of Asphondylia saro-
thamni
. Gall on stem of ramble
caused by Lasioptera
rubi
. Galls on Sisiine of a ies
caused
schineri
by <Agromyza
. Leaf of snowberry enined
by Chromatomyia ob-
scurella
. Leaf of holly blotched by
Chromatomyia ilicis
. Bibio marci (males and
females)
PSYLLID 2,
Leaflets of ash injured by
Psyllopsis fraxini
Leaves of box injured ey
Psylla buxi . :
Young form of eee cra-
tegi :
_XX1
XXll LIST OF
343. Tip of hawthorn shoot in-
jured by Psylla crategi
Twig of alder injured by
Psylla alni . :
344,
CICADIDE.
345,
346,
347.
Typhlocyba ulmi
Typhlocyba ulmi
Young form of Typhocyta
ulmi :
ILLUSTRATIONS.
COLLECTING, PREPARATION,
AND MOUNTING.
348. Simple arrangement for
dissecting specimens
under a magnifying-
glass .
349, Brouose of honey-t bee
| 350. Tongue of house-fly
351. Life-history stages of
“« Swallow-tail” Butter-
fly
379
384
384
385
FOREST ENTOMOLOGY.
INTRODUCTION.
Ir may appear somewhat paradoxical to say that ‘‘ Forest Entomology”
differs from the ‘‘ Entomology of the Forest.” Under the latter head-
ing the major portion of the science of entomology may be included,
inasmuch as the student of general entomology, or the specialist of
any particular group, will often find the forest one of his happiest
hunting-grounds. This is due not only to the varieties of arboreal
food and the varied forest flora, but to the game-preserving laws or
customs continually furnishing carrion food, and demanding a varied
cover for game-birds and feathered songsters, which doubtless act as
sources of dissemination for many species of insects with comparatively
poor powers of locomotion. With regard to “ Forest Entomology,”
even in its widest sense we can only embrace directly all insects pre-
ferring an arboreal diet, and indirectly all other insects parasitic on
arboreal-feeding insects.
As the field of natural history becomes broader and_ broader,
natural science tends more and more towards specialisation; and
while it is essential that the young student should gain a compre-
hensive view of kindred subjects, the adult who aspires to pose as
a public instructor cannot make progress in any branch without
limited concentration. Perhaps this narrowing is more essential in
entomology than in many other branches of natural history.
The science of entomology may be studied from two different
aspects—viz., from that of the collector, and of the economic ento-
mologist or investigator.
The collector, who generally limits his work to one or two groups,
A
2 FOREST ENTOMOLOGY.
tries by observation and comparison to classify his captures according
to the difference in colour, size, and other variations. He also strives
to enrich the local fauna by fresh captures. On the other hand, the
economic entomologist seizes these data of the collector or systematic
biologist, goes a step farther, and considers insects in relation to
man, his person and property, either in so far as they affect his
industrial products, his cultivated plants, or the wild plants of nature.
From a husbandry point of view, the science of economic ento-
mology may be divided into three principal parts—viz., garden pests,
farm pests, and forest pests. The last is obviously the most difficult
to deal with.
Before any pest can be satisfactorily checked, it is indispensable to
study the life-history of the insect—viz., the egg, the larva, the pupa,
and the perfect insect,—and then to deal with that stage in which
the most practical results can be obtained.
Hitherto it has been customary to study only those insects which,
by their numerical strength, have been injurious in the forest, but
I venture to think it would be far more interesting and educational,
either as an economic or a biological subject, to study all insects
which prefer an arboreal diet. To carry this out, two methods of
arrangement suggest themselves —viz., a botanical and an ento-
mological. With regard to the former, it would be necessary to
classify the respective trees, and then arrange those insects which
feed on them. This method has been adopted by some American
writers. It has, however, this drawback, that while several insects
are fastidious as to their diet, others (except for the distinction
between hardwoods and conifers) are general feeders. Several
German writers follow an entomological method, and this course
appears to be far more educational to the student of forest
entomology.
As the forest is a field literally teeming with varieties of animal
life, it may just be as well in passing to remind the practical husband-
man and general naturalist that there are numerous creatures in the
forest, under rotten bark and so forth, which are not in scientific
language insects. Such creatures are snails, centipedes, spiders, and
worms of various genera.
Hence two questions arise—viz.: (1) What relative position do
insects occupy in the animal kingdom? and (2) What is an insect!
As regards the position of insects in the animal kingdom, natur-
INTRODUCTION. 3
alists differ slightly in their arrangement; but it may be said that
insects constitute a subdivision of the animal kingdom known as
Arthropoda, which are characterised by having jointed limbs, and,
as a rule, a distinctly divided body.
They rise in an ascending series in the following order—viz. :
ARTHROPODA (4 classes).
1. Crustacea . . Crabs, Lobsters, $c.
2. Aracunipa . . Mites, Scorpions, Spiders.
3. Myriapopa . . Centipedes and Millepedes.
4, Inseota . .. 2) Insects;
In answer to the question, What is an insect? the general definition,
with some common exceptions, is that an insect is a creature whose
body is divided into three parts, has two antenne, six legs, and, as
a rule, passes through four stages of metamorphosis.
Accepting this general definition, it may be said that the creatures
which, in point of anatomical structure and economic injuries, approach
nearest to insects, are mites and spiders; and as a rough-and-ready
classification, 1 may be said that a mite is a creature whose body
is of one piece, a spider two pieces, and an insect three.
The mites most injurious to vegetation are the Eriophyide
(Phytoptide), or four-footed mites. Spiders do not affect trees
directly, and therefore need not be considered. We find a certain
species of red-spider! injurious to the foliage of ivy and other plants,
sucking the juices from the leaves, and causing them to assume a sere
appearance,
The whole realm of Entomology is divided into seven general or
principal orders—viz., CoLnzoprrra (beetles); OrtTHopPTERA (earwigs,
crickets, grasshoppers, and locusts); Nruroprera (dragon-flies) ;
Hymenoptera (ants, bees, and saw-flies); Lepipoprera (butterflies
and moths); the Hemrprera, including the various species of bugs ;
and Diprera (two-winged flies).
The Hemiptera is subdivided into two principal divisions—viz.,
Hemiptera-Heteroptera, including the bugs; and Hemiptera-Homop-
tera, including Aphide or plant-lice, Cicadz, Psyllide, and Coccide
or scale-insects.
' The so-called ‘‘red-spider’’—-the dreaded enemy of the gardener—is only
a species of mite.
FOREST ENTOMOLOGY.
With the exception of Orthoptera and Neuroptera, all the other
orders are represented in forest entomology. Hence the necessity of
versatility in entomological knowledge will be apparent.
Insects are further arranged into Families, Sub-families or Tribes,
Genera, Species, and Varieties. There is, of
course, no sharp distinction between a species
Fig. 1.—Eggs of White Ermine
Moth (Arctia menthastri) on
grass. (Photo by A. Flatters,
Manchester.)
and a variety.
In order to understand our subject a little
more fully, let us, by way of introduction,
briefly consider the life-history and structure
of a typical insect.
It has just been remarked that, as a rule,
insects pass through four stages of metamor-
Fig. 2.— Eggs of
the Lackey Moth
(Bombyx neus-
tria) on birch
twig. Found in
Cheshire.
phosis—viz., egg, larva, pupa,
and perfect insect. When an
insect passes through all. these
stages, the metamorphosis is
said to be complete. When,
however, it does not,—as, for
instance, in the case of Aphide
or plant-lice, — the metamor-
phosis is said to be incomplete.
Let us follow a typical ex-
ample of a complete metamor-
phosis, commencing with the
egg stage.
The eggs of insects. are always
deposited in the immediate vicin-
ity of the food for the larve, as
in figs. 1 and 2. In cases of
many arboreal insects the eggs
are often very difficult to dis-
cover. Sometimes they are con-
eealed within the buds, in the midribs of’ leaves, the roots, bark,
or other convenient places, according to the food of the larve.
Insects adopt many devices to protect their eggs against weather and
natural enemies, such as covering them over by a gummy secretion,
the shedding of hairs, the formation of cocoons, and so forth. ‘The
egos of insects possess very strong powers of vitality, and frost gener-
INTRODUCTION. 5
ally has very little effect on them. They vary very much in size,
form, and markings. Some are smooth and spherical, others cor-
rugated, sculptured, elongated, and tailed.
The structure and development, as seen under the microscope, form
not only a very interesting study, but present many difficult biological
problems. Amongst the higher egg-producing animals no egg will
develop without male fertilisation, but amongst insects there are many
exceptions to this rule. In numerous cases eggs laid by virgin moths
have been known to develop. Amongst saw-flies, certain generations
of gall-wasps, plant-lice, and others, we have reproduction by virgin
females. This law is known as parthenogenesis, or virgin reproduc-
tion without the intervention of a male, and a few special peculiarities
will be considered under the respective families.
The morphological structure of the egg is somewhat complicated,
more especially when we remember the philosophical writings of
Weismann and others.
The term larva, caterpillar, maggot, or grub is generally applied to
insects as they hatch out from the egg, and at this stage they gener-
ally differ in form and structure from the perfect insect. On the
other hand, the term “nymph” is applied to the creature when it
TYPES of LARVAE TYPES of LARVAE TYPES of LARVAE
Meares
aha
raw oe OS GS Oe ee
A
nee meen Growiforn Suva ior
Fig. 3.—Typical forms of larve. (Flatters.)
bears a very strong resemblance to the perfect insect, as, for example,
in the case of mites and Hemipterous insects.
The larva of a moth, on hatching from the egg, is usually a seg-
mented body possessing six true legs. The caterpillar of a saw-fly has
six true legs, like the larva of a moth, but has also several additional
“‘prolegs,” and consequently is easily distinguished. The maggot of
a fly is footless, Fig. 3 represents typical larve.
6 FOREST ENTOMOLOGY,
In the case of the Aphidide or greenfly, scale-insects, and plant-bugs,
the young in the first stage, whether hatched from eggs or produced
alive by the parent insect, resemble the perfect insect very much more
than those of beetles, moths, and flies. But whatever shape and form
they may take, the young insect in the first stage is always scientific-
ally known as a larva. We have in forest insects all forms and
classes of larvee, and this variety is of great interest as a biological
question. For instance, we find, as arboreal-feeding insects, active
six-legged larve of a greenish colour, and harmonising with the foliage
or lichens on the bark ; while on the other hand we find the footless
whitish grub feeding within the wood. Thus we have two important
factors in the theory of evolution brought before us—viz., the absence
and apparent absence of legs through disuse, and the harmony of
colour to surroundings as a protection against natural enemies.
In the larval stage the insect feeds voraciously, and as a rule grows
very fast. The skin of the creature, however, does not grow beyond
certain limits, and when this stage is arrived at, the creature halts, as
it were, throws off its skin, assumes a fresh coat, often of a different
colour, and again commences feeding. ‘This
process is known as moulting, and occurs
several times during the larval stage until full
erowth is reached. The duration of larval
life in arboreal insects is very varied indeed.
In some cases the period occupies only a few
days, in others several years,
The pupa, or third stage of the life of an
insect, is a period of rest or quiescence, when
the insect takes no food. It is the period of
quiet transformation, when the ugly crawling
caterpillar is being transformed into the beauti-
ful moth, or the carrion maggot into the swift
airy fly. The pupal forms and habits of forest
insects are very varied. Thus in beetles all the
parts of the future insect are visible, saw-flies
Fig. 4.—Typical pupal form and moths form cocoons, and the two-winged
of an insect. (Flatters.)
flies form cases. Some descend into the ground
to pupate, while others form hard cases on the food-plant. Fig. 4 may
be considered, for general purposes, as a typical pupa.
The stages thus referred to—viz., egg, larva, and pupa—are the
INTRODUCTION.
7
periods of growth and development. As soon as bursting from the
pupal case takes place, the creature is then literally the perfect insect,
inasmuch as there is no further change or development. It is well to
bear this in mind, as it is a popular notion amongst
certain people not conversant with natural history
that small moths and flies are simply ‘‘ young ones.”
Such, however, is not the case, for while there is
often a difference in size amongst individuals, of
the same species, it should be remembered that
no growth takes place after full pupal emergence.
In demonstration of this, perhaps a typical case
may be taken—viz., that of the Small Tortoiseshell
Butterfly, Vanessa urtice. Fig. 5 represents the
pupal case. In fig. 6 we have a representation of
the first emergence from the pupal case ; in fig. 7,
Fig. 5.—Pupal case of
Small Tortoiseshell
Butterfly (Vanessa
urtic). (Flatters.)
which is later,
Fig. 6.—First emergence of Tortoiseshell Butter/'y from pwpal case.
(Flatters.)
the wings are slightly more expanded ; and in figs. 8 and 9 we see
a representation of the fully developed butterfly. The whole process
Fig. 7.—Emergence of Vortoiseshell Butterfly more fully advanced.
(Flatters.)
of development, which is chiefly a question of wing expansion, takes
at most only a few hours.
8 FOREST ENTOMOLOGY.
In many cases where we have incomplete metamorphosis, the insect
is injurious in all its respective stages, as, for instance, in Aphid
and Cicade. On the other hand, when the metamorphosis is com-
plete, we find the insect injurious in larval and perfect stages, or
Fig. 8.—Fully developed Tortoiseshell Butterfly. (Flatters.)
simply injurious in the larval stage alone. The perfect insect (or
“‘imago,” as it is termed in entomology) often takes no food what-
ever, except sipping water or juices, and the duration of life is often
so short as to have become proverbial.
As a branch of economic entomology, the student of forest insects
should strive to ascertain where and when egg-deposition takes place,
how long the insect remains in
. Zo the egg stage, how long before
the first moult and between the
other larval moults, when and
how long it remains in the pupal
stage, and the time and appear-
ance of the perfect insect —in
short, a full life-history.
With regard to the structure
Fig. 9.—Fully develoned J ortateeshel atieoTe of insects, it may be repeated,
and must always be borne in
mind, that an insect is a creature whose body is divided into
three parts—head, thorax, and abdomen. As a biological subject,
insect anatomy and physiology is a very broad and _ interesting
INTRODUCTION. 9
one, inasmuch as serial section-cutting and the highest powers of
the microscope must be employed. This, though highly inter-
esting in itself, is certainly not of vital importance to the young
student of forest entomology. It is, however, indispensable that the
salient features of head, thorax, and abdomen should in all cases be
well studied, and in some special instances be committed to memory.
It is upon these points that generic and specific characters depend.
The advanced student with a fair amount of leisure would do well to
study the internal anatomy of insects.
The head is theoretically composed of a number of pieces, but in
general appearance is made up of one piece. On the under side it
Rreabosers
House Fiu.
“Dealhs- head. Noth Beerle.
Fig. 10.—Typical mouth parts of insects. (Flatters.)
bears the mouth, which is adapted either for biting or sucking. The
mouth arrangement separates the whole of the class Insecta into two
principal divisions—viz., Mandibulata, or biting insects ; and Haustel-
data, or sucking insects. The biting mouth of the beetle and the
_trunk-like proboscis of the moth are cases in point. Fig. 10 repre-
sents typical mouth parts of insects.
The eyes in many cases form a prominent part of the head, and are
of two kinds—compound and simple. The latter are termed ocelli.
In some insects—as, for example, in the house-fly and hive-bee—the
compound eyes cover nearly the whole of the head. The orbit of the
eye is covered by a transparent skin termed the cornea. An examina-
tion under the microscope shows that the surface of the cornea is
10 FOREST ENTOMOLOGY.
made up of a large number of six-sided cells, each of which is termed
a corneal facet (fig. 11). The ocelli or simple eyes are placed between
the compound eyes, or just in the middle of the forehead.
The antenne, or horns, rise from the head. They are composed of
several joints, and form good points for the discrimination of species.
Any text-book of general entomology, or monograph of some particular
croup, will show that specific points very largely depend on the
antenne. This, for instance, is the case with the Aphidide or plant-
lice. The joints of the antenne have to be counted and compared.
By a joint is meant not so much the division line between the pieces
RE ies 3
i 4 fj
Pol 5 Pl Ki vate tes
7%. Gi
CSut"4 oy
Fig. 11.—Compound eye of insect as seen under the microscope. (Flatters.)
as the actual portions themselves if separated at these lines. In
counting joints we must begin from the head outwards, making sure
the horn is properly and clearly separated from the head. As a rule,
the antenna is stouter at the junction with the head, and gradually
tapers towards the other extremity: thus we say in a general way,
from base to apex. The antenne receive various designations, accord-
ing to the structure, as, for example, in fig. 12. The physiological
functions of the antenne are not fully understood, but they are sup-
posed to be, to some extent, sense-organs.
The thorax or middle segment is theoretically composed of several
INTRODUCTION. al
pieces, and from this portion the wings and legs arise.
It is further
considered as being divided into three distinct portions—viz., prothorax,
mesothorax, and metathorax.
These segments vary in pro-
portion in different insects,
and they also vary in the re-
spective stages of the life of
an individual insect. The
thorax and its component
are. of
importance in the discrimin-
parts considerable
ation of species, as, for in-
stance, in the Hymenoptera.
The third segment is known
as the abdomen, and is very
variable in form, according
to order and genus. It is
generally composed of nine
segments, and bears the
organs of reproduction.
The wings, as appendages,
LAMELLATE.
PERFOUATE
ows
PECTWATE.
« FSSSATE CLUB SERRATE
Fig. 12.—Typical forms of antenne. (Flatters.)
are very important points in the discrimination of genera and species.
In fact, some writers use the wings
as a basis of classification. So far
as forest entomology is concerned,
it is highly essential to make a
detailed study of the structure of
the wings of saw-flies, gall-flies,
Aphidide, and Diptera.
The structure of the leg is also
of importance in the classification of
species. If we separate a leg from
the body of the insect and examine
it, from the connection with the
body to the tip, we shall find it is
composed of several parts. The
leg is attached to the body by a
----Coxa.,
B “--“Trochanfer.
Ss SSS ah
} -—Tibta.
Fig. 13.—Typical form of leg. (Flatters.)
joint called the cova ; next to this is a very small portion known as
the trochanter, which serves as a sort of joint or hinge connecting the
1, FOREST ENTOMOLOGY.
femur ; then we have a long joint called the ¢ibia ; and finally, the
joint called the tarsus, which is known as the foot, Fig. 13 is a
representation of the different parts of the leg.
The foregoing characters represent the more important points as
regards external structure, but it is somewhat more difficult to deal
with internal structure and function. To deal with too many details
would simply embarrass the ordinary student, and at the same time
the subject cannot possibly be intelligible to the student if too few
points are presented.
The accompanying diagram (fig. 14), representing a longitudinal
GENT ELSE: " j —
tS
a
By Be
Fig. 14.—Diagram of longitudinal section of an insect, showing principal anatomical points of an
insect. (From ‘Text-Book of Zoology,’ by Dr J. E. V. Boas.)
1-3, first and third pairs of legs cut away; a, anus; c¢, cerebral ganglion; ch, mesenteron;
e, proctodeum ; g, genital aperture; h, heart; k, crop; m, mouth; n, ventral ganglion;
sp, salivary glaud; w, malpighian tubule; @, ovary.
section of an insect, shows the relative position of the more important
anatomical points from a side view.
~The nervous system of an insect resembles that of most other
animals, inasmuch as the terminal seat of the nerve-centres is the
brain, whence proceed other nerve-centres and nerves all over the
body. The nerves receive impres-
sions from the outside world, which
react on the organism, and thus stim-
ulate or restrain muscular action.
Fig. 15 shows a photograph of a
horizontal section through the head
of a honey-bee.
Fig. 15.—Horizontal section through the head uate 6
of a worker bee, showing eyes and brain. The various convolutions of the
(Section and photo by A. Platters. brain should be noted; and as the
development of these convolutions is indicative of intelligence, it is
no wonder that the bee, in this respect, is considered as approaching
nearer to man than any other animal.
The respiratory organs of an insect are composed of a system of
~ ae
minamer ee). = 7
INTRODUCTION. ia
tubes, which are well represented in fig. 16. These tubes, or trachee,
ramify throughout the whole of the body; and the air passes into
them by means of special open-
ings known as spiracles, which
are situated alongside the body
of the creature. These spiracles
are somewhat complicated open-
ings, Inasmuch as they open to
receive air, shut to maintain a
supply, and again open for ex-
pulsion. The act of breathing,
therefore, is somewhat after the
nature of a bellows, inasmuch as
air is received at a special open-
ing and driven throughout the
tubes. In addition to the func-
tion of breathing, it is obvious
that the inflating of the tubes
is associated with the machinery
of flight. Fig. 17 is a photo-
graphic representation of a
trachea from a butterfly.
The organs concerned with
feeding and digestion occupy a
considerable space in the body-
cavity of many insects. From
actual specimens this can only
be understood by careful dis-
section and microscopical man-
ipulation. The accompanying
figure, however (fig. 18), taken
from Miall and Denny, will con-
vey a very good idea of these
internal organs.
In the centre of the figure
the food-canal is represented.
Fig. 16.—Diagram of the chief trunks of the tracheal
system of an insect ; the central nervous system is
also shown.
a, antenne ; 0, eye; st’, anterior stigma; /, longi-
tudinal trunk. — After Kolbe. (From ‘Text-
Book of Zoology,’ by Dr J. E. V. Boas.)
At s we have the salivary glands and reservoir which contain the
saliva, which is not only beneficial in digesting the food within
the canal, but in some sucking insects is mixed with the crude
14 FOREST ENTOMOLOGY.
sap of the plant before the juice is taken up by the proboscis.
At ¢ we have the long crop, and below this we have the gizzard,
which organism in some species is a favourite object for the micro-
scope. Then we have a stellate arrangement of the cecal tubes or
blind tubes; and proceeding from this there is the stomach, which
is simply a tube. At & we have the kidney tubes,.and then the
small and large intestine, ending in the rectum and anus. In fig. 19
Fig 17.—Trachea of butterfly. (Flatters.)
we have a representation of the heart, which is a long muscular tube.
separated by valves.
Having now considered the various structural details of an insect,
it may be well to turn briefly to the reproductive organs, the func-
tions of which serve to perpetuate the race. Insect reproduction
may be either sexual or asexual. In the former, the union of two
dissimilar cells is required—viz., a small_active (male) sperm cell
(spermatozoon) with a large (passive) female cell (ovum) for the
production of new individuals. In the latter class, female cells or
INTRODUCTION. 1
nr
eggs give rise to new individuals without the intervention of male
(parthenogenesis).
The reproductive organs of insects may, according to instructions
given in certain works on microscopy, be carefully dissected from the
abdomen, but the accom-
panying figures, together with
the explanation, convey a
very good idea of the repro-
ductive organs of insects.
The accompanying figures
and explanation have been
selected because they are not
only large insects, but arboreal
in their habits. It may also
be noted that, as regards
insects, the hive bee has been
carefully worked out in this
respect, so that reference to
any of the more important
works on the bee would be
found very helpful.
Genital organs. — “ The
female, as in other Arthro-
poda, possesses a pair of
ovaries. Each consists of a
varying number of tubules
(ovarioles), which usually ex-
tend like fingers from the
anterior end of the oviduct.
Each ovariole is surrounded
by a thin membrane, and is
immature anteriorly, consist-
ing of small homogeneous
cells ; farther back there are
larger cells, young ova, lying
Fig. 18.—Food canal of cockroach.
s, salivary glands and reservoir ; ¢c, crop (the gizzard
below it); cw, cecal. tubes (below them the
stomach); k, kidney tubes; i, intestine; 7, rec-
tum. Twicenatural size. (From ‘The Cockroach,’
by Miall and Denny.)
in the middle of the tube, and surrounded by smaller cells, which
provide them with nutriment, and also secrete the shell (chorion)
for the fully developed egg.
The mature ova occupy the posterior
ends of the ovarioles, and pass thence into the oviduct. When an
16 FOREST ENTOMOLOGY.
egg passes into the latter, the corresponding portion of the ovarian
tubule shrinks, and thus the egg next in front is brought nearer to
the duct. The two oviducts unite to form an unpaired portion, the
vagina, which opens ventral to the
anus, either freely on the surface
or into a cloaca, an invagination
occurring at the hinder end of
the body. There is usually an
evagination of the vagina which
serves as a receptaculum seminis,
and one or a pair of accessory
glands, which secrete either a
sticky fluid to attach the ova to
foreign bodies, or the mucus sur-
rounding them (eg., in insects
which lay their eggs in water). Sometimes there is also an’ evag-
ination of the vagina to form the bursa copulatrix, into which the
Fig. 19.—Diagrams of the heart of an insect.
Fig. 20.—Female genital organs of the cockchafer.
On the right, the ovarioles are lying together in the natural position; on the left they are
separated, and two are cut away. g, vagina; k, glands which open into the receptacula ;
1, oviduct; 0, segments of the ovarioles, containing almost ripe ova; o’, regions of the
same, containing immature ova; p, bursa copulatrix, ; 7, anterior; 7’, 7”, posterior buds
of the ovarian tubules; s, glands; sg, receptacula ovoruin. (After Boas.)
penis of the male is inserted in copulation. Not infrequently
there is at the female aperture an ovipositor (Locusts), consisting
of complicated knife-like or dagger-shaped lamine, or a sting
-——
es
INTRODUCTION. Lz
(Hymenoptera) ; or the last abdominal segments, which then are thin
and elongate, and may be telescoped, serve in this capacity (Diptera
and others). The chorion is often very hard, frequently covered with
a delicate and regular sculpturing, and always provided with one or
more openings, the micropyles, through which the spermatozoa may
enter. The outer form of the eggs varies: it may be spherical, oval,
discoid, rough, stalked, &e.
“The male genitalia are for the most part a repetition of those of
the female. There is a pair of testes, each consisting of several long
seminal tubes or shorter seminal pouches, situated at the end of the
Fig. 21.—Male genital organs of the cockchafer (penis not drawn).
b, vesicula seminalis; g, vas deferens; k, glandular appendages; r, widened region of the
duct of the same ; ¢, testis, consisting of six seminal pouches. (After Boas.)
vas deferens. The two vasa deferentia unite to form a single duct,
which opens in a similar position to the vagina of the female. Each
of the vasa deferentia widens posteriorly to form a vesicula seminalis.
Special glandular appendages frequently open into these ducts, or into
their common portion. There is a more or less complicated copu-
latory organ, an evagination of the body wall, through which the
terminal portion of the seminal duct is continued, and capable of
partial or complete retraction when not in use. In many it may
possess hard chitinous portions, and lies hidden within the cloaca,
from which it may be protruded during copulation.” ?
1 Text-book of Zoology by Dr J. E. V. Boas, pp. 242, 243.
B
18 FOREST ENTOMOLOGY.
References to Literature consulted.
Boas, Dr J. E. V. Text-book of Zoology. English transl. 1896.
Cambridge Natural History, The. 1899.
Carpenter, Geo. H. Insects, their Structure and Life. 1899.
Fisher, W. R. Forest Protection: Schlich’s Manual of Forestry. 1907.
Kaltenbach, J. H. Die Pflanzenfeinde aus der Klasse der Insekten. 1874.
Kéllar, V. A. Treatise on Insects Injurious to Gardeners, Foresters, and
Farmers. 1840.
Nisbet, John. The Forester. 1905.
Packard, A. 8. Insects Injurious to Forest Trees.- U.S.A., 1890.
Taschenberg, Dr E. L. Einfiihrung in die Insektenkunde. 1899.
Theobald, Fred. V. Insect Life. 1896.
ik)
CHAPTER I.
ERIOPHYIDZ (PuHytToPrip®) oR GALL-MITES.
Tue Eriophyide, or gall-mites, are so small in size (being only visible
when viewed under a very strong pocket lens or microscope) that we
can only recognise them in the forest through the medium of their
injuries. In other words, being practically invisible, the young student
in forest entomology cannot associate the creature with its injuries, as
in the case of most insects; and further, as the injuries caused by
those creatures are in appearance so closely allied to the damage done
by many species of parasitic fungi, the beginner may either overlook
or misunderstand them. Perhaps, therefore, the best method of
commencing the study of this group of arboreal mites is through
the medium of a common horticultural species—viz., the currant-bud
mite. In fact, it may be truly said that the study of gall-mites
in this country has received special attention on account of the
species on black currant having become a common garden pest in
many parts of the country. The general appearance of this pest is
only too easily recognised by the swollen buds, known in some
localities by the graphic term “blind bud.” The creature causing
this widespread trouble has long betn known by the name of
Phytoptus ribis (Westw.)
The common garden pest referred to has its equivalent in the
forest, producing “blind buds” and other abnormal growths on
several kinds of trees. The latter may be various forms of galls on
the leaves, rollings of leaves, or deformation of flower and fruit, &c.
The abnormal growths arising from the action of gall-mites were at
one time considered by botanists as a species of micro-fungi, and
termed “ Erineum.” Frank gives a very interesting account of those
abnormal hairs on the leaves,! which are either caused by the gall-
1 Die Krankheiten der Pflanzen, Pd. iii, 1896.
20 FOREST ENTOMOLOGY.
mites or otherwise associated with them. He says they were divided
(where considered as micro-fungi) into three orders—viz., Taphrina,
Fr., Erineum, Pers., and Phyllereum, Fr. The illustrations as given
by Frank are suggestive of this being rather an interesting microscop-
ical study, inasmuch as we see the contrast of normal with abnormal
hairs through the action of mite agency. In some cases the apparent
cluster of hairs may, on examination, prove a genuine micro-fungus,
so that, by careful microscopical observation, the student can be
acquiring knowledge in a kindred subject.
With regard to the ‘blind bud” on black currant, it may be noted,
as showing the history of the study, that the first authentic public
announcement of the existence of the disease was made at a meeting
of the scientific committee of the Royal Horticultural Society held on
March 2, 1869 :—
‘Specimens of a disease in shoots of black currant from the Rev.
A. Fitch were then produced, Mr Berkeley remarking that the outer
bracts were hypertrophied, and in consequence the delicate divisions
of the inner part of the bud were badly nourished, and death ulti-
mately ensued. The chairman pointed out its probable analogy with
the galls in hazel produced by a Cecidomyia, which was confirmed by
Prof. Westwood, who stated that the disease in black-currant shoots
was produced by an extremely minute four-legged Acarus.”—‘ R. H.S.
Journal,’ New Series, vol. ii., pt. 3, 1870.1
With regard to the Hriophyide generally, it may be stated that Mr
Andrew Murray was the first to collate the information concerning
these mites in a general way, and he gives a very interesting account
of them in his ‘Economic Entomology.’ ?
Within the last few years elaborate researches have been made by
Dr Alfred Nalepa of Vienna, and to his writings all interested in the
subject must refer. About forty-five species, arboreal and others, have
been found in Britain. He has established various genera, families,
and sub- families; but unfortunately he has seen fit to change the
generic name Phytoptus to Eriophyes, and this term has been adopted
by all writers on economic entomology.
The difference between a healthy and a diseased bud is very
‘<The Currant-bud Mite or Currant Gall- Mite,” by R. Newstead, in
Journal of Royal Horticultural Society, vol. xxv., pt. 3. 1901.
* Economic Entomology—Aptera: South Kensington Museum Science Hand-
books.
7 ee ee
—— oe
ERIOPHYID.© OR GALL-MITES. om
easily recognised. In the former the buds are comparatively
small and pointed, whereas the latter are swollen and rounded.
A longitudinal section made in winter or spring through the centre
of both classes of buds will show a difference of structure. In the
ease of the healthy buds—as, for ex-
ample, in the currant-bud mite—the
embryo leaves can be seen, and they
are always close at the apex, while in
the diseased buds the structural fold-
ings of the leaf are broken up, and
the apex always open. The same de-
scription holds good in forest trees in-
fested by Eriophyide.
The life-history and microscopical
characteristics of the genus Hriophyes
form a most interesting study. It
belongs to the sub-family Eriophyide
(Phytoptide),—gall-mites of the order
Acarina.
The mite is of a light yellowish
colour, and varies very much in size
according to species. Perhaps the size
of the creature may be approximately
put down as the 53, to z,45 of an
inch in length, and it is obviously
indistinguishable by the naked eye.
Fig. 22 may be regarded as a typical
mite.
The body is of a vermiform shape,
and, like mites in general, is of one Fig. 22.—Phytoptus calycophthirus,
: : Nal. (Eriophyes rudis, Canest.)
piece, and with few appendages. Hence — (Photographed from Nalepa’s ‘Gen-
a creature of such simple structure (aa! Wee ey Peeee:
alfords but few points for specific differ-
ences ; nevertheless, Nalepa gives a full description of a typical
mite, together with a detailed description of the respective
species.}
The form of the body is an elongated ellipse, narrowing towards the
posterior end ; and the cephalo-thorax is about the same breadth as
1 Das Tierreich, 4 Lieferung (Eriophyide). 1898.
FOREST ENTOMOLOGY.
bo
bo
the abdomen. ‘The head terminates in a snout-like projection, and
the maxillary palpi are used as antennae.
The group is known as the “ four-footed ” mites, and when viewed
from the under side the four legs can be seen distinctly. The articula-
tions of the legs, although well marked, are rather difficult to deter-
mine. The tarsus, or foot, is provided with a double claw: one half
is terminated by a few fine bristles, called by the Germans “ Fieder-
borste,” or feather bristles, and the other half is a simple claw.
The abdomen is divided into a series of from 60 to 90 ring-like
segments, according to species, and there are several hairs on the
abdomen. These are variable in size, but should, as far as
practicable, be noticed under the microscope, whether the dorsal,
ventral, or side aspect of the creature is being presented for examina-
tion. The rings, hairs, and the regular or irregular markings afford
good points for classification. At the extremity of the body are
two very long hairs, and rather important claspers, which the creature
uses as a means of anchorage. Doubtless, also, the hairs assist the
mite in the act of locomotion.
The eggs are round or elliptical. There are two rather indistinct
stages, larva and nymph. The species in the buds of black currant
and hazel lend themselves for periodical examination, and the mites
can be seen in their various metamorphic stages.
As regards the physiological functions of the mites, the following
notes from Mr Connold! may be quoted—viz. :
“The mites have no special respiratory or circulatory organs. The
exchange of gases takes place through the body; nor is there any
organ like a heart. The fluid, therefore, which is analogous to
blood, moves freely and irregularly throughout the body. The
nerves are in four pairs. The cesophagus passes through the brain
ganglia.
“They are devoid of stomach, digestion taking place in the larger
intestine. Salivary glands are wanting, and also Malphigian tubules.
“The skin is an exceedingly thin, colourless layer of chitin.
Beneath it lies a network of branched cells, which contain slight
colouring pigments.”
From a botanical point of view, or as regards the injuries done to
the host-plant, the mites may be divided into three great classes—
viz., those feeding within the buds, and consequently causing “blind
' British Vegetable Galls, by Edward T. Connold, 1901, pp. 82, 33.
ERIOPHYIDZ OR GALL-MITES. Ap
”; those living in various forms of galls; and those causing
buds
malformations of flowers, fruit, or leaves. The last division presents
a very considerable variety, inasmuch as the leaves may be folded or
puckered, and the leaf-veins enlarged in various ways.
As regards classification, Nalepa divides the family into two sub-
families—viz., Eriophyine and Phyllocoptine.
I. Number of the back and belly half-rings almost equal ; abdomen
therefore similarly ringed ; ventral side always, dorsal side
asarule punctured. 2 ; : Eriophyine.
II. Abdomen not similarly ringed; dorsal half-rings distinctly
broader than the belly half-rings . . Phyllocoptine.
Sus-Famity ERIOPHYINA.
SYNOPSIS OF THE GENERA.
Abdomen without dorsal median furrow. 1, Genus ERIoPHYEs.
Abdomen with dorsal median furrow . 2, Genus Monocnetvs.
Species living in Buds.
These may very easily be seen under the microscope, eating the
vital parts of the bud. The infested bud, therefore, is transformed
into an abnormally large swollen “blind-bud,” which, instead of
bursting into flower or leaf, becomes the dwelling-place and feeding-
ground of many mites. Here we may again quote from the literature
on the “ Currant-bud Mite.”
With regard to the actual number of mites tenanting a single bud,
Newstead says of Phytoptus (Eriophyes) ribis :—
“The number of mites tenanting a single bud would vary according
to the time of year. By desire of Mr Spencer-Pickering I last year
(January 9, 1900) selected a medium-sized bud-gall, and in it counted
2748 individuals ; allowing for many individuals destroyed in dissect-
ing the bud, I should put the number in round figures at 3000.
Larger buds would contain considerably more, and in March it would
be safe to add half as many more.” !
1 «<The Currant-bud Mite or Currant Gall-Mite,” in Journal of Royal Horti-
cultural Society. 1901.
24 FOREST ENTOMOLOGY.
ERIOPHYES AVELLANE (N al.)
The nut-tree mite is found in filbert and cob-nut plantations. The
swollen and deformed buds can easily be recognised before the devel-
opment of the leaves; and they are also afterwards conspicuous, as
shown in the accompanying illustration (fig. 23).
The species living in buds of hazel lend themselves more or less to
periodical examination throughout the whole of the year. Having
examined them in February from young hazel plants, I found the
enlarged buds, more especially the infested
terminal bud, conspicuous as globular balls
about } inch in diameter. Numerous mites
were found in all portions of the bud,
from the outer scales to the centre. They
were discovered in all stages—viz., eggs,
larve, nymphs, and perfect mites. This
species of mite is larger than the species
found on the black currant. The eggs are
whitish, smooth, and oval. The nymph is
approximately about one-half or one-third
the size of the perfect mite, and the four
legs are stretched out in the direction of
the mouth.
An examination of the swollen buds
during May, when the leaves were half
Tig 8 aber eeuollen dens developed, showed the infested buds
ee Enophyes avellane ftq- be tenanted am all” parts; and sa
few mites crawling along the leaf-stalks.
They were in all stages —viz., full-grown mites, nymphs, and
egos,
In July another examination was made, and it was found that the
mites were chiefly in the interior portion of the swollen buds. There
were a few on the leaf-stalk and on the portion of the stem adjacent
to the infested buds. At this time the swollen buds were quite half
an inch in diameter, and the young buds for the forthcoming season
were just formed.
bo
Or
ERIOPHYIDA OR GALL-MITES.
ERIOPHYES RUDIS, Canest., on the leaf-buds of Betula alba.
Synonymy of mite (Connold) :—
Phytoptus rudis, Canestrini.
Phytoptus calycophthirus, Nalepa.
In fig. 24 two swollen buds on birch are represented. They were
found in High Legh, Cheshire, and cut from the same branch, and
in close proximity to a “ witches’-broom ”—that peculiar bird-nest-like
appearance seen on birch and horn-
beam, of the growth and development
of which Miss Ormerod gives a very
interesting account, from personal ob-
servations made during 1876 and 1877,
while resident in the neighbourhood of
Isleworth.! There is no doubt, from
the description and illustration given
by her, and more especially from the
appearance of the actual branch itself,
seen in the South Kensington Museum,
that the abnormal branch growths were
heavily covered with swollen buds in-
fested by Eriophyine.
I had, in consequence of Miss
Ormerod’s description, for a long time
examined many “ witches’ - brooms,”
without finding a single “blind bud.” — Fi: f amooness soe ues an
The accompanying figure shows the
first infested buds I discovered in any way closely associated with
a ‘“bird’s nest.” The orthodox opinion as to the cause of ‘ witches’-
broom” or “bird’s nest” is that it results from a fungus inhabiting
the tissues, known as Hxoascus.
With reference to ‘“witches’-broom” being the result of fungal
growth, Tubeuf, speaking of experimental infection, says :—
“‘In the case of the Exoascex, two points were cleared by the aid
of artificial infection,—the penetration of spores into leaves of host-
plants, and the production of witches’-brooms. Sadebeck, by means
of infectious Exoascus epiphyllus on Alnus incana, has produced
1 Manual of Injurious Insects. Second edition.
26 FOREST ENTOMOLOGY.
witches’-brooms artificially, thus proving that these malformations
really originated from the mycelium of Hxoascus.” 1
As the cause of the “ witches’-broom” is ascribed both to mites and
fungi, it is suggestive of the advantages and pleasures of original
microscopical investigation. Still, these abnormal growths might
have accrued from excessive development of adventitious buds, caused
by the constant irritation of the Eriophyine without the presence of
Hxoascus.
I have found this species in several parts of Northumberland.
ERIOPHYES PSILASPIS (Nal.)
Phytoptus taxi (Murray).
This species (fig. 25) was first discovered by Professor Sir Thiselton
Pp g
Dyer in the spring of 1875 doing immense damage to young hedges,
Wig. 25.—A bortive swollen buds caused by Eriophyes
psilaspis on English yew.
which damage had hither-
to been ascribed to frost.
I found it plentiful on
the under side of the
lower branches of a
yew-tree at High Legh,
Cheshire, from which the
photographic illustration
was taken. I have often
found it very injurious to
young yew-trees in the
nursery - lines, and also
occasionally on yew
hedges.
As this species is cer-
tainly injurious, it is
well to have recourse to
some remedial measures.
In the case of hedges,
where regular trimming
is resorted to, it would be well to burn all prunings; and as regards
the young yew-trees in nursery-lines, it would be best to hand-pick the
infested buds, say about the latter end of May, and burn them.
‘ Tubeuf, Diseases of Plants induced by Cryptogamic Parasites. English
edition, by W. G. Smith. 1897,
=
ERIOPHYIDZ OR GALL-MITES. ad |
Species living in Galls.
There are numerous species living in galls on the leaves of various
trees, but the following are a few typical examples. They are not
true galls, however, but simply pseudo-galls; and it is important to
compare the structure of the pseudo-galls of Eriophyine with the true
galls of gall-forming insects. The former is simply an abnormal thick-
ening of the leaf, with an opening or passage leading into the pseudo-
gall. The opening is surrounded by hairs, which doubtless act as a
protection against the inroads of parasitic acari and other natural
enemies. The true gall, on the other hand, is always closed, and the
form variable and immaterial. Some species of leat-miners (Lepidop-
tera) form conical galls or cases on the upper side of the leaf, but the
passage communicates between the epidermal skins, and has no open-
ing through the under side of the leaf, as in the gall of Eriophyine.
ERIOPHYES TILLE (typicus) (Nal.)
In fig. 26 we have represented what are popularly known as “nail-
galls” on the leaves of the lime-tree—Tilia europea. This is a very
interesting species, inasmuch as _nail-galls
were first considered by Réaumur, the
celebrated French entomologist, to be a
special vegetable formation accruing from
the action of animal life: but in the
absence of any description it is doubtful
whether he saw the real tenant, or simply
a parasitic lodger.
Mr Andrew Murray remarks: ‘‘ Whether
Réaumur saw them or not, at least no one
else did for about 100 years after. About 4, Dp kecusitgalletnon Lay bf
1832 and 1834, however, the publication ey ne EE
of M. Duges’ valuable papers on the
classification of the Acaridx, to which we have already had so often
to refer, gave an impulse to their study, which led to fresh dis-
coveries ; and M. Turpin observed in the nail-galls of the lime leaf a
quantity of very minute, semi-transparent, fleshy mites, of a new and
hitherto unknown form,—a narrow creature with two pairs of small
legs at its head, and some kind of sucker apparatus at its tail, on
28 FOREST ENTOMOLOGY.
which it rests and raises itself, swaying about its body. He regarded
it as a species of Sarcoptes.” }
Here is an account of the first true conception of the family Eri-
ophyide, and the species under consideration is in consequence a most
important one.
ERIOPHYES MACROCHELUS (Nal.)
To all lovers of natural history, no walk is more charming than a
South Country lane, with its tall rough hedges and rich flora. The
hedges are generally well stocked with the field maple (Acer cam-
pestre). The upper surface of the
leaves of the field maple are often
covered with small galls, and a
careful examination will show that
there are two sorts,—a larger and
a smaller variety. The larger —
which are, as a ‘rule, rather
sparsely distributed on the leaves,
and generally on the midrib and
veins—are the galls of H#. macro-
chelus. These galls are very vari-
able in many ways, both as regards
Bigs Oe Gate on Wenonah ea ole colour and structure. They may
(Acer, campestre) caused “dy: Eviophyes'* pe solitary . or “etegarious,, single or
coalesced, glabrous or pubescent,
and either on the veins or spread over the leaf. They appear
quite early in summer, but may be considered fully developed in
August. Fig. 27.
ERIOPHYES MACRORHYNCHUS (Nal.)
Phytoptus myriadeum (Murray).
This is the other species of gall on the field maple, and may easily
be recognised from the former species by being smaller in size, and
much more crowded on the leaves. It is very abundant in southern
England, but not at all common in the north or in Scotland. Fig. 28.
' Economie Entomology—Aptera: South Kensington Museum Science Hand-
books.
ERIOPHYIDAZ OR GALL-MITES. 29
ERIOPHYES L&VIS (Nal.)
This species is found on the leaves of the common alder (Alnus
glutinosa). The galls are found on the upper surface of the leaves, and
are gregarious, often so abundant as to
cover almost the entire surface of the
leaf, generally glabrous, and very variable
in colour. Fig. 29.
ERIOPHYES AXILLARIS (Con.)
This species is also found on the leaves
of the common alder, but they differ from
2 5 : Fig. 28.—Galls on leaf of field
the previous species, inasmuch as they maple (Acer campestre) caused by
5 <}0 : Eriophyes macrorhynchus.
are always found on the midrib, or in
the axils of the primary veins from the midrib. The galls are
larger than the previous species, smooth, and varying in colour from
Fig. 29.—Galls on leaves of common Fig. 30.—Galls on midrib of the leaves of common
alder (Alnus glutinosa) caused alder (Alnus glutinosa) caused by Eriophyes
by Eriophyes levis. axillaris.
light-green to dark-brown, and always found in pairs. In section
they are hollow, and lined with hairs. Fig. 30.
ERIOPHYES TETANOTHRIX (/@vis) (Nal.)
This gall is found on the leaves of Salix caprea. This species of
willow is very common, and, as every botanist knows, very variable
as regards the size and shape of the leaf. The galls of this species
are generally found on the small-leaved variety, and on the upper
30 FOREST ENTOMOLOGY.
surface of the leaf. A section of the gall, which is comparatively
easily made, shows that the walls are very thick.
There are many other species forming galls on leaves of our forest
trees and shrubs in many parts of the coun-
try, as, for example, on the leaves of the
“Wayfaring tree” (Viburnum lantana), fig.
31, which was photographed from a leaf
taken in a Surrey lane.
Species causing Malformation of Flowers,
Fruit, or Leaves.!
ERIOPHYES FRAXINI (Karp).
This species attacks the flowers of the
common ash (Fraxinus excelsior), and gives
rise to what may popularly be called de-
formed fruit, as the injuries are most com-
monly observed when the fruit is ripe. It
aie nd tae Wibeten iat. is, however, more correctly a malformation
g tree (Viburnum lan
tana) cused by Erlophyes of the flower, as the mites attack the flower,
and by means of a symbiotic action give
rise to the forms as seen in fig. 32. It is very local in some
parts of the country, and sometimes peculiarly so to one tree in a
whole district. It is very common in some parts of Northumberland
and Berwickshire.
ERIOPHYES TILIARIUS (Con.)
This species attacks the flower-bracts of the common lime (Zvi
europea). Having only found this species once, which was in
Northumberland, I give the following note from Connold,? who has
figured the species :—
“These galls begin to form on the margin of the bract as small
elevations. The feeding of the mites causes the edge of the bract to
rise upwards and curl over towards the midrib, producing a roll which
sometimes extends 30 to 40 mm. in length, and continues to roll
! For a full and interesting account of ‘‘Gall-Mites” under similar classification
to the aboye, see ‘ Die Krankheiten der Pflanzen,’ Frank, vol. iii., 1896.
* British Vegetable Galls, p. 170.
ERIOPHYIDA OR GALL-MITES. ol
over upon itself until the middle of the bract is reached. When
thus affected, the bract may curve into a crescent shape, the roll itself
Fig. 32.—Malformation of the flower of ash (Fiaxinus excelsior) caused by Eriophyes fraxini.
forming the inner margin of the concavity, or it may be otherwise
considerably distorted. No harm is done to the flowers, nor does the
bract fall until the usual time, hence the
mites are not destructive to the fruit.”
ERIOPHYES GONIOTHORAX (Nal.)
This species is very common on the leaves
of the common hawthorn (Crategus Oxyu-
cantha). On healthy trees and hedges we
may only find an isolated affected leaf, but
sometimes on an isolated bush in a wood we
may find almost every leaf affected. The pig. 33.—xages of hawthorn lea,
damage itself is easily recognised, as the [vino Heo
outer edges of the leaf are rolled inwards,—
the roll itself being very slender, and of cord-like appearance. If
fresh leaves are gathered, and kept in a box or on a table until they
an FOREST ENTOMOLOGY.
become slightly flabby, they can then be very easily opened ; and if
examined under the microscope, the mites can be seen in great num-
bers. Fig. 33 is a representation of a single hawthorn leaf rolled by
this species.
ERIOPHYES AUCUPARI® (Con.)
This species may be taken as a typical example of surface-injuries
to leaves by gall-mites. The leaves are injured on both sides, but
the form of the leaf is
not injured. Examples
of this injury are very
common in Northumber-
land, but so far I have
not been fortunate enough
to see the mite under the
microscope. Fig. 34.
Several other arboreal
species may be found;
or, In other words, many
instances of malformation
on leaves, flowers, and
fruit may be recognised,
which on microscopical
examination will show
Eriophyine. Those mites,
however, may not always
be the direct cause of
the injuries referred to,
inasmuch as the primary
cause may be due to
minute parasitic fungi,
and the mites simply finding congenial association in the diseased
spots. Hence the enthusiastic student will find this dual nature of
parasitic disease a stimulus to encourage original investigation.
Several other species may be found rolling the leaves of our forest
trees and shrubs, as, for example, the species forming rollings or
small galls on the edges of the leaves of blackthorn (Prunus spinosa),
fig. 35.
Fig. 34.—Surface of leaflets of mountain-ash (Pyrus
aucuparia) injured by Eriophyes aucuparize.
ERIOPHYIDA OR GALL-MITES, 33
Genus MoNOCHETUS.
M. suucatus (Nal.)
This genus contains a single species on beech, which is figured by
Connold.! ‘These most interesting galls do not appear to be common :
they are very local where they
occur. The affected leaves are
situated on the new wood of
the year. They are attacked
while expanding, and instead
of opening out into a flat blade,
the primary offshoots from the
midrib are caused to remain as
nearly parallel as possible with
it, and the areas which they
enclose are pushed upwards,
giving both sides of the leaf
a deeply striated appearance.
They continue to grow in
leneth, and ultimately bend in- Fig. 35.—Edges of leaves of blackthorn (Prunus
Seas? spinosa) rolled inwards by species of Kriophyes.
wards, assuming a cymbiform
shape. The edges of some meet and produce a pod-like growth.
Owing to their excessive pilosity, they are like velvet to the
touch.”
Susp-Famity PHYLLOCOPTIN 4.
In connection with this sub-family, it may be mentioned that
Nalepa gives several instances of Continental mites belonging to
the respective genera of the sub-family, and associated with many
of our forest trees. It is therefore possible that we have here, so far
as systematic forest entomology is concerned, a practically unworked
field. Fig. 36, a, represents the dorsal surface, and } the side view
of Phyllocoptes carpini Nal.* The figures are specially given as
showing the variety of structure in these minute creatures, and the
suggestiveness of this field for original microscopical research.
The most familiar instance, however, is the species attacking the
1 British Vegetable Galls, p. 176.
2 From ‘ Beitriige zur Systematik der Phytopten,’ von Dr Alfred Nalepa, 1889.
C
34 FOREST ENTOMOLOGY.
upper surface of the leaves of the common sycamore (fig. 37). It is
now known by the name of Phyllocoptes acericola, Nal., and Connold
gives the following synonymy—viz. :
PHYLLOCOPTES ACERICOLA, Nal.
Volvulifex aceris, Amer.
Ceratoneon vulgare, Bremi.
Phytoptus aceris, Murray.
The galls are very common on the upper surface of the leaves of
sycamore (Acer pseudo-platanus). In some instances they are very
thinly scattered over the leaf, in other cases
quite gregarious. They are very beautiful in
colour, varying from orange-yellow to purple.
They appear soon after the leaves develop, and
may be found throughout the
whole summer season.
Such are a few typical speci-
mens of arboreal Eriophyide
living in buds or forming
galls; and, as just stated,
there may be many found on
trees, but with the exception
of two species—viz., those on
hazel and yew—they are not
Fig. 36.—Phyllocoptes carpini. very destructive, and certainly
a, dorsal surface ; eee (Copied from not to be compared with the
species on black currant.
From the foregoing remarks it will be seen that the study of
Eriophyide is purely a microscopical one. The bases of classification
are so minute, and the points of discrimination so difficult to deter-
mine, that the question naturally and suggestively arises whether
we have the same or different species of mite doing several kinds
of injury. As bearing on the specific differences of mites found on
different food-plants, I may say, from practical and local examinations,
that I have only once found Eriophyes ribis on black currant in
Northumberland, near Newcastle-on-Tyne, whereas the species on
hazel is about as common as in Cheshire, where Z. ribis is a direful
pest. Hence it would conclusively appear that the mites on the
;
ERIOPHYIDZ OR GALL-MITES. 35
respective food-plants are distinct species, and therefore very fastidious
as to food.
Mr Newstead, Curator of the Grosvenor Museum, Chester, carried
out a number of observations with regard to the species on black
currant, and found that there was a succession of broods from
February to September. He also discovered that when the buds
shrivel up and become unable to support the mites, they migrate
to the leaves and leaf-stalks, and enter the newly formed buds
towards the end of July, where they remain until the following
spring.
From preliminary observations I find that there is a slight difference
between the habits of the species on hazel, compared with that on
black currant, inasmuch as the
“blind buds” of the former do
not shrivel up so quickly as the
latter. Consequently the swol-
len buds of hazel are teeming
with life about the latter end of
July, while comparatively few
are on the leaves and leaf-stalks.
The buds for the coming year
were then formed, and the mites
would be able to move from
one “house” to the other
without camping out during Pg. $7-— Gull on leet oyumere (Acer peed
nature’s building operations.
The life-history of those species living in galls is not so easily
followed. For instance, I have examined the buds and twigs of
a lime-tree, from the same branches which year after year produce
galls on the leaves, without finding a single mite. Then, again,
certain willow leaves are infested annually by a micro-fungus of
the rust order, on the under side of the leaves, which invariably
harbour those mites, and yet neither “leaf-galls” nor “blind buds”
could be found on the tree whither the mites would be supposed to
migrate from the fungus excrescence, whose existence as a rust only
lasts for a month or two.
On the under side of the leaves of some lime-trees a white growth
is often found, which is known as a vegetable hypertrophy. This also
harbours mites, and yet no nail-galls may be seen on the leaves of
36 FOREST ENTOMOLOGY.
the same tree. Hence it may be concluded that the life-history of
some “ locally” resident species is more or less involved in obscurity.
Consequently the following remarks are appended from an authority
on economic entomology. Mr French says :—
“ With regard to the life-history of these singular little animals,
Mr Crawford gives it as his opinion that there are two ways in which
the mite survives the winter, when all leaves are shed: first, by
hibernating among the hairs of, and in, the leaf-bud; and secondly,
by forming colonies under the tender bark of the last year’s growths,
as I have found them in both situations. It may be the eggs are laid
in the buds, as very young leaves, when still unfolding, have often
very small galls, which are then of a pink colour. I expect, there-
fore, that the majority of the mites quit the leaves on the approach
of their fall, to take up their winter quarters in these places. The
mites that fall with the leaves would soon die, but their eggs might
be blown about with the decayed leaves, and by chance alighting on
pear-trees, colonise them. ‘The wind, birds, and insects are doubtless
the principal means of disseminating this pest in the summer time.
The number of living Phytopti on an ordinary-sized pear-tree that
is badly attacked must amount to thousands, if not millions, so that,
allowing for a most lavish waste of life, the chances of a few being
carried alive to other pear-trees in the neighbourhood must be
considerable.”
References to Literature consulted.
Collinge. Black-Currant Gall-Mite. 1904.
W "W W 1907.
Connold. British Vegetable Galls. 1901.
Frank. Die Krankheiten der Pflanzen, Bd. iii. 1896.
French. Insects of Victoria. 1891.
Murray. Economic Entomology—-Aptera.
Nalepa. Phytopti—Genera und Species.
" Das Tierreich. 1898.
Newstead. The Currant-Bud Mite. 1901.
Réaumur. Mémoires des Insectes. 1732.
Tubeuf. Diseases of Plants, &c, 1897.
1 Insects of Victoria. 1891.
37
CHAPTER II.
COLEOPTERA (BEETLES).
Or all the families of Insects, with the exception of Lepidoptera,
none appear so common, or so easily distinguished by the non-
entomologist, as the Coleoptera or Beetles. They are easily recog-
nised by their apparent absence of wings, though they are not wing-
less, as the true wings are covered by two hard horny wing - cases
known as elytra, which are spread out during flight. The mouth is
Pee Oe
*-F =
Fig. 38.—Typical larve of beetles. (From photo by A. Flatters.)
formed for biting, hence they are mandibulate ; and the body, lke
that of all other insects proper, is divided into three distinct portions
—viz., head, thorax, and abdomen.
Beetles undergo complete metamorphosis, passing through the
various stages of egg, larva, pupa, and imago or perfect insect. Fig.
38 represents typical larvze of beetles.
The general student or collector of Coleoptera finds the forest a
very happy hunting-ground, inasmuch as every portion of it is rep-
38 FOREST ENTOMOLOGY.
resented by most of the respective families. Thus the ground under-
neath yields the various orders of ‘‘ ground - beetles” or Adephega,
while in the air above many species may be caught from time to time
on the wing. Carrion-beetles may be found on “ keepers’ trees” and
in dead carcases, while the bark of trees affords hiding- places for
many species.
It is, however, from the economic point of view that the Coleoptera
are really of special interest to the forester, inasmuch as the various
parts of the tree become the feeding-ground of respective families and
species of beetles. Thus the roots are attacked by the larve of certain
species, the bark tunnelled and trunk
bored by others, while some beetles are
injurious to the foliage and shoots in
both larval and perfect forms.
In order to understand the anatomy
of beetles,! it would perhaps be best to
take a common ground - beetle, trisect
it into its main divisions, —viz., head,
thorax, and abdomen,—and then carefully
note the general structure of each division
and its respective appendages. ‘This is
also very important from a_ biological
point of view, for undoubtedly if insect
ff
‘i
5 sagt fl!
SS ft
SSE PS.
Se
Fig. 39.—Head of Cici : of, 2
"2 GueghineD. oe anatomy be generally considered, it will
a, with jaws closed; b, with jaws be found that there is not a difference
open; J, labrum; ¢, clypeus.
(From Fowler's ‘British Coleop- jn structure of the various orders, but
tera.’) noe ne
simply a modification of similar parts.
The anatomy of the mouth parts of the beetle affords a very good
case in point.
Head.—Viewed from the top side, the eyes and antenne are the
most salient features. Fig. 39 shows all the respective parts: / is the
labrum or upper lip, which can be seen from the upper side. Ac-
cording to writers on beetle anatomy, the portion immediately behind
this, 6, is called the clypeus, ¢, or shield of the mouth, and behind
this is the head proper, 0.
In the -Rhynchophora the head is prolonged into a snout, called
the rostrum, which is a true portion of the head, and in no sense a
1 For full particulars of structure, the student is advised to consult Fowler’s
‘Coleoptera of the British Islands,’ vol. i.
Se eee ee
COLEOPTERA, 39
trunk. On each side of the rostrum there is usually a groove into
which the long first joint of the antennz generally lies when the
insect is at rest. These grooves are called scrobes, and are useful
characters in the determination of the Rhynchophora. ‘The anterior
portion of the head is called the forehead or front, and the central
portion the vertex.
The antenne are very variable in the Coleoptera, and in many
eases afford good points for the discrimination of genera and
species. The eyes are generally very prominent.
The thorax, of course, can be easily recognised, but it must be
remembered that the transverse division line as seen trom the upper
surface does not represent the length of this segment, inasmuch as
it projects on the under surface and extends under the abdomen.
In other words, the under side of the thorax projects beyond the
apparent divisional line, and the anterior portion of the abdomen
therefore rests upon the thorax.
It is of importance to well understand the structure of the thorax,
more especially in the case of Scolytide or ‘ bark - beetles.” The
thorax proper is made up of three parts—the prothorax, mesothoraz,
and metathorax ; and here again we must study the upper and under
surfaces of those divisions. In the upper surface these divisions are
known as pronotum, mesonotum, and metanotum, and the under
surfaces the prosternum, mesosternum, and metasternum. As regards
the upper surface, the visible portion of the mesonotum is known as
the scutellum, which is a small but important triangular space,
wedged in, as it were, between the elytra and thorax. From the
under surface of the thorax we get the legs, and from the upper the
elytra and wings.
The abdomen does not, as a rule, present many important features,
either as to external anatomy or as to points of classification. The last
segment or pygidium is rather important, inasmuch as it contains the
organs of reproduction. The legs spring from the thorax, and are
attached to the body by a joint called the cova. The next joint is a
very small portion known as the paracoxva (Fowler), and attached to
this we have the strongest portion, known as the femur. The next
portion is the ¢ibia ; and the last division is a most important one—
viz., the tavsus. Not only in beetles but in all orders the number of
joints forming the tarsus must be noted. In the Coleoptera we have
the whole family subdivided, according to the number of joints in
4
0
FOREST ENTOMOLOGY.
the tarsus, into four divisions—viz., Trimera, Tetranera, Heteromera,
and Pentamera.
Fig. 40.—True wings of beetle.
a, folded; b, unfolded.
This division is, of course, more or less arbitrary.
The wings of beetles
are rather peculiar, as
what corresponds with
the wings of other in-
sects are the elytra
These
or wing-cases.
have sometimes a very remarkable sculpturing, the use of which is
unknown.
Fig. 41.—V'ypical beetle: Pterostichus vulgaris, L.
(male); wpper side. (From Fowler's ‘ British Coleop-
OMAR POD =
tera.’)
. Labrum.
. Labial palpus.
. Maxilla.
. Maxillary palpus.
Mandible.
. Antenna.
. Front of head.
. Supra-orbital sete.
. Pronotum, ordinarily
called ‘‘ thorax.”
. Anterior lateral pore.
. Angular pore.
. Scutellum.
. Basal fold of elytra.
. Seutellary stria.
. Suture of elytra.
. Sutural angle.
. Femur.
. Tibia.
. Spurs of tibia.
. Tarsus.
. Onychium and claws.
. Stigma.
. Pygidium.
In repose, these two elytra are very well fitted together :
the junction line is known
as the suture. The wings
proper, which correspond to
the posterior pair of other
insects, present a very vari-
able structure, so far as the
arrangements of nerves and
cells are concerned. The
size and general structure
are compatible with the
folding up under the elytra
(fig. 40). In some forms
they are considered apter-
ous, but though in such
cases the wings are never
used, and the elytra some-
times soldered together, rudi-
mentary wings may often be
found.
Throughout the respective
families modifica-
tions of general anatomy
present themselves. In the
Rhynchophora or weevils,
for instance, there is a
prolongation of the mouth
called a rostrum, which,
various
as Canon Fowler remarks, is a true portion of the head, and in
no sense a trunk.
Classification.—N otwithstanding the many works on Coleoptera,
oe a
COLEOPTERA. 41
we have no fixed system of classification or method of arranging
beetles. In catalogues they are generally grouped into families
according to the number of joints of the tarsi: thus those ‘ possessing
five joints to all the tarsi have been termed Pentamera ; those with
five joints to the front and middle legs, and only four to the hinder,
Heteromera , those with apparently only four to all the tarsi, Tetramera ;
and those with apparently only three to all the tarsi, Tr/mera.” 1
In looking over a list of Coleoptera, the systematic student will
obviously note that he enters the domain of beetles associated with
forest trees deep down in his list. It is also, however, somewhat
Fig. 42—Typical beetle: Dytiscus marginalis,
LL. (male), under side (water-beetle). (From
Fowler’s ‘ British Coleoptera.’)
1. 1st ventral segment of abdomen.
2. 2nd ” ” ”
3. 3rd ” ” 2”?
4. 4th ,, ” ”
Rit 53 e
6. 6th ” ” ”
7. Prosternum, terminating in prosternal
process.
8. Episternum of prosternum.
. Episternum of mesosternum.
. Epimeron of mesosternum.
. Metasternum.
. Wing of metasternum.
. Episternum of metasternum.
. Coxal cavities,
. Coxe (posterior pair very largely devel-
oped for the support of the swimming
legs).
16. Trochanter.
17. Femur.
18. Tibia.
19. Dilated tarsus or palette, and cupules
of male.
20. Oar-shaped tarsus.
21. Coxal process.
22. Epipleura of elytra.
23. Genital armature.
a
OO PON Os
remarkable, so far as hunting-ground is concerned, that where the
student in forest insects begins, the systematic man and the student
of many forest insects might claim mutual association all along a
considerable portion of the list. It is, however, only essential to
select the more salient species, and in doing so many arboreal species
will have to be omitted. On the other hand, so as to present any-
thing like completeness, many species would have to be considered
which are not of great importance from the purely economic point
of view.
As regards the details of structure, the student would do well to
refer to figs. 41 and 42, together with the explanation as given by
1 Rye, British Beetles, p. 41.
42 FOREST ENTOMOLOGY.
Fowler. These points should be thoroughly mastered, as the ready
discrimination of species from a systematic point of view will depend
upon the same.
Famity LUCANIDA.
Fowler says that “the three British genera of the Lucanide may
be distinguished as follows :—
‘J, Eyes more or less divided ; ligula and maxille covered by the
mentum; antenne geniculate; posterior femora extending
beyond margin of elytra.
‘‘], Eyes divided for scarcely half their diameter Lucanus, L.
“2. Eyes divided for nearly the whole of their diameter
Dorcus, M‘Leay.
‘II. Eyes entire; ligula and maxille not covered by mentum ;
antenne straight ; posterior femora not extending beyond
margin of elytra : : ; Sinodendron, F.”
Lucanus cEeRvuS (Linn.)
This large handsome insect, which may be termed the king of
British beetles, is chiefly confined to the southern counties. It is of
Fig. 43.—Stag-beetles.
a, male; b, female, slightly reduced.
a pitchy-black colour, with slightly brownish elytra, and often
measures about two inches in length, The mandibles are very large,
—
——
Ee a ee
COLEOPTERA. 43
more especially in the males. In fact, these peculiar features easily
distinguish the insect ; and this abnormal development of the male
gives rise to its name of “stag-beetle,” because
the mandibles projecting in front of the head
resemble the horns of a stag. Darwin says
that the size and strength of the mandibles
are of great advantage in fighting for the
possession of the females. These insects fly
during the evening, and rest on the stem,
sipping at any juicy portion they can find.
Fig. 43 represents the male and _ female
insects,
It is in the larval stage that this species
is most injurious to timber trees, more especi-
ally oak and ash (though hornbeam is con-
spicuously mentioned by Kaltenbach,! and
alder and beech by Altum”). The larva is
white, with ferruginous head, nearly cylin-
drical, and of a soft fleshy consistence. It
is said that they live for six years as larve, ae ep,
during which time they gnaw into the roots En by larva
and eat the solid wood. In fig. 44 a piece
of ash timber tunnelled by the larva of the stag-beetle is
represented.
Dorcus PARALLELOPIPEDUS (Linn.)
To the beginner in entomology this species is suggestive of a small
specimen of the female stag-beetle. At least, this was my incipient
feelings when I first discovered this species under decayed bark in
Gloucestershire several years ago. The larve live in old decaying
beech and several other trees.*
SINODENDRON CYLINDRICUM (Fabr.)
This is another beetle which may be found in decaying wood. I
have reared the beetle artificially, taken from decayed wood and
fed on damp sawdust. I have also tracked the perfect insects by
1 Die Pflanzenfeinde aus der Klasse der Insekten, p. 638.
Forstzoologie, vol. iii. p. 120.
® Commander J. J. Walker, R.N., informs me that he has seen several very large
ash-trees in Cobham Park, Kent, completely destroyed by Dorcus parallelopipedus.
44 FOREST ENTOMOLOGY.
following up the frass at the bottom of a decayed standing tree,
which betrayed the presence of males and females. My first dis-
covery of this sort was in Acklington, Northumberland, July 3, 1902.
Mr R. S. Bagnall pointed out to me that the sickly beech and holly
trees in Gibside, Co. Durham, were very much injured by this species.
The beetle is shining black, about half an inch long. The male
has a conspicuous hooked horn in front of the head. The female has
also a slight horn, but it may require the aid of the lens to see it.
Famity SCARABAIDZ.
Genus MELOLONTHA.
This is exclusively an arboreal genus, inasmuch as it only contains
two species, both of which are arboreal in their habits. Fowler gives
the following specific characters—-viz. :
“Two species of Melolontha are found in Britain; they may be
distinguished as follows :—
“J. Pygidium elongate in both sexes, and gradually narrowed to
apex ; average size larger : : . M. vulgaris, ¥.
“TI, Pygidium shorter, constricted at base, and very slightly widened
at apex ; average size smaller . . M. hippocastani, F.”
The chief distinguishing character of the genus is in the structure
of the antenne, which are clubbed, and the club has seven Jamelle in
the male and six in the female.
MELOLONTHA VULGARIS, Fab, (Cockchafer).
The cockchafer, otherwise known in this country as the May bug
or May beetle, in Germany as the Maikdfer, and in France as Le
Hanneton, is injurious both in the perfect and larval forms. The full-
grown beetle feeds on the leaves of oak, elm, sycamore, and other
trees, and the larve on the roots of grasses and young trees. In the
midland and southern counties of England the seedlings in nursery-
lines often are destroyed by the larve (fig. 45).
Its life-history, as given by all English entomologists, may be
briefly told. The eggs are deposited by the female insect during the
summer, underneath the ground, from six to nine inches below the
surface. About thirty or forty are said to be deposited by a single
insect. They hatch out in about six weeks, and during the first year
COLEOPTERA. : 45
attain the length of about 16 to 18 mm. They live from three to
four years in the larval stage, and when full-grown are about 1} inch
to 1} inch in length, and about } inch to } inch in breadth. They
have six legs, the figures of which in various works appear to show the
third or last pair as the longest, whereas they are considerably the short-
Fig. 46.—The common cockchafer or May beetle
(Melolontha vulgaris).
a, beetle (male—natural size); b, feeler of male (7
Fig. 45.—Young beech seedling, lamellee — magnified four times); c, feeler of
the roots of which have been de- female (6 lamella—magnified four times); d,
stroyed by larva of May beetle larva or grub (natural size); ¢, chrysalis (seen
(natural size). (From ‘The from below — natural size). (From ‘ The
Forester,’ by John Nisbet.) Forester,’ by J. Nisbet.)
est, and the middle pair are a trifle longer than the other two. All the
legs aré more or less hairy. The jaws are powerful. They are a dirty
white colour, with a ferruginous head, and become darker after being
lifted out by workmen when trenching or levelling old “cops” or
hedges. After feeding for three or four years the larva descends a
trifle deeper, scoops out a recess, pupates in the autumn, and changes
to a perfect insect in summer (fig. 46).
46 FOREST ENTOMOLOGY.
The above account of the life-history may be only taken as regards
England, or perhaps the north of France, as in Germany the cycle
period is shorter in the south than in the north, thus showing that
heat or geographical position is an important factor in life-histories.
Preventive and Remedial Measures.
This insect is injurious both in the perfect and larval stages, but more
especially in the latter, and it is obvious that some remedial measures
should be given. At the same time, it may be remembered that as
this insect is so common and injurious in certain parts of the country,
many practical men, according to local circumstances, have adopted
their own respective methods of prevention and remedies. A few
hints, however, may be given.
As regards the injuries done by the perfect beetle, they are of course
entirely confined to the foliage, and the only remedial measures which
could be adopted with any degree of success would be to place sheets
under the most likely resting-places or feeding-ground of the beetles,
and then to beat them on to the sheets, collect, and destroy them.
The larve, however, are much more difficult to deal with, and
as they live for three years in the larval stage, it is highly essen-
tial that some practical methods should be adopted to lessen their
attacks. From a forestry point of view, we have therefore to deal
with them either in the young plantation or in the nursery. It is, of
course, more difficult to deal with them in the former. In this case,
before we can suggest any remedial measures, perhaps the most practi-
cal or effective way is to remember the nature of their life-history. It
must be borne in mind that the female beetle prefers depositing her eggs
on a grassy surface, as, for example, on an old pasture-field. If, there-
fore, it were practical to keep the young wood comparatively free from
erass, 1t would obviously lessen the attacks, inasmuch as the females
would not select the surface of the young woods for egg-deposition.
How far this could be carried out would depend largely upon local
circumstances or conditions. If, for example, it were possible to have
either a clean surface or, say, to cultivate potatoes between the plants,
we should do much to lessen the attack, and at the same time be
adopting a method which, in the case of portions of land planted for
rapid landscape effect, would perhaps be the best means to adopt.
As regards the nursery from an estate point of view, we must
COLEOPTERA. 4
remember that nurseries are of two kinds,—either temporary or per-
manent. ‘The former, as is well known from a practical point of view,
is very advantageous ; but in selecting a site for a temporary nursery
we should not choose a spot adjacent to a wood which is known to be
swarming with cockchafer beetles, nor should we, as far as possible,
select an old pasture-field, unless it were found possible to cultivate it
with potatoes or other root crops, which, from the nature of the work-
ing, would either facilitate the picking out of the grubs, or otherwise
checking them in some practical way, prior to the cropping with young
trees. As, however, the larve are quite as partial to the roots of
young trees in the nursery-lines as they are to the roots of grass, we
must adopt one of two methods,—either to make the surface of the
nursery very distasteful to the female beetle as a spot to lay her eggs,
or otherwise we must check or trap the larve themselves. With re-
gard to making the ground distasteful to the female beetle for egg-
deposition, we might regularly, from the beginning of May to the end
of July, sprinkle the surface with paraffin, sulphur, or in fact anything
which would have a tendency to keep the female beetles off. With
regard to collecting the larve in the nursery, without doing injury to
the young plants a method of trap trenches might be adopted. If,
therefore, the nursery plot is a comparatively large one, we might cut
trenches at certain intervals, parallel with the lines, fill in those trap
trenches with sods of grass, rolls of bark, weeds, partially decomposed
turf, burned sods, layers of cow-dung, and such similar refuse as could
be conveniently collected. From time to time those trenches might
be turned up, the larve collected, and the materials replaced.
Another remedy for the larve is, of course, to periodically green-crop
a portion of the nursery ground either for one or two seasons, as by so
doing we should be able to pick out a great many of the injurious
larve ; and in the case where the seedlings were to remain in the ground
following such cropping, say for one season only, the nursery crop
would be removed before any considerable damage would ensue.
MELOLONTHA HIPPOCASTANI (Fabr.)
“The beetle (fig. 47) greatly resembles the common cockchafer, but
is smaller, being only 20 to 25 mm. long. Antenne and legs dark-
brown or black. Tail shorter, more abruptly tapering, and somewhat
clubbed at its extremity.
48 FOREST ENTOMOLOGY.
“Life-history and economy.—In West and South Germany, similar
to those of the common cockchafer, with which it swarms, but in
smaller numbers. In East and West Prussia in the midst of great
Scots pine woods, this species alone destroys
forests, the common cockchafer confining its
attacks to agricultural lands. It does not
merely attack horse-chestnut, as its name
implies, but nearly all trees. The larve are
highly destructive to young Scots pines three
to six years old, but in their fourth summer
they attack the roots of poles fifteen to eigh-
teen years old, and even those of older trees.
Season for swarming early (April). The eggs
Fig. 47.— Melolontha hippo-
castani. (From ‘ Forest Pro- ar c : “ -
faction,’ by W.R. Fisher), 1220 laid eight to fourteen days afterwards,
10 to 14 inches deep in dry soil, but in moist
soil only 24 to 4 inches deep. The larve appear in.July, and pupate
in August of the fifth year, about 1} foot deep. The chafers come
out in September and October, but remain underground till the next
spring. A more northern insect than the common cockchafer ; in Great
Britain confined to Scotland and the extreme north of England.” !
Genus AGRILUS.
This genus is probably more important in forest entomology than
hitherto considered. There are five British species, and it would be
well for the student to give them special attention.
Agritus viripis, Linn. (the Beech Aygrilus).”
As this is a south-country species, and one which I have not
found, the following is copied from Mr Theobald :—
“ Although rare, this beetle has been complained about as a eH
amongst sapling beech-trees, whilst it is also said to attack birch,
alder, aspen, and oak.
“The damage is done by the larve of this beetle, which burrow
' Forest Protection, by W. R. Fisher (Dr Schlich’s Manual of Forestry), vol.
iv. p. 209, second edition, 1907.
° The Animal Pests of Forest Trees.
COLEOPTERA.
49
between the bark and the sapwood, and form winding passages even
into the wood, the tunnels increasing in size as the larve grow. Now
and again they completely girdle
the stem, and then the upper part
dies right away. As a rule, the
bark over the passage splits and
leaves behind a_ ragged crack,
which is very characteristic of the
damage done by this beetle. It
appears to prefer weakly and un-
healthy saplings, but sound ones
may be attacked (figs. 48 and
49).
“The beetle (fig. 50) is about
one-quarter of an inch long, and
belongs to the family Buprestide,
—long, slender beetles of usually
metallic colour, This species varies
from olive-green,- bluish- green, to
blue-black ventrally ; the apex of
the elytra diverge, and are slightly
Figs. 48 and 49.—Injury caused to beech sup-
dentate. They appear in June and lings by Agrilus viridis, L. (natural size).
: : c a, larval gallery, exposed by removal of
July, and fly in bright sunshine. the bark ; b, old larval galleries, ex-
The eggs are placed on the bark
posed by rupture of the bark; ¢c, trans-
verse oval flight-holes of the imago.
of the saplings near the ground, (From "Forest Protection,’ by W. R.
Fisher.)
usually singly, and exposed to the
sun, The larve appear in August ; they are white and legless, with
broad first segment, usually somewhat flattened.
They live in the trees for two or three winters,
and pupate in April and May in the bark or
sapwood, the cocoons being made of fragments
of wood. ‘The beetles emerge through holes
which are oval below, straight above. They
so seldom occur in this country that no further
reference is necessary. Where it does do
damage saplings should be smeared with clay,
lime, and sulphur to stop the beetles egg-
Fig. 50.—Agrilus viridis.
(From ‘Forest Protec-
tion,’ by W. R. Fisher.)
laying, and all infested saplings should be pulled up and burnt
early in May.”
D
50 FOREST ENTOMOLOGY.
Famiry ANOBIIDZ.
The student of forest entomology, as a rule, finds his insects either
on sickly or healthy living plants, but the members of this family are
all found on dead wood, and are, therefore, apparently only indirectly
connected with forestry, but they are nevertheless often very
important as regards estate buildings. Perhaps the most familiar
examples of the injuries of beetles belonging to this family are the
“holes” or “ worm-eaten” furniture in our cottages, and the injuries
of a similar character done to timbers in our buildings. Again, in the
forest proper, we find small holes in dead thorns, and also on those
portions of old-standing trees where the wood is often dead on
one side.
With regard to these injuries in roofing timber, it is rather remark-
able that home-grown timber should be more seriously affected than
foreign timber. Hitherto I have not found any special reason
assigned for this. It may be that in home timber more of the sap-
wood is used than in foreign timber—for, as a rule, insects do not
attack the heart-wood ; or another explanation may be in the respective
methods of seasoning.
There is nothing in the general appearance of the workings which
can suggest any distinction of species beyond the size of the
exit - holes.
Judeich and Nitsche! consider this group important in forest
entomology, and therefore divide it in the following manner, accord-
ing to the damage done by the respective species :—
I. The larvee inhabit the bark of old stems without particular
injuries.
II. The larve live in still standing trees, whose timber they tech-
nically injure.
III. The larvee inhabit the upper branches, and their injuries often
cause death.
IV. The larvee gnaw the young shoots, and thus destroy them. |
V. The larvee inhabit and destroy coniferous cones.
VI. The larve destroy comparatively old worked dry wood, planks,
baulks in the wood stores, house utensils, furniture, We.
This biological arrangement, though departing from the systematic,
is a very convenient one to the forester of this country, more especially
1 Forstinsektenkunde, vol. i. p. 343.
COLEOPTERA. 51
as the insects themselves are not considered of primary importance,
and it would be well, therefore, to give the respective insects which
cause the particular injuries referred to in each division, but unfortun-
ately we cannot get, owing to absence or rarity, the British species to
fully coincide with the German arrangement in question.
In the first group Judeich and Nitsche give Anobiwm emar-
ginatum, a species not recorded in Britain. These writers, how-
ever, say that it is not an injurious species, and only lives in
the bark of old spruce-trees.
Trine ANOBIINA.
Fowler divides the tribe into the following genera :
I. Elytra with punctured striz distinct, at all events at sides;
posterior cox distant.
1. Antenne sub-contiguous at base, with the last three joints
slender and long, especially in male § Dryophilus, Chevr.
2, Antenne distant at base, with the last three joints enlarged,
evidently broader than preceding.
(1) Thorax not margined at sides . : Priobium, Mots.
(2) Thorax margined at sides : 5 . Anobium, F.
II. Elytra without punctured striz ; posterior coxze contiguous.
1. Tarsi with the fifth joint broad ; tibize stout Xestobium, Mots.
2. Tarsi with the fifth joint elongate ; tibia slender
Ernobius, Thoms.
PRIOBIUM CASTANEUM (F.)
This beetle is very common in Northumberland, in old dead thorn
hedges. On May 26, 1905, I cut up a number of dead thorn stems
from a hedge (fig. 51) and found several fully developed beetles, to-
gether with a few fully developed larvee inside the stem. I laid aside
a few pieces in a bag, and the beetles hatched out about the middle
of June, or three weeks later.
The beetle is oblong,
legs red ; head fairly large, with prominent eyes ; thorax broader than
long, and narrower than elytra. The division between the elytra
forms a deep furrow, and the longitudinal markings on the wing-
covers are beautifully parallel, so that under a strong lens it looks like
corduroy. Length about 4 mm.
of a dull reddish-brown colour ; antenne and
FOREST ENTOMOLOGY.
Or
bo
XESTOBIUM TESSELLATUM (F.)
This insect, which is given as an example in the second group, is
the largest of the British Anobiide, and, according to Fowler, is
recorded from many English localities, but very rare in Scotland.
The beetle is a large species, being about 7 mm. long. The head is
rather deeply sunk in the thorax, and the whole body is therefore
cylindrical and rather convex. The ground
colour is dark-brown, but it is thickly covered
over with a yellowish pubescence, and towards
the abdomen there is an indistinct yellow band ;
antennee reddish, legs dark-brown.
I am indebted to Mr Hereward Dollman for
kindly sending two specimens.
The tribe Anobiina contains the species
found in old wood in houses, and in dead
wood generally. With regard to the former,
the beetle popularly known as the “Death
Watch” is perhaps the most familiar example.
The poet says,
“The solemn death-watch clicked the hour she
died,”
Tigiet = Partion of ada naw. and this saying is simply the expression of a
thorn stem burrowed by larve synerstitious belief that the noise which the
of Priobium castaneum. r ; ;
creature makes, and which is obviously most
distinct in the stillness of night by a sick-bed, is associated with the
supposed prognostication of a solemn death-warning. Several species
are said to produce this noise, but the best examples are Anobiwm
domesticum and Xestobium tessellatum.
ERNOBIUS MOLLIS (L.)
This species is very common in Northumberland, on larch and
spruce palings or poles. It prefers very dry wood. I have hatched
it from a spruce pole which had done duty as a flagstaff for several
years. On finding larve under the bark in September, I cross-cut
the pole into small pieces, and placed them in a bag, hung from the
rafters of an open shed, and the beetles hatched out in intervals
from the middle of June to the end of July. I have discovered them
COLEOPTERA. 53
in large slabs which had done duty as a rustic covering on an
important hut for six or seven years. The larve feed on the surface
wood, just below the bark,
making irregular markings,
as seen in fig. 52. They
pupate below the surface
of the bark, and _ often
remain in their burrows
after cutting out their
exit - holes, or otherwise
lodge in the burrows of
the bark. In the middle
of June they may be dis-
lodged by gentle tapping,
and thus collected freely.
The perfect beetle is
from 33} to 5 mm. long,
oblong, of a light ferrugin-
ous colour, and slightly
covered with a pale pub-
escence. Eyes large and Fig. ee eee eee mone oe
black ; antenne _ slender.
Elytra rather long, with parallel sides; legs rather lighter in colour
than body, and comparatively slender.
LONGICORNIA.
This group (so named because of the length of the antenne) is one
which the general collector of Coleoptera is very anxious to get well
represented in his cabinet. They are of special interest to the student
of forest entomology, inasmuch as the larve are wood-feeders, feeding
both in the living stem and on dead timber.
The larve are large, whitish grubs, and in many cases may
be easily recognised in consequence of the prothorax being broader
than the rest of the body. The head is, as a rule, compara-
tively small, and armed with strong mandibles and short anten-
nx. The legs, when present, are short or rudimentary, and locomo-
tion is often assisted by fleshy tubercules which protrude from the
body.
54 FOREST ENTOMOLOGY.
Fowler! divides the Longicornia into the three following families :—
I. Prosternum considerably produced in a blunt process behind
anterior coxe ; thorax margined, with the sides armed with
spines or teeth; labrum very small, usually connate with
clypeus . : - : : ‘ Prionide.
II. Prosternum not, or scarcely, produced behind anterior coxe ;
thorax not margined, with the sides sometimes armed with
spines and teeth, but usually simple in one species ; labrum
free and distinct.
(a) Anterior tibia not grooved on their inner side
Cerambycide.
()) Anterior tibise grooved obliquely on their inner side
Lamiide.
Famity PRIONIDZ.
Genus PRIONUS.
This genus contains only one species, and that species embraces the
whole of the family of Prionide as represented in this country.
Prionus corarius (Linn.)
This handsome beetle is somewhat rare in this country, being chiefly
confined to the south of England. The large larve bore into living
oak-trees, and do considerable damage. There is only one British
species, but several species are found in America, affecting various
trees.
The beetle itself is about 14 inch in length, of a dark-brownish
colour, slightly shining, lighter below, robust antenne, serrated in
males, thorax black, comparatively square, and with spines at sides.
It has the habit of fixing itself to the trunk, and flying at night. The
female emits a very strong odour. The larve when fully fed are
about 3 inches in length, of a whitish colour, and tapering consider-
ably towards the anal end. At this stage they move towards the
outer side of the trunk, and form a cocoon, whence the beetles
emerge in July.
EWolle it 5 Zid
Ou
or
COLEOPTERA.
Famity CHERAMBYCIDZ.
The most salient characters of this great family of beetles are—
body more or less cylindrical, with very long slender antenne ; larve
called ‘ borers,” their bodies cylindrical, usually footless.
This great family includes a large number of species, many of
which are wood-borers, and they are alike interesting to the general
collector and student of forest entomology. ‘The latter may often be
able to hatch them, from larve in either fresh or dead wood, while
the former may often enrich his collection with specimens found on
the flowers of large umbelliferous plants.
The duration of the larval stage is very varied. They may, asa
rule, live from one to three years, but instances are given of the
perfect insects appearing from furniture which
had been made of timber lying cut prior to using
for several years.!
AromIa MoscHata, Linn. (Musk Beetle).
This species is so named because of the pecu-
har odour which it emits, which has been com-
pared to the otto of roses. In the larval stage
it is very destructive to willow-trees, and very ER Eaoe aan
often attacks lime-trees, but it is generally Hag Noes by
found in the rough stems of old_ pollarded
willows, and, in fact, is said to be very common in all willow-growing
districts.
The beetle is a very pretty and handsome insect, about an inch or
more in length, with a strong spine on each side of the thorax. The
colour varies from a rich sapphire to an iridescent peacock-green. In
the male the antenne are 14 time as long as the body ; in the female,
a little shorter than the body.
Crytus arretis, Linn. (Wasp Beetle).
This beetle (fig. 53) derives its common name from its general ap-
pearance, which resembles a wasp. The body is rather more than half
' As the genera and species in this family, given as arboreal, are so compar-
atively few, it is not considered advisable to add generic characters.
56 FOREST ENTOMOLOGY.
an inch in length, black, with bright yellow bands, beautifully marked
behind the head and across the body. The general appearance is
rather suggestive of designs for carriage decoration. The legs are
rather long, and of a light terra-cotta colour. The antennz are about
half the length of the body, partly black, and partly the same colour
as the legs.
This beetle is not an arboreal insect, in the true sense of the term,
inasmuch as it does not attack living trees, but it is nevertheless a
timber insect. In looking for arboreal insects we may come across it
under the bark, and its appearance, habits, and specific characteristics
justify the student of forest entomology placing it in his cabinet.
Genus RHAGIUM.
This genus is one which, though entirely arboreal, is not of very
great economic importance in forestry. It is, however, one of those
insects which it would be well to get familiar with, inasmuch as I
have perhaps had more specimens of Rhagium bifasciatum sent me
for identification, as being found in the forest, than any other class
of insects. There are three species in the genus, two of which are
very common in Northumberland — viz, R. bifasciatum and R.
inquisitor.
The following, according to Fowler,' are the specific characters :—
I. Antenne very short; elytra rather strongly pubescent, without
distinct oblique yellowish bands.
1. Head straight behind eyes; raised lines on elytra ceasing
considerably before base . : . RR. inquisitor, F.
2. Head narrowed behind eyes ; raised lines on elytra continued
almost to base : : R. indagator, Gyll.
II. Antenne longer; elytra feauly pubescent, with two strongly
marked oblique yellowish bands on each R. bifasciatum, F.
RHAGIUM INQUISITOR (F.)
The beetles may very easily be reared from the larve, which may
be looked for in ash, oak, and other logs which have been lying in the
woods until the bark has decayed and the sapwood dissolved into a
black moist powder. The larve when full-fed are about an inch in
length, pure white, with a light-brown head. If the larger-sized
specimens are collected in February and March, and kept in the
1 Vol. iv. p. 231.
‘
Or
COLEOPTERA.
black material in a moist condition, they will develop into beetles
about the beginning of April. Fig. 54 is from a photograph of the
beetle.
RHAGIUM BIFASCIATUM (Fab.)
This is a very common arboreal species in many parts of the
country. In very warm days in July the beetle may be seen flying
about amongst young fir woods, or lodging amongst the leaves of
young Scots pines. During the summer months it may be found in the
early morning, amongst the freshly cut sawdust, in the pit underneath
the circular saw, where a portable sawmill is erected in a fir wood.
During the winter and spring months the perfect beetles may also be
found, together with many specimens of the larve, in old fir roots,
Fig. 54.—Rhagium inquisitor Fig. 55.—Rhagium bifasciatum
(natural size). (natural size).
and more especially in roots where the trees have been blown down.
I once found quite a colony in such a place in November, and as the
beetles were fully developed, it is possible that they pass the winter
in the perfect stage, after changing from the pupal stage in autumn,
as so large a colony in one root could not be accounted for on the
lines of hibernation. Another very happy hunting-ground for this
species is in dead Scots pines which have been left standing until their
condition is simply a mass of dry dust. I found quite a colony of
the perfect beetles issuing from trees of this class on May 19, 1905,
at Lyham, in Northumberland. After the exit from such trees, the
stem shows so many holes that it looks like having been severely
shot at with small bullets. As a rule, it cannot be considered an
injurious insect, though in Cheshire I once found an oak log consider-
ably destroyed by the larve of this species.
The perfect beetle (fig. 55) is shining and of a darkish mottled
58 FOREST ENTOMOLOGY.
appearance. The conspicuous features of colour are two yellow
oblique spots on each elytron—that is, four spots on the abdomen.
The antenne are a uniform brown colour. Legs black, with brown
coxz,—brown next the body and black next the femur, and the
remainder of the leg brown. The thorax has very strong lateral
spines. Length 15 to 22 mm.
Faminy LAMIIDA.
From the systematic point of view, Fowler says, ‘The chief
distinctive character of this family is found in the fact that the
anterior tibize are obliquely grooved on their inner side: as a rule the
palpi have the last joint cylindrical and pointed.”
Fowler divides the family into twelve genera, the majority of which
are associated with trees or timber, but two only may be considered—
viz., Acanthocinus and Saperda, the former because of its peculiar
appearance and structure, and the latter because of economic
importance,
I. Femora distinctly clavate ; thorax with lateral spines or tubercles.
1. Antenne much longer than the body ; upper surface smoother.
(1) Antenne in male four times as long as the body ;
anterior coxe rather widely distant; size large
Acanthocinus, Steph.
b, Antenne 1l-jointed . : . Saperda, F.
ACANTHOCINUS EDILIS (Linn.)
The following description of this handsome insect is taken from
Rye’s ‘ British Beetles’ :—
“Astinomus (Acanthocinus) cedilis is conspicuous for the enormous
length of its antenne, especially in the male. This also occurs at
Rannoch, where it may be not uncommonly seen flying across the
glades of the Black Forest with its long appendages streaming behind.
It loves to settle on felled logs with its antennz spread out like com-
passes, from which habit it is termed by the Highlanders ‘Timber-
man,’ a name curiously enough applied to it in Lapland and Sweden,
where it is common. If two males come within range they inevit-
ably fight, for which reason, and also on account of their delicate
structure, it is difficult to obtain quite perfect specimens.
COLEOPTERA. 59
“The larva makes wide galleries and perforations in pine stumps,
forming a nidus with coarse-gnawed fragments, near the surface, in
which it changes to pupa. In this state the antenne are turned
downwards, and recurved towards the middle of the head. It appears
to be full-fed at the beginning of the summer, and after remaining
two or three weeks in the pupa state, changes to the perfect state,
staying as such in its nest until the following summer.”
The body of the beetle is about ? of an inch in length, while the
antennz measure quite 3 inches,
Rannoch, or the “ Black Forest,” in Perthshire, referred to, is a
Fig. 56.—Acanthocinus edilis (half natural size).
very happy hunting-ground for the entomologist. This is due to the
fact that it is the remains of the old Caledonian Forest. Fig. 56 is
from a photograph of the beetle.
Genus SAPERDA.
Head with vertical forehead. Larve without distinct legs, almost
parallel-sided, and 11-jointed. Thorax longer than broad, without
side spine. Genus exclusively arboreal.
60 FOREST ENTOMOLOGY.
Synopsis of the Species.
Size large, elytra contracted towards the extremity, without any distinct
patches ; body covered with greyish-yellow hairs ; legs dark
S. carcharias,
Size smaller, elytra cylindrical ; thorax with yellowish side band ;
each elytron with four or five yellowish flecks . 8S. populnea.
I am indebted to friends for the specimens in my collection, but as
I have not had any opportunities of studying this genus in the forest,
the following account of the two species is taken from Professor
Fisher’s ‘ Forest Protection’ (Schlich, vol. v., 1907 edition).
SAPERDA CARCHARIAS, L. (Large Poplar Longicorn).
Description.—Beetle (fig. 57) 23 to 30 mm. long, grey or brownish-
yellow, dotted with many shining black points. Thorax short and
Fig. 58. — Larva of Saperda
Fig. 57.—Saperda carcharias. (From ‘ Forest carcharias. (From ‘ Forest
Protection,’ by W. R. Fisher.) Protection,’ by W. R. Fisher.)
cylindrical. Elytra with the shoulders prominent, narrowed _pos-
teriorly, and bluntly spined at the apex.
Larva extending up to 36 mm. in length, without legs, cylindrical,
yellowish-white, with the mandibles and segmental shields brown, the
latter on the dorsal surface of segments 3-10, and the ventral surface
of segments 2-10 (fig. 58).
Life-history.—Season for flight : June and July.
The eggs are laid in June in crevices in the bark of poplars,
especially near the ground.
———
OO
COLEOPTERA. 61
The larve emerge in July and August, and live and hibernate in
the wood, pupating in May of the 3rd year.
The pupe lie head downwards in a chamber blocked with a plug of
wood-dust.
The imagos emerge in June of the 3rd year.
Generation biennial. The insect is rather common in a few parts
of Great Britain, chiefly in the eastern counties.
Relations to the forest.—The larve bore into young, healthy
poplars, and also into willows ; aspen and black poplar up to 20
years old are specially attacked. Seedling trees are liable as a
rule to be attacked from their 5th year, and suckers from the
3rd year.
The larve make vertical galleries, which reach the centre of the
tree: these become gradually filled with wood-dust, which is forced
out of the tree by the grubs through a bore-hole, and becomes heaped
up at the base of the plants. The stem is attacked near the ground,
and reacts by developing a large irregular swelling, the bark of which
is fissured. Such perforated saplings are easily broken by the wind.
This insect is chiefly of importance where poplars are grown on a large
scale, as in France. It is sometimes associated with Sesia apiformis,
Fabr., and Cossus ligniperda, Faby.
The beetles in June and July eat roundish holes in poplar leaves,
but this injury is unimportant.
SAPERDA POPULNEA, L. (Small Poplar Longicorn).
Description.—Beetle 8-13 mm. long, greenish-grey to dark brown,
covered with yellow-grey pubescence ; thorax with three lines of
pubescence ; elytra with the median line, and a broad lateral stripe,
and three or four spots on each side pubescent. Antenne blackish,
and each segment up to two-thirds of the length of the antennz with
grey pubescence. Larva 13-15 mm. long, yellowish, and resembling
that of the preceding species.
Life-history.—The female deposits her eggs in May and June in
eracks on the bark of young aspens, less commonly on other species
of poplar, sometimes on willows. Seedlings of 2 to 6 years old and
suckers are preferred.
Generation biennial. The larva hatches in July, bores through the
bark, and eats a circular gallery round the sapwood. The stem, usu-
62 FOREST ENTOMOLOGY.
ally one of the smaller branches, reacts by forming a gall-like swelling,
which, however, is not found on willows. See fig. 59.
In the second summer the larva changes its course, boring upwards
along the middle of the stem for about an inch. The flight-hole is
circular, and situated on the swollen por-
tion. Pupation in April of the third
year.
This insect is usually found in open
sunny places, and is not uncommon in
the Midlands and south of England. It
seldom kills the trees, but cripples the
branches and prevents growth. Where
it is abundant, hardly a branch can be
found free from its gall. Fig. 59 is
a representation of injuries.
Trine CHRYSOMELINA.
Genus MELASOMA.
There are three species in this genus,
The: Bouin camel bo om a all of which are arboreal; but as two
Oe by lurve of Saperda are very local, the species described may
be taken as typical, and generic char-
acters need not be given. Not having found the species considered,
the following is taken from Fisher.'
Metasoma popuul, L. (Red Poplar-leaf Beetle).
Description. —- Beetle 10 to 12 mm. long, of an obovate shape,
blackish-blue, the elytra brick-red, their extreme tip black ; thorax
narrower than the elytra, its sides rounded, broadly raised and coarsely |
punctured ; antenne short, compressed, thickened towards the ends.
Larva 6-legged, of a dirty white colour, with many black spots, and
two white lateral projections on the second and third segments.
Pupa sharply narrowed towards the posterior extremity, brownish-
yellow, with regularly distributed black spots and stripes.
Life-history.—TVhe season for flight is in May and June.
1 Forest Protection, 1907 ed.
—T
COLEOPTERA. 63
The @ lays her yellowish-white eges in clusters of 10 to 12, in all
100 to 150, on the under side of the leaves of young poplars. The
larvee emerge in June or July, feed openly on the leaves, and if
disturbed exude a milky-white fluid, with an odour of bitter almonds.
Pupation takes place in July and August ; the pupe hang reversed
from the leaves by their pointed end.
The beetles emerge by the end of August, and after October
hibernate under leaves or moss, reappearing in the open in April.
Generation annual, but frequently double, when the beetles hiber-
Fig. 60.—Melasoma populi.
a, beetle; b, larva; c, pupa.
oe ae Fig. 61.—Injuries done by Melasoma populi.
a, leaf bitten by beetle ; b, leaf bitten by larve. (From
‘Forest Protection,’ by W. R. Fisher.)
nate ; larve appear in May and June; pup 3-4 weeks later, new
beetles 10 days later. Fresh larve in August, the second generation
closing in the middle of September. Locally common in many parts
of the British Isles, chiefly in South England.
Relations to the forest.—The insect, both in the larval and beetle
stages (fig. 60), attacks young poplars and sometimes aspen shoots.
Occasionally they are found in osier-beds, especially on Salix pur-
purea, L., and 8S, rubra, L., &e. The larve attack the leaves, which
are completely skeletonised, the parenchyma being eaten and the veins
left intact. The imago eats holes out of the leaves (fig. 61).
The attacks last from June to August.
64 FOREST ENTOMOLOGY.
Genus PHYLLODECTA.
This is truly an arboreal genus. The beetles are usually of a bronze
or metallic colour, oblong shape, parallel sides, rather long antenne,
elytra with beautifully punctured strie.
Fowler gives the following specific characters—viz. :
I. Punctured striz of elytra irregular, colour blue
P. vulgatissima, L.
IJ. Punctured striz of elytra regular.
1. Forehead broadly excavated ; antennze longer ; colour dark
blue . : . ; : P. cavifrons, Thoms,
2. Forehead with a slight depression, not excavated ; antennz
shorter ; colour, as a rule, bronze . LP. vitelline, L.
The two species P. vulgatissima and P. vitellinwe are often con-
founded, and very difficult to distinguish by the practical man,
affording, perhaps, a good case in point where the services of the
systematic Coleopterist would be valuable.
>
PHYLLODECTA (PHRATORA) VITELLIN® (Kirby).
This beetle (fig. 62), which is in many parts of the country popu-
larly known as the willow beetle, is about one-sixth to one-eighth of
an inch in length, of a_bluish-black
metallic colour, with a dash of bronze
or green above and more below. The
body is oval-shaped, with longitudinal
punctured rows on the elytra.
The perfect insects hibernate in
rotten wood and underneath the bark
of trees, more especially such rough
parts as those on Ontario poplar and
the excrescences on ash caused by the
fungus Nectria ditissima. In such
Fig. 62 —Phyllodecta vitelline Places I have often found them in
es eae, Hes enlarged. mid-winter. On the arrival of spring
and the general appearance of vegeta-
tion they leave their sheltering places, and betake themselves to the
osiers or poplars.
The female deposits her eggs in small clusters, generally six eggs in
COLEOPTERA. 65
a cluster, on the under side of the leaves of willow, sallow, or poplar.
Whether the female deposits more than one group, I am at present
unable to say. The eggs very soon hatch out, and the larve do im-
mense damage by eating the green portions, leaving only the vascular
portion,—in fact, skeletonising the leaves, and giving the affected
portion of the plant a very dirty-looking appearance (figs. 63 and 64).
They feed on the under side of the leaves, moving
in straight rows like soldiers marching in single
rank, They are rather larger than in the perfect
state, and are of a dirty-looking colour.
The damage done to the willow, more especi-
ally the osier (Salix viminalis), is by no means
confined to the larval stage. The perfect beetles
do immense damage to the young rods by eating
the tender portion of the extreme point,—in fact,
eating the growing point; and as length is the
main object of osier-growing, it is obvious the
damage cannot be exaggerated. Damage of a
similar nature to rods of the second year’s growth
likewise causes a great loss to willow-growers,
inasmuch as the shoots throw out a number of
small lateral branches, instead of increasing in
growth by length. Hence they are very much
depreciated in value.
Hitherto I have not been able to work out the
full life-history of this insect. Some naturalists
assert that it is double-brooded, but in all prob-
ability we have a succession of perfect insects
appearing throughout the summer.
As regards remedies, the usual insecticide-
dressings of quassia, Paris green, &c., would no * pT eee
doubt help to keep it in check, but I have found Tae Uaioe ne
that the best way is simply to go over the
rows of twigs and shake the beetles into an old jar containing
paraffin.
A very interesting account of the damage done to a large sewage
farm in Lymm, Cheshire, will be found in Miss Ormerod’s Manual ;
and my esteemed friend Mr J. Mort, who had then, and still has,
charge of the farm in question, assures me that the beetles have all
E
66 FOREST ENTOMOLOGY.
but disappeared as the result of annually shaking them into paraffin.
I can fully endorse this, not only from adopting the same method,
but also on account of frequent pleasant per-
sonal inspections of Lymm Sewage Farm along
with Mr Mort.
RHYNCHOPHORA.
This section embraces a very large series of
insects, both to the systematic student and the
arboriculturist. As, however, the main distin-
guishing generic characters are given, it would
be superfluous to give too many detailed sec-
tional characters. In a general way (exclusive
of the Scolytide) they may be characterised as
M8 Navtiied nina ‘snouted” weevils. Many of them are easily
ital beetle (ree yeared from the larval stage, but it would be
well for the enthusiastic student to collect this
class of insects from palings, trunks of trees, stone walls, &c., as by
so dog he would not only gain a knowledge of the section, but
many important points bearing on the life-history of arboreal species
could be ascertained.
The family Curculionide contain certain weevils which are either
injurious or otherwise interesting as forest insects, perhaps more
especially those which cut and roll leaves in a peculiar manner, either
for the benefit of the larve or the perfect insects.
To the systematic student of Coleoptera this is, comparatively
speaking, a very large family, and many species may be beaten from
different deciduous trees, but the student of forest insects may confine
his attention to the leaf-cutting and leaf-rolling species. With a
view, therefore, not to overload the student in the details of classifica-
tion, it is intended to give as few systematic characters as possible.
ATTELABUS CURCULIONIDES (Linn.)
This leaf-rolling beetle is very plentiful in some parts of the
country. I have found it in Delamere Forest, Cheshire, at Newball
in Lincolnshire, and also in the southern side of the county of North-
umberland. As regards the date of appearance, I found it, together
COLEOPTERA. 67
with the rollings, in the former place on June 15, 1895, and on—
June 20, 1896.
The work of the female beetle is very easily recognised in the
form of ‘thimble yess
cases,” constructed ki
by rolling up the
oak (or, more rarely,
Spanish chestnut)
leaves (fig. 65). |
These are chiefly
found on young
shoots, growing as
underwood. On un-
rolling the cases Fig. 65.—Oak-leaves rolled by Attela-
bus curculionides.
Fig. 66.—Attelabus cur-
culionides (natwral
size). (Photo by A.
Flatters.)
on the dates men-
tioned, a single egg was found in each case. The egg is a small
spherical body, of an orange colour.
The perfect beetle (fig. 66) is about 6 mm. long, of a bright
rufous-brown colour; thorax and elytra smooth; legs all black
and shining; antenne black and 12-
jointed ; head black, and eyes of a
chocolate colour. y
DeEporats BETULE (L.)
This species of leaf-rolling beetle is
abundant in many parts of the country,
but I have found it most plentifully at
Kielder, Northumberland. The leaves
(of birch) are cut much in the same
manner as by the preceding species, but
the case is rolled lengthwise instead
of in a globular form (fig. 67). The a
rolled portion somewhat resembles a Fig. Sere eens by
kind of paper bag used by grocers or
confectioners, and made by rolling a square-cut piece of paper round
the hand. The chief injuries are done by the female insect: she
interferes only with the vitality of a certain portion of the leaf. She
begins rolling operations by making an incision on the outer edge of
68 FOREST ENTOMOLOGY.
the leaf in the form of an S or ogee curve, until she reaches the mid-
rib, over which she skips and cuts another S line, until she reaches
the upper and outer edge of the leaf at about the same distance from
the midrib as where she made the first incision. The rolled portion
is partially weathered, and the other portion remains quite fresh. I
have searched many of the cases, but hitherto
have not found any eggs as in Aftelabus, though
several perfect insects have been found shelter-
ing within the folds.
The beetle (fig. 68) is about 2 or 3 mm,
long, of a black, shining, metallic colour, and
striated. The beak is more or less widened
Fig. 68.—Deporaiis betule at the tip end. The head is not narrowed
Gitte (Photoby 4. into a neck behind the eyes. The antenne
are 11-jointed, and the beetle is on the whole
a very pretty insect, though not so brilliant as the species of the
closely allied genus Rhyncophora; but the metallic hue depends
very much on the angle of light.
Genus OTIORRHYNCHUS.
i
This genus is perhaps more important to the gardener than the
forester, and the young student may get them in the first instance by
collecting in the garden.
OTIORRHYNCHUS PICIPES, Fabr. (Clay-coloured Weevil).
This insect is most injurious in the perfect stage, and generally
feeds at night on the shoots of various plants—viz., vines, raspberries,
and strawberries in the gardens, and on thorns and other plants in the
nursery and forest. I have only found it twice as a forest pest,—once
doing much damage to several classes of young trees in the nurseries
of Messrs Caldwell & Sons, Knutsford, Cheshire, and also on young
thorn hedges in High Legh, Cheshire. The latter case was accidentally
discovered in the following manner, A farmer once applied to me for
wire-netting as a protection against rabbits, which were, he said, eat-
ing the shoots of a recently cut-off hedge: the “cutting off” had
been done the second year after planting. Knowing that the hedge
in question was in the middle of a ploughed field, and where I thought
no rabbits could be near, I at once refused the request pending a
COLEOPTERA. 69
personal inspection. On arriving at the spot, I found the bark of the
quicks badly eaten from the cut, half-way down to the soil. In vain
I tried to persuade the farmer that it was insect and not rabbit
damage; but on lifting the small clods of
soil, the insects were found in great numbers,
and so beautifully did the soil blend with
the colour of the insect that only a practised
eye could detect them. As a remedy we
sprinkled paraffin on the soil, but a sudden
change of favourable wet weather following
a prolonged drought perhaps had _ better
effects than the paraffin dressing.
The perfect beetle (fig. 69) is about 7
to 8 mm. in length, or from one-fourth
to one-third of an inch. The head and _ es
Fig. 69.—Otiorrhyuchus picipes
thorax are blackish in colour, and the Cra (Photo by A.
elytra bearing to brown. This blending
of black and brown gives it the appearance of clay, hence the
name. Under the microscope the body has a scaly appearance.
The legs are ferruginous, and the. clubbed
antenne 12-jointed.
The lJarve live in the soil, and are whitish,
legless, and somewhat hairy. The pup show
all parts of the perfect insect.
OTIORRHYNCHUS SULCATUS (Fabr.) é
Fig. 70. — Otiorrhynchus
suleatus (vine. weevil),
5 oa, 7 ic Oo n natural size. (Photo by
_ This beetle (fig. 70) is generally found in pepe
vineries, and is popularly known as the vine
weevil. I once found it in Cheshire eating the young leaves of
the common blackthorn. It is larger than the previous species,
and of a dull black colour, varied with ochreous-yellow scales on
elytra.
Genus STROPHOSOMUS.
This genus may be characterised by the eyes being extremely
prominent, appearing in some species as if almost detached from the
head. The head is also large and triangular. There are several
species in this genus, but only two, namely, S. coryli and S. capitatus
70 FOREST ENTOMOLOGY.
(obesus), may be considered as arboreal. The former is often recorded
as doing considerable damage in this country, and the latter as being
injurious to certain young trees on the Continent. It is, however,
possible that the injuries of the latter species may have been overlooked
in this country.
Synopsis of the Species.+
I. Elytra not fitting tightly into the base of thorax ; scrobes slightly
but plainly deflexed.
1. Elytra with the suture denuded at base, forming a black longi-
tudinal patch at scutellum . : ‘ S. coryli, F.
Il. Elytra with the suture not denuded at base.
1. Erect hairs on elytra very distinct, if viewed sideways ; thorax
rugosely punctured . SS. capitatus, De G. (obesus, Marsh).
STROPHOSOMUS CORYLI (F.)
Various accounts have been given of this beetle doing considerable
damage by feeding on the foliage of larch, oak, birch, &c., in com-
paratively young plantations. It has also been recorded that con-
siderable damage has often been done by it to several species of
young trees in the nursery.
The insect, from a collector's point of view, may frequently be
beaten from several species of young trees.
This beetle is from 4 to } inch in length, almost spherical in form,
and of a uniform brownish-grey colour. The antenne and legs are
ferruginous, elytra with moderately punctured strie.
STROPHOSOMUS CaAPiTaTUS, De G. (oBEsus, Marsh).
This beetle is often found very injurious to the foliage of birch, and
may be beaten in showers from young trees or coppice in early
summer. The leaves are entirely riddled, so that where perfect
foliage is an important point a slight depreciation ensues throughout
the season.
The beetle is very much like the preceding species, but slightly
smaller in size and very globular in form,—a character, however, very
typical of the genus.
1 Fowler, vol. v. p. 189.
COLEOPTERA. veil
PoLyDRUSUS MICANS (F.)
I found this species very abundantly feeding on oak leaves of the
epicormie branches at Reedsmouth, Northumberland, May 15, 1901.
It could not be said, however, that they were doing appreciable
damage to the trees. Usually local, and not common.
The beetle is rather large and conspicuous, being from 7 to 9 mm,
in length, and the whole body is of a uniform coppery colour, and
being rounded, the colour varies in detail as the result of refraction ;
legs and antenne red, the club of the latter somewhat darker.
Genus PHYLLOBIUS.
This genus contains a large number of species, most of which may
be found in the forest. They are generally got in the early part of
the year, and often do considerable
damage to the foliage. As a rule,
the species may be recognised by
their more or less brilliant colouring.
One species, viz, P. urtice (alnett,
F.), is very common on nettles, and
though not an arboreal species, might
nevertheless be taken as a_ typical
example of the genus. It is quite
possible the specific distinction, as
associated with forest trees, may
hitherto not have been carefully
recognised.
PHYLLOBIUS MACULICORNIS (Germ.)
This beetle was discovered as doing
considerable damage on recently Ps: Folin of mountainah eatn
planted trees of mountain-ash and
birch at Kielder, in Northumberland. In fact, the trees were
quite defoliated as the result of their injuries.
On mountain-ash, fig. 71 is given as an example of the injury
referred to by the beetle.
" FOREST ENTOMOLOGY.
Hyxopius apretis, Fabr. (Pine Weevil).
This is considered one of the worst insect enemies the forester has
to deal with ; in fact, it may be said to be the most dreaded beetle.
From an entomological point of view, it is very closely allied to the
genus Pissodes, and it may therefore be well to state that the chiet
generic difference is that in Hylobius the antenne are inserted on
the rostrum near its apex, while in Pissodes the antenne are inserted
Fig. 72.—Young spruce plants gnawed by Hylobius abietis.
a, parts gnawed ; 6, parts still covered with bark.
about the middle of the rostrum. It is well to remember this
important distinction, inasmuch as many specimens of Hylobius abietis
are very small in size, and may therefore, to the non-entomologist, be
confounded with specimens of Pissodes pini, more especially when
found in fresh sawdust, and apart from the respective injuries with
which they are associated.
The pine weevil is injurious in the perfect state alone, chiefly to
young coniferous trees from four to seven years old. Older coniferous
1 As there is only one species in the genus, generic characters need not be
given.
COLEOPTERA. To
trees do not suffer so severely, but they have been known to attack
young hardwoods, more especially when mixed with coniferous trees,
They eat the tender shoots, both bark and cambium, in such a manner
as to present an appearance of rabbit damage (fig. 72). In our
country the plants most used for planting are about three to four
years old, and when such are attacked after being recently planted it
is obvious they are not strong enough to resist the injuries, and the
consequence is that many die off, and expensive replanting has to
be resorted to. When the bark of older trees is eaten the injuries
are not so severe. The weevil is especially fond of young shoots, and
the vital cambium is therefore eaten with the bark.
The beetle (fig. 73) is a dull black colour, but brightened by several
fairly large yellow spots on the elytra, which collectively form irregu-
lar bars. There are also a few yellow
scales on the thorax. The rostrum
is very stout, with the antennez in-
serted at the apex. Legs black, and
femora armed with a strong stout
spine. Length from 8 to 14 mm.
As regards the life-history of this
insect, it affords a very striking con-
trast to the life-history of some ; Cae
‘ Fig. 73.—Hylobius abietis (pine weevil).
moths, as, for example, those which a, beetle (natural size); b, larva(natural
appear and disappear within cer- OE nee ney Meet) es
tain prescribed dates. The pine
weevil may, with special entomological knowledge, be found in all
stages throughout the year. This fact, together with an unworked
life-history, led to great diversity of opinion. Thus Altum, who
carefully studied the species, maintained that a generation required
two years for its complete development, while Eichhoff considered it
more probable that there were two generations in a single year. This
point has now been decided by Von Oppen, who has done very
valuable work by working out its life-history from observations
carried on under circumstances approximating to its natural con-
ditions. Asa result of his careful investigations, he found that the
beetle was endowed with great vitality (extending over two years),
and further, that it has the power of re-copulation and repeated egg-
deposition. Hence this would account for the insect being found in
all its respective stages at one and the same time. A single gener-
74 FOREST ENTOMOLOGY.
ation, however, takes about fifteen months for complete development.
The beetles swarm, or rather leave their winter quarters, about the
beginning of April. These old beetles, therefore, deposit eggs on
the roots of trees which have been felled about two or three years.
The larve hatch out in about three weeks’ or a month’s time, and
feed until about May or June of the following year. They then
pupate for a short time, about three weeks being considered the
regular period, and appear as perfect beetles about June or July. The
late swarmers are comparatively harmless, as they soon hibernate
under rough grass and heather, ready to do double duty the following
year. The larve commence eating just under the bark, but do not
reach the bottom of the bark and the surface of the wood until about
the end of September. Then for the remainder of their feeding-period
they make long winding galleries,
It may be noted that there is a common opinion that the
insects lie for three years in the larval stage, and therefore it is
advisable to give the ground three years’ rest in consequence. The
amount of rest is quite practicable, but I am, from personal
examination, of opinion that they rather prefer attacking the roots
that have been cut for three years, and only live for a season in
the larval stage.
Preventive and Remedial Measures.
As this is a very destructive beetle, it is advisable that, as far as
practicable, the insect should be kept well in check.
As regards dealing with the beetle, the only remedy is collecting
and destroying. Success in this respect will greatly depend on the
method of local work and its associations. My own experience has
been in connection with cutting a portion of a large tract of pure
Scots pine every year with a movable sawmill in the wood, and also
replanting a portion of the ground annually. At first the replanting
was done on the heels of the cutting, and the result was that the
plants were eaten off wholesale, and replanting had to be adopted.
In the summer season the sawdust hole was carefully examined every
morning and the beetles from the fresh sawdust destroyed. So much
for beetle destruction. Now as regards the destruction of larve. In
the winter season all branches accruing from the trees felled in summer
were burned on the ground, and as many fires as possible made on the
COLEOPTERA. 15
stools of felled trees. This had the effect of destroying the breeding-
places. When the fires were in progress they were greatly augmented
by loose heather and other rubbish on the ground. This to some
extent had the effect of reducing the congenial conditions for the
hibernation of the prospective beetles during the coming winter ; and
finally, when the burning was completed, the land was temporarily
fenced and stocked for three or four years with sheep and
cattle. This had a remarkable effect, inasmuch as the bark was
removed from the roots, thus utterly destroying the breeding-ground
for the larve, and altogether improving the soil for the future
planting.
It is obvious, however, that this method can only be adopted where
fir woods are on a large scale. If, however, sudden replanting has to
be done with coniferous trees, where a mixture of pine-trees had formed
the previous crop, it would be well, if at all practicable, to uproot
the pines, or otherwise render the roots unfit for breeding-places.
Trenches might be made in the ground, and fresh sawdust scattered
in them ; or otherwise, lay pieces of fresh pulled bark on the ground,
rough bark upwards, to act as traps for catching the perfect beetles.
Genus PISSODES,
This genus is very closely allied to the foregoing. The genus
Pissodes contains two species in this country—viz., P. pint and P.
notatus ; but there are several species found on the Continent, and it
may therefore be some inducement for British workers to keep a
sharp look-out for additional species, together with their respective
injuries,
So far as our present knowledge goes, it cannot be said that the
Pissodes can be compared with Hylobius as regards forest injuries,
inasmuch as the former in the larval stage confine their attacks to
sickly trees, and in the perfect stage gnaw at the tips of young Scots
pine trees, but are not injurious in any appreciable sense.
The structural details of the genus are well described by Dr Stewart
MacDougall : !—
“The species belonging to this genus have a longish rostrum. Near
the middle of the rostrum the elbowed antenne are inserted, their
1 «The Biology of the Genus Pissodes,” Proceedings of the Royal Society of
Edinburgh, vol. xxiii.
76 FOREST ENTOMOLOGY.
long basal joint almost reaching the small, slightly-projecting eyes.
The prothorax is narrowed in front, and its posterior margin, on
examination with a lens, may show two slight excavations. The
scutellum is round and raised. ‘The elytra quite cover the abdomen.
Femur untoothed, tibia straight, and with a curved hook at the point.
The third joint of the tarsus is broad and two-lobed, and the terminal
fifth joint ends in two simple claws.”
Synopsis of the Species.
I. Size larger: thorax short in proportion with the sides, more
rounded ; elytra with narrow transverse band behind the
middle . , : ; ; : : P. pin.
II. Size smaller: thorax large in proportion with the sides, less
rounded ; elytra with a broad though not over-distinct trans-
verse band behind their middle . : . LP, notatus,
PissopEs PINI (Linn.)
This species is very closely allied to Hylobius abietis, and to the
young student very much like small specimens of the latter, inasmuch
as both species may be found together in the mornings in the fresh
sawdust pit underneath the circular saw. Where a temporary sawmill
is erected in a Scots pine wood, it may be well to try and distinguish
the two species. As many specimens of H. abietis are comparatively
small, it is well, for the sake of distinction, to bear in mind that the
chief difference lies in the position of the antenne. In H. abietis, as
already mentioned, the antennz are inserted on the rostrum near its
apex ; and in the genus Pissodes the antennz are inserted about the
middle of the rostrum.
Apart from the sawdust heaps, this species is found most abundantly
in the larval stage. As arule we may look for the larvee in dead
standing Scots pine-trees from twenty to thirty years of age, more
especially under the rough portion of bark. At times they may be
found on cut trees lying on the ground, but not so plentifully as on
dead standing trees. Nitsche gives spruce and Weymouth pine as
food-trees. In the winter season the presence of the larvee may be
recognised by the bark being very much torn about, from the ravages
of insectivorous birds in search of the larvee as food.
COLEOPTERA. Th
As the larvee are always found on back-going or dead standing trees,
this species cannot be considered as directly injurious. It would
therefore appear, on first consideration, that the forest should not
only be kept free from dead trees, but also that all heavily suppressed
trees, showing distinct symptoms of death or premature decay, should
be cut. This principle, however, pushed too far, would not be in
keeping with first-class forestry, inasmuch as unbroken canopy must
be maintained throughout the period of growth, more especially in
youth and middle age, and dying or recently dead trees are quite
useful for estate purposes, provided proper creosoting be adopted.
Fig. 74 is from a photograph of cocoons on dead standing trees
underneath the bark,
The life-history of the genus has been most carefully worked out
by Dr Stewart MacDougall, who
proved from both observation and
actual experiments that the dates
of appearance of perfect insects
were variable, as also the period
of time required for larval and
pupal duration itself. In North-
umberland the _ perfect beetles
emerge respectively most plenti-
fully about the middle of July.
The female beetle lays her eggs
in the bark, and the larve hatch
soon afterwards. At first the larve
move from the egg-chamber in
different directions, forming a sort of star, but later on the markings
appear in long, broad, irregular lines, generally running lengthwise
with the stem.
The larval markings are, as a rule, most conspicuous on the bark.
After the larva is fully fed it scoops out a chamber in the stem, and
covers itself over with the scooped-out chippings. Each larva makes
a chamber for itself, and those specimens which are fully fed in the
autumn pass the winter in the larval stage, pupate in the spring, and
appear as beetles during the summer. The chamber acts as a double
means of protection, inasmuch as it minimises the attacks of insect-
ivorous birds, and also shields the creature from injuries when the
loose bark is removed from the stem.
Fig. 74.—Cocoons of Pissodes pini on stem of
Scots pine (reduced).
78 FOREST ENTOMOLOGY.
The larva is a white, fleshy, legless, wrinkled grub, with brown
head and strong jaws. It generally is in a semicircular form, and
about half an inch in length.
The beetle (fig. 75) is dark pitchy-brown in colour, and sparsely
sprinkled over with yellow scales. The rostrum is longer than the
thorax ; antenne terra-cotta colour, with darker club. Thorax roughly
punctured, with a distinct raised middle line; elytra deeply punc-
tured, broader than the thorax at its base. On each elytron there are
four yellow spots, two in front and two behind the middle. Length
about 2 inch or 8 to 10 mm.
PissoDEs NoTatus (Fabr.)
It is very doubtful if this insect 1s so common as entomologists
maintain. Fowler gives ‘‘Chat Moss, near Manchester; Sunderland,
probably introduced in Scotch timber - laden
ships,” and “Scotland, rare Highlands, on
Scotch firs Dee and Moray districts.” Per-
sonally, I have not found it in this country,
but found it in Belgium, August 1905, near
the roots of Scots pine stems from five to
eight years of age. Fig. 76 is a very good
representation of the cocoons. It often hap-
pens that in plantations of pure Scots pine
Fig. Ca ae pint = from four to ten years of age, many plants
die off, just as we wish them to be produc-
ing close canopy. Numerous suggestions have been given from time
to time that the deaths referred to are due to fungi, but it is just
probable that they die off in consequence of being badly handled in
the nursery, or very badly planted by the notch method, and there-
fore having their roots twisted. I have examined many dead Scots
pines of the type referred to in Northumberland with a view to find-
ing P. notatus, but so far the search has been unsuccessful. Dr R.
Stewart MacDougall found that imported German specimens were
spreading in Scotland, so that it is probable we might have an
attack through insects having been imported in pit-props or other
materials.
1 P. gyllenhali, Schon., and P. piniphilus, Hbst., are introduced.
2 It has been taken at Woking and Bournemouth by Commander Walker.
COLEOPTERA. 79
As the genus Pissodes has been so admirably worked out by Stewart
MacDougall, I take the liberty of quoting the following conclusions,
which have important biological and practical bearings :—
“1, The Pissodes have a remarkably long life in the imago stage.
This long life is characteristic of both sexes.
“2. Copulation and egg-laying are not single acts which, once accom-
plished, terminate the life of the individual, but both may be often
repeated. The same individuals which have paired and bred in one
season may, after hibernation,
still further proceed to a new
season’s reproduction.
“¢3. Hibernation takes place in
the month of November, and in
a season of average temperature
ends in March, in exceptionally
mild weather even earlier.
“4. Ege-laying takes place in
all months from April (in a
very favourable season, even in
March) to September inclusive.
“5, As adult beetles may be
met with during all this period,
the length of time necessary for
individual development loses some
of the significance that up till
now has been assigned to it in
relation to exterminative meas-
ures, because a comparatively
limited flight-period being dis-
proved, corresponding limited and
definite swarm - periods can no longer be relied on.
“6, Still, limiting our view to one cycle and the earliest - laid
egos of that cycle, the generation is typically a yearly one.
“7, As the first imagos issuing in the summer, as a result of eggs
laid earlier in the same year, are not immediately able to proceed to
an efficient copulation, but require some time for ripening, there is
little likelihood of there being in our climate two generations in direct
descent in one calendar year,”
As regards remedial measures, however, they are very simple,
Fig. 76.—Young pine-stem barked to show pwpal-
beds of Pissodes notatus. (From ‘The For-
ester,’ by J. Nisbet.)
80 FOREST ENTOMOLOGY.
inasmuch as all attacked trees are generally in such a back-going con-
dition that the forester should, as far as practicable, cut them out of
the wood as soon as the attack is observed.
Genus ORCHESTES.
Antenne distinctly bent, and inserted behind the middle of the
trunk ; head small, and the upper surface almost entirely occupied by
the eyes, which are only separated by a narrow bend; thorax very
small in proportion to the abdomen. Scutellum small but dis-
tinct. Elytra long, and well covering the pygidium ; femora strongly
developed.
ORCHESTES FAGI (Linn.)
The Orchestes fagi, or beech-leaf miner beetle, is, as its name
implies, very destructive to the foliage of beech-trees. The most
conspicuous portion of the damage is that done by the larve, which
gives the tree the appearance of having suffered severely from late
spring frosts. In fact, even practical men often erroneously attribute
the injuries to frost. There is, however, this practical distinction
between the two—viz., that frost generally shrivels up the entire leaf,
whereas the injuries done by this beetle only affect one-half.
The beetle hibernates during the winter months under fallen
leaves, in the crevices of bark, or, in fact, under any rough cover.
It makes its appearance on the first warm days in spring, simul-
taneously with the opening of the leaves. It does not expose itself
very much during the day, but in the night-time moves on to the
young leaves, in which it cuts small circular holes, giving the foliage
the appearance of having been shot at. The female deposits her eggs
in the midrib, and as a rule about half-way down. The eggs hatch
in about ten days, when the larva immediately makes a straight cut
across the leaf to the outer edge, but generally in the same direction
as the lateral veins, so that it lands near the apex of the leaf. It
then turns inwards, and eats a fairly large portion of the parenchyma,
thus exposing the epidermal skins, and causing the large blotch referred
to (fig. 77). The small, straight, larval track from the midrib to the
outer edge is very important, inasmuch as its method is entirely
confined to Coleoptera, and is a decided mark of distinction from the
injuries caused by Hymenoptera, &c. The larve are full fed in
COLEOPTERA. 81
about twenty days. Then they pupate in a small white cocoon
within the leaves, and come out as perfect insects in about another
fifteen days’ time.
In 1904, at Alnwick, Northumberland, the eggs were deposited
about Ist to 10th May, and the insects first appeared about June 24.
On account of their pupating within
the leaves, they are very easily hatched
artificially.
The larva when full fed is about
one-third of an inch in length, creamy
white in colour, and has a rather flat-
tish brown head.
The beetle is about an eighth of
an inch in length, of a slaty - black
colour, with grey pubescence, and
rather coarse lines of punctures on
the elytra. The legs and antenne EAC Us ame ee
atesmuichi eprown 1) colour and thie =) 0% byilanvaiand. holes ean: by, beetle
5 ? (Orchestes fagi).
femore of the hind legs are well
developed, which enables the creature to jump when startled, and this
characteristic, together with the ample wings, which they can readily
use, enables the creatures to get out of the way very rapidly.
The worst damage I have ever seen done by this insect was in
Gibside, Co. Durham. This was pointed out to me by my friend
Mr R. 8S. Bagnall. The foliage of the old beech-trees looked as if it
had been riddled with showers of shot: not a single leaf had escaped.
ORCHESTES QUERCUS (L.)
This species is often found on oak leaves, and is red or brownish-
red in colour, and the body clothed with a silky yellowish pubescence.
It is generally found on the leaves of suppressed or over-shaded trees,
and if extremely abundant, imparts a yellowish tinge to the body of
the foliage.
ORCHESTES ALNI (L.)
This species is somewhat variable in colour, and those specimens
I have hatched out were from elm leaves collected in a Surrey lane.
They were of the variety which had reddish elytra, with darkish
head and thorax.
82 FOREST ENTOMOLOGY.
This genus is well worth careful study, more especially as they
prefer an arboreal diet ; and having regard to their habit of pupating
within the skins of the injured leaf, they can be very easily hatched
artificially. The small size of the insects themselves, and the neces-
sity of magnification for the discrimination of specific characters, give
an additional interest to the
study of the genus.
The student should make a
careful study of the specific
characters as given by Fowler.
Genus CRYPTORRHYNCHUS.
Scutellum large and distinct—
episterna of metasternum not
covered by elytra and well
developed.!
CRYPTORRHYNCHUS LAPATHI
(Linn.)
This insect is often found in
the south of England, doing con-
siderable damage to alders of
the black and white varieties,
willows, poplars, and birch. It
generally attacks alders in pref-
erence to the other trees, and pre-
fers young trees from four to six
Fig. 78, a, b.—Larval burrows of Cryptorrhyn- B S g
chus lapathi in alder stems. (From ‘Forest years of age.© The insect is
Protection,’ by W. R. Fisher.) Gite ;
injurious both in the larval and
perfect forms. The beetle eats the bark and sapwood of young shoots,
and the larva gnaws under the bark, sometimes penetrating into the
pith, thus doing considerable damage to the young stems—so much so,
that they break off and die. Fig. 78, a, b, shows typical damage.
The beetle flies about the end of April or beginning of May. The
larvee are said to appear in about fourteen days after egg-laying, and
1 Fowler, vol. v. p. 328.
> Commander Walker has always found it in and about osier-beds.
COLEOPTERA. 83
the beetle emerges in autumn, and winters either in the galleries or
under moss.
The beetle, fig. 79, is from 7 to 8 mm. long, and is very character-
istically coloured. The prevailing colour
is black, with a distinct variegated
band of pinkish-red at the base of
the elytra, and with a more or less
distinct band across the middle of the
elytra. The whole body is covered with
rather coarse, imbricate, yellowish-white
scales. The rostrum is stout, and can
be folded into a depression under the
thorax. Fig. 79.—Cryptorrhynchus lapathi.
As regards remedies, it will obvi- ee Protection,’ by W.
ously be the best means of extermin-
ation to cut down the infested shoots containing the larve or perfect
beetles, and burn them.
Genus BALANINUS.
This genus contains several species which are all arboreal, and
therefore of special interest to the student of forest entomology. The
species B. nucuwm may, however, be taken as typical of the genus.
The most remarkable generic character is the very long, slender
rostrum, which varies in length according to the species, but is often
longer than the whole of the remainder of the body. The length of
the rostrum enables the insect to pierce fil-
berts, acorns, walnuts, &c., in which they ee,
deposit their eggs.
BALANINUS NucuM, L.
It often happens that on eating filberts 4, g9palaninns nucum
or hazel-nuts we either find a very large (eniarg?d).- (Ehsto, by A-
: . ) Flatters.)
white grub, or otherwise a hollow shell con-
taining frass or powder. ‘Those grubs are the larve of the nut weevil.
The beetle, fig. 80, is easily recognised by its very long snout (being
longest on the female) and elbowed antenne. The whole body is
dark-brown in colour, but brightened by variegated markings and
? 5 5 5
short depressed hairs. Length 5 to 7 mm.
84 FOREST ENTOMOLOGY.
The beetles appear early in spring, and may then be beaten from
the bushes. The female bores a hole with her proboscis in the very
young nut, and then deposits an egg. In a short time the grub
hatches out, and feeds on the fleshy portion of the nut. When full
fed in the autumn, the larva leaves the nut and pupates in the soil,
appearing as a perfect beetle in spring.
When filberts or hazel-nuts are considered of importance as fruit,
the pest may be kept in check by beating the perfect beetles into
a sheet or umbrella in spring; or the
infested nuts, so far as they can be
recognised, may be gathered before
the escape of the larve and burned.
Genus RHOPALOMESITES.
RHOPALOMESITES Tarpy1 (Curt.)
This beetle is considered almost
exclusively an Irish species. It is
injurious to half-dead beech tim-
See ah * ber, and it may therefore be said
ag Bae ote Tei" ™ that it considerably hastens its
decay. Fig. 81 is a representation
of the damage done to half-decayed beech planking. Iam indebted to
Professor Carpenter, Dublin, for the specimen from which the photo-
graph is taken.!
References to Literature consulted.
Altum. Forstzoologie, iii.
Carpenter, G. H. Entomological Papers.
Fisher, W. R. Forest Protection.
Fowler. British Coleoptera.
Judeich und Nitsche. Forstinsektenkunde.
Kaltenbach. Die Pflangenfeinde.
MacDougall, Dr R. Stewart. The Biology of the Genus Pissodes.
Nisbet. The Forester.
Niisslin. Leitfaden der Forstinsektenkunde.
Ormerod, E. A. Manual of Injurious Insects.
Packard. Insects Injurious to Forest Trees. U.S.A.
Rye. British Beetles.
Theobald. The Animal Pests of Forest Trees.
1 Comparatively rare in England. Commander Walker has taken it at Ply-
mouth, and has it from the Hastings district.
CHAPTER III.
COLEOPTERA—SCOLYTIDZE (BArk-BEETLES).
From the point of view of forest entomology, one of the most im-
portant groups of insects is that of the beetles known as Scolytida,
inasmuch as they are practically all tree-feeders. As a general rule,
they attack only dead, dying, or back-going trees, and therefore it is
possible that, from a purely economic point of view, their importance
may have hitherto been over-estimated by many writers. At the
same time, there are a few exceptions to this general rule. For in-
stance, in one stage of its life-history Hylurgus (Hylesinus) piniperda
attacks the healthy shoots of Scots pine trees ; and Prtyogenes biden-
tatus often attacks sickly and unhealthy young trees, and thus kills
outright what otherwise would have recovered.
Many of the beetles are exceedingly small in size, which fact, coupled
with their minute structural points, makes them of great interest to
the working entomological microscopist.
In a general way the bulk of this family are known as bark-borers,
and the Germans consequently call the whole group “ Borkenkiifer,”
or bark-beetles. But this is only a general term, for, as a rule, the
majority bore deeper, and leave their impressions, or all-important
markings, just under the bast, and immediately over the surface of
the wood. Others, again, bore directly into the timber, but, as a rule,
these wood-boring species confine their attacks entirely to the sap-
wood, and rarely penetrate into the heart-wood. Thus we have, in a
general way, three divisions—viz., those which bore into the bark,
those which work on the surface of the wood, and those which bore
directly into the timber. So far as classification is concerned, we
cannot make any arbitrary divisions, but the characteristic markings
themselves are about as suitable data for the discrimination of species
as it is possible to get.
86 FOREST ENTOMOLOGY.
As the respective genera and species show variation in life-history
and markings, it would perhaps be well for the student to study the
salient features of a typical bark-beetle, as regards the formation of a
brood, and its subsequent life-history.
With regard to the formation of the brood, there is one important
point to be noted—viz., that some genera are monogamous, whilst
others are polygamous. In the case of the former, the initial opera-
tions are always conducted by the females, whereas, in the latter, they
are always made by the males. ;
Take a typical monogamous species. Both sexes hibernate during
the winter months, but the female awakes first, and betakes herself
to a suitable tree, where she scoops out a small chamber, and then
takes a sort of nuptial flight, as it were, for she returns generally
accompanied by the male, and copulation takes place either within
the chamber or immediately outside it. The female then com-
mences her work in earnest. She makes a straight tunnel, and
deposits eggs right and left alternately. Her presence can always
be recognised by the frass, or bore dust, made by the workings,
which is deposited outside the burrow. The male is generally
found just at the entrance of the burrow. As the female moves
along, she often makes little bore-holes over her tunnel, for the pur-
pose of ventilation.
In due time the larvee hatch out, and moving along their respective
galleries, which broaden according to larval growth, they finally
scoop out a chamber, and then pupate. It is important to note, as
we shall consider presently, that it is the particular angle made by
the junction of the larval with the maternal galleries which gives the
peculiar markings of the respective species. The fully formed beetle
eats its way through the bark, which, after the swarming or flight
period, looks as if it had been riddled with shot. The holes made by
the exit of the beetle can, however, by careful inspection, be distin-
guished from those made by the mother for ventilation, as the latter
are always made over her own tunnel.
In those cases where the initial operations are conducted by the
males, the excavation is a sort of circular chamber, where several
females, generally from four to six, assemble, and within which
copulation takes place. Hence it is called by the Germans ‘“‘ Rammel-
kammer,” or brood-chamber. The females then make their respect-
ive galleries, all radiating from the brood-chamber. The male very
COLEOPTERA—SCOLYTID. 87
soon afterwards dies. In nearly all cases the female dies at the end
of the burrow, after the deposition of eggs.
In a general way the appearance of many species of insects is very
much affected by climatic conditions, and the Scolytide are especially
susceptible to the influence of weather. Thus the first appearance of
the hibernating species in spring depends on the warmth and sun-
shine. The weather also affects the swarming of the brood, and the
colour of the beetle is therefore sometimes variable, as specimens
which swarm soon after changing from the pupal to the perfect stage
are light as compared with those fully developed specimens which, on
account of unfavourable weather, have had to remain for a consider-
able time within the food-plant. The markings, too, are sometimes
affected, as the perfect beetles, in their quarantine stage, often make
markings beyond the pupal recesses.
These remarks apply to the markings of a typical bark-beetle ; but
the student, we repeat, must make a very careful study of the mark-
ings, because they are so definite in character that from them alone
the species can always be determined.
Tt must also be borne in mind that there is a sharp and definite
distinction between certain species which feed on conifers and others
which feed on hardwoods, inasmuch as we never find coniferous
feeders living in hardwoods and vice versa. This distinction, how-
ever, applies to species, and not to genera. For example, take the genus
Cryphalus. Thus C. abietis and C. picece feed on spruce and silver fir
respectively, while C. fugi and C. tilie live on beech and lime.
The various parts of the tree itself also harbour different species,
and therefore several species may be found on one tree. Take, for
example, a comparatively young Scots pine tree. In the top twigs we
may have Pityogenes bidentatus, and in the smaller branches H7/lastes
palliatus. The stem may harbour Hylurgus (Hylesinus) piniperda,
and the root-surface Hylastes ater.
The mother-gallery is a- most important character, and no illustra-
tion is quite complete unless it is shown. The mother-gallery, as
a rule, is either perpendicular or horizontal — that is to say, it is
perpendicular when running in the same direction as the standing
stem, and horizontal when running across the direction of the stand-
ing stem. The mother-gallery may be either single- or doubie-armed,
and in working she makes one arm at a time.
A more detailed consideration of the galleries or markings may now
88 FOREST ENTOMOLOGY.
be made, taking the very lucid diagrammatical plate from Judeich and
Nitsche. In fig. 82, a, we get a simple single-armed mother-gallery,
Fig. 82.—Typical workings of Scolytide.
a, Single-armed mother-gallery, showing equal larval galleries and pupal recesses; 6, short
mother-gallery and radiating larval galleries; c, single-armed short horizontal mother-
gallery and long right-angled larval galleries; d, double-armed horizontal mother-gallery
with right-angled larval galleries; e, two-armed mother-gallery of a polygamous species ;
J, four-armed mother-gallery of a polygamous species; g, five-armed mother-gallery of a
polygamous species ; h, star-gallery of a polygamous species; 7, ladder-gallery of a wood-
boring species ; k, forked mother and larval galleries; /, an irregular ladder-gallery; m, a
family gallery. Copied from Judeich and Nitsche.
with the larval galleries radiating slightly from the mother- gallery.
COLEOPTERA—SCOLYTIDA. 89
If we take, therefore, the middle of the mother-gallery as a centre, we
shall see that the larval galleries, in a geometrical structure, somewhat
resemble the stones forming an arch, inasmuch as they all radiate
from a common centre. In fig. 82, b, we have a very short mother-
gallery, with radiating larval galleries. In fig. 82, c, we have a single-
armed mother-gallery and right-angled larval galleries.
In fig. 82, d, we have a double-armed horizontal mother-gallery,
with practically right-angled larval galleries. In fig. 82, e, we have
similar mother-galleries of a polygamous species. In fig, 82, /, we have
a four-armed mother-gallery, with right-angled larval galleries.
In fig. 82, g, we have practically a repetition of 82, b, except that
the mother-galleries are horizontal.
In fig. 82, h, we have a star gallery formed in a slightly different
way, inasmuch as the circular central portion is made by the male,
and the female galleries radiate from the male chamber, while the
larval galleries again radiate from the mother-gallery.
In the foregoing it should be noted that all the young beetles finally
leave (swarm) by gnawing new flight-holes; but in the remaining
figures, as representing distinct wood-borers, the young beetles finally
leave (swarm) through the old bore-holes.
In fig. 82, 2, we have a “ladder gallery ” in wood, where the mother-
gallery is horizontal and the larval galleries perpendicular. The larval
galleries are very short, as in Trypodendron lineatum.
In fig. 82, /, we have forked mother and larval galleries, making
collectively a sort of gallery of pipes, as it were, on a comparatively
even plane, as in 7. monographus.'
In fig. 82, 7, we have a representation of a horizontal mother-gallery
and perpendicular larval galleries. It may be considered as illustrative
of T. dispar.
In fig. 82, m, we have a representation of a family-gallery, as in 7’.
Saxeseni?,
The generations of the Scolytide are very variable. In the German
literature we note two or more broods per year of a species which only
produces one brood in the north of England ; and again we get some-
times two broods per annum of a species in the south of England
which only produces one brood a-year in the north. These varia-
tions are by no means universal, but the student must be careful to
note them.
1 This species is not found in England.
90 FOREST ENTOMOLOGY.
The general structure of the beetles themselves is somewhat peculiar.
The most salient feature, which gives the Scolytide their particular
form, is the shape of the thorax, which is nearly always of equal
breadth with the elytra; and in several genera the thorax also acts as
a sort of hood which covers the head, and thus, looking at the creature,
the head itself is very often invisible. Hence, when looking at the
beetle, it may be noted that the visible portions—namely, thorax and
abdomen—present together a sort of oval or cylindrical form. In
many species the elytra have anal hooks, which are occasionally of
importance in determining species.
The under side of the abdomen is sometimes of considerable import-
ance, as one or more of the segments may have
special projections, as, for example, in Scolytus
multistriatus.
As regards special structural details, the mandibles
are stout, curved, or slightly toothed. The antenne
are short, inserted between the eyes, and form good
points for the discrimination of species. They are
divided into three parts —fig. 83: the club (c),
the funiculus (F), and the scape (s). In German
literature these parts are known by the names of
club, whip, and shaft respectively. The eyes are
Fig. 83.—Antenna of of special interest, inasmuch as they may be of
Hylesinus crenatus. ; C
(Camera -lucida one body deeply cleft in the middle, or other-
sketch.) A 10 a6 :
wise distinctly divided into two parts. The legs
should be carefully noted, as in many species they are too small for
examination by a good lens, and form interesting objects when pre-
pared as microscopic slides. ‘They are, as a rule, short and stout in
all the respective parts, with toothed femur and a five-jointed variable
tarsus, which is terminated by a double claw.
The larve are fleshy white or yellowish white, with pale yellowish
head. ‘They are footless, and broadest at the head, tapering towards
the anal segment. The respective species cannot always be recognised
by their structure, but many species may be distinguished by their
habits and the nature of their galleries. The pup are, as a rule, pale
white, and show all parts of the perfect insect.
To the physiological biologist this group may, on the principles of
Natural Selection, be considered as of special interest as presenting
COLEOPTERA—SCOLYTID &. 91
some very suggestive points. For example, the white, footless, taper-
ing larve associate the thought of adaptability for tunnelling ; and
the circular form of the body, the short antenne, buried head, and
stout legs of the adult, eloquently proclaim the suitability for boring
and clearing out the bore dust without injury to, or obstruction from,
the appendages.
There is also another very suggestive problem—viz., the association
of the male and female in the same burrow. It has been noted that
copulation may take place outside the main entrance or, as a rule,
just immediately inside the entrance, where a special chamber, known
as the chambre de copulatrix, is formed. After fertilisation the female
makes a burrow, in which she deposits eggs right and left in miniature
recesses. The male remains behind, and either guards the female or
the eggs against natural enemies, or clears out the frass or bore dust
excavated by the female. In a single-armed gallery the sexes may
therefore easily be determined by position, inasmuch as by following
up the gallery from the entrance we come first upon the male, and
afterwards the female. Such is the method in a single-armed gallery ;
but in many cases the gallery is double-armed, and the female works
one arm at a time, then retires and works the other arm. Now, why
this double arm? and why this second working shift? Is it possible
that it may be for re-copulation? We know that in some insects
this is an essential for reproduction, as, for example, in the case
of Hylobius abietis, and it may be possible that such is the case in
certain species of Scolytide. This is only a suggestive thought,
but doubtless much may be learned by observation in this sphere of
entomology.
As regards general measures for getting rid of the beetles, various
suggestions have been offered; but seeing that, as a rule, they only
attack dead or dying trees, it is obvious that the best preventive
measure would be, either to keep the plantations as healthy as possible
or to get rid of the dead and dying trees. Branches should always be
burned, and, as far as practicable, when the insects are in the larval
stage.
With a view to collecting the beetles for the purposes of scientific
study, it is well to cut down certain trees or branches and leave them
on the ground, to act as decoy stems or traps; and in searching for
certain species it is often advisable to look on the under side of the
branch and in places where the ground is rather moist,—moisture
92 FOREST ENTOMOLOGY.
being often an essential condition,—though, as they are rather fastidi-
ous as to the amount of moisture, it would be useless to look for them
in extremely wet places.
SCOLYTID.
The family is divided by Fowler into the following sub-families
—viz.:+
I. First joint of tarsi (or metatarsus) much shorter than the
remaining joints united; sides of thorax not emarginate
for the reception of the legs; eyes oblong or divided; head
never broader than thorax : : ; Scolytine.
II. First joint of tarsi (or metatarsus) almost as long as the
remaining joints united ; sides of thorax emarginate for the
reception of the legs; eyes round, subconvex ; head broader
than thorax ‘ ; ; : . Platypodine.
ScoLyTINz.
This sub-family embraces the whole of the genera of Scolytide,
with the exception of Platypus, which is a genus containing a single
species. The whole of the other species in the family are divided by
Fowler into the three following tribes :—
I. Thorax not prolonged over the head, which is always in part
visible from above, and is terminated by a short snout ;
thorax without any marked asperities on its anterior portion ;
third tarsal joint nearly always bilobed.
A, Abdomen strongly raised obliquely from near apex ; thorax
bordered at sides . : : : : Scolytina.
B. Abdomen not, or only slightly, raised, as a rule regularly
cylindrical ; thorax not bordered at sides. Hylesinina.
II. Thorax prolonged over the head, which is sunk in the thorax
when the insect is at rest, and is more or less globose;
thorax almost always furnished with more or less distinct
warty asperities in front; third tarsal joint simple
Dryocetina.
! British Coleoptera, vol. x.
COLEOPTERA—SCOLYTID®. 93
Trise SCOLYTINA.
Genus SCOLYTUS.
The genus Scolytus confines its attacks exclusively to the broad-
leaved trees of the forest or fruit-trees of the orchard.
The chief generic characteristics are: Knob of antenne large, larger
than the whip; eyes longish and linear; body smooth; therax much
darker than the elytra.
Synopsis of the Species.
I. (1) Second ventral segment of abdomen without projection. Elytra
shining, thickly punctured ; third and fourth segment in both
sexes furnished with a small tubercle. Mother-gallery per-
pendicular. Livesinelm . ; . Scolytus destructor.
(2) Thorax very finely punctured, especially on the disc. Mother-
gallery long and perpendicular. Generally in fruit - trees.
S. prunt.
(3) Thorax very finely punctured, especially on the disc. Mother-
gallery short and horizontal ; very long larval galleries. Lives
in oak . : : : : : S. intricatus.
IT. (4) Second ventral segment with a strong horizontal projection.
Perpendicular mother-gallery. Lives in elm, poplar, cherry,
plum, pear, and oak . ; ; . 8S. multistriatus.
ScOLYTUS DESTRUCTOR (Oliv.)
Scolytus Geofroy?, Goetz (Eichhoff).
" 1 (Judeich and Nitsche).
Eccoptogaster scolytus, F. (Altum).
This beetle chiefly confines its attacks to elm-trees, and is therefore
commonly known as the “elm bark beetle.” It is a dreaded pest in
elm-growing districts, as for example in many parts of the south of
England and in the London parks. The perfect beetles appear about
the middle of June, and the female commences her boring operations
either in a newly felled trunk or an unhealthy tree. Previous to
making the burrow proper, she makes a sort of pseudo-track in a deep
furrow of the bark; and as the male appears about this time, it is
94 FOREST ENTOMOLOGY.
doubtless during this initial boring operation that copulation takes
place. She then makes her burrow proper, which is from 1 to
4 inches in length, and therein deposits from 100 to 160 eggs.
This operation is said, as a rule, to take about three weeks to
complete.
The markings are very characteristic, more especially when the
mother-gallery is comparatively short. The mother-gallery is straight
and single-armed (fig. 84). Taking, therefore, the middle of the gallery
as a centre, it may be noted that the larval galleries do not quite
Fig. 84.—Markings of Seolytus destructor Fig. 85.—Showing ‘‘ evit-
in bark of English elm. holes” of same.
run at right angles with the mother-gallery, but point slightly towards
the extreme ends; and as we look towards either end of the mother-
gallery, it is noticeable that the angle becomes more acute, and con-
sequently the spaces between the extreme ends of the larval galleries
widen. Hence if a line were drawn all round the extreme ends of
the larval galleries, it would form an oval-shaped figure, with the lines
radiating from the centre to the outer edge. Fig. 85 shows the holes
whence the beetles have emerged.
The beetle (fig. 86) is about 4%; of an inch in length. The thorax is
black and shining, and the abdomen light-brown. The beautiful sharp
contrast of colour is a conspicuous feature, and thus affords a rapid
ite)
or
COLEOPTERA—SCOLYTID.
means of recognition. The thorax is large, and the length exceeds
the breadth. The antenne and legs are ferruginous.
The larvze are white, fleshy, footless grubs, with very strong chitin-
ous head and wrinkled body. They are full-fed towards the end of
July, and by the beginning of August perfect beetles may be found.
Many of the larve pass the winter in cocoons, and appear as perfect
insects in May.
As this species is very destructive, the following practical remarks
regarding prevention may be quoted :—
“One of the most important considerations, in regard to prevention
of attack, is the removal of all centres of infestation, from which the
beetles might spread to the sound trees.
“The possibility of clearing away or treating infested standing
trees or infested limbs depends, of course,
on local circumstances ; but whatever care
is exercised in other ways, it is very un-
likely that much good will be done in less-
ening attack, so long as the inexcusable
practice continues of leaving trunks of in-
fested elms lying, with their bark still on,
when containing myriads of these maggots,
which are all getting ready shortly to change
to perfect beetles, and to fly to the nearest
growing elms. Such neglected trunks may ig. 86.—Seolytus destructor.
be seen in our parks and rural woodyards Aout Toho) aaa ce aes
all over the country, where, without diffi-
culty (as I have myself often found), the hand may be run under the
bark, so as to detach feet and yards in length from the trunk, all
swarming with white Scolytus maggots in their narrow galleries.
“This bark, with its contents, ought never to be permitted to
remain. Where it is loose, it may be cleared of many of the maggots
by stripping it off and letting the poultry have access to it ; or, if still
partly adhering, it may be stripped from the wood by barking tools,
and burnt. But if allowed to remain swarming with maggots,
it is a tangible and serious cause of injury; and if our landed
proprietors were fully aware of the mischief thus caused to their
own trees, and those of the neighbourhood, they would quickly get
Tid Ofelia
1 Miss Ormerod, Manual cf Injurious Insects, 1890.
96 FOREST ENTOMOLOGY.
ScoLyTUs PRUNI (Ratz. )
At first sight this species very much resembles the preceding, but
it is smaller, and the sculpturing of the elytra is very much finer.
The thorax is shining black, and the elytra ferruginous. Antenne
and legs brown. Length 34 to 44 mm.
This species is generally considered as exclusively belonging to the
orchard, and living in plum, pear, or apple. Eichhoff, however, says
that it has been found in hawthorn, mountain ash, and elm.
Several years ago I found in Cheshire very fine markings in a
Fig. 87.—Markings of Scolytus pruni Fig. 88.— Markings of Scolytus
in branch of apple. multistriatus in bark of elm.
strong limb of wild cherry, which was doing duty as a fencing-post
in a farmer’s hedge, and I have since concluded that in all probability
they were the markings of this species.
Fig. 87 is from a photograph of markings on branch of apple
found in Gloucestershire.?
ScOLYTUS MULTISTRIATUS (Marsh).
Thorax black, shining, somewhat longer than broad ; elytra pitchy-
red; antenne and legs light-brown; elytra with close and finely
1 Commander Walker has seen an apple-tree apparently killed by this species
at Wolvercot, near Oxford.
COLEOPTERA— SCOLYTIDA. 97
punctured striz ; abdomen thickly covered with hairs, and, viewed
sideways, there is a strong horizontal projection on the under side of
the abdomen, which is peculiar to this species.
Length 2 to 3 mm.
This species makes its galleries in thin-
barked elm. The mother- gallery is from
one to one and a half inch in length, and
perpendicular with the stem. The larval
galleries are approximately at right angles
to the mother-gallery.
I found the piece of bark which pro-
duced the photograph for fig. 88 in Glouces-
tershire, and Mr Morse, Leeds, sent me
insects for description.
This species is said to be double-brooded.
ScOLYTUS INTRICATUS (Ratz.)
The species is said not to be at all com-
mon, and only once have I found any trace
of its markings in Northumberland. Mr
A. C. Forbes informs me that it is common
in Wilts on oak limbs broken by wind. I
found the specimen which supplied the
photograph for fig. 89 in Belgium, on an
oak stake, and just recently I found it fairly
common at Newball, in Lincolnshire. The
mother-gallery is horizontal and short, being
about 3 to 1 inch in length. The larval
galleries run at right angles to the mother-
gallery, and are about 2 inches in length.
The beetle, fig. 90, is described by Fowler
as being about ‘3-4 mm. long, black, shin-
Fig.89.—Markings of Scolytus
intricatus on oak pole.
Fig. 90.—Scolytus intricatus.
(From Fisher’s ‘ Forest Pro-
tection.’)
ing, elytra duller, with the antenne and legs ferruginous, and the
femora and elytra pitchy brown or pitchy red.”
Altum cites a case! where 50,000 oaks, 25 to 30 years old, were
killed by this species.
1 Forstzoologie.
G
98 FOREST ENTOMOLOGY.
Trine HYLESININA.
The tribe Hylesinina is divided into the following genera by
Fowler—viz. :
I. Eyes not divided ; third tarsal joint nearly always dilated and
bilobed.
(i) Funiculus of antenne with seven joints.
1. Club of antenne globose or ovate.
A. Anterior coxe contiguous ; first joint of the club of
the antenne very large, shining, the following very
short . ‘ : : : Hylastes, Er.
B. Anterior coxze widely distant ; first and second joints
of the club of the antenne large, almost equal, the
following very short i . Hylastinus, Bedel.
2. Club of antennz compressed, oblong . Hylesinus, F.
(ii) Funiculus of antenne with six joints.
1. Anterior cox narrowly separate ; thorax with long villose
hairs at sides ; length 4-5 mm. . Myelophilus, Eich.
(Hylurgus pars, Brit. Cat.)
9. Anterior coxze rather widely separate; thorax evenly
pubescent ; length 25 mm. . Cissophagus, Chapuis.
(iii) Funiculus of antenne with five joints.
Club of antennze oval, nearly globose, formed of four
joints, fitting closely together Xylechinus, Chapuis.
(Carphoborus, Brit. Cat.)
Club of antennz formed of three loose detached joints
Phlcophthorus, Woll.
II. Eyes completely divided; third tarsal joint entire, not broader
than the preceding ; antenne with a solid ovate club, and
with the funiculus five-jointed : . Polygraphus, Ey.
Genus HyYLASTES.
This genus is interesting to the collector, but not specially so to the
forester. Fowler gives five and Barbey eight species. They can be
readily distinguished by their general cylindrical appearance. The
thorax is not broader than long, and has long, smooth, punctured
lines, and the abdomen is practically uniform with the thorax. The
COLEOPTERA—SCOLYTID 2. 99
whip of the antennz is seven-jointed, the club acorn-shaped and not
severely compressed.
There are two species, more or less generally distributed throughout
the country—viz., H. palliatus and H. ater—which may be considered
as the more important arboreal species.
Synopsis of the Species.
Thorax not very long, and rugged at sides. Elytra distinctly reg-
ularly punctured. Centre line raised. In stems of spruce or
Scots pine . : ; Hy. palliatus.
Thorax longer than broad, aides of aronotam almost equal and
parallel. Centre line of thorax not raised. In stems of young
Scots pine near the root. ; : : 2) ly ater.
HYLASTES PALLIATUS (Gyll.)
The beetles hibernate in dead trees, and appear about the latter
end of March or beginning of April. They generally select spruce-
trees which have been felled the previous winter, and it is best to
look for them on stems of trees lying on the ground, especially where
the branches have been cut off by the woodman’s axe. If the wood-
man should have made a few false blows, and not have done his work
very well, the imperfect result is an advantage to the beetle, inasmuch
as the jagged pieces form a sort of lodgment, and often quite a colony
of twenty or even more beetles may be found in such places.
The larve appear about the latter end of April or beginning of
May. The arrangement of the markings is very difficult to follow.
At first the mother-galleries are perpendicular, but they often deviate,
and the larval galleries may radiate in any direction. Thus we
simply get a confusion of markings.
In comparatively large stems of spruce we generally find the
markings made in the bark, but in branches of Scots pine we find
them on the wood. Fig. 9i is taken from a Scots pine branch.
Eichhoff says that this species is double-brooded. This is so in
some cases in Northumberland, and often the second brood remains
fully developed within the bark, and swarms in spring. Again, I
have found that this species is often single-brooded in Northumberland,
so that as regards life-history the matter requires further elucidation.
100 FOREST ENTOMOLOGY.
The beetle (fig. 92) is about 3 to 34 mm. long, and of a darkish-
brown colour throughout. The interstices are deeply, but uniformly,
} _ ys “3
Fig. 91.— Markings of Hylastes
palliatus on branch of Scots
pine.
punctured, and studded with warts, so that
it is slightly rough in appearance.
Hy.astTes ATER (Payk.)
This species is known as the black pine
bast-beetle, and may be easily recognised
by its uniform black colour and elongated
appearance. I have found this species in
Northumberland at Corbridge Fell. In
the winter months it is fairly common
under the comparatively thin bark of
Scots pine logs of six to nine inches
diameter (tops left lying on the ground
after removing large stems), more especi-
ally on the under side where lying in a
fairly moist position. The perfect beetles,
on leaving their winter quarters in early
summer, are very much attracted by the
resin which exudes from the butt-end of the stem on newly felled
Scots pine trees. Such embedded specimens are not much use for
the cabinet, though they may to some extent be clarified by
Fig. 92. —Hylastes palliatus.
(From Fisher's ‘ Forest Pro-
tection.’)
portion of the stems of
of age, more especially
immersion in turpentine. On July 3, 1907,
I found a plentiful supply of this species
at Corbridge Fell on a recently sawn stack
of rails of Scots pine. They were moving
about on the rails, but on attempting to
bottle them they nearly all feigned death.
The habits of this species would therefore
appear to be somewhat different from the
family, inasmuch as the beetles of this family
generally pass their time within the food-plant.
As regards its true relation to the forest,
the breeding-places proper are at the lower
young Scots pine trees from 6 to 10 years
unhealthy trees, which are obviously going
back, in consequence, perhaps, of the reaction from careless planting.
COLEOPTERA—SCOLYTID. 101
The brood-gallery is very simple, of a slanting direction, and the
larval galleries short and inconspicuous.
The beetle is elongated, cylindrical, black, shining, and smooth.
Elytra with coarse crenate striae. Length 4 to 5 mm.
Genus HyYLESINUS.
This genus is a very important one to the student of forest insects,
inasmuch as all the species are strictly arboreal insects, and the group
therefore has been termed ‘ Hylesinide or wood-devourers.” Three
of the species feed on ash and one on elm.
Synopsis of the Species.
(1) Black or dark-brown, without scales. Size large. Mother-
galleries single- or double-armed ; short, and horizontal. Larval
galleries very long and tortuous. Found in strong bark of old
ash stems . : : : ; . HM. crenatus.
(2) Variegated with greyish scales. Size smaller. Double-armed,
fairly long mother-gallery, and right-angled or slightly radiating
larval galleries. Lives in comparatively young ash stems or ash
poles : : ‘ : : HI, fraxini.
(3) Elytra black, with yellowish dorsal streak. Short horizontal
mother-gallery ; sometimes very long running larval galleries,
at other times short crowded larval galleries. Lives in small
branches of ash : ‘ : 5 . HH. oleiperda.
(4) Beautiful variegated colour. Size very small. Double-armed
short mother-gallery ; short larval galleries. Lives in elm.
H, vittatus.
HYLESINUS CRENATUS (Fabr.)
This beetle is always recorded to have been found in ash in this
country, though two or three German writers give instances of its
being found in oak. It is also said to be widely distributed, but, so
far as I ascertained, it was not at all common in Cheshire, though
very common in Northumberland ; and it appears to be common in
Lincolnshire.
It is by no means clear that the eggs are always deposited in felled
timber, though it may be looked for on recently felled old trees with
102 FOREST ENTOMOLOGY.
rough bark, or on old standing trees which are considerably past their
best. It often happens with trees of the latter character that one
side of the stem presents bark harder and more nearly dead than the
other, and the beetles should be looked for on the less vigorous side.
The presence of a few exit-holes will often assist in revealing the
abode of this species.
The life-history of this species is not quite so clear as one nana
wish. In some cases the generation is said to be double-brooded,
whilst in other cases there
are two generations in three
years. The flight period is
about the beginning of April,
or about the middle of Oc-
tober. The female makes a
short, bent, and deep gallery,
which is, as a rule, double-
armed, but single-armed gal-
leries are often found.
As a rule, the larve have
no decided method of mak-
ing galleries, and it is there-
fore very difficult to accept
any particular markings as
typical. This difficulty is
intensified by their boring
habits, inasmuch as you
—_ —— may find them either in the
Fig. cit RAL a lacey eas on ash stem deep bark or in the wood
itself; therefore when the
bark is removed the markings found on the wood are often only part
of the workings. When, however, we do find the extreme length
of the workings, they are generally about 6 inches long, and often at
right angles to the mother-gallery. In consequence of the extreme
length of the galleries, much harm may be done to very old trees,
as these galleries may encircle the stem, and thus hasten decay.
Fig. 93 is a representation of the markings of this insect.
The beetle (fig. 94) is about 4 to 5 mm. in length, of a convex form,
pitchy black throughout, somewhat shiny, and with comparatively long
antenne. The latter are often ferruginous in colour, with the shaft
COLEOPTERA—SCOLYTID A. 103
and whip clothed with long ciliate hairs. The elytra are very coarsely
striated, thus imparting to the insect a rather rough appearance.
The legs are generally pitchy black.
The larve are long, legless, white maggots, with brown head and
jaws. They pupate just immediately beneath the outer skin of the
rough bark, so that in looking for the full-fed larve we must dig very
lightly.
To prevent the spread of this insect, it is best to cut down all
back-going old trees with very rough bark ;
and this is in keeping with good forestry,
as an ash-tree, above all others, depreciates
very rapidly in value if left standing after
it has reached maturity.
HYLESINUS FRAXINI (Fabr.)
This species is commonly known as the ash-
bark beetle. Miss Ormerod, in her valuable
work, says: “The beetles are often attracted
in large number by newly felled ash trunks, 5, 94, prylesinus crenatus.
in the bark of which they propagate, and oa SEG
from whence the new brood spreads _ to
the neighbouring trees, mainly attacking those that are sickly or
decayed, or young trees, which they sometimes injure to a serious
extent.” So far as my experience and personal observations go,
I have found that the beetles only attack very sickly or half-dead
trees, but never healthy or young ones. When marking trees in
Cheshire, I have observed the dead standing trees had been attacked
by the beetle, but this had always been done just when the trees were
in a half-dead condition.
The life-history of this beetle is very easily followed. About the
end of March or the beginning of April the beetles emerge from their
winter quarters, and are attracted in considerable numbers to newly
felled trees or poles. In Cheshire I always discovered this species
on comparatively large stems, but in the south of England they are
very common on poles. The female beetle generally appears before
the male. She then commences to make a straight tunnel, and on
the appearance of the male, copulation takes place. The female
makes her tunnel perpendicular with the stem, deposits her eggs,
104 FOREST ENTOMOLOGY.
and the male remains near the entrance. The mother-gallery, fig.
95, is double-armed. The total length of the mother-gallery (includ-
ing both arms) is about 4 to 6 inches when made in the stem, and
about 14 to 24 inches when made on the pole. Mr A. C. Forbes,
who has studied very carefully the life-history of this insect,!
found that the female first bores one half of the arm, and then
proceeds to work the other half. The eggs are laid right and left,
and are rather variable in number. When found on the stem of
a comparatively large tree, they often amount to 120, but when on
the pole, half this number
may be found.
The larve commence
hatching out about the
middle of April or begin-
ning of May. At first they
are of a slightly reddish
colour, but the fully de-
veloped larve are white,
with dark head and jaws,
and tapering to a_ blunt
point at the end. The
larval galleries are about
1} inch in length on the
stem, and about 2 to 1
inch long in the pole. The
perfect beetles emerge about
the first week in August,
through individual exit-holes, and the bark consequently looks as if
it had been riddled with shot.
The perfect beetles then betake themselves to healthy ash-trees
or newly felled ash logs, where they hibernate for the winter,
and emerge in March or April. It is very questionable if they
do any harm to the standing trees, as they simply bury them-
selves in the bark, though Judeich and Nitsche give a figure of
“bark roses” resulting from the beetles hibernating, which in all
probability is the work of the fungus known as WNectria ditissima
following in the train of the bark puncture or wound made by
the beetle.
Fig. 95.—Markings of Hylesinus fraxiui on ash stem
after removal of bark.
1 See Trans. High. and Agr. Soe. Scot., 1899.
COLEOPTERA—SCOLYTIDA. 105
The beetle (fig. 96) itself is about } inch in length, oval form, pitchy-
brown or ashy-grey colour; under side of abdomen covered with thick
erey hairs ; the antenne and tarsi of a yellowish-brown colour.
Various remedies have been given for this insect pest, including
the recommendation of planting on
suitable soil, &c. ; but such advice
is largely unnecessary, Inasmuch as
it only attacks felled logs or dying
trees and poles, and all practical
forestry insists on cutting back-
going ash-trees more quickly than
any other species of tree, in order
to prevent rapid depreciation of
the timber.
(From Barbey.)
Hy esinus oLErperDaA (Fabr.)?
This beetle is found on ash, but,
in contrast to the preceding species,
is always got on the small top-
shoots. It is, however, as a rule,
a South Country species, the
branches shown in fig. 97 being
from a tree in Wiltshire. It is a
species which hatches out very
readily in confinement, so that the
branches containing the larvee may
simply be put in a box in winter
and left there until the beetles
appear, about the end of July.
The mother-gallery is very short,
being only about half an inch in
length, and apparently only single, eM ei Sranchas of ashe
armed. The larval galleries vary
very much in length, being from half an inch to two inches. They
are often crowded so closely together that every portion of the space
becomes pitted with larval furrows.
1 T found the three species—viz., H. crenatus, H. fraxini, and H, oleiperda—
all in Belton Park, Lincolnshire, July 1907.
106 FOREST ENTOMOLOGY.
The beetle (fig. 98) is comparatively small, being about 2 to 3 mm.
in length, bluntly ovate, pitchy black, and covered with yellow bristles
and hairs. The thorax is broad at the base, tapering towards the
head. The wing-cases are marked with punctured lines. There is
an irregular yellowish dorsal streak be-
tween the two elytra. The legs and
antenne are yellowish.
The beetle derives its specific name in
consequence of attacking the olive-trees
in Italy. Fowler says the species has
been found abundantly in beech near
Frankfort.
Se ein Rees Hyesinus virratus (Fabr.)
- This species is found on branches
of elm. The specimens in my collection
have been hatched out from branches
received from Wiltshire, and judging
from those hatched, the time for swarm-
ing is somewhat variable. In 1904
the beetles did not appear until the
end of June and beginning of July. In
_ 1905 I found that a few had escaped by
_ the end of April, and on cutting into
the branch on May 6, I found perfect
beetles in several burrows on one side
of the mother-gallery, and active larve
in the arms of the opposite side, hence
one might infer that the flight period
varies. It is possible, however, that
—— the general time for swarming is just
oer e ea cae a Bua after midsummer. My friend, Mr A.
C. Forbes, who has carefully worked
up the family in the south of England, informs me that he never
could find any workings until the beginning of August. It would
seem that Eichhoff had not been able to work up this species
personally, for he says that one person informed him that it
swarmed on May 21, and another worker found it swarming in
August. Hence he concludes, reasoning from analogy, that the
COLEOPTERA—SCOLYTIDA. Of
species is double-brooded, whereas it was possibly due to erratic
swarming.
It may be noted that the larve work in the bast and on the sur-
face of the wood. The bast is a lightish-
cream colour, and the frass from the larve
is a deep dark chocolate.
The mother-gallery is two-armed, the total
length being about 1} inch. ‘The larval gal-
leries are at right angles with the mother-
gallery, and vary in length from } to } an
inch. The workings are petals in com-
paratively small branches (fig. 99).
The beetle (fig. 100) is the smallest species
of the group, and, viewed with a strong lens,
certainly the prettiest. The form is more Fis vr eee a
linear than any of the other species. The
thorax is slightly grey, and the elytra are beautifully variegated,—
so much so, that the colouring is suggestive of a moorfowl’s egg
The antenne are lightish-brown, and the whip portion is compar-
atively long. The legs are also light-brown.
Genus HyLURGUS.
Upper side of body clothed with scanty hairs; thorax long hairs at
the sides. Eyes entire and longish. Whip of antenne thread-like
and six-jointed; club ovate. First tarsal joint longest; third very
broad. FElytra extremely punctured.
HyYLurGUS PINIPERDA (Linn.)
Myelophilus piniperda, L. (Eichhoff and Fowler).
Hylesinus piniperda, L. (Judeich and Nitsche).
The above synonyms show that leading entomologists use different
generic names. The practical forester of this country has always under-
stood it as Hylurgus, but Fowler adopts Myelophilus as the generic term.
The genus contains two species, and Fowler! gives the following
key—viz. :
I. Second interstice of elytra flattened, and without tubercles at
apex ; - : . HH. piniperda, L.
II. Second interstice of ely i ae depressed, and with a row of
small tubercles at apex j : . HA. minor, Hart.
1 British Coleoptera, vol. i. p. 419.
108 FOREST ENTOMOLOGY.
HyLuRGUS PINIPERDA (Linn.)
This beetle is very destructive to the young shoots of Scots pine,
and has an interesting life-history. During the winter months many
of the perfect insects hibernate in rough bark, or otherwise bore a
hole in the bark of healthy standing trees, just enough for covering,
but this winter burrow is in no way injurious to the standing tree.
The burrows, however, on the stem of the tree may be best seen
Fig. 101.—Shoot of Scots pine, showing the
entrance-hole, and a slice removed to Fig. 102. — Showing mother and larval
show the boring of a pine beetle. (From galleries in process of formation. (From
‘The Forester,’ by J. Nisbet.) ‘The Forester,’ by J. Nisbet.)
months after the exit of the beetle. The exit-holes are clean-cut
openings, surrounded by a fringe of hard resin, which has in conse-
quence issued from the bottom of the excavation, as the boring has
been sufficiently deep to reach the vital bast. A few of the beetles
hibernate in the shoots, which fall with the buried insect in autumn
(fig. 101), In early April or the end of March they withdraw from
their winter-quarters and commence their breeding operations. The
female beetle either selects a sickly standing tree or the stem of
healthy trees which have been felled during the previous winter, and
COLEOPTERA—SCOLYTID&. 109
makes a slight burrow in the bark. Having scooped out a circular
chamber, she then returns to the outer world, and re-enters the
chamber accompanied by the male. In this chamber copulation takes
place, after which the female proceeds to bore farther into the stem,
almost at right angles to the first-scooped portion of the chamber.
The main or mother gallery is therefore a straight line, with a bend at
the bottom, or entrance, somewhat resembling a golf club (fig. 102).
The total length of the mother-gallery is about three inches, and there
are generally two or three air-holes directly over the gallery. In
about ten or twenty days after
the first eggs have been de-
posited the larve hatch out,
and proceed to eat their way,
more or less at right angles, to
the mother-gallery. At first,
therefore, the markings are
very characteristic, as in fig.
102; but later on the larval
markings are very much inter-
mingled, as in fig. 103, which
is a photograph from a_ por-
tion of bark, and shows the
intermingling of larval gal-
leries from several adjacent
broods.
At first the larval galleries
are very fine and thread-like,
Fig. 103.— Portion of bark of Scots pine, showing two
but as the grubs enlarge the mother-galleries and larval workings.
galleries widen, and pupation
takes place at the end of the larval gallery. It should be noted that
both larval and mother galleries are always made in the bark, and
never in the wood, though the frass always lies on the wood after the
removal of the bark. Thus the beetle in question is a bark beetle.
The beetles escape from the pupal chamber by making direct exit-
holes, and thus the numerous flight-holes in the bark indicate that
a new generation has escaped.
The beetles arising from the first-deposited eggs hatch out in about
three to five weeks, generally towards the end of June, and these
early hatched beetles, on quitting the galleries, deposit eggs in the
110 FOREST ENTOMOLOGY.
bark of felled trees, preferring those trees which have been felled in
late spring or early summer. But meanwhile the stem-mother has
kept on depositing eggs, and beetles hatch out from the parent burrow
throughout the season, but more especially in the autumn. Thus the
perfect beetles arising from the second brood, together with the late
swarmers just referred to from the original burrow, quit the bark
practically simultaneously, and bore into the young leading shoots of
the Scots pine branches, entering the pith, and thus damaging the
shoots, so much so that they fall to the ground, and the beetles there-
fore may be found inside the pith of those shoots which so literally
strew the ground of pine woods in autumn.
Some specimens leave the shoots to hibernate in the bark, and
others remain in the shoots over winter, to come
out again in the following spring. The contin-
ual destruction of shoots gives the tree the
appearance of being clipped or stumped, and
the pruning habits have given rise to the insect
being called in Germany the ‘ wood-gardener”
or “ forester.”
The perfect insect (fig. 104) is about 5 mm.
or + of an inch in length, of a pitchy bronze
colour, head and thorax approaching to black,
Fig. 104.-Hylurgus legs same colour as body, with light tibie. The
piniperda. (From
‘The Forester,’ b a aaa : wre : o
TIRES en y elytra, or wing-cases, are rough, and rounded over
the sides, so that a transverse section of the
abdomen would be nearly circular. The elytra should be carefully
noted, and Dr Somerville gives the following detailed description :——
“The elytra are lustrous, slightly pubescent, and traversed longi-
tudinally by rows of fine punctures. The interspaces between the
punctated rows are somewhat wrinkled, and each contains a row of
hairy tubercles. These tubercles, in the case of the second interspaces
on either side of the middle suture, are only present as far as the
point where the elytra begin to bend downwards towards the apex ;
whereas in the other interspaces they are continued down the apical
declivity to the edge of the elytra. This peculiarity is most marked
in the male, though in both sexes it is quite observable with the
unaided eye when the insect is held in a good light with its back
towards the observer—that is to say, when the apical declivity is
examined obliquely. Owing to the want of hairy tubercles in the
COLEOPTERA—SCOLYTID®. pel
two interspaces mentioned, these are seen to be smooth and lustrous,
and appear like shining lines or shallow grooves on the apical declivity.
This point is of much importance, for it is only by means of it that
we can with certainty distinguish this insect from Hylesinus minor.” '
The larva is a white footless grub, with a light canary-coloured head.
The middle portion of the grub is yellow, and the tail portion pure
white. The pupa is whitish and shining, showing all the parts of the
perfect insect.
Preventive and Remedial Measures.
Though this is certainly a very destructive insect, yet, in the
absence of special damage by gales, it can be held in check by fairly
good forest management. This consists largely in destroying the
breeding-places, which, it must be remembered, are either in the stem
of cut trees or in sickly standing trees. Much, of course, will depend
on the felling season, and on the interval elapsing before manufactur-
ing. If, say, the trees were cut in September and manufactured by
March, no evil effects would accrue ; but if they were felled in March
and not cut up at the sawmills until September, it would be entirely
to the advantage of the beetle. Hence, if cut during the latter period,
various checks should be adopted. For instance, the bark might be
partially cut off as in the custom of chipping the “four sides” of the
log to lessen railway carriage, which would have the effect of so drying
up the bark, or otherwise separating it from the log, to such an extent
that the necessary conditions for propagation would be very much
destroyed. If, however, the logs are not thus dealt with, then they
should be barked at the sawmill from June to August, and all bark
burned. Thus many larve and beetles would be destroyed.
If, on the other hand, we wish to lessen the breeding-places in
standing trees, all sickly trees should be removed. But while the
latter may be recommended on entomological grounds, we should bear
in mind that ‘“‘ pure” woods of Scots pine should never be heavily
thinned, but, on the contrary, an unbroken canopy should always be
maintained. Another measure for eradication may be adopted in
felling certain trees as catch or trap trees, and then burning the bark
of the same.
From a practical point of view, it may well be asserted that the
1 Trans. High. and Agr. Soc. Scot., 1891.
112 FOREST ENTOMOLOGY.
barking referred to would not pay ; but having regard to the damage
arising from the perfect beetle to the shoots of young trees, or
where a nursery with young Scots pines is in the neighbourhood,
it might be quite advisable to check the pest in this way. It often
happens that young Scots pine plants in the nursery are injured by
the beetle.
The very small tops and branches of Scots pine lying on the ground
are not suitable for the breeding purposes of this insect, though they
are used by other beetles. The larger branches, however, may be used
for breeding purposes, and it is therefore advisable, both for checking
the beetles and for the health of the crop, to keep woods entirely free
from dead trees and all brushwood. Hence it may be seen that, so
far as the health of the woods is concerned, it is not a good practice to
leave the fresh or half-dead branches on the ground for cover. At the
same time, it is only fair to note, in the interests of game-cover, that
the perfectly dry dead branches which may at times be pruned off
from the base of the stems of Scots pine are not used by beetles for
breeding purposes.
HyLureGus MINOR (Hart.)
This insect is considered by many coleopterists as purely a Con-
tinental species, though a few workers consider it a British species.
Hence Fowler says it is rare, and gives Deeside and Braemar as
districts.
The beetle is smaller than the preceding species, and may be
recognised by noting the bristle-bearing tubercles continued on the
second interstice of the elytra.
Not having found the species, I quote from Professor Fisher as
regards the relation to the forest :—
“ H. minor, Hart., chiefly attacks the Scots pine, but has also been
found on the spruce. It prefers poles, but may attack 50- to 70-years-
old trees. The mother-galleries are large, regular, double-armed, and
horizontal, with a rather long entrance-burrow, and groove the sap-
wood deeply. The injury which its breeding causes is therefore
ereater than that of H. piniperda, as the circulation of the sap is
more endangered by these horizontal galleries. It is not, therefore,
surprising that quite sound trees are killed by it, or, at any rate,
become stag-headed.
“The larval galleries are short, not very numerous, and terminate
COLEOPTERA—SCOLYTID.®. its
in a deeply cut pupal chamber. This beetle, unlike the preceding
species, is said not to confine itself to the borders of a pine wood, but
to be found deeper in its interior.
*« HT, minor also bores into the pith of young pine shoots in the
same way as H. piniperda.”}
Genus PHLG@OPHTHORUS.
Antennal whip five-jointed ; club of antenne three-jointed and very
distinctly divided ; abdomen not raised towards apex.
‘
a
f
E ; j ie —) ee
Fig. 105.— Markings of Phiceophthorus Fig. 106.—Markings of Phlceophthorus
rhododactylus on gorse (whin) stem. rhododactylus on broom.
PHL@OPHTHORUS RHODODACTYLUS (Marsh).
This is one of our smallest British wood-feeding beetles, and is found
in gorse and broom stems. It is very common in Northumberland.
Fig. 105 represents the markings on whin and fig. 106 on broom. The
beetles may be looked for about the beginning of April, more especi-
ally on half-dead gorse stems,—those stems, in fact, which were alive
the previous year, but have been broken down by the heavy snows of
1 Forest Protection, 1907.
H
114 FOREST ENTOMOLOGY.
winter. They deposit their eggs in small irregular clusters, and the
larvee move about in all directions from the mother-gallery, so that
the markings are very irregular. These larve
are transformed into fully developed beetles
by early autumn, when some leave the brood-
places, whilst others remain at the far end of
the larval galleries for the winter and leave the
following spring. I have kept them in con-
finement over the winter, and they worked the
same stem as they had done the previous
Fig. 107.—Phleophthorus ve
EUOTO Rea CR The beetle (fig. 107) is about 15 mm. in size,
Barbey.) _ ; i
of a dull, blackish slaty colour, with slight
greyish pubescence. The thorax is beautifully striated, and the
body somewhat globular in shape.!
Susp-Famity DRYOCATINA.
This is rather an extensive tribe, and as the whole of the
genera are practically arboreal insects, it is perhaps well to ap-
pend the following synoptical key, slightly modified from Fowler
—V1zZ.:
I. Funiculus of antenne with four or five joints, size variable.
i. Eyes entirely divided; club of antenne without sutures.
Beetles bore directly into the woody stem.
TRYPODENDRON, Steph.
ii. Eyes entire or slightly emarginate.
1. Elytra clothed with scale-like pubescence, and sometimes
with fine raised hairs in addition, not excavate at apex ;
scutellum very small; club of antenne with distinct
sutures. Beetles small, generally working in thin bark.
CrYPHALUs, Er.
2, Elytra without scale-like pubescence, glabrous or with
outstanding hairs; club of antenne orbicular and com-
pressed.
1 There appears to be some confusion as regards the nomenclature of the two
species of Phlocophthorus—namely, P. rhododactylus and P. Spartii. The insect
known abroad as P. Spartii is given by Barbey as feeding on broom, and
P. rhododactylus as feeding on branches of the spruce.
COLEOPTERA—SCOLYTIDA, 115
A. Base of thorax finely bordered; prosternum with a
short process; size very small; club of antenne
divided by three constricting sutures into four
joints : : : PriryorutHorvs, Eich.
B. Base of thorax not bordered.
a. Club of the antenne with the second joint cresc-
ent-shaped, and completely embracing the sides
of the first joint, which is oval; scutellum
rudimentary ; elytra with reflexed portion dentate
in the male, not dentate in the female
XYLOCLEPTES, Ferr.
b. Club of antennz truncate at apex, the basal joint
being corneous, and the remaining joints lying
within it; mentum broadly cordate, sub-mentum
large and concave anteriorly . Dryocmrss, Eich.
b’, Elytra excavate at apex, which is horizontal or almost
horizontal behind the apex of abdomen.
Tomicus, Latr.
6”, Prosternum without or with a very short process
between the anterior coxe.
(a) Tibize almost linear, without furrows for the re-
ception of the tarsi; apex of elytra with large
teeth in the male, and with a strong impression
on each side of suture in the female.
PriryoGENEs, Bedel.
(6) Tibiz dilated, furnished with furrows for the
reception of the tarsi; apex of elytra without
large teeth or deep impressions in the sexes.
XYLEBORUS, Eich.
Genus CRYPHALUS.
The members of this genus are very small insects, and may
certainly be overlooked by nearly all except the trained economic
entomologist. Six British species have hitherto been recorded on
poplar, lime, spruce, beech, &c. They are all so very small in size
that they cannot be seen to any advantage without the microscope or
strong pocket-lens.
Fowler gives six British species, but as two are rather rare, we may
confine ourselves to four species. As the beetles are exceedingly small
£06 FOREST ENTOMOLOGY.
in size,—from 1 to 2 mm.,—the characters are entirely microscopical.
The following generic characters may be given :—
Pronotum as broad as long, with small hump projecting in front
portion. Elytra slightly hairy, conspicuously punctured, and well
covering the abdomen. Whip of antennz four-jointed ; joints very
small; club comparatively large; tibia broad, and toothed on outer
edge.
The following are the specific characters, according to Fowler—
Viz.:
I. Club of antenne with the sutures transverse, almost straight ;
body behind thorax, only twice as long as broad.
1. Eyes entire; thorax with four transverse rows of granules in
front : : : C. tilie, Panz.
2. Eyes emarginate on ae aa nior border ; thorax confusedly
granulate.
A, Elytra with very short, scarcely visible, hairs; rows of
punctures on elytra not very fine, and placed in- some-
what impressed striz ; : C. abietis, Ratz.
B. Elytra with long raised hairs ; rows of punctures on elytra
very fine : : : C. picee, Ratz.
IT. Club of antenne with the sutures strongly curved ; body
behind thorax three times as long as broad; elytra Sein
strie . : : : : é C. fagi, Nord.
CRYPHALUS ABIETIS, Ratz.
This species is found on dead spruce branches,—generally at knots
of the branches. It is considered rare, but this arises probably
from its being overlooked, for I have found it in the south of
England, and again in the north-east of Scotland. Figs. 108
and 109.
Eichhoff says it is double-brooded, as the first brood swarmed in
February and March, while snow was still on the ground, and the
second brood appeared about the latter end of July.
I received a portion of a stem of young Douglas fir, heavily
attacked by this insect, from Mr A. C. Forbes, Bowood, Wiltshire.
As a rule, this tree is almost immune from insect attacks. Mr Forbes
has again sent me an example of this species on Douglas fir from
Cockle Park, Northumberland.
COLEOPTERA—SCOLYTID&. 117
CrYPHALUS TILIZ, Panz.
This species confines its attacks to dead or dying branches of the
lime, and is said to be extremely local. I am indebted to Mr Morse,
Leeds, for the specimen as represented by
photograph in figs. 110 and 111. He found
it at Newnham, Gloucestershire, in May 1906.
The mother-gallery is horizontal, and may be
either single- or double-armed. ‘The bark, at
the selected portion of the branch, is exceed-
ingly thin, and the female beetle bores just
deep enough to skim the surface of the wood.
The larval galleries run at right angles to the
mother - gallery, but owing to the thinness of
the bark, and the peculiar structure under-
lying the thin covering, it is with great
difficulty that a specimen may be prepared
for illustration.
All German writers say there is a double
generation. Fig. 108. — Markings of
The beetle is small in size, oval, and ieee abietis. (Prom
circular if considered in section through the
body, pitchy brown, with reddish-brown antenne and legs, Thorax
broader than long, with small protuberances on the sides. Elytra
with very finely punctured stria, but the gen-
eral appearance is rough and scaly. Length
1 to 15 mm.
CRYPHALUS PICE.
I have not found this species. Fowler says
it is very rare. Barbey says it lives exclusive-
ly on the silver fir (Weisstanne), though at the ;
same time he gives two exceptions, one on the Fis: eee ne
root of spruce and the other on the larch. He
also adds that it is a very deadly enemy of silver fir when associated
with another beetle named Tomicus curvidens, Germ., and gives a
very interesting account of the injuries. It would be well, therefore,
for students in this group to keep a good look-out for this species.
(hitherto considered rare), more especially in the south of England.
118 FOREST ENTOMOLOGY.
CRYPHALUS FAGI, Fabr.
This species is found generally on branches or small stems, but is
said to be very local. Mr Morse supplied me with the specimen
from which the photograph is taken (fig. 112).
I only got one specimen from the branch, which was elongated,
slender, and of a shiny, dull black colour.
Fig. 110.—Showing ‘‘ ewit- Fig. 111.—Markings of Cryphalus Fig. 112.—Markings
holes” of Cryphalus tilize tilie on lime. The white hori- of Cryphalus fagi
in lime. zontal lines are the mother- on branch of beech.
galleries.
Barbey says the chief character lies in the form of the antenne
elub.!
Genus PIrtYOPHTHORUS.
Fowler says—‘ Genus as defined by Eichhoff presents the follow-
ing characters: Antenne with a five-jointed funiculus and an oval
non-compressed club, which is constricted by transverse sutures divid-
ing it into four distinct joints ; thorax as long as or longer than broad,
bordered at base and distinctly narrowed in front; elytra cylindrical,
with simple rows of punctures, and with impunctate interstices; the
apex is obliquely truncate, and presents a depression on either side of
1 Die Bostrichiden Central-Europas.
COLEOPTERA —SCOLYTID£. EL9
suture; it is not armed with spines or teeth, but the raised sides of
the apical depression and the sutural margins sometimes possess a
row of small setigerous tubercles.” !
PITYOPHTHORUS PUBESCENS, Marsh.
This is a very small species of beetle, which often follows in the
train of unpractical planting of young Scots pine trees. There is an
age of plant known in the trade as 2 yrs.-3 yrs.,—that is, two years
in the seed-bed and three years in the nursery lines; in other words,
only once transplanted in five years. In this class the bill of
mortality is a very high one, and the beetles prefer the dead trees
of the class referred to, and may be looked for near the top of the
stem, where the thickness of the stem is about equal to that of an
ordinary drawing-pencil.
Genus XYLOCLEPTES.
Fowler remarks: “The genus may be known by having the second
joint of the club of the antenne crescent-shaped, and completely em-
bracing the sides of the first; the funiculus is five-jointed; the
scutellum is indistinct; and the apical portion of the elytra is
strongly inflexed in the male and fully inflexed in the female.” ?
XYLOCLEPTES. BISPINUS (Duft.)
This species is found on the dead stems of Clematis vitalba, and
is, generally speaking, a South Country species. I am indebted to
Mr Hereward Dollman for the specimens in my collection, He
records them as being common at Ditching, in Sussex.®
According to Eichhoff, the mother-gallery is two-armed, and the
insect has a double generation. The beetles pass the winter in the
galleries, and appear in April or May. The first generation is devel-
oped by June or July, and the second from August till October. As
the latter time is rather a prolonged period, it is probable that the
late swarmers from the first brood may be confounded with the early
swarmers of the second brood.
1 British Coleoptera, vol. v. p. 433. 2 Thid., p. 435.
3 Commander Walker has found it abundantly in Kent, and sparingly in the
Oxford district.
20 FOREST ENTOMOLOGY.
The beetle (fig. 113) is elongated and cylindrical, of pitchy brown
colour. The thorax is darker than the elytra, and longer than broad.
Legs rusty brown colour, and the antenne and tarsi lightish-yellow.
In the male the apex of the elytra is much inflexed, with a tooth
on each elytron, and the suture is so raised
on the inflexed portion as to form a small
keel.
In the female the apex is most feebly
inflexed, and the extreme apical edges are
rounded.
Genus DRYOCETES.
The genus Dryocetes may be said to
Fig. 113.—Xylocleptes bispinus. be of very minor importance, so far as
(From Barbey.) : zi
economic forest entomology is concerned.
The whip of antenne five-jointed ; elytra distinctly punctured, and
covered with fine pubescence and smooth.
Dryocx&TEs viLLosus (F.)
I found this species very plentifully in the rough bark of an old
dead standing oak in Chatsworth Park, Derbyshire. I have also, more
Fig. 114.—Mother-gallery of Dryocetes villosus in Fig. 115.—Dryocetes vil-
bark of oak. losus. (From Barbey.)
recently, had its markings pointed out to me by my friend Mr R. S$.
Bagnall, in Gibside, Co. Durham (see fig. 114). These markings were
on an old dead standing oak. The beetle (fig. 115) is of a reddish-
COLEOPTERA—SCOLYTID&. PZ
brown colour, and clothed with pale pubescence which might almost
distinguish the species. Length 2 to 3} mm.
The other two species of this genus, which may be overlooked, are
D. alni (fig. 116) and D. coryli. The former is said to be found on
beech, and the latter on dead twigs of hazel and hornbeam, but both
rare, especially the latter.
These two species are about the size and appearance of P. bidentutus.
Genus Tomicus.
The species of this genus are all feeders on coniferous trees, but
some of the species are rather rare. They all make peculiar mark-
ings,—so much so, that in conse-
quence of the strongly marked pat-
terns the species have been termed
“« typographers,”
Some of the species are poly-
gamous, and the
main galleries
can be traced
from the start-
ing - point or
breeding - cham-
ber (Rammel-
kammer’).
Fowler gives
five species as
it] Fig. 116.—Dryocetes Fig. 117.—Tomicus sexdentatus. (From
British, but I alni. (From Barbey.) = Barbey.)
have only found
one in Northumberland—viz., 7. acumdnatus. It is perhaps theffirst
record for the county, and I am obliged to Mr R. S. Bagnall for
identification.
The principal generic characters are: antenne whip five-jointed ;
thorax large, with a wrinkled little lump in front and punctured be-
hind ; wing-covers at the point pressed and toothed.
ToMmIcUS SEXDENTATUS (Born.)
This is a large handsome beetle (fig. 117), pitchy dark-brown colour,
12, FOREST ENTOMOLOGY.
pronotum smooth, and elytra deeply punctured ; abdomen covered with
long hairs; and the apex deeply and obliquely excavated, showing teeth _
on each side. Antenne and legs ferruginous. Length 54 to 7 mm.
Fowler gives as a habitat recently dead firs near London, and Mr
R. S. Bagnall places it as an introduced species to Hartlepool. It
is a very rare insect.
Tomicus acuMINATUS (Gyll.)
This insect is of a uniform terra-cotta colour, and slightly pub-
escent. Thorax longer than broad, and a shght depression in centre ;
the elytra fully cover the abdomen.
Eyes black; antenne and _ legs
yellowish.
The main characters, which are
microscopical, are found in the
toothed abdomen. There are three
teeth on each elytron ; the third
tooth is the longest. In the female
the third tooth is formed into a
sort of hook, whereas in the male it
is a sort of blunt forked spine.
This is by no means a common
species, and I found it in Beanley
Wood, Northumberland, July 1906.
Fig. 118 shows the markings.
: Genus PITYOGENES.
Fig. 118.—Markings of Tomicus acumin-
one eo we he genus: Pityocenes, saccordime
to Fowler, contains three species,
but I have only one species, viz., P. bidentatus, which in many dis-
tricts Is very common. DBarbey, who may be considered as a leading
German authority, places P. bidentatus in the genus Tomicus, but I
venture to think that Fowler’s separation is a very good one, on the
ground that in Pityogenes “in the males only the apex is excavate,
and is furnished with strong teeth,” and also that ‘the females have
a deep impression at the apex of the elytra near suture.” Under a
strong lens this character is well maintained,—so much so, that the
thorax has a quite “nipped ”-like appearance.
COLEOPTERA—SCOLYTID2. i eo)
PITYOGENES BIDENTATUS (Herbst. )
Pityogenes bidens (Fabr.)
This is a common beetle, but, being small in size, is very apt to
be overlooked. Its breeding-places may be broadly divided into two
classes—viz., on small dead fir-branches,
and on sickly trees, say from 18 inches
and upwards, which have been trans-
planted in the nursery - lines, or those
which have been transplanted in young
woods,
As regards the former class of food-
materials, and as forming a commence-
ment in the study of its life-history, it
may be looked for amongst the small
branches of Scots pine, chiefly on the
under side of the branch, either where
trees have been felled during the previous
winter, or on branches which have been
broken off by the wind. The small bore-
holes, together with the frass, reveal the
abode of the insect. If the thin bark be
removed carefully, we may find a star-
shaped marking, as in fig. 119. This is
a typical beginning of the markings of
this species. The central portion is scooped
out by the male, where several females,
generally from four to six, assemble, and
after copulation each female makes her
own gallery. The larve arising from each
respective female make their own par-
ticular design of markings, and this con-
fusion gives rise to various irregular de-
signs, such as shown on fig. 120. The
same branches may harbour beetles the fol-
lowing year, but the markings are always
best followed in recently cut branches.
As regards the sickly trees infested by
t
t
Fig. 119.—Markings of Pity-
ogenes bidentatus (initial
stage).
Fig. 120.—Fully developed mark
ings of Pityogenes bidentatus.
this insect, the principal damage is to pines, large transplanted
Douglas firs, and so on. The transplanting of such class of trees,
124 FOREST ENTOMOLOGY.
say from six to twelve years of age, is often rather risky, more
especially if followed by a dry summer. Under such circumstances
the bill of mortality is a heavy one, and the beetles are generally
found on the dead or most sickly trees. It is just possible that,
though the beetles are always found on dead or dying trees, they may
be the means of partially killing several trees of the pine tribe.
It often happens that many transplanted Austrian pines hang, as
it were, for one season,—that is to say, they make no growth, but
simply remain green. If there be no insect enemies, the trees will
recover the following year, but a severe beetle attack often kills what
might otherwise recover. In the case of
Douglas firs, the brown foliage emphatically
declares the dead plants.
Altum! relates that 100,000 seven-year-old
plants were killed in one season by this beetle.
In this country such an attack would be
considered primarily due to, and afterwards
accelerated by, the absence of healthy con-
ditions,—that is to say, that the trees had
been planted at the wrong season of the year,
Ba Os in eee and on too dry a situation.
tatus. (From Fisher's With regard to the life-history of the in-
ae a sect, I have found it in all its various stages
throughout the whole year, and am therefore persuaded that Eichhoft’s
remarks regarding the respective broods are right—viz. :
“J, Spring swarm in May or June; larve in May, June, and July ;
pup and imagines in July and August.
“TI. Summer swarm from July till October; larve in July, August
till October, and over winter ; pupze and imagines in Sep-
tember or October till May.
“TIT. Autumn swarm from August till October, larvee over winter,
imagines and swarms and broods in May and June.” ?
The beetle (fig. 121) is from 2 to 3 mm. long, pitchy black in colour,
shiny, and covered with a very fine pubescence ; antenne and legs
ferruginous ; thorax constricted in frent and punctured behind, and
it has a sort of pinched appearance. The elytra have distinctly
punctured rows. The male can be very easily distinguished by its
having a projecting hook on each elytron.
1 Forstzoologie. 2 Die Europiiischen Borkenkiifer.
COLEOPTERA—SCOLYTID2. =
Or
As this beetle has proved a veritable pest on the Continent, and
also occasionally in this country, it would be well to guard against its
ravages. Perhaps the best preventive would be to remove or burn
all comparatively young fresh branches which would come in prox-
imity with any fairly large coniferous trees planted out, either in
parks or villas, for immediate effect.
Genus TRYPODENDRON.
The beetles of this genus are entirely different in their workings
from the sections hitherto considered. The Trypodendron mother-
beetle bores directly into the stem of the tree for about 4 to } inch
deep, directly towards the centre or pith, but when this depth is
Fig. 122.—Block of wood shown in perspective to illustrate the workings of the genus
Trypodendron. (After Eckstein, and copied from Niisslin.)
reached she bends slightly round and then bores in a somewhat
curved direction, parallel to the circumference of the tree, and always
preferring the sap-wood. After she has taken the bend referred to
she makes a sort of recess or basket, alternately right and left, of the
main gallery, and places a single egg in each recess. In due time
the eggs hatch out and make short galleries at right angles to the
parent gallery. Each gallery points upwards or downwards. As
regards space, each gallery alternates, and thus we get “ladder
galleries” formed. When fully developed, the offspring creep out
at the entrance made by the mother-beetle.
The accompanying figure, fig. 122, taken from Niisslin, is a sort of
perspective representation of an infested block, and gives a very good
idea of how the insect bores into the stem.
The generic characters are: Eyes divided in two parts; knob of
ZIG FOREST ENTOMOLOGY.
antenne large and solid, longer than the four-jointed whips; thorax
transverse or globose, with four projecting corners. Female with a
convex forehead. Elytra ending abruptly, but without teeth.
The following are the specific characters, according to Fowler :—
“T, Apical declivity of elytra with a very distinct furrow on each
near suture; elytra without distinct longitudinal streaks at
sides; thorax black . : ; . TL. domesticum, L.
“TT, Apical declivity of elytra without, or with an indistinct, furrow
on each near suture; elytra with more or less distinct longi-
tudinal streaks at sides; thorax more or less red, at all events
behind.
i. Elytra with the punctured striae moderately deep; club of
antenne subsecuriform, straight on one side, and some-
what rounded on the other . 2 Lf quercis mie:
(stgnatum, F.)
ii. Elytra with the punctured striz superficial ; club of antennz
rounded on both sides and at apex = 7. lineatum (O1.)”}
T. uingatum (Ol.)
This insect bores into spruce timber. It will bore into timber
lying on the ground, which may have been cut during the winter, but
Fig. 123.—Workings of Trypodendron lineatum Fig. 124. — Trypodendron
in spruce timber. lineatum. (From Fisher’s
a, cross section of wood ; b, longitudinal section. ‘Forest Protection.’
2 co}
by preference it attacks broken stumps—that is, standing portions of
trees which have had two-thirds of their tops broken off by a winter
gale. The female seems to be rather fastidious, as the material must
1 Fowler’s British Coleoptera, vol. v.
COLEOPTERA—SCOLYTIDA. 127
neither be too fresh nor too dry. She bores into the tree for an inch
or more, and at about half an inch from the entrance commences to
deposit her eggs. The larvee soon hatch, and bore at right angles
to the tunnel of the parent, but in the longitudinal direction of the
stem, either upwards or downwards ; but the larve eat only a small
portion of the timber, about twice the length of their own bodies,
and they pupate in the recess thus formed. The perfect insect eats,
or rather makes, its way out at the hole in the stem made by the
entrance of the female. Fig. 123 shows the workings of this
beetle.
The beetle (fig. 124) is about 3 to 4 mm. long, and cylindrical in
form. The head is generally buried, as it were, in the thorax,
which is blackish in colour. The
elytra are yellowish-brown, with
irregular black bands running
along them. ‘These bands are not
always complete, but they are the
salient feature distinguishing this
from the species next mentioned.
I have found this species in
two districts in Northumberland
—viz., at Lyham, near Belford,
in spruce, and in Scots pine, at
Countess Park, North Tyne; but
it is by no means common in the
county.
TRYPODENDRON DOMESTICUM
(Linn.)
oe : = Fig. 125.—Markings of Trypodendron domes-
This species bores in oak, beech, : ticum in oak timber.
and birch, selecting the large a, cross section ee b, longitudinal
ection.
limbs of trees which have been
felled the previous year and left lying on the ground. Its presence
may be very easily recognised by the amount of bore-dust lying on
the surface. It should be looked for about the end of May or
beginning of June, when many specimens may be found, as whilst at
work it often appears on the surface of the trunk. Fig. 125 shows
the workings of this beetle. In size it is about the same as the
preceding species ; but the prothorax is entirely black, and the elytra
2s FOREST ENTOMOLOGY.
livid yellow over the whole surface, the irregular lines in the previous
species being entirely absent.
Trypodendron quercus, Eich., is a species I have not found, but
Fowler says it is fairly common in Sherwood Forest.
Genus XYLEBORUS.
The following are the chief characters of the genus, according to
Fowler :—
“'Tibiee broad, more or less serrate, and furnished with furrows for
the reception of the tarsi, which are rather short ; prosternum excised
as far as the cox, and furnished with a very short process; thorax
rough in front, and not margined behind ; elytra without an impressed
Fig. 126.—Xyleborus dispar (male). Fig. 127.—Xyleborus dispar (female).
line along suture, with the apex not excavated but slightly reflexed,
furnished with more or less distinct tubercles, which are sometimes
almost obsolete; punctured striz distinct, interstices closely and
rather finely punctured in rows; eyes emarginate ; the club of the
antennze has the sutures very slightly curved, and the funiculus is
five-jointed.” !
XYLEBORUS DISPAR (F.)
“Beetle, ¢ 2mm., 9 3mm. long (figs. 126 and 127). Pitch-black,
the antenne and legs testaceous-red. @ short, convex, ovoid, and very
hairy, with the thorax granular in front, punctured towards the base,
with a smooth median line. The ¢ cylindrical, its thorax in front
1 Fowler’s British Coleoptera, vol. v.
COLEOPTERA—SCOLYTID.®.
strongly asperate.
123
Elytra strongly arched at the declivity, with rows
of deep punctures, and raised tuberculate interstices between them.
“The season for flight is in May. The
2 bores into several kinds of broad-leaved
trees to lay her eggs, in preference below a
branch, but never near the ground, attack-
ing felled wood and young standing trees.
Fig. 128 represents the workings.
“The larve appear in June, pupate in
July in the secondary galleries, and the
beetles emerge in August. They hibernate in
the galleries, and there is only one generation.
This beetle is not everywhere common on
the Continent, and till recently it was re-
garded as one of the rarest British insects,
but since 1891 it has been destructive in
certain Gloucestershire fruit-orchards.” !
References to Literature consulted.
Altum, Dr Bernard. Forstzoologie. 1875.
Barbey, A. Die Bostrichiden Central-Europas,
1901.
Eichhoff, W.
1881.
Forbes, A. C. “The Bark-beetles of the Ash”
—Trans. High. and Agr. Soc. Scot. 1899.
Fowler, Rev. Canon. British Coleoptera, vol. v.
1891.
Fiirst, Dr Hermann.
lands. 1893.
Hopkins, A. D. Insect Enemies of the Spruce.
U.S.A. Bulletin, No. 28. 1901.
Judeich und Nitsche. Lehrbuch der Mittel-
europiischen Forstinsektenkunde. 1895.
Niisslin, Dr Otto. Leitfaden der Forstinsekten-
kunde. 1905.
Ormerod, Miss E. A.
Insects. 1890.
Somerville, Dr W.
High. and Agr. Soc. Scot.
Die Europiischen Borkenkiifer.
The Protection of Wood-
A Manual of Injurious
SSE
Fig. 128.—Burrows of Xyleborus
dispar in an oak sapling (nat-
ural size).
a, entrance-hole, usually under
a twig; 0, mother-galleries ;
c, commencement of lateral
galleries ; d, completed lateral
galleries, in which the larve
lie. (Figures and explanation
from Fisher's ‘Forest Pro-
tection.’)
“The Pine Beetle” (Hylesinus piniperda L.)— Trans.
' Forest Protection, by W. R. Fisher: Schlich’s Manual of Forestry. 1907. Cf.
Miss Ormerod’s report on this very interesting beetle, 1889, pp. 92-98; quoted in
Fowler, vol. v. p. 448.
I
130
CHAPTER IV.
HYMENOPTERA—OAK GALLS.
ConsIDERED entomologically, the subject of gall-forming insects is a
very wide one, inasmuch as we find that certain insects belonging to
the various orders, from Acarina to Hymenoptera, form galls. The
galls on oak-trees are of special interest to the student of forest
entomology, and also to the biologist.
Although the systematic study of galls is a comparatively modern
one, many kinds of galls were known to the ancients, and several
strange theories were from time to time propounded as to their origin
and growth. As it was known that vegetable galls were tenanted by
animal life, it was thought the plant contained a soul, able to impart
life to the animal. Some considered that galls were stepping-stones
from vegetable to animal life, while others thought eggs were drawn
up by the sap and ultimately developed into galls. Pliny, the Roman
naturalist, knew that flies were produced from certain vegetable galls,
but he associated many superstitions with his knowledge. For in-
stance, he says that the events of the year were prognosticated as to
the respective larve transforming into spiders, worms, or flies.
The first systematic writer on galls was an Italian physician, who
gave an account of the galls of Italy and Sicily in 1686. The second
writer recorded, on the subject, was Dr Derham, Canon of Windsor,
who published his observations in the Boyle Lectures, 1711-1712.
It is questionable whether he knew of the Italian writings, but it is
said that when the two lists are compared the coincidence is very
striking. Neither of these writings was known to Linneus or
Fabricius. Linneus called the group Cynips, but comprised all
species of Hymenopterous parasites with true gall-makers. West-
wood, in 1839, working out the genus Cynips of Linneus, termed
the order Cynipide, and gave some descriptive details. These, briefly
HYMENOPTERA—OAK GALLS. 131
considered, are as follows: “ Antenne 13- to 15-jointed ; wings few
nervures; palpi short; head small and transverse; thorax thick,
oval ; abdomen much compressed ; peduncle short ; antenne inserted
middle of face.”
Hartig was the first to restore order and improve the classification.
He separated the true gall-makers from the various species of parasites,
and then subdivided the parasites into true parasites, inquilines or
guest-flies, and commensals.
Thus a true parasite preys directly on the larva of the gall, and after
undergoing its own metamorphosis finally kills its host. Inquilines or
guest-flies prey on the substance of the gall, and, as a rule, indirectly
kill the gall-forming insects. Commensals are generally found in large
galls, living as lodgers in the substance of the gall, but do not kill the
insect.
These statements are corroborated by Ratzeburg in his ‘ Forst-
insekten,’ published in 1844. Afterwards we find several workers
in the field: Bassett, a Canadian, 1865; Riley, an American, 1873 ;
Adler,! a German, 1875; and Cameron of Manchester, 1892. The
work of the last-mentioned writer was published by the Ray Society
in 1892.
Before dealing with galls from a purely entomological standpoint, it
may be interesting, in view of the scientific importance of the subject,
to consider galls botanically, in so far as their morphological structure
and origin are concerned. With regard to morphology, it must be
borne in mind that a gall is not a structureless tumour, but a dis-
tinctly differentiated structure, and, as a subject, the histology of gall
structure would prove an interesting study in itself.
Firstly, we have galls of cellular tissue, but with no differentiation of
separate layers, as, for example, the currant gall or Spathegaster bacca-
rum. Secondly, galls similar to these, but containing an inner gall,
as, for instance, the leaf-twisting gall caused by Andricus curvator.
Thirdly, galls developing vascular bundles throughout the cellular
tissue, with distinct epidermis as weil as differentiated inner galls, as,
for example, the large root-gall caused by Aphilothrix nodult. Fourthly,
_ galls, as, for instance, the marble gall, having a complicated structure.
1 This work was translated by Dr Stratton, and published by the Oxford
Clarendon Press in 1894; and I beg to acknowledge my indebtedness to this
important work for much of the foregoing, and also for many of the statements
which follow.
oz FOREST ENTOMOLOGY.
In support of the complicated structure of the marble gall the
following may be quoted—viz. :
“Tf a transverse section of a young marble gall, 3 mm. in thickness,
be made at the end of June, it will be found, according to Beyerinck,
to exhibit the following structure: a larval chamber surrounded by
(1) a thin layer of primary nutritive tissue ; (2) a thin layer of cells
containing crystals ; (3) a thin layer of primary starch cells; (4) the
layers of the cambium ring; (5) a thick layer of large cells, rich in
tannin and traversed by vascular bundles; (6) a layer of small
meristematic cells; (7) colourless hypodermal cells; (8) epidermis
with unicellular hairs containing red pigment in their cell contents.” !
The origin and development of vegetable galls, more especially those
on the oak, is a subject which has puzzled eminent scientists, It was at
first considered by naturalists that the Cynips deposited simultaneously
with the egg a drop of irritating fluid, which caused the sap to flow
round the egg, and thus a globular form would be the result. In other
words, gall-formation was considered the result of chemical action.
Darwin adopted this view, and says: “As the poisonous secretion of
insects belonging to various orders has the special power of affecting
the growth of various plants ; as a slight difference in the nature of the
poison suffices to produce widely different results; and, lastly, as we
know the chemical compounds secreted by plants are eminently liable
to be modified by changed conditions of life.—we may believe it
possible that various parts of, a plant might be modified through the
agency of its own altered conditions.” In the ‘Origin of Species,’
p. 572, he says: “‘ When we see the symmetrical and complex out-
erowths caused by a minute atom of the poison of a gall-insect, we
may believe that slight changes in the chemical nature of the sap or
blood would lead to extraordinary modifications of structure.” In
another work he says: “The complex and extraordinary outgrowths
which invariably follow from the insertion of a minute drop of poison
by a gall-producing insect show us what singular modifications result
in the case of plants from a chemical change in the nature of the sap.”
This view, on the strength of the great naturalist, was adopted by Sir
James Paget, Prof. Riley, and others. From the fact that so°’many
eminent men have been puzzled with this subject, it is obvious that
the question is a difficult one.
1 Adler, p. 163, written by Dr Stratton.
2 Animals and Plants under Domestication, p. 9.
HYMENOPTERA—OAK GALLS. ae
The two important factors at work in connection with gall-formation
are the activity of the vegetable sap on the one hand and the influence
of the animal agency on the other. JBotanically considered, gall-
formation cannot take place unless in direct contact with vital cells
—that is, those cells specially set apart for growth and development.
In the woody portion of the tree, from the root to the extremity of
every branch, there is a special zone of formative cells known as the
cambium ring which plays the part of growth in the theatre of life.
A section of leaf shows practically two layers of cells,—a layer of
closely packed cells on the upper side, known as palisade cells in
consequence of their resemblance to a paling fence; and a sort of
double layer on the under side, arranged in opposite direction to the
palisade cells. The under cells of the leaf are considered to be those
most actively associated with growth and assimilation. When eggs
are deposited in a normal winter bud, before there is any differen-
tiation of structure between the upper and under side of the leaf, we
often find the gall structure on both sides of the leaf, but the pre-
ponderance of structure is always on the under side. This is notice-
able in the case of Spathegaster baccarum. In order to fully under-
stand the formation of gall structure on different parts of the tree, as
associated with special cells, it is obvious that recourse must be had
to section-cutting with the microtome, as well as to minute micro-
scopical investigation.!
As gall-formation cannot take place unless in contact with special
cells, it follows, therefore, that the insect must deposit the egg with
the greatest exactitude, otherwise abortive galls would be the result.
In the artichoke gall, for example,—a species formed in buds,—we
often find many abortive galls. This may be the result of an egg
being deposited in a bud which had been previously pricked by
another gall-forming insect, and the vital cells of the plant thus be-
coming injured ; or the premature death of the larval creature within
the gall may have arrested the development of the gall. Considering,
from the entomological side, the effect of the insect on the vegetable
structure, it has been proved that the wound resulting from egg-laying
is at once healed up, and that there is, according to the species, a
considerable lapse of time from egg-deposition to hatching. During
this period the egg derives oxygen from the air, through the medium
1 For a full account of gall structure see ‘Pathologische Pflanzenanatomie,’
von Dr Ernest Kiister.
134 FOREST ENTOMOLOGY.
of the prolonged egg-stalk. Adler discovered that in two species gall-
formation commenced just as the larva was about to escape from the
egg. It is, of course, difficult—in fact, in most cases impossible—to
see the egg within the gall, but the same observer found that as the
larva grew and fed, so the gall increased in size. In other words, no
gall-formation took place until just immediately before hatching, but
the growth of the gall proceeded simultaneously with the development
of the larva. Hence it may be inferred that oak-gall formation is the
result of the excitatory action of the larva acting in conjunction with
the vitality of the vegetable cell. It must be borne in mind that this
special method of gall-formation is only applicable to oak galls, as galls
formed by some species of Hymenopterous insects, as, for example,
in the case of the common bean-like gall—Nematus gallicola—formed
on both sides of the willow leaves, is more or less of an amorphous
structure, and practically fully developed before any embryological
changes take place within the egg.
In consideration of the variety of gall-structure, and the comparative
sameness of larval anatomy, the question may be asked, Is there a
mechanical difference in the direct action of the larva or a chemical
difference in the composition of the excitatory emanations? In other
words, as the larve are exactly similar in structure and action, what
are the factors which produce variations of structure, size, and colour?
Thus in point of anatomical structure the larvee of the Cynipide are
practically identical, and, as previously remarked, the galls vary in
size, colour, and complex structure.
The question of gall-formation, as considered in relation to the
theory of evolution, is somewhat difficult to understand, but, at the
same time, is extremely interesting to the philosophical scientist.
Darwin somewhere in his writings remarks that if it could be proved
that any one creature worked for the good of another creature, his
theory would fall to the ground. Of course, this remark is only illus-
trative of the general principle of natural selection and the “survival
of the fittest,” and must not be confounded with the principle of
altruism, as, for example, the care of the parent for the offspring.
Now, in oak-gall formation, and all its complexity of morphological
structure, we cannot believe that the oak would form these galls in a
disinterested way for the good of the insect, nor, on the other hand,
as being of any advantage to the oak itself, considered as a vegetable
organism. The oak gall is, therefore, a distinctly differentiated struc-
HYMENOPTERA—OAK GALLS. 1 gS 13,
ture, apparently formed for the good of the insect, which, as remarked,
would be against the principle of the theory of evolution; and in
view, therefore, of the extreme interest of this question, I have taken
the liberty of quoting the following on “ Vegetable Galls” by Mr
G. J. Romanes in ‘ Darwin and after Darwin.’ Mr Romanes says—
“The other instance to which I have alluded as seeming at first
sight likely to answer Darwin’s challenge is the formation of vegetable
galls. The great number and variety of galls agree in presenting a
more or less elaborate structure, which is not only foreign to any of
the uses of plant-life, but singularly and specially adapted to those
of the insect-life which they shelter. Yet they are produced by a
growth of the plant itself, when suitably stimulated by the insect’s
inoculation ; or, according to recent observations, by emanations from
the body of the larve which develop from the eggs deposited in the
plant by the insect. Now, without question, this is a most remark-
able fact; and if there were many more of the like kind to be met
with in organic nature, we might seriously consider whether the
formation of galls should not be held to make against the ubiquitous
agency of natural selection. But inasmuch as the formation of galls
stands out as an exception to the otherwise universal rule of every
species for itself, and for itself alone, we are justified in regarding
this one apparent exception with extreme suspicion. Indeed I think
we are justified in regarding the peculiar pathological effect produced
in the plant by the secretions of the insect as having been in the first
instance accidentally beneficial to the insects. Thus, if any other
effect than that of a growing tumour had been produced in the first
instance, or if the needs of the insect progeny had not been such as
to have derived profit from being enclosed in such a tumour, then, of
course, the inoculating instinct of these animals could not have been
developed by natural selection. But given these two conditions, and
it appears to me there is nothing very much more remarkable about
an accidental correlation between the effects of a parasitic larva on a
plant and the needs of that parasite, than there is between the simi-
larly accidental correlation between a hydatid parasite and the nutri-
tion furnished to it by the tissues of a warm-blooded animal.
Doubtless the case of galls is somewhat more remarkable, inasmuch
as the morbid growth of the plant has more concern in the correlation
—being, in many instances, a more specialised structure on the part
of a host than occurs anywhere else, either in the animal or vegetable
136 FOREST ENTOMOLOGY.
world. But here I may suggest that although natural selection cannot
have acted upon the plant directly, so as to have produced galls ever
better and better adapted to the needs of the insect, it may have so
acted upon the plants indirectly through the insects. For it may very
well have been that natural selection would ever tend to preserve
those individual insects, the quality of whose emanations tended to
produce the form of galls best suited to nourish the insect progeny ;
and thus the character of these pathological growths may have become
ever better and better adapted to the needs of the insects. Lastly,
looking to the enormous number of relations and inter-relations
between all organic species, it is scarcely to be wondered at that
even so extraordinary an instance of correlation as this should have
arisen thus by accident, and then have been perfected by such an
indirect agency of natural selection as is here suggested.
“ Aoain, quite independently, and still more recently, Mr Mivart
alluded in ‘Nature’ (vol. xli. p. 41) to the difficulty which the
apparently exceptional case of gall-formation presents to the theory
of natural selection. Therefore I supplied (vol. xl. p. 80) the sug-
gestion given in the text—viz., that although it appears impossible
that the sometimes remarkably elaborate and adaptive structures of
galls can be due to natural selection acting directly on the plants
themselves,—seeing that the adaptation has reference to the needs’ of
their parasites,—it is quite possible that the phenomena may be due
to natural selection acting indirectly on the plants, by always preserv-
ing those individual insects (and larve) the character of whose
secretions is such as will best induce the particular shapes of galls
that are required. Several other correspondents took part in the
discussion, and most of them accepted the above explanation. Mr
T. D. A. Cockerell, however, advanced another and very ingenious
hypothesis, showing that there is certainly one conceivable way in
which natural selection might have produced all the phenomena of
gall-formation by acting directly on the plants themselves (vol. xl.
p. 344). Subsequently, Mr Cockerell published another paper on the
subject, stating his views at greater length. The following is the
substance of his theory as there presented :—
“Doubtless there were internal plant-feeding larvee before there
were galls; and, indeed, we have geological evidence that boring
insects date very far back indeed. The primitive internal feeders,
HYMENOPTERA—OAK GALLS. 137
then, were miners in the roots, stems, twigs, or leaves, such as occur
very commonly at the present day. These miners are excessively
harmful to plant-life, and form a class of the most destructive insect-
pests known to the farmer: they frequently cause the death of the
whole or part of the plant attacked. Now, we may suppose that
the secretions of certain of these insects caused a swelling to appear
where the larve lived, and on this excrescence the larve fed. It is
easy to see that the greater the excrescence, and the greater the
tendency of the larve to feed upon it, instead of destroying the
vital tissues, the smaller is the amount of harm to the plant. Now,
the continued life and vitality of the plant is beneficial to the larve,
and the larger and more perfect the gall, the greater the amount of
available food. Hence natural selection will have preserved and
accumulated the gall-forming tendencies, as not only beneficial to the
larvee, but as a means whereby the larve can feed with least harm to
the plant. So far from being developed for the exclusive benefit of
the larve, it is easy to see that, allowing a tendency to gall-formation,
natural selection would have developed galls exclusively for the
benefit of the plant, so that they might suffer a minimum of harm
from the unavoidable attacks of insects.
“But here it may be questioned, Have we proof that internal feeders
tend to form galls? In answer to this I would point out that gall-
formation is a peculiar feature, and cannot be expected to arise in
every group of internal feeders. But I think we can afford sufficient
proof that wherever it has arisen it has been preserved ; and further,
that even the highly complex forms of galls are evolved from forms
so simple that we hesitate to call them galls at all (‘ Entomologist,’
March 1890). The paper then proceeds to give a number of in-
dividual cases. No doubt the principal objection to which Mr
Cockerell’s hypothesis is open is one that was pointed out by Herr
Wetterhan—viz., ‘the much greater facility afforded to the indirect
action through insects, by the enormously more rapid succession of
generations with the latter than with many of their vegetable hosts
oaks above all’ (‘ Nature,’ vol. xlii p. 394). This difficulty,
however, Mr Cockerell believes may be surmounted by the con-
sideration that a growing plant need not be regarded as a single
individual, but rather as an assemblage of such” (vol. xli. pp.
559, 560).
With regard to the insects producing oak galls, the transformations
ike FOREST ENTOMOLOGY.
of the Cynipide are complete. They pass through four stages—viz.,
ego, larva, pupa, and imago (fig. 129).
The egg (fig. 129, a) is pyriform, with one end elongated, terminat-
ing as a prolonged penduncle. Adler supposed the function of this
organism to be respiratory, it having long peduncles when deeply
embedded and difficult of access to oxygen, and shorter when access
is easy.
The eggs of the Cynipide are often laid in winter, thus contrasting
Fig. 129.
a Egg of Cynips. (Copied from Adler and e Ovipositor of Neuwroterus lenticularis.
Stratton.) (From camera-lucida sketch.)
b Larva of Cynips. f Wing of Spathegaster baccarwm. (From
ce Pupa of Cynips. photograph.)
d Gall-fly, Teras terminalis (oak - apple). g Antenna of Spathegaster baccarum. (From
Male. (From photograph.) camera-lucida sketch.)
with the eggs of many species of saw-flies, which are deposited when
nature is active. There are other interesting points about the eggs
which will be considered later on.
The larvae are white, footless, and fleshy grubs, with thirteen
segments (fig. 129, 6). There is considerable diversity of time regard-
ing the larval stage.
In appearance the pupe are similar to the larvae, and some organs
of the perfect insect are discernible. Fig. 129, ¢.
ad
HYMENOPTERA—OAK GALLS. 139
The imagines, apart from the salient features to be considered
under general anatomy, present very few interesting habits. They
are inactive, take no food, but are known to imbibe water, and a most
interesting point is the variation in the time of appearing.
The males differ from the females in having longer antennee, and
also have one or two more joints than in the case of the female (fig.
129, d). The female has a very large abdomen, and the precise shape
of the abdomen again differs according to species, which depends on
the form of the ovipositor (fig. 129, ¢). It is to be remembered that we
have two forms, the sexual and asexual or agamic, and that specific
characters are not very distinct; therefore we have to rely on the
galls themselves for the most important points of discrimination of
species.
The following are the most distinguishing features, according to
Cameron ! :—
“‘ Cynipide.—Abdomen petiolated—z.e., not attached by its entire
breadth to the thorax.
“ Abdomen pedunculated, trochanters biarticulate, antenne 12 to 15
jointed and never elbowed, prothorax reaching to the insertion of
the wings; wings without a stigma, and with 1 radial and 1 to 3
cubital cellules, the second when present being minute, usually
triangular; the sub-costal cellule large, always present; the other
cellules badly defined or absent ; submarginal nervure absent ; abdo-
men compressed, ovipositor originating close to the base of the
abdomen, the borer usually semi-spiral, and with parts free; larve
apterous, never spinning a cocoon ; eggs stalked ; antenne in ¢ stouter
than ¢ ; legs, claws simple in Cynips, cleft in some species of Andri-
cus and Neuroterus.
“‘Chalcidide.?— Wings having a stigma; no radial or cubital
cellules; antenne elbowed; prothorax not reaching to insertion of
wings.”
The details of a wing of Cynips, fig. 129, 7, should be carefully
studied, as the wings of the genuine oak-gall fly differ very much
from the various species of parasitic flies which are associated with
the Cynipide.
' Monograph of the British Phytophagous Hymenoptera, vol. iii. pp. 142,
147. Ray Society.
? This family contains many of the parasites found in oak galls, therefore it is
most important to recognise the contrasting points.
140 FOREST ENTOMOLOGY.
Adler! arranges the species in the four following groups—viz. :
I. NEvuROTERUS. III. Dryopwanta.
IJ. APHILOTHRIX. IV. Broruiza.
In attempting to give some detailed account of the various species
of oak galls whereby the galls themselves may be recognised in the
forest and the insects verified after hatching in confinement, it is
obvious there are several ways open for adoption.
We might follow a botanical method and describe the galls on buds,
leaves, fruit, and roots; or we might adopt an entomological course,
and describe and compare the various species as found on the respect-
ive parts of the tree. But we shall adhere
to the arrangement of Adler, because we may
then follow the commonest species and have
a direct bearing on a most important biological
law—viz., the alternation of generations.
Firstly, take
1, NEUROTERUS LENTICULARIS, O1.? (Oak-
spangle Gall).
This gall is very common throughout the
country from July to September. The galls
are scattered promiscuously on the under side
of the leaves (fig. 130), are more or less circular,
and develop in July from objects resembling
si apa eae Ne ate: pin- points. They are clothed with stellate
terus lenticularis (ovk- airs on the upper side, but smooth on the
spangle gall). z i ‘
under side of the surface, pressing against the -
leaf and very slightly attached to the leaf. They are raised in the
centre, tapering to thin edges on the leaf, and with the outer edge
lying flat on the leaf. If specimens which lie on the ground over
winter be measured in March, just before the flies hatch out, it will
be found that they have the same breadth as in autumn, but have in-
creased considerably in thickness. At this time of the year they will
measure about 4 mm. in breadth and 24 mm. in thickness.
1 Alternating Generations, p. 8. Translated by Dr Stratton. 1894.
2 The figures 1 and la represent alternating species. Thus 1 alternates with
la, 2 with 2a, and so on. It should be noted also that the generations marked
la, 2a, &c., produce insects of both sexes, whereas insects in the generations
marked 1, 2, &c., are all females.
HYMENOPTERA—OAK GALLS. 141
Fly: colour black, shining, length about 2 to 2.5 mm. The thorax
is rather dull in appearance ; abdomen shining and almost round in
form when looked at from the side. The legs are of a lightish-brown
colour. The wings are iridescent and considerably longer than the
body ; antennze brownish, 15-jointed, the seven apical joints being
nearly equal in size and much smaller than the basal joints (fig. 131).
The insects hatched out in Northumberland from March 23 to April
12, 1906, and only lived for about ten days within the glass case.
Prior to understanding the subject, a curious fact had often sug-
gested itself to me as a problem difficult of solution—viz., if the
insect appears in March, and lives only for a short time, where does
it find leaves to deposit its eggs on for the next generation, seeing
that leaves do not often appear until
the end of May or beginning of . /
June? The first thought which sug-
gested itself was that the eggs were
deposited in the buds, and when the
leaves unfolded the galls would de-
velop. Then the problem appeared
more difficult, inasmuch as the spangle /
galls chiefly appear, not on the first
Gewel ee te tl ne Fig. 131.—Neuroterus lenticularis.
evelopec eaves trom he winter (Drawn by J. Patten, jun.)
buds, but on leaves not appearing
until July—in other words, on the young shoots which grew after
the fly of the Neuroterus lenticularis must have been dead.
Dr Adler, before commencing to work out the subject, must have
been likewise puzzled, and accordingly he commenced a series of ex-
periments in 1875. He grew a number of young oaks in flower-pots,
hatched out the spangle-gall flies in March, and induced them to
deposit eggs in the young oak buds, under glass, when the leaves
unfolded and developed, together with the galls resulting from the
previous deposition of Cynip eggs of the spangle-gall species. The
galls, instead of being spangle galls, were another type—viz., Spathe-
gaster baccarum or currant gall (figs. 132 and 133), The galls were
different, and the flies also, for they were sexual, males as well as
females being found, whereas in the previous species the insects were
all females. Adler then induced Spathegaster baccarum to deposit
eggs on the leaves, and obtained as a result the oak-spangle galls,
—the galls on the leaves of the young shoots. Thus the oak-spangle
142 FOREST ENTOMOLOGY.
_gall-fly — Neuroterus lenticularis — deposited eggs in the bud and
produced the currant gall; and the gall-flies of Spathegaster baccarum
or currant gall produced the spangle gall. In short, flies of the one
species deposited its eggs and produced the galls and flies of the other
species. Thus Adler demonstrated to the scientific world what had
only been previously guessed at—viz., the important biological law
of the alternation of generations in oak galls. This is a very important
biological law which is not uncommon amongst certain animals com-
paratively low in the scale of organisation, and is no doubt essential
to the wellbeing and continuation of species. In view, therefore, of
Fig. 132.—Galls of Spathegaster baccarum o7 Fig. 133,—Galls of Spathegaster
mule flowers of oak. baccarum on leaves.
the biological importance of the subject, it may be well to contrast two
important and to some extent allied phenomena—viz., Dimorphism
and Hetercecism—as compared with alternation of generations.
Dimorphism means, two forms of the same thing. Thus certain
chemicals and minerals crystallise in two forms, and are called
Dimorphous, and if in three forms, Trimorphous. In animals we
have seasonable dimorphism, as change of colour in winter or
adaptation to environment; sexual dimorphism, as instanced by the
difference between male and female in the peacock and pea-hen. In
the lower order of plants and animals inany instances might be given.
Hetercecism in animal and plant life means a change from host
to host in order to complete a life cycle. Thus the tapeworm found
—
HYMENOPTERA—OAK GALLS. 143
in man passes its early stage in the pig, and the latter stage in man.
Certain plant diseases pass one stage on weeds and the other on trees.
These are two typical instances from animal and plant life.
Alternation of generations is totally different from these phenomena,
inasmuch as two distinct generations alternate one with the other.
In fact, this may be best understood when we say that the children
never resemble their parents, but are always facsimiles of their
grandparents.
Having mentioned two distinct genera resulting from alternat-
ing generations, the question arises, Are the two genera widely
separated in point of general appearance or anatomical details? Adler
considers they are, and accordingly adopts Neuroterus and Spathe-
gaster as generic terms. But Professor Mayr of Vienna classifies
the two genera as Neuroterus, and this classification is adopted by
Cameron.
The main distinguishing features are slight differences in colour and
in general stoutness, Neuroterus being stouter than Spathegaster.
The abdomen differs in size and appearance, resulting from the size
and shape of the ovipositor (fig. 129, e), which must be viewed in the
relation of adaptation, a long ovipositor being necessary for penetrating
buds, and a short one for leaves.
la. SPATHEGASTER BACCARUM (Htg.)
The galls are found on the flowers and leaves (figs.132 and 133).
They are pea-shaped, smooth, glossy-looking, soft and succulent, of a
greenish colour, but have often a few bright-red spots. They are
situated on the under side of the
leaves, but often penetrate through the
upper side and rise slightly above it.
The specimens found on the male cat-
kins are generally smaller than those on
the leaves, and slightly more reddish
in colour.
The fly (fig. 134) has a black shin- Fig. 134.—Spathegaster baccarum.
ing body, about 24 mm. in length,
antenne brownish, 14-jointed in the male. The legs are yellow, with
black coxe at the base. Tarsi 5-jointed ; wings longish, broad at the
apex, and about 8 mm. in expanse. In a comparatively forward
144 FOREST ENTOMOLOGY.
season they may be found in the Midlands about the end of May,!
but more commonly in the middle of June. At the same season of
the year as we find the spangle gall, two or three other species of
Neuroterus may be found.
2. NEUROTERUS FUMIPENNIS (Htg.)
Gall on the under side of oak leaves, circular in outline, smaller in
size and brighter in colour than the spangle gall (fig. 135); but the
principal difference is that the spangle gall is razsed in the centre and
Fig. 135.—Galls of Neuroterus Fig. 136.—Galls of Spathegaster tricolor.
fumipennis. (Drawn by P. J. Brown.)
the outer edge lying flat on the leaf, whereas the species in question
has the outer edge of the gall raised and slightly depressed in the
centre. Thus the individual galls somewhat resemble a saucer,
According to Adler, larval development does not begin until March
(by the time Neuroterus lenticularis has hatched), and the flies appear
about the end of May. The same authority says this fly is easily
distinguished from all the other species of Neuroterus. Size 2 mm.
Thorax dull black; base of abdomen orange ; legs, including the
femora, orange ; wings, especially at the tips, smoky.
1 May 27, 1895, in Cheshire.
HYMENOPTERA—OAK GALLS. 145
2a. SPATHEGASTER TRICOLOR (Htg. )
The sexual species forms a pea-shaped hairy gall of light-yellowish-
green colour (fig. 136), appearing about the end of June or beginning of
July. They are found in clusters
on the under side of the leaves.
The hairs fall off when the
gall matures, and then it may
be mistaken for Spathegaster
baccarum, which, however, is
over by this time.
The fly is a very slender
insect, the wings when spread
out being comparatively long
in proportion to the body.
The body is about 2 mm. long, and the expanse of wings 8 mm.
The body is black throughout, legs all yellow, and the wings
rather cloudy. Males and females very much
alike.
Fig. 137.—Galls of Neuroterus leeviusculus.
3. NEUROTERUS L&VIUSCULUS (Schenck. )
This gall (fig. 137) is very much like the
two previous species In general appearance,
but not so common or so numerous on the
leaf. The form is similar, but in this
species the gall is nearly smooth except on
a well-defined knob in the centre, which is
covered with hairs. I have not reared the
fly, but found the gall fairly common both
in Cheshire and Northumberland.
3a. SPATHEGASTER ALBIPES (Schenck.)
Fig. 138.—Galls of Spathe-
This is the agamic species of WV. leviusculus, — gasteralbipes. (Drawn by
P. J. Brown.)
and I have only found it in one district—
viz., at Pauperhaugh, in Northumberland, about the beginning of
June. The gall of this species (fig. 138) is more or less oval, tapering
to a blunt point, and of a slightly yellowish-green colour. The galls
K
146 FOREST ENTOMOLOGY.
sit closely on the leaf, and they give rise to deep windings on the
edge of the leaf, which is said to be caused through the gall originat-
ing on a rudimentary leaf within the bud.
4, NEUROTERUS NUMISMATIS, Ol. (Button Gall).
This gall (fig. 139) is very common in the autumn. It is very
pretty, circular in shape, about 2 mm. in diameter, hard, with a shal-
low depression in the centre. I have not hatched the flies nor found
the alternate form—viz., 4a SPATHEGASTER VESICATRIX (Schltdl.),—
which are found on the under side of the leaf, and are rather incon-
spicuous, as they are embedded in
the substance of the leaf.1
There is another species in the
quite sure about fixing the genera-
tion cycle. This is the gall of
5. NEUROTERUS OSTREUS (Htg.)
This is a very small gall, not
larger than a leaden pellet, and al-
ways formed on the midrib of the
leaves, and very slightly attached.
It is very prettily marked, and the
pale- yellowish colour brightened
by red spots is suggestive of the
markings of a miniature egg of some bird. It is common in
September and October. From the early matured galls flies hatch
out in October, but those not maturing until October do not yield
gall-flies until the following spring. I kept some in confinement, and
they hatched out on April 25, 1895. The fly is about 2 to 25 mm.
in length, of a black shining colour, with dull thorax, legs yellowish
in slender portion and dark at top next to body ; antennz longish and
slender, wings comparatively long.
As Dr Adler is not quite certain about the generation cycle of this
species, it may be best to quote his own words—viz.: “I strongly
suspect that the sexual generation belonging to NEUROTERUS OSTREUS
Fig. 139.—Galls of Neuroterus numismatis.
1 T have since received this species from Mr E. T. Connold.
group of which Adler was not -
HYMENOPTERA—OAK GALLS. LAF
is to be sought for in SPATHEGASTER APRILINUS,” and this conjecture
has since proved to be correct.
5a. SPATHEGASTER APRILINUS (Gir.)
The galls of this species are formed in buds, but the formation is
so obscure as to be frequently overlooked. In fact, we should con-
sider them abortive buds, and the best way to find them is to look
for abortive buds just after the leaves develop. It should be noted
that undeveloped buds, frequently found in oaks after the early
flushing of the leaves, are due to the attacks of this species. In
order to hatch those galls it is best to collect them about the end
of April or beginning of May.
The fly is described by Adler as follows: ‘Length 2.5 mm.,
black thorax, somewhat shining; scutellum wrinkled, abdomen shin-
ing, antenne black, legs dark-yellow, coxze and basal half of the
femora blackish. Males and females similar in colouring.”
Genus APHILOTHRIX.
The second group, according to Adler, having alternate generations,
is the Aphilothrix-Andricus Group. The genus Aphilothrix includes
a large number of gall-flies found
only in the female sex. The genus
Andricus yields the sexual form.
6. APHILOTHRIX RADICIS (Fabr. )
This gall (fig. 140) is found on
the lower part of the trunk, or are
just on the horizontal portion of fis: Peer aie Sp Tas. In
the root above ground. At first it
appears as a large softish mass, but ultimately it becomes quite hard
in the centre, and a section made in mid-winter will reveal a many-
chambered gall with a fully developed fly in each chamber. They
hatch out about the latter end of April.
The fly is reddish-brown, with longitudinal stripes on the thorax.
The abdomen is somewhat dark, and the thorax is covered with a fine
silky pubescence. The antenne are dark-brown. Length from 5 to
148 FOREST ENTOMOLOGY.
6mm. The alternating species is 64 ANDRIcUS NoDULI (Htg.), which
makes galls in the woody portions of young shoots.
7. APHILOTHRIX CoRTICIS (Linn.)
The galls of this species are found inserted in the young bark
which is formed where the stem has been injured, or in the tender
bark which forms in the “healing over” process after a branch‘‘has
been sawn off (fig. 141). Sometimes they may be found in clusters,
Fig. 141.—Galls of Aphilothrix corticis in por- Fig. 142.—Galls of Aphilothrix
tion of bark ‘‘healed over by occlusion.” globuli.
but as a rule they are distributed over the young bark. It often
happens that the rim of under-bark surrounding the cut-off branch is
very much torn, and this arises from birds tearing out the galls and
lacerating the bark. ‘The flies hatch out in June, and the alternating
species, according to Adler, is 7a ANDRICUS GEMMATUS, a species found
in the terminal buds.
8. APHILOTHRIX GLOBULI (Htg.)
The gall (fig. 142) of this species is a beautiful green globular gall,
formed in the bud for the coming year. It may be found in Sept-
HYMENOPTERA—OAK GALLS. 149
ember projecting from the bud-scales, and would perhaps measure
about + inch in diameter. I found it very common in Delamere
Forest, Cheshire, but have not hatched the fly.
8a. ANDRICUS INFLATOR (Htg.)
This gall (fig. 143), which is the alternating species of A. globuli, is
originally formed from a bud. In general appearance it is somewhat
like the thickened portion of that part of a turnip immediately above
the bulb which is finally
surmounted by the leaves.
The gall proper is really
within the woody portion,
and during the year in
which eggs are deposited
growth is not perceptibly
interfered with, but the
next year the portion
affected by the insect
agency swells, and the
adventitious buds formed
thereon give rise to the
tuft of leaves referred to.
The galls are not very com-
mon, but may be looked
for in June, and the flies
emerge only in July.
Fly—size 2 to 4 mm. Fig. 143.—Gall of Andricus inflator.
Head and thorax black,
slightly shining; abdomen in the female black above, red or orange
beneath,—in the male entirely black ; legs orange, but the posterior
tibize and coxe dark ; antenne dark, pale at the base.”—Adler.
The next gall to be considered is very common in the sexual form,
but not so general in the agamic stage. The latter is, according to
Adler’s classification, APHILOTHRIX COLLARIS (Htg.), and the former,
ANDRICUS CURVATOR (Htg.), or the leaf-twisting gall.
The gall of (9) ApHILoTHRIX COLLARIS is formed upon a bud, and,
being concealed, may easily be overlooked. Adler says: “In Sept-
150 FOREST ENTOMOLOGY.
ember and October the gall becomes loosened and falls to the ground,
and a few may remain, but only inquilines and parasites are reared
from those adherent galls.” The flies are said to be difficult to rear
from the galls, as after the galls are mature a year and a half passes
before the appearance of the flies.
9a. ANDRICUS CURVATOR (Htg.) !
This alternating generation with Aphilothrix collaris 1s a very
common gall, and may be found about the beginning or middle of
Fig. 144.—Galls of Andricus Fig. 145.—IJnjury done to leading shoot
eurvator. by gall of Andricus curvator.
June. The galls are formed on the ribs of the leaves. They form
irregular thickenings of the leaf-surface, and cause the leaf to twist
inwards (fig. 144). Sometimes we find the extreme tip of the twig
affected by the gall-formation, and, as a consequence, a swelling
takes place where the terminal shoot bends, and grows at right angles
1 From this point the alternation of generations is not followed.
HYMENOPTERA—OAK GALLS. ou
to the more upright twig. The portion thus affected seldom does any
more good, but, when this occurs on minor twigs, the tree is not
appreciably injured (fig. 145). When, however, several galls are on
one leaf and very abundant on a young tree, the leaves are arrested in
their development, and the result in the aggregate would diminish
growth and cause disfiguration. The gall itself is an irregular swell-
ing, of a green colour, and pod-like in structure. When opened, the
central cavity is comparatively large, and contains a small brownish
seed-like pod, which is the inner gall, wherein is found the larval form
Fig. 146.—Galls of Aphilothrix quadrilineata on flowers of oak.
of the gali-tly. This inner gall is not attached to the wall of the outer
gall. The galls may be looked for in May, and the flies appear in June.
The fly is about 1.5 to 2 mm. in size. Body and antennz shining
black ; legs lighter in colour; wings more or less hyaline.
The two following species of the Aphilothrix group are not
associated by Adler as connected with the alternation of generations,
but are nevertheless more or less common.
APHILOTHRIX QUADRILINEATA (Htg.)
The gall of this species, fig. 146, is found on the flowering catkins
about the end of May or beginning of June. It is very small in size,
152 FOREST ENTOMOLOGY.
and may not inaptly be compared to a miniature rifle-bullet with
longitudinal ridges added on.
I have not succeeded in rearing the fly, which Adler says is very
difficult, and does not appear until the following April. It is very
common in Alnwick parks.
APHILOTHRIX ALBoPUNCTATA (Schltdl)
The gall of this species is a very pretty little object, and is
formed in the bud (fig. 147). It somewhat resembles a small
acorn. It is green, spotted with red, and
is about 5 to 6 mm. long. The larve are
gregarious, and the gall is not chambered.
The galls were very common in High
Legh, Cheshire, and were found in May.
The flies hatched out about June of the
same year.
ANDRICUS RAMULI (Linn.)
This gall is known as the cotton gall, as it
occurs on the flower and resembles a ball of
cotton-wool (fig. 148). The hairs are inter-
woven so as to form a sort of felt. The galls
are many-chambered, or polythalamous. This
Fig. 147.—Galls of Aphil-
othrix albopunctata.
is by no means a very common gall. I have
found it twice, —once in Wales, in June
1901, and again in the Alnwick parks, July 1898. The flies
hatch out in July.
APHILOTHRIX FECUNDATRIX, Htg. (Adler).
Andricus fecundatrix, Mayr (Cameron).
This gall is known as the artichoke gall. It very much resembles
a hop-flower, with imbricated scale. At first it is of a green colour,
but becomes brown with age. In collecting those galls when mature
much care is necessary to obtain the imagines. The real gall is a
small acorn-shaped body within these scales, but so very loosely
HYMENOPTERA—OAK GALLS. 153
attached that, if not careful, our hop-like galls may be nothing else
but empty husks (fig. 149).
Cc
Dryophanta Group.
The galls of this group are always found on the under side of the
leaves, and in order that we may verify the galls in the forest, it may
Fig. 148.—Gall of Andricus ramuli (cotton gall). Fig. 149.—Galls of Aphilothrix fecundatrix
(Drawn by P. J. Brown.) (artichoke gall).
be better to confine ourselves to the group and not to the cycle
generation.
DRYOPHANTA SCUTELLARIS, Htg. (Adler).
Dryophanta folii, Mayr (Cameron).
This is known by the graphic name of ‘cherry gall.” It is compara-
tively large, about the size of a small cherry or marble, and always
springing from the veins of the leaves, more especially the midrib. It
is slightly attached to the vein. The colour varies from light-green
154 FOREST ENTOMOLOGY.
and yellow to red on one side. It is fairly common in some parts of
the country, but is more or less local (fig. 150).
DRYOPHANTA LONGIVENTRIS (Htg.)
This gall (fig. 151) is somewhat like the previous species, and is also
found on the midrib of the leaves. It is brilliantly coloured with red
and white stripes, and its rind may be
either smooth or slightly corrugated. It
is fairly common in some parts of North-
umberland.
DryoPHANTA Divisa (Adler).
The galls are about the size of a small
pellet or buck-shot, and are found thickly
studded on the under side of the leaves,
springing from the veins (fig. 152). They
may be looked for from June to October, and
at first they are of a bright-red colour, but
they gradually change to a light-brown to-
_ wards maturity. The surface is smooth, with
a slight depression in the centre. The struct-
Fig. 150.—Gall of Dryophanta re is hard and woody, with a comparatively
scutellaris (cherry gall).
thick wall and small single larval chamber.
From a dozen to twenty may sometimes be found on one leaf.
The flies hatch in October and November, and are about 4 to 5 mm.
long. Antenne dark - brown ;
head and thorax brown ; ab-
domen black, and legs of a
lighter brown than body; wings
longer than body. .
Biorhiza Group.
The first to be considered in
this group is BroRHIZA APTERA
(Fabr.) The galls of this
species are found on the roots of the oak, sometimes on the
smallest tips, at other times on strong roots. The galls may
Fig. 151.—Galls of Dryophanta longiventris.
HYMENOPTERA—OAK GALLS. 155
very often be found by workmen when trenching or uprooting trees in
winter. They are of a coffee-brown colour, and vary in size, but the
average is about the bulk of a common pea
(fig. 153). They are generally procured in
clusters, which very much resemble the honey-
combs of the moss-bee, Bombus muscorum.
Adler says that, after many observations, he
found that the flies issue in December and
January, but adds that other observers found
the time of their appearance rather variable.
This last remark I can quite endorse, inas-
much as galls found by workmen in February
did not hatch until well on in spring. In
this case there is no mistaking the species or
confounding with parasites, imasmuch as the
specimens are all apterous.
The fly varies in size from 4 to 7
mm. long, wingless, with a rather slender
thorax. The form is somewhat spider-like,
and the whole body of a uniform brownish
colour.
With regard to the alternate form, Adler
made many observations, and found that the
Fig. 152.—Galls of Diyo-
phanta divisa.
eggs deposited by Biorhiza aptera result in the formation of the
well-known oak-apple.
Adler watched the ege-laying process very closely, and found that
the insect did not de-
posit the egg immed-
iately after making the
incision, but acted on
the principle of “one
thing at a time,” inas-
much as she carefully
pricked the buds and
then returned to deposit
the eggs in previously
prepared channels. In
this way he found that
Fig. 153.—Galls of Biorhiza aptera.
on January 27, 1878, the fly deposited 582 eggs during 87 hours.
Towards the end of May these galls were fully developed oak-apples.
6 FOREST ENTOMOLOGY.
TERAS TERMINALIS (Fabr.)
The gall of this species (fig. 154) is the well-known oak-apple or
King Charles apple, which is worn by country boys in the south of
England on the 29th May. When first the oak-apple appears, it is
of a very beautiful scarlet colour. On waking a longitudinal or
transverse section, we find that the interior of the gall is many-
chambered, and the outside soft, spongy, and rich in tannin.
The gall matures in June, and the flies emerge in July. This being
the case, and considering that the
gall is abundant and common, it
is very easily reared.
With regard to the fly, I have
made from microscopical observa-
tions the following notes :—
Length of body 2 mm.; breadth
or expanse of wings 5 mm. ; wings
slightly pubescent, with short
hairs; head and thorax brownish ;
abdomen considerably narrower
than thorax, blackish, shining,
ego-shaped, and pointed; eyes
black and shining; three ter-
minal joints of antennze more
slender than the other joints.
The males are paler than the females, and always winged, but the
females have often rudimentary wings.
The alternate generation between Biorhiza aptera and Teras ter-
minalis has been demonstrated by Adler and corroborated by Beyerinck,
and yet notwithstanding this there are apparent natural difficulties to
fully realise the same correctly. First of all, we have the agamic
generation Biorhiza aptera living on the roots and always apterous.
But the next generation is often found on the tops of comparatively
Fig. 154.—Gall of Leras terminalis (oak-apple).
tall trees, and the question arises, How do the apterous flies in a
natural state reach the topmost boughs to deposit their eggs?
We have seen that apterous insects are often born amongst oak-
apple flies. This might be considered advantageous in assisting the
insect to deposit its eggs on the roots. The apterous flies on the oak-
apple are the exception, but the apterous flies from the root galls, so
.
HYMENOPTERA—OAK GALLS. LT
far as hitherto ascertained, are a rule without any exception. Yet
another point is noticeable—viz., that galls appear on certain levels,
certain zones of height; and here we find the apterous flies, in order
to reproduce the next generation, have reached the highest zone.
There is a special entomological interest attached to the oak-apple
gall, inasmuch-as the list of parasites reared and given by Cameron
is quite a little study in itself. The interest is intensified on account
of various species appearing throughout the whole year.
BIoRHIZA RENUM (Htg.)
This is a kidney-shaped gall, as the name implies (fig. 155). It is
not very common, but when found is generally abundant on the under
side of the leaves, and
arranged in rows attached
to the veins. It is found
in September and October,
but though I found it sey-
eral consecutive years in a
Cheshire lane, I yet failed
to rear a single fly, —
which is described as wing-
less, and of a brownish-red
colour.
By experimental breed-
ing Adler found the fly
alternated with Tricon-
ASPIS MEGAPTERA = (c7ust-
alis), which is found on
adventitious buds on old
oak stems near the roots.
The gall is about the size
Fig. 155.—Galls of Biorhiza renum (kidney gall). ofa large pea, of a beauti-
ful pink colour, soft and
succulent. This gall may be first observed towards the latter end of
April, and by the middle of May we find it fully matured, and the
insects hatching out. It is very generally distributed throughout the
country, but is not always equally abundant every year. Thus in
1893 it was very common, but comparatively rare in 1894 and in
158 FOREST ENTOMOLOGY.
1895, and again fairly abundant in 1896. In 1897 I found one as
late as May 23 in Cheshire, and it hatched out next day. It may be
found either singly or in masses, and each gall is single-chambered.
The perfect insect is one of the prettiest of the gall-flies. The head
and thorax are black, and abdomen of a bright shining appearance.
The wings are considerably longer than the body, and the general
appearance handsome and slender. Having observed that the fly from
B. renum on the leaves was apterous, contrasted with long-winged flies
from Trigonaspis megapteru,
it may be observed in passing
that the apterous flies deposit
their eggs on adventitious buds
on the stem from one to three
feet from the ground.
There is another curious
point worthy of notice.
Cameron gives Tvrigonaspis
megaptera as the agamic form,
and Biorhiza renum as the
sexual, Adler, on the other
hand, gives Tiigonaspis meg-
aptera as the sexual, and
Biorhiza renum as the agamic
form. Cameron describes the
male of Biorhiza renum, and
Adler describes the male of
Trigonaspis megaptera under
the synonym of Trigonaspis
crustalis, tg.
Perhaps the inference
which might be drawn from this apparent contradiction is, that
while the various families of insects appear to be well worked by
leading authorities, it is nevertheless essential in practical entomology
that all points should still be verified.
Fig. 156.—Galls of Cynips Kollari (marble gall).
Cynips Kounarti (Htg. )
The next and last species I shall deal with is the very common
one known as ‘marble galls” or Cynips Kollari,—often very abun-
HYMENOPTERA—OAK GALLS. 159
dant on oak bushes and young trees. ‘This gall is now widely dis-
tributed over the British Isles (fig. 156). It is often called the Devon-
shire gall, from the fact of its first appearing in that county and
causing great alarm.
The galls are from } inch to 1 inch in diameter, and, as a rule,
almost a perfect ball. In some cases two galls coalesced, but in the
centre one grub may only be found. As a rule, the gall may be
perfectly smooth, but in some cases it is warty. At other times they
may be found dwarfed in size and shrivelled, but when such is the
case they are generally chambered, and inhabited by parasites,—thus
contrasting with the true larval chamber, which is normally single
and smooth.
The fly appears at various times, according to locality, from the
latter end of April to beginning of June. As the fly is very easily
hatched out, and being of a fairly large size, the following detailed
description from Adler and Stratton may be given—viz. :
‘‘ Fly.—Length 4 to 6 mm. ; whole body reddish-yellow ; looked at
from above, the head appears widened behind the eyes; cheeks half
as long as the eyes, without wrinkles; antenne filiform, thirteen-
jointed, second joint longer than thick, thirdjjoint the longest, twelfth
and thirteenth joints partially united. ‘Thorax brown, covered with
short hairs ; parapsidal furrows complete ; scutellum with two thickly
haired fovee at its base; metanotum black, vertical, overhung by the
scutellum. Abdomen smooth and shining; second segment covering
half the dorsum, very dark above, with two large hairy spots; the
other segments fringed with silky hairs. Ovipositor long and spiral.
Venter exposed. Wings as long as the fly, hyaline, finely haired ;
radial cellule open at the margin, elongate, with the areolet opposite
its base; basal abscissa of the radius angled ; cubitus opposite to, but
not reaching, the middle of the transverse basal nervure ; legs yellow,
margin of the fore tibie fringed with short depressed hairs; hind
cox broad; claws bifid.” +
SYNOPTIOAL TABLE oF Oak GALLS.
With a view to readily ascertain the name of any gall, it may be
considered advisable to arrange them according to the respective parts
of the oak-tree on which they may be found.
1 Adler and Stratton, p. 164.
160 FOREST ENTOMOLOGY.
I. On the Leaf.
A. On the under surface of the leaf.
Currant gall found either singly or in groups—green or tinged
with red —soft, succulent, smooth, about 5 mm. diameter. In
May and June; soon shrivels up after escape of fly
Spathegaster baccarum.
Pale, about 4 mm. diameter, soft, in clusters and hairy. July
Spathegaster tricolor.
Cherry-like gall, softish, generally singly but sometimes in clusters.
July and October : : : . Dryophanta scutellaris.
Smaller than previous species; harder, and beautifully marked
with reddish stripes. July to October . Dryophanta longiventris.
Like a small pellet, smooth, beautifully spotted. August to Oct-
ober 3 : : 4 : é . Neuroterus ostreus.
Kidney-shaped, often in clusters on veins. September and October
Biorhiza renum.
Button-like gall, conspicuously depressed in centre, surface like silk
velvet, light-brown colour. Autumn . Neuroterus numismatis.
Covered with stellate hairs, raised in centre, flat at outer edge,
spangle gall. Late summer and autumn. Neuroterus lenticularis.
Not covered with hairs, nearly smooth, white or yellowish, outer
edge turned up. Late summer and autumn Neuroterus leviusculus.
Centre of gall concave, edges conspicuously turned up
Neuroterus fumipennis.
B. On the margin of the leaf.
(1) No inner gall.
Smooth, spindle shaped, causing fairly deep indentations of leaf
Neuroterus albipes.
Smooth, red-ribbed, and leaf on which it is found often looking as
if abruptly cut. - : : . Aphilothrix marginalis.
(2) With an inner gall.
An irregular globular swelling, outer surface hard, lightish-yellow
colour, : : ; . Andricus curvator.
HYMENOPTERA—OAK GALLS. 1G
IJ. In Buds.
Polythalamous ; very large, spongy, apple-like. In terminal buds,
or often on lateral buds on terminal shoots. May and June
Teras terminalis.
Monothalamous. In April and May, on trunks of old trees, gen-
erally near the ground, like a round drop of sealing-wax
Trigonaspis megaptera.
Like marbles on twigs or young trees in nursery ; green from July
to September, and light-brown throughout the winter; either singly
or in clusters . ‘ Cynips Kollart.
Spindle-shaped, ith long nadine J “ly and August
Aphilothrix callidoma.
Ovoid, green, spotted, smooth, hard . Aphilothrix albopunctata.
Gall wholly enveloped in leaf-scales . Aphilothrix fecundatrix.
Gall very thin, and to all appearance only an undeveloped bud. In
April and May . : : . Spathegaster aprilinus.
Globular, green, projecting frat bud scales in September and Octo-
ber . : ; ; Aphilothriz globult.
Terminal twig magia ath a tuft of leaves, growing from the
inflated portion . : : j : . Andricus inflator.
Irregular swellings on twig . . : . Andricus nodult.
IU. On Roots.
Polythalamous ; soft when young, woody when mature. At base
of trunk, or on strong roots, on surface of ground. October and
winter. é Aphilothrix radicis.
Mee suiatanons but eee in ernie clusters on rootlets of old
trees. October and winter. ; : . Biorhiza aptera.
IV. On Bark.
On young bark around a pruned branch, when cut off close to stem.
Early summer. , : : ; Aphilothrix corticis.
V. On Flowers.
Large mass of woolly hair, resembling a ball of cotton-wool. In
June and July . : : : : . Andricus ramult.
162 FOREST ENTOMOLOGY.
Spherical, smooth, and soft currant-like mass. May and June
Spathegaster baccarum.
Ovoid, slightly ribbed on sides like miniature rifle-bullet
Aphilothrix quadrilineata.
Note.—In the above synoptical table I have largely followed the
arrangement of Adler, but I have given only those species I have col-
lected, with the exception of Aphilothriz callidoma, which I received
from Mr Connold of St Leonards-on-Sea.
Oak Gatts: THEIR Economic INTEREST AND TEACHINGS.
With regard to oak galls, or the Cynips, considered as an insect-
pest, the only species I have ever found so numerous as to cause
appreciable damage was Cynips Kollari. This was in a plot of
transplanted oaks in a nursery in Cheshire, and the galls were so
abundant that the whole of the trees had to be burned.
Though individually the species of galls are not, as a rule, so
numerically strong as to be looked upon as a pest, yet collectively
they give rise to injuries which retard the longitudinal growth, and,
in many cases, ‘‘prune” the tree into shapes and forms exactly the
opposite to what practical forestry requires — as, for example, see
fig, 145. Hence they have important associations in practical
forestry, as well as interesting biological teachings.
There is no tree more difficult to train into a straight pole than
the oak, and it is just possible that this is often due to the effects
of the gall insects; therefore the best preventive against the injurious
effects is to be found in careful cultivation in the nursery and young
plantation. The evil practice of selling by height, irrespective of age,
has had disastrous results on the sylvicultural growing of oak. Thus
it often happens that nurserymen, having height in view, allow seed-
lings to grow for three years prior to transplanting, and then after
transplanting allow them to stand for three or four years in the
nursery - lines, then again transplant, and finally sell individually
over several consecutive years. But if the nursery work is bad,
the method of planting out by the purchaser is sometimes worse ;
for we often see large oaks planted out in a “mixed” plantation,
and towering three or four feet above the more hardy species, which
were planted under the name of “nurses.” Apart from the excellent
HYMENOPTERA—OAK GALLS. 163
method of sowing the acorns direct, the better sylvicultural method,
and one which will overcome gall insect - pests, is to transplant in
nursery-lines good seedlings at one year old, because at this age we
get a better root in proportion to the top than at two years. Then
if growth is vigorous in the nursery-lines, transplant the very best
specimens only the following year into the mixed wood, together with
the more hardy nurses, or otherwise in a young wood, where the
nurses have been planted as an ameliorating species in advance.
The remainder of the oaks in the nursery-lines, which will obviously
improve as the result of “quartering,” may also be planted out in
the young wood during the following year.
Of course it must be borne in mind that the above remarks apply
only to planting extensively, and under the protection of wire-
netting.
References to Literature consulted.
Adler and Stratton. Alternating Generations: A Study of Oak Galls and Gall-
Flies. 1891.
Cameron, Peter. A Monograph of the British Phytophagous Hymenoptera.
Vol. iv: Ray Society. 1893.
Cameron, Peter. Galls of Mid-Cheshire. Manchester Mic. Soc. 1891. 8 pp.,
lie ple
Fitch, E. A. The Galls of Essex. Trans. Essex Field Club.
Gardeners’ Chronicle. Articles on Galls from 1854.
Lubbock, Sir John. Origin and Metamorphosis of Insects. 1876.
Mosley, 8S. L. Yorkshire Galls. Naturalist, Sept. 1892.
Romanes, G. J. Darwin and after Darwin. Pt. I. 1892.
164
CHAPTER V.
HYMENOPTFRA—SAW-FLIES, Ere.
CONSIDERED as a division of entomology, perhaps no class of insects is
more important than the Hymenoptera. To the student of insect
anatomy and physiology they are, as a whole, the most highly
differentiated and organised creatures in the insect world. The
student of mental phenomena finds in this group instances of rare
intelligence and instinctive forethought, often surpassing anything in
the animal kingdom ; and the humble but patient observer who
studies life-histories will also find abundant scope in this important
division. When we remember that this order embraces (besides
many others no less distinct in their structure and their habits)
saw-flies, gall-flies, ichneumons, ants, bees, and wasps, the truth of
the above assertions will be apparent.
To the student of forest entomology they present a fairly wide field,
inasmuch as saw-flies and gall-flles may be considered as injurious
insects (though not always to any great extent), and ichneumons, on
the other hand, may be considered as beneficial insects.
To some extent, therefore, in a general way, the student must study
the salient features of the whole order, but unfortunately at the
present time entomologists are by no means agreed as to classification
either as regards the whole order or some of the most important
sections.
As regards the special study of Hymenoptera in its relation to the
forest, it may be said that on beating trees and bushes many larve of
several species may be found, and by breeding the same a good
representative collection might be obtained. This, however, would
be too general for forest entomology, and it is better, therefore, to
confine our studies to the more destructive or general species.
The Hymenoptera have by some been divided into Terebrantia and
HYMENOPTERA—SAW-FLIES, ETC. 165
Aculeata, according as the ovipositor of the female is modified into
a “boring instrument” or a “sting.” But this distinction is often
hard to maintain, and also appertains only to one sex, which is un-
satisfactory. Another division—viz., into Sessiliventria and Petiolata,
according as the abdomen is attached to the thorax over its whole
width, or at one point only by a narrow and stalk-like first segment—
is not open to the above objections, and is here adopted.
The Sessiliventria are also called by English writers “ Saw-flies,”
and by German “ Blattwespen ” (7.¢., leaf-wasps). Such Hymenoptera
as are of special interest to the forest entomologist belong mostly to
this division, and I have therefore thought it worth while to call
attention to the further classifications which have been introduced
into it by specialists, and to indicate some of the writings on the sub-
ject which are likely to assist such students as desire to master it to
a greater or less extent.
The most useful complete works dealing with the saw-flies of large
areas as a whole are—
Kriechbaumer’s collection of Klug’s writings on Blattwespen (Ber-
lin, 1884); Hartig’s ‘Families of Leaf and Wood Wasps’ (Berlin,
1860) ; Thomson’s ‘Hymenoptera Scandinavie,’ vol. i. (Lund, 1871) ;
Andre’s ‘Species,’ vol. i. (Beaune, 1879); and (for British genera
and species) Cameron’s Monograph, &c. All these works, however,
are beginning to get old; and since their appearance much new
light has been thrown upon the group by a very able and original
German naturalist (Pastor F. W. Konow), who has published a vast
number of short articles and revisions of particular genera, and is now
issuing a monograph (on the very largest scale) of the saw-flies of the
whole world. Consequently several names of species, and even genera,
hitherto in common use are destined to be superseded before long,
and some may be said to be already out of date. A series of papers
by Mr Morice now appearing in ‘The Entomologist’s Monthly Maga-
zine,’ entitled “ Help-notes,” &c., has for one of its chief objects to
inform English students of the alterations in the British list (at pres-
ent resting mainly on Cameron’s work), which seem to be required in
consequence of Konow’s researches hitherto ; and also to facilitate the
study of the subject, by fresh tabulations of generic and specific char-
acters, which the writer hopes will generally suffice to guide collectors
to a correct determination of the specimens taken by them.
In view, therefore, of the importance of Morice’s “ Help-notes,” I
166 FOREST ENTOMOLOGY. |
beg to give at considerable length some of his “notes,” together with
his illustrations, as I know of nothing more helpful to the student
who wishes to make a thorough study of the insects in question.
“*The head is nearly always broader than long, and generally about
the same breadth as the thorax. The eyes are large, and ocelli are also
present. Behind the ocelli there is a quadrangular space, bounded
latterly by distinct furrows, known as the vertical area. The spaces
bordering the compound eyes are the orbits. The space containing the
ocelli, and reaching to the insertions of the antenne, is the frons, and
part of this space surrounded by furrows is called the pentagonal area.
‘Looking at the face and below the antenne we see the clypeus
and labrum. ‘The space between the eye and base of the mandible
is termed the gena.
“The back of the head, facing the thorax, is the occiput.
the occiput and the compound eye lie the tempora.
“The details of the thorax, which furnish many very important
characters, can hardly be made clear except by diagrams. I give
therefore now an outline camera-lucida sketch of the thorax in
Tenthredo mesomela, L., viewed from two aspects—(fig. 157) dorsally,
i.e., from above ; (fig. 158) laterally, z.e, from the side :—
Between
a (in both figures), pronotum. (the central slit in this is
bb, tegulee. what Cameron calls the
c, middle (or front) lobe of meso- blotch).
notum. hh, cenchri (the space between
dd, side lobes of mesonotum.
e, scutellum (or better, perhaps,
scutellum mesothoracis, to
distinguish it from /).
Ff, postscutellum (better scutellum
metathoracis).
g, propodeum or median segment
them is the metanotum).
é (in fig. 158), prosternum.
/, mesosternum.
m, Moetasternum.
n, mesopleura.
o, metapleura.
Ppp, COX®.
** Note.—The unlettered areas in fig. 157 are parts of the meso- and
meta-thorax, which are seldom, if ever, referred to in descriptions, and
I therefore ignore them.
The shaded space indicates a very deep
impression between the meso- and meta-thoracic regions.
‘“‘T may add that—
the pro-thorax includes the areas a and k ;
the meso-thorax includes the areas ¢, d, and e in fig 157; » and J
in fig. 158 ;
HYMENOPTERA—SAW-FLIES, ETC. 167
the meta-thorax includes the areas fin fig. 157, 0 and m in fig. 158;
the propodeum (g in both figures) is an originally abdominal seg-
ment, transferred to the thorax in pupation.
“The thorax of a saw-fly can easily be broken. up into its three
constituent parts of pro-, meso-, and meta-thorax. If the front and
middle coxe are seized in two pairs of pincers and pulled apart, the
pro- and meso-thorax part company. Similarly, by tearing the middle
cox away from the hind coxe, the meso-thorax can be separated
from the meta-thorax. The so-called propodeum, though theoreti-
cally an abdominal segment, is so firmly attached to the meta-thorax
that when the abdomen is broken off (eg., in a dried specimen by
Fig. 157.—Thorax of a saw-fly: dorsal swrface— Fig. 158.—Lateral or side view of
i.e., as seen from above. (Sketch by Rev. F. Jig. 157.>
D. Morice. From ‘ Entomologist’s Monthly
Magazine.’)
pushing it roughly downwards), the propodeum always remains with
the thorax.
“Tn fig. 157, h, h, the ‘cenchri’ are two singular organs with some
resemblance to little tegule. They are always present in Tenthred-
inidz, but I cannot find that their function has as yet been discovered.
They belong to the meta-thorax, and mark its base.
“Regarding the neuration of a saw-fly’s wing, the first thing to be
done is to realise the course of the longitudinal nervures = the
‘veins, —the thick single lines. It will be seen that they are much
longer than the transverse = the ‘nerves.’ They are also more
uniform throughout the whole group, and much less liable to vary
abnormally in individual specimens. We commence with them partly
168 FOREST ENTOMOLOGY.
on this account and partly because they divide the wing into areas
named from them, and from these areas again are named most of
the (transverse) ‘nerves’ and the ‘cells’ or divisions of the areas
bounded by them.
“Starting from near each other, and near the base of the wing, five
main ‘veins’ run, all more or less in the direction of its apex, but
radiating apart, like the fingers of an extended hand.
“The first pair start at a@ and ). these are the costa and the sub-
costa. The costa follows the actual margin of the wing, and the
sub-costa runs nearly parallel to it for about half the length of the
wing, when it bends upwards and unites with the costa at f, just
before the stigma (the shaded area in fig. 159).
“From d and e start another pair, the brachius and the humerus.
Fig. 159.—Typical upper wing of saw-jly. (Sketch by Rev. F. D. Morice. From
‘Entomologist’s Monthly Magazine.’)
These run both somewhat parallel to the lower margin of the wing,
but neither of them coinciding with it. Again, for about half the
total length of the wing, the humerus turns upward and joins the
brachius at g (just as at f the sub-costa joins the costa). The
brachius is continued a little farther to ~, and there disappears.
“The fifth of these ‘veins,’ starting at c, is called the medius.. It
runs at first straight along the middle of the wing (equidistant, there-
fore, between the two pairs described above) for half its length. Then
it bends downwards as though to join the brachius, but at ¢ turns
suddenly off, resuming its horizontal course, then (at w) is again
deflected, and reaches the margin at v.
“Besides the above five main veins, we have two which may be
called subsidiary. They are confined to the superior (apical) quarter
HYMENOPTERA—SAW-FLIES, ETC. 169
of the wing, and have the appearance of branching out of the sub-
costa. One leaves it just before its junction with the costa (at a
point about h), and, bending first down and then a little up, finally
joins the costa (on the margin of the wing) at its apex /. This is the
radius. The other—called the cubitus—leaving the sub-costa earlier
(i.e., nearer its base) at J, bisects, roughly, the area between the
radius and the apical portion of the medius, and so proceeds not
always in so straight a line as the figure shows to the point y on the
margin.
“Thus we have in all five main and two subsidiary longitudinal
nervures or ‘veins,’ and these divide the wing into longitudinal
areas or ‘fields,’ as follows.
“ Between the costa and the sub-costa is contained the intercostal
field. Between the brachius and the humerus is the humeral field,
familiar to all students of saw-flies under the name of the ‘lanceolate
cell.’ Then between the sub-costa and the medius lies the medial
field, and between the medius and the brachius the brachial field.
(A certain similarity in form and size will probably have been noticed
by the reader between the intercostal and humeral fields and the
medial and brachial fields respectively. This will help him perhaps
in forming a mental picture of the neuration as a whole.)
“Next we have the radial area lying above the radius, and the
cubital area below the radius and above the cubitus. Between the
cubitus and the apical half of the medius comes a continuation of the
medial area, which, if regarded as distinct from it, may be called the
discoidal field. That part of the wing lying below and as it were
outside of the neuration system—z.e., that which is bounded in-
feriorly by the actual inferior margin of the wing and superiorly by
the humerus as to its basal half, and by the medius as to its apical
portion—is called the anal field.
“ Owing to the disappearance of the brachius without reaching the
margin, there is no complete longitudinal line of division between the
brachial and anal areas. But for practical purposes the transverse
nerve, f z, may be regarded as separating them.
“We come now to the transverse elements of the neuration—
Konow’s ‘ Nerven’ sensu restricto.
“Often (though not in my figure) the radial area is crossed by one,
very rarely by more than one. ‘Then the radial area is said to be
‘divided,’ or, as some authors express it, ‘there are two radial cells.’
170 FOREST ENTOMOLOGY.
Similarly, the cubital area shows, practically without exception,
either, as here, two, or perhaps more often three, nerves connecting
the radius with the cubitus (i 2, jp). These, as crossing the cubital
field, are called the cubital nerves (1st, 2nd, &ec.), and the divisions
into which they cut up that field are the cubital cells. (Three seems
to have been the original number of the cubital nerves. Where only
two appear, either the first or second of the original three has
vanished. Thus in Hmphytus the first has gone, leaving only the
second and third; whereas in Dolerus the two surviving nerves are
the first and third, the second being absent.)
* Although these radial and cubital transverse nervures give, both
as to their number and direction, obvious and easy characters for
distinguishing both genera and species, they are unluckily liable, as
already mentioned, to considerable variation,—disappearance, duplica-
tion, displacement (within certain limits), irregular (atavistic) reap-
pearance, &c., in particular specimens, or even in one wing of a
specimen and not in the other; so that it is very unsafe to trust
wholly, or even chiefly, to them in ‘determinations.’
“Very much more constant and trustworthy are the characters to
be drawn from the three nervures which cross the median field—viz.,
1 q (perhaps the most important nerve in the whole wing), the dis-
coidal nerve, m s, and on the medial nerves (1st and 2nd), the two
latter being better known probably to English readers as the Ist and
2nd ‘recurrent,’ and the former as the ‘basal.’ The characters of
these nerves can hardly ever mislead us, and are of the utmost con-
sequence in determining not merely genera or species, but families
and tribes,—such characters, e.g., as whether the discoidal nerve
strikes the sub-costa close to the origin of the cubitus (as in fig. 159),
or considerably before it (7.e., between the points 0 and / in that figure),
or whether it strikes (e.g., in Lyda, &c.) not the sub-costa at all, but.
the cubitus ; and again, whether the discoidal and Ist medial nerves
are convergent (upwards) or sub-parallel, whether the two medial
nerves are received in the same cubital cell or in two different ones,
&c. The importance of these points for ‘determination’ will appear
abundantly when we come to construct our future tables. Two more
transverse nerves only appear in my figure—viz., 7, w, the areal nerve
(called by Thomson rather oddly nervus transversus ordinarius, and by
Mr Cameron —e.g., see his Tables of Species for Emphytus—the
transverse median), and ¢, w, the anal nerve. Of these the former is
HYMENOPTERA—SAW-FLIES, ETC. yall
the more important, its direction and the point at which it is re-
ceived in the cell above it giving several useful characters.
“We have now, I believe, dealt with all the nervures which are
regularly present in the upper wing of a saw-fly. But certain others
which appear only in particular genera or families are for that very
reason especially useful for ‘determinations.’ Thus, between the
costa and sub-costa may lie a 6th longitudinal nervure, and this may
ultimately either run simply into the sub-costa somewhere near /, or
be forked at its apex into two branches, one joining the sub-costa and
the other the costa. Or, in the same region (the intercostal field),
there may be a transverse nerve stretching from the sub-costa to the
costa, either before or after the point where the former receives the
discoidal nerve. Or, as in Avge, the costa, instead of lying wholly on
the margin of the wing, may quit it just before its apex, and bend
down to meet the radius, thus cutting off from the rest of the radial
area a little subtriangular apical cell (cellula radialis appendiculata).
Lastly, in the humeral area (‘lanceolate cell’) we have a number of
important characters for determining genera depending partly on the
presence or absence of transverse in that field, and partly on certain
modifications in the structure of the humerus itself, especially in its
basal part. These characters we have now to examine.
“Tt will be seen by reference to fig. 159 that the humerus (quite near
its base) shows a strong inclination to unite with the brachius, long
before it ultimately does so, at gy. Generally this inclination is, if we
may say so, suddenly checked: the humerus, though approaching very
near the brachius, starts off at a tangent, and gradually recedes to a
respectful distance from it, before taking the final curve by which it
ultimately reaches it. Sometimes, however, the inclination is not
checked: the humerus continues its approach to the brachius till
it actually reaches it, and so the two veins for a while coincide,—it
may be only for a moment or for a considerable distance,—but always
separate again, so as to enclose a spindle-shaped space between them
before their final point of union. Again, sometimes the humerus,
without quite reaching the brachius at the (sub-basal) point alluded to
above, all but does so, and throws a ‘short perpendicular’ nerve
across the narrow interval which separates it from its companion vein.
Yet again the humerus, soon after its origin, seems to vanish and pres-
ently to reappear emerging from the brachius, though it has never
been seen to join the latter. Lastly, sometimes—though never, I
Li2 FOREST ENTOMOLOGY.
believe, in conjunction with any of the phenomena described above—
an ‘oblique cross nervure’ runs over (the apical portion of) the
humeral area, cutting it into two divisions, the apical one ‘com-
pletely enclosed,’ and very much smaller than the other.”
TENTHREDINID: (Lear - wasps).
This family is known in Germany by the name of “ Blattwespen ”
or Leaf-wasps, and the designation answers our purpose very well,
inasmuch as the larve are always injurious (in very varying degrees)
to the foliage of many species of forest trees, but more especially to
Scots pine, larch, thorn, willow, and poplar. They are, however, only
injurious in the larval stage.
The classification, for the purposes of the present work, of this
family is somewhat difficult, for two reasons—(1) I need only to deal
with afew genera and species, taken as it were here and there from the
whole family ; and (2) the publication, now slowly proceeding, of a
very important German monograph of the saw-flies of the world has
already caused the abandonment in many cases of generic and specific
names hitherto employed in British works, and will doubtless yet
more disturb our present nomenclature within the next few years.
I propose, therefore, to adopt the following merely provisional
division of the insects into three sub-families, according to Konow,
as follows—Cimbicides, Lophyrides, and Nematides.
CIMBICIDES.
Genus TRICHIOSOMA.
The following are the generic characters according to Morice : 1—
“Claws simple; hind femora generally toothed conspicuously
beneath ; very pilose, brown-looking insects, with abdomen fuscous or
black above (but sometimes more or less rufescent at the apex and
beneath).
“SYNOPSIS OF BritisH TRICHIOSOMA.
1. Abdomen black, not bronzy; dull, closely and rather coarsely
punctured, and clothed right up to the apex with long, loose,
grey, sub-erect hairs. (Attached to the birch) T. Lucorum, L.
1 “Entomologist’s Monthly Magazine’ for Aug. 1903.
HYMENOPTERA—SAW-FLIES, ETC. ay
Abdomen at least slightly metallic, somewhat shining, puncturation
finer and more remote, hairs on apical segments shorter . 2
2. Abdomen rufescent beneath and often at the sides. (Attached to
willow) ‘ : P T. stnvatica, Leach.
Abdomen bronzy-black throughout ; : : : 3
3. Tibie, at least in 9, black or dark-brown. (Attached to hawthorn)
T. Trprais (Steph.)
Tibie yellow. Apical segments of abdomen clothed with longer
hairs than the last species. (Attached to willow)
T. LATREILLEI, Leach.”
This synopsis is extremely interesting from a collector’s or nature-
student’s point of view, but for practical purposes any species which
the local collector may find most abundantly may be taken as a type
of the other species.
TRICHIOSOMA TIBIALIS (Steph.)
This species is generally attached to hawthorn, and the pupal
cocoons may generally be found on the twigs of switched hedges,
more especially on twigs near
the base of the hedge. As
a rule, however, the cocoons
are opened by insectivorous
birds. The collector, there-
fore, should try as far as
possible to gather these
cocoons in the early autumn,
and place them in a jar for
hatching purposes. When
this is done, the flies are
very easily reared, and they hatch out from the middle of March to
the end of April. Fig. 160 is from a photograph of this species, and
fig. 161 is a representation of the pupa.
It is best, in rearing flies from the larval stage, to try and collect, as
far as possible, the fully developed larve, as when the larve are col-
lected at an early stage they do not feed readily in confinement, and
a great proportion of them die off. Fig. 162 is a representation of
the larvee on a hawthorn leaf.
Fig. 160.—Trichiosoma tibialis.
174 FOREST ENTOMOLOGY.
It should be noted that, from a systematic point of view, the species
attached to hawthorn has hitherto been known as T7richiosoma lucorum,
but modern classification associates the latter name with another
species which is attached to birch-trees.
This species is in every way an interesting forest insect, but in
no sense whatever can it be termed an injurious insect. The large
and somewhat pretty larva may often be
found on thorn hedges, when we are quietly
searching for anything of an arboreal
interest.
The larva (fig. 162) when young has
a greyish- white appearance, largely due
to a powdery covering, which appears
dusted over the body. As it gets older
the colour is a blend of green with
light yellow, with a yellowish face
and black eyes. It may be looked
for in July. It is not a voracious
feeder.
The pupa (fig. 161) is a hard brown
cocoon, £ inch to | inch long, and 2 inch
to 4 an inch in breadth. It opens by a
lid for the exit of the perfect insect. It
may be looked for during the winter
months on thorn hedges, more especi-
ally towards the bottom of the hedge.
The perfect insect may be seen hovering
Fig. 161.—Pupa of Trichiosoma 10 thorn hedges in March and April. It
Hea REECE en) may be mistaken by the uninitiated for
a bee. It is a brownish colour, head,
thorax, and abdomen hairy. Antenne dark-brown. Legs a lght-
brown. ‘The wings are clear. Length 6-10 lines.
The genus Cimbex is very closely allied to Trichiosoma, but in a
general way the former may be distinguished from the latter as being
less hairy. For practical purposes we may group the two genera
together ; and Judeich and Nitsche, though giving different generic
characters, adopt this method for general description.
~I
On
HYMENOPTERA—SAW-FLIES, ETC. 1
LOPHYRIDES.
Genus LOPHYRUS.
The species belonging to this genus are relatively very small.
The males are smaller than the females, and have double pectinated
antenne ; and the larger females have single (but slightly) pectinated
antenne. In this country only two species have been recorded, but
in Germany eight or ten species are mentioned. All the species are
arboreal in their habits, and hitherto recorded as feeding on the
foliage of Scots pine. It would be well for the student of forest
insects, more especially
those living in Scotland,
to keep a sharp look-out
for unrecorded species.
They are double - brooded
during the year, and there-
fore lend themselves for
rapid results as regards
observation.
LOPHYRUS PINI
(Linn.)
In consequence of the
immense damage done to
young Scots pine planta-
tions, this insect may be Fig. Meee he leaf.
classed as a_ veritable
forest pest. The larve live sociably, and have voracious appetites, —
so much so, that the leading shoots are quite defoliated, giving the
twigs the appearance of having been clipped with a pair of scissors ;
and wherever such wholesale damage is to be gauged by area, it is
obvious a severe visitation is In reality an alarming pest.
The saw-flies appear in early summer, but the time seems to vary
in localities. Thus in Cheshire I often found the females lodging
amongst the leaves about the end of May, whereas in Northumber-
land the males (which generally precede the females) appeared on
July 4, 1901. This was from specimens I had kept from an autumn
176 FOREST ENTOMOLOGY.
brood over the winter. Of course it is possible that this may be
by no means considered the first appearance in the county, or in
fact any reliable guide as to dates for the country generally, as
(fortunately) it is not very plentiful in Northumberland.
The females deposit their eggs on the leaves, and the larve hatch
out in from two to three weeks.
The larve, when full fed, are about 25 mm. long. The general
colour of the body is a light yellowish-green. The head is light-
brown. At every pro-leg are two black dots, and often black dots
are conspicuously scattered over the body.
The pups, or rather the pupal cases, are very hard and brown.
The male puparia are about 10 mm. long by 5 broad. The female
Fig. 163. —Lophyrus pini, Pine saw-fly Fig. 164.—Lophyrus pini, Pine saw-fly
(male). (From ‘ Forest Protection,’ (female). (From ‘ Forest Protection,’
by W. R. Fisher.) by W. R. Fisher.)
puparia are about 15 mm. long by about 7 broad. The perfect
insects escape by a lid, but if the pupa has been parasitised, the
parasite simply escapes by a minute circular opening.
The male (fig. 163) has a wing expansion of 15 mm. ; body black,
legs testaceous, with black femorz ; antennz doubly pectinated. The
female (fig. 164) has a wing expansion of 20 mm. The head and
thorax are darkish-brown, and singly serrated antenne. The middle
portion of the abdomen is strongly banded black, while the portions
above and below this black band are, on careful examination, double
bands of yellow mixed with black. The upper wing has one radial
and four cubital cellules.
Life-history. —As before stated, the life-history is somewhat
variable. In a general way it may be said that the female (which
HYMENOPTERA—SAW-FLIES, ETC. ibe
is very sluggish) cuts slits in the leaves with her saw-like ovipositor,
and lays her eggs in the slits. These hatch out in about two or
three weeks’ time, feed on the leaves of last year’s terminal shoots
(at this stage they often eat about half of the leaves—see fig. 165),
and pupate in July. A portion of those larve hatch out in August,
and thus we get a second brood from a portion, while others remain in
the pupal stage (fig. 166) until the following spring. ~The larve
Fig. 165.— Foliage of Fig. 166.—Pupal case of Fig. 167.—Foliage of scots
Scots pine eaten by Lophyrus pini (pine pine eaten by larwe of
larvee of pine saw-fly. saw-fly). pine saw-fly. Injury
Injury done by first : done by second brood of
brood of the season. the season.
issuing from the second brood eat the foliage of the current year (see
fig. 167).
In Northumberland the first male of the second brood ap-
peared on September 1, 1904, and the females about a week
later.
As this is a very troublesome pest, it follows that some specific
remedies ought to be given. Keep the young woods in very good
health, and encourage all birds which would open and pick the pupe
from their cases.
The larve might be collected by chipping off infested shoots
and letting them fall into paraffin. The cocoons might also be
collected, as far as practicable. For the perfect insects smeared
traps might be laid against the young trees in April. It should
M
178 FOREST ENTOMOLOGY.
be remembered that it is amongst the very young plantations
that most damage is done.
Lornyrvus rurus (Klug).
Miss Ormerod writes! regarding this species :—
“‘T have also had observations, with specimens during this year, of
much injury being done by the caterpillars of the Lophyrus rufus of
Klug on three or four thousand acres of young Scots fir in Argyle-
shire. These caterpillars are of a greenish dusky grey, with black
heads, a fine lighter line along the back, and a dusky line above the
spiracles. The abdominal sucker feet and abdomen below yellow-
green. The specimens sent me on the 10th of June had spun
their cocoons by the 23rd. The flies may be looked for from
August onwards. The females are reddish; the males black,
with abdomen beneath and legs red. It was observed that
trees ten feet high were not so seriously attacked as those from
two to six feet high.”
NEMATINZA (NemartIveEs).
This sub-family is of considerable interest in forest entomology,
inasmuch as a great many of the species are arboreal feeders. Many
of them are amongst the first insects to appear on the wing in spring.
On a sunny day single specimens may be seen flying for a short
distance, and then lodging amongst grass or other harbourage. They
can then be very easily placed in a chip-box or bottle. They may
also be collected from the flowers of sallow, which forms a sort of
general food for spring insects. As regards feeding habits, they may
be divided into two principal classes—viz., those whose larve feed
on the foliage, and those which form galls chiefly on willows.
They are injurious in the larval stage only.
As regards size, they range from very small to mediun-sized insects,
perhaps from 2 to 12 mm. They are for the most part smooth,
shiny, and rather soft-bodied, variously coloured, with 9- jointed
antenne, usually elongate, slender, and tapering ; anterior wings, with
simple, seldom - divided, radial cell. Hind wings always with two
discal cells, and with completely enclosed lanceolate cell.
1 Manual of Injurious Insects, 2nd edition, p. 255.
HYMENOPTERA—SAW-FLIES, ETC. 179
TABLE OF GENERA.!
Anterior wings with simple radial cell.
Lanceolate cell widely contracted in the middle.
Second and third cubital cells each receiving a recurrent vein.
Third to fifth, sometimes sixth and seventh, antennal joints
of the male with a more or less prominent branch at the
tip; antenne of the female somewhat compressed, and
with sharp projection at tip of basal joints
Crapius, Llig.
Joints of antennze without projections at tip; third antennal
joint curved at the base, in the male with a short, blunt
fork beneath, and in the female with a sharp projection
TricHiocamMpus, Htg.
Lanceolate cell petiolate.
Third transverse cubital wanting. : Evuura, Newm.
Third transverse cubital present.
Claws bifid, clypeus usually emarginate.
Tip of the eighth dorsal segment of the male with a small,
blunt, more or less awl-shaped projection ; antenne of
female filiform, small species 2 to 5 mm. long; stigma
often having clear base; sheath often pointed at tip;
gall inhabiters . : : Pontanta, Cost.
Eighth dorsal segment of male broader, obtusely pointed,
or not at all produced at tip; antenne distinctly taper-
ing toward tip; stigma not lighter at base ; sheath not
pointed at tip; body more robust.
Last ventral segment of male obtusely triangularly
produced at tip; sheath of female of the usual
form ; posterior tibize simple.
Mesonotum and pleure shining; antenne
long and slender, usually lighter coloured
beneath; head, viewed from the front,
almost round; labium but slightly pro-
jecting; sheaths usually narrow and
delicate . ; : Preronts, Jur.
1 Adapted from ‘Revision of the Nematine of North America,’ by C. L.
Marlatt. Washington: 1896. In this table three or four genera are omitted,
as they are not, so far as hitherto-recegnised, associated with forest insects.
180 FOREST ENTOMOLOGY.
Last ventral segment of male excavated at tip, not
obtusely triangularly produced ; sheath of female
very broad, or the posterior tibiz and _ tarsi
thickened.
Posterior tibiz and tarsi very broad and
flattened : ; Crasus, Leach.
Posterior tibiz and tarsi not flattened.
Posterior tibiz and tarsi thickened, tibie
externally with longitudinal furrow
Ho.cocneMg, Knw.
Posterior tibiz and tarsi simple; sheath
very thick and stout . Nematus, Jur.
Clypeus truncate.
Pentagonal area more or less distinct ; eighth
dorsal segment carinated, sub - produced ;
sheath simple; elongate species
LyGmHonematus, Knw.
Genus CULADIUS.
This genus, which is now known to systematists as Trichiocampus,
is a part only of the old genus Cladius. The name Cladius is still
kept for C. pectinicornus, &e. It has the third joint of the antennz
curved, and the species on Lombardy poplar has an orange-red
abdomen.
Crapius (TRICHIOCAMPUS) VIMINALIS (Fall.)
This insect may be found in the larval stage on the leaves of
Lombardy poplar. The larvee feed in company on the under side of
the leaves, generally from three to five in a row, each larva touching
its neighbour, and all keeping in perfect line. The larve are a
beautiful light-orange colour, with dark head, and clothed with strong
hairs. There are also rows of black flecks across the rings. Length
from 15 to 22 mm.
The female insect has black head, thorax, and antenne ; abdomen
light-yellow ; legs in all parts light-yellow. Wings with light-brown
veins and stigma. The male is similarly coloured, but the antennze
are dark-brown. Length of female 9 mm.; spread of wing about
18mm. Male 6 mm. ; spread of wing 13 mm.
HYMENOPTERA—SAW-FLIES, ETC. 1st
Evura (CRYPTOCAMPUS) PENTANDR&, Cam.
Large woody galls are formed by this insect on willow-stems,
generally of the species Salix pentandre. This insect is not at all
common, and certainly very local. Although the attacked bush is
often very valueless either from an esthetic or an intrinsic point of
view, yet the galls are often so numerically strong as to do great vital
injury to the bush itself. An infested bush, from its extremely local
habits, becomes quite an interesting object.
The galls themselves may be first noticed near the extreme end of
the twigs, being an enlargement on the twig (see fig. 168), about the
end of June. During the early
summer months the galls are of
a close woody structure, but
towards the autumn they are
more or less hollow, and contain
a comparatively large amount of
dirty black frass. Several larve
are found within one gall. It
may happen on inspection that
each larva is enclosed within a
cocoon. This condition I found
on January 5, 1900, but it must
not be inferred that the larvee
are fully fed, as the cocoon may
Fig. 168.—Galls of Euura pentandree on shoots
of Salix pentandre.
be either for protection or shelter.
The larvee commence making their pupal cocoons about the middle
of April, for by April 28, 1900, they were all in the pupal stage.
The larvee when full fed are about 8 to 9 mm. long, of a uniform
slaty-whitish colour, with darkish head. The six true legs are well
developed, and there are six pairs of thoracic legs.
The flies hatch out from the 9th to the 15th of May. The length
of the body is about 2 lines. Expanse of wings 6 lines; antenne
9-jointed. Body wholly black ; legs brown, with darkish trochanters.
PoNTANIA SALICIS (Christ. )
Nematus bellus, Zad.
The galls are formed on the leaves of Salix caprew (goat willow).
It is generally most abundant on hilly districts. In some seasons it
LS2 FOREST ENTOMOLOGY.
is very common at Kielder, Northumberland. The galls are on the
under side of the leaves (fig. 169), and as a rule a single specimen is
found on each leaf, though at times two galls coalesce together.
They may be either glabrous or slightly hairy, and as a rule the galls
which coalesce generally develop min-
lature warts. The colour is greenish-
yellow, with small reddish spots, and
the average diameter from 6 to 8 mm.
It may be looked for from July to
September.
Each gall contains a single larve.
The grub is very active, and the
frass is found within the gall. As
Be: flee whe <larvee. qupate in the soil; it sis
well to gather the galls fairly early
for artificial breeding. The flies hatch out about the beginning of
May (May 9, 1905).
Female. — Head and thorax black ; antenne dark-brown ;
abdomen black, with yellowish bands at division of segments.
Under side of abdomen yel-
low and black. Legs pale,
testaceous. Wings hyaline.
Stigma dark-fuscous.
Male.—Colour very much
as in female. Smaller in
size, and antenne stouter.
PoNTANIA BELLA (André).
The galls of this species
(fig. 170) very much re-
Fig. 170.—Galls of Pontania bella on leaves of semble those of the pre-
Salix viminalis. :
ceding, except that they are
always found on S. viminalis, which is perhaps the most important
distinction to the practical man.
The insects are also very much like those of the previous species ;
but they hatch out much later in the season—viz., about the end of
June.
HYMENOPTERA—SAW-FLIES, ETC. 183
PoNTANIA PROXIMA, Lep.
This species was sent by my friend Mr Forgan, Bowood, Wiltshire,
in stems of golden willow. No swellings: only indication is small
hole in stem. Larve bore in pith. This hatched May 14, 1902, in
confinement.
Fly.—Head, body, and antenne black. Legs more or less test-
aceous. Wings black. Antenne 7-jointed. Larve, white body,
brown head, .5, inch in length.
PoNTANIA GALLICOLA (Steph. )
Nematus vallisnerit, Htg.
Nematus gallicola (West).
In almost every country ramble the leaves of Huntingdon willows
may be seen covered with the bean-shaped galls caused by N. gallicola.
The galls (fig. 171) are
always formed on both sides
of the leaf. They are of a
rosy colour, and therefore
contrast with the green leaf.
A section of the gall, to-
gether with a description of
its development, would be
interesting. In the centre of
the gall we get the paren-
chyma of the leaf so en-
veloped by the gall that this
green substance becomes the
food of the larva.
There are two broods in
the year. By collecting the
galls fairly early in autumn,
before the larve quit them lead eae: ON Outenia eailicolaon
gdon willow.
for pupation, they may be
easily hatched out artificially. They quit the galls, and form small
leathery cocoons. The flies appear about 9th May in Northumberland.
The second brood is said to hatch out in August.
184 FOREST ENTOMOLOGY.
PoNTANIA ISCHNOCERUS (Thom.)
Nematus ischnocerus, Th.
I have only found this species at Kielder, Northumberland.
Cameron gives three localities—viz., Rannoch, Braemar, and New
Fig. 172.—Galls of Pontania ischnocerus on
species of Salix.
Galloway. Fig. 172 is a rep-
resentation of the galls on the
leaves of a species of Salix.
This species cannot in any way
be considered as an important
forest insect, except in so far as
it is of interest in a collection.
Genus PTERONUS.
This genus contains a number
of species which have been
selected from the old genus Nematus, as regards structure and life-
history peculiarities.
Fig. 173.—Leaf of goat willow
(Salix capree) eaten by larvee
of Pontania salicis.
Perhaps the best plan for the student to
master the same from a typical species is
to work out the life-history of the goose-
berry saw-fly, P. ribesti, Scop., hitherto
known as Nematus ribesti. For specific
characters the systematic student is advised
to refer to the “Synoptic Table of British
Pteronus,” by Rev. F. D. Morice, in the
‘ Entomologist’s Monthly Magazine’ for
June 1906.
PTrERONUS SALIcIS (Linn.)
It often happens that in our early
summer or late autumn rambles we find
bushes of Salix capree defoliated by saw-
fly larve, as in fig. 173. In this case the
insects proved to be P. salicis, as identified
by Rev. F. D. Morice.
The perfect insect has black antenne, black or dark-brown stigma,
and in both sexes a bright orange-coloured abdomen.
The insect is double-brooded, and can be very easily hatched out.
HYMENOPTERA—SAW-FLIES, ETC. 185
CR&SUS SEPTENTRIONALIS, Leach (Cameron).
Nematus septentrionalis, L.
This species is said to be very common in some parts of the country ;
and Cameron says the larve feed on poplar, aspen, birch, willows,
hazel, and mountain ash. I have not, however, found it on any
of these plants, but in Cheshire it was very common on, and
sometimes quite injurious to, alder.
Fig. 174 is from a photograph on
alder.
The perfect insect may easily be
recognised by the peculiar flattened
formation of the tibiz and _ tarsi
(fig. 175 a), and black colour of the
hind legs. Head and thorax black,
abdomen black and brown, antenne
as large as the body. Wings
hyaline. Spread of wings 16
mm. in male and 24 mm. in
female.
The larve (fig. 175 B) are bluish-
green, with black head ; head, ex-
treme end of abdomen, and prolegs
quite yellow; one or two rows of
black dots along the body. Length
about 30 mm.
The perfect saw-fly is a black —-
and light-red insect. In both sexes Fig. 174.—Larve of Croesus septen-
head, thorax, and anal portion of ay gree
abdomen black ; remainder of abdomen light-brown. Wings hyaline ;
stigma in female black, in male light-brown. Length of male
7 mm.; span of wings 16 mm.; female 11 mm.; span of wings
24 mm.
T have not worked out the life-history of this species, but Judeich
and Nitsche say there is a double generation, the flies appearing in
May and August. It is very probable that this may be so in the
south of England, while in the north of Scotland there may
be only one generation a-year. It is not very common in
Northumberland.
186 FOREST ENTOMOLOGY.
Nematus (Hoicocneme) Ericusoni, Htg. (the large Larch Saw-fly).
This insect, though fairly common in some parts of this country, is
not even mentioned in any English literature relating to forest ento-
mology. Cameron writes :! “Erichsonti does not appear to be a com-
mon species. I have only seen a specimen taken by the Rey. T. A.
Marshall, of which I did not know the locality. Mr Dale records it
from Glanvilles Wootton.” In German literature Judeich and Nitsche,?
and also Niisslin,? only slightly refer to this species. Packard *#
Fig. 175.
A, Craesus septentrionalis ; B, Larvie of Cresus septentrionalis. (From F, V. Theobald’s
‘Animal Pests of Forest Trees.’)
reports it as being injurious in some parts of America, and it is also
recorded as being injurious in Canada.® In 1906 it appeared in con-
siderable numbers in Cumberland, so much so that the Board of Agri-
culture requested Dr R. Stewart MacDougall to inspect the injured
1 Monograph of British Phytophagous Hymenoptera, vol. ii. p. 51.
* Forstinsektenkunde, Band i., seite 661.
° Leitfaden Forstinsektenkunde, seite 359.
4 Fifth Report of the United States Entomological Commission. Forest
Insects, by Packard. 1890.
° Canadian Entomologist, Nov. 1834.
HYMENOPTERA—SAW-FLIES, ETC. LS 7
plantations and report (see ‘Journal of the Board of Agriculture,’
October 1906). I had in the same year found this species sparsely dis-
tributed in Northumberland. As this hitherto rare species has suddenly
appeared as a destructive insect, it affords a good case in point of the
necessity for the student being well grounded in general entomology.
The damage done by this species consists in defoliating larch-trees
of various ages (see fig. 176) ; and as the injury is done whilst the trees
are vigorous, it is obvious that the increment is not only appreciably
affected, but the health of the tree may be considerably impaired. As
the larch is very susceptible to disease, it is important that everything
be done to obviate injuries of all sorts.
Dr MacDougall thus describes the insect: “ Adult.—The adult
Fig. 176.—Foliage of larch injured by Fig. 177.—Nematus Erichsonii.
larve of Nematus Erichsonii.
saw-fly measures up to 2 inch, or a little over, in length, and in spread
of wings just less than an inch (see fig. 177). The ground colour is
black. The head and thorax are black; the first joint of the abdo-
men is black ; then follow joints coloured red, the end of the abdomen
again being black. The mouth parts, the two front pair of legs, ex-
cept at the part next to the thorax, and the upper parts of the femora
of the hind legs, are reddish or reddish-yellow. The tibize are yellow-
ish or pale in the upper parts. The antenne are nine-jointed and
somewhat thick, and taper towards the apex. With a lens the head
and thorax are seen to be sparsely and finely pubescent, and the thorax
is markedly punctured. The wings are glossy, and slightly clouded
below the stigma.
188 FOREST ENTOMOLOGY.
“ Egg.—The egg is longish oval, and measures just over a millimetre
in length. It is white in colour.
“ Larva.—The full-grown caterpillar measures three-quarters of an
inch, or a little over, in length (see fig. 178). It has a round, black,
hairy head, with a single ocellus on
each side. On the upper surface, all
down the back, the colour is grey-
| ereen; the sides are lighter; the
under surface is yellowish-green. If
one uses a lens, there will be seen
on the abdominal segments transverse
rows of minute warts with spines.
Fig. 178.—Larve of Nematus Erich- orn C c
sonii (slightly reduced). The spiracles along each side are
brown. ‘The legs number twenty—
viz., three pairs of thoracic legs,
2 3 é a which are black, and seven pairs of
abdominal legs, which have the colour
Se ea Hin ied) sO: the under side of the body. The
head is followed by twelve segments
or joints: 1, 2, and 3 are thoracic joints, and each bears a pair of
legs ; 4 to 12 inclusive are abdominal joints; 4 has no legs; 5, 6,
7, 8,9, and 10 have each a pair of legs; 11 has no legs; and 12,
the last joint, carries a pair of legs.”
Fig. 179 is a representation of the pupe.
LYGHONEMETUS SAXESENI, Htg.
Nematus abietinus, Ch.
This insect, though often a very great pest on the Continent, is not,
as a rule, very abundant in this country.
The injuries may, however, be recognised from the leading shoots of
branches of spruce from twenty to sixty years of age being defoliated.
This species has been recorded as being rather injurious in Cumberland,
and I have found it fairly common at Kielder, in Northumberland.
The larva may be beaten from the spruce branches during the summer
months. It is about half an inch in length, and of a uniform green
colour, very much resembling a spruce needle. The eyes are black.
As regards the perfect insect, I have so far not been successful in
hatching it, though several have pupated all right, and ‘therefore
HYMENOPTERA —SAW-FLIES, ETC. 189
cannot give any description. It would be well, therefore, for the
student to work it out, more especially as it is not mentioned by
Cameron except as a synonym; and the assumption that the above-
named insect is the one responsible for the damage on spruce is
based on the description given by German writers, together with
correspondence from Mr Morice.
SIRICIDZ (Woop-wasps).
As regards forest insects, this family is represented by the genus
Sirex. The injuries are chiefly done by the larve to back - going
standing trees, and timber of a secondary class is therefore further
depreciated by the larval borings.
The trees which are attacked
are Scots pine, silver fir, spruce
fir, and larch.
The genus Sirex is represented
in this country by two species !
—viz., Sirex gigas, Linn., and S.
juvencus, Linn. There are three
species in Germany—viz., S. juv-
encus, S. gigas, and S. spectrum.
SIREX Gicas, Linn.
This fine insect often attracts
considerable attention in estate :
timber-yards, where logsof Scots ‘Fs: ee nee iy ieee oe GREE)
pine, spruce, silver fir, and larch
are cut up, more especially where the cut logs have been either lying
for some time in the yard, or where sickly or previously blown trees
(which were unfit for sale) have been brought to the sawmill yard.
This insect is credited with being a very destructive species, but
this appears to be an exaggeration, inasmuch as it always attacks
sickly timber. Fig. 180 is from a photograph of injuries done to a
plank of silver fir (Abies pectinata). =
a
1 There is a third species—viz., S. noctilio—but it is very difficult for the
practical man to distinguish it from S. juvencus. All three occur in England,
but systematic men consider that juvencus is evidently far rarer than
noctilio.
190 FOREST ENTOMOLOGY.
The female Sirex, which is armed with a long ovipositor, lays her
eggs in Scots pine and silver fir trees which are either sickly or
injured. The full life-history does not seem to have been worked
out, either by German or English entomologists, but it is said that the
larve attain their full development in about seven to eight weeks,
but that they live from two years in the larval stage, and appear as
perfect insects the third year. They make a sort of rough semi-
circular route, at first boring deeply into the wood, and then turning
towards the outside, in fact often just immediately within the bark.
Although the perfect insects do not appear until July, both sexes
may often be found within the logs in November as perfectly devel-
oped insects. One of the best consignments of those insects I ever
Fig. 182.—Sirex gigas (male), Fig. 181.—Sirex gigas (female),
reduced. reduced.
had sent was captured by a miner issuing from props within the
coal-pit.
The darvw are whitish and soft. The head is scaly, and armed
with strong jaws, and there is a blunt hook at the extremity of the
tail segment. They are about 14 inch in length, and about } to 2
inch in diameter. I have never found any pupal stage except as
tightly packed forms of the perfect insect.
The female (fig. 181) is usually 1# inch in length from head to ex-
tremity of ovipositor, and about 4 to 3 inch in breadth. The antenne
are filiform, yellow, and 18- to 25-jointed. The head is black and
hairy ; eyes and ocelli black. There are two yellow portions behind
each eye. The thorax is wholly black and hairy. The abdomen is
made up of nine joints, the colour being banded of yellow and black.
There is a black velvety band across the middle of the abdomen,
on either side of which there is a yellow band, the abdominal segment
HYMENOPTERA—SAW-FELIES, ETC. 191
being terminated by the ovipositor. ‘The wings are over two inches
in expanse, and the legs are yellow.
The male (fig. 182) is smaller than the female, and with compar-
atively long antenne. The abdomen is flattish and brown through-
out, except the first segment, adjoining the thorax, which is black.
The absence of the ovipositor is of course the salient point in quickly
determining the sex. The legs are also darkish-brown.
SIREX JUVENCUS, Linn.
The habits of this insect are almost identical with the preceding
species. There appears, however, to be a difference of opinion
a
Fig. 184.—Sirex juvencus (female), reduccd.
s ,
oS tee
Fig. 183.—Spruce timber injured by Sirex juvencus.
a, shows transverse section of timber; b, shows
longitudinal section of timber. Fig. 185.—Sirex juvenecus (male), reduced.
amongst various writers as regards the trees upon which they are
found, and it is possible either species may be general feeders on the
trees named; but so far as my observations go, I should say Sivex
juvencus on spruce and larch, and Stree gigas on Scots pine and silver fir.
Fig. 183 is a representation of injuries done to the timber of spruce.
The larve are narrower and more elongated, and more of a dirty-
white colour.
In general outline the female (fig. 184) resembles that of Screx
192 FOREST ENTOMOLOGY.
gigas, except that it is smaller, and the antenne and entire body of a
shiny metallic or steel-blue colour. The legs are also darkish.
The male (fig. 185) resembles the female except in being smaller.
The thorax and first thoracic segment are steel-blue. The legs are
darkish, with the segments flattened.
MISCELLANEOUS HYMENOPTERA.
As the section of this order known as Phytophagous Hymenoptera
is so large that it would require practically a lifetime for the student
to grasp, it is obvious, having regard to the size
of the field in forest entomology, that any at-
tempt to give correct systematic classification in
its entirety would overload the chapter. It is
therefore deemed advisable to give the following
insects as ‘‘ Miscellaneous Hymenoptera,” without
any attempt at classification.
Vespa Crasro, L. (Hornet).
When one’sees a hornet’s nest, or rather
the hornets moving in and out of their nest
in a hollow of a tree trunk, they may be con-
sidered as belonging to the realm of the general
entomologist, rather than to the student of
forest entomology. In this country they are
confined to the south of England, and do dam-
age to young stems of ash and alder. In Ger-
many, where they must in some places be very
numerous, Dr Altum gives a very detailed de-
scription of the damage they do to various forest
trees, much after the illustration given. I re-
ceived a damaged young elm from Newmarket,
discovered by Mr Bond, Lambton; and Mr Forgan, —
Fig. 186.—Injury done to Bowood, Wilts, kindly forwarded me specimens
eee Brown of young ash-trees which were considerably
damaged, of which fig. 186 is an illustration.
Fig. 187 is from a photograph of a hornet kindly sent me by Mr
A. Cameron, forester, Longleat, Wilts.
HYMENOPTERA—SAW-FLIES, ETC. 193
RHODITES EGLANTERLA, Hte.
The galls are found on leaves of dog-rose (Rosa canina), generally
on under side of leaves, but also on upper surface and sometimes on
leaf-stalks. They are very
pretty spherical galls, about
3-5 mm. diameter, with
beautiful blending in colour
of yellow, green, and red,
having a small attachment
to leaf, and with a large
inner cell.
They may be looked for
from July to September,
but may be very easily over-
looked. The galls, when
fully developed, fall to the ground. The larva pupates within the gall.
Fig. 188 is a representation of the galls on the under side of the leaf.
Fig. 187.—Hornet (Vespa Crabro).
Fig. 188.—Galls on under side of leaf of dog-rose Fig. 189.—‘‘ Moss or pin-cushion gall,”
(Rosa canina) caused by Rhodites eglanteriz. caused by Rhodites rosze.
RuopiTes ros#, Htg.
This insect, through its oviposition, causes the familiar growths on
dog-rose (Rosa canina) known as “ Robin’s pin-cushion,” ‘ Moss galls,”
‘* Bedeguar galls,” &c. This gall (fig. 189) is common in every lane,
N
194 FOREST ENTOMOLOGY.
and may be considered one of the most remarkable gall-growths
arising from insect agency, which causes modification in the vegetable
organism. It may originate either from a bud or leaf. First of all,
we get a very sudden ‘moss-gall,” and each hair is a_ beautiful
feathered structure. Later on we get a conglomeration of woody
cells, varying in number from three or four to thirty or forty. Each
cell contains a single grub; the interior is smooth and clean, and the
outside hardy and woody. The growth is complete by the end of
August, and the first flies appeared in confinement June 9, 1901,
Northumberland, and again on July 9, 1906.
MEGASTIGMUS SPERMOTROPHUS, Wachtl.
This insect, both in point of damage and structure, is entirely
different from all the other genera and species belonging to the order
Hymenoptera which we have been hitherto considering.
It is the only known hymenopterous insect directly injurious to
the seed, and it belongs to the sub-order Petiolata, which are char-
acterised by a constriction between thorax and abdomen. To this
order belong the bees, wasps, and ruby flies, and a large series known
as the Parasitica, of which a very large number of examples may
be found from parasites bred from the various species of oak galls.
In fact, Cameron gives species of Megastigmus as parasitic on several
species of galls.
This insect has been very fully worked out by Dr R. Stewart
MacDougall,! by whose kind permission I herewith give the follow-
ing notes from his valuable paper.
The damage was first discovered by Mr John Crozier, forester,
Durris, near Aberdeen. So far as Scotland is concerned, Durris
may be almost called the home of the Douglas fir, and therefore Mr
Crozier wrote in the following terms to Dr MacDougall :—
“The insect has, for some years back, been causing a serious loss
to our stock of Douglas fir seed. I noticed its presence on coming
here nine years ago, but it had no doubt been in the estate before
that time. Seed was plentiful, however, and as the damage was
comparatively trifling I did not pay much attention to the fact.
Now, however, it has assumed a more serious aspect, as the seed
1 Transactions of the Royal Scottish Arboricultural Society, 1906. Vol. xix.,
Rte sspmose
' HYMENOPTERA—SAW-FLIES, ETC. 195
on many of the older trees from which I formerly collected my
supply, in good years amounting to over 300 bushels, is not worth
the trouble of gathering. I have raised some millions of plants on
this estate, but unless this pest can be kept in check, it will be
impossible to keep up the stock from home-grown supplies.”
Fig. 190 is a representation of injuries done to the seeds of Douglas
fir (Pseudotsuga Douglasii). The small holes show the exit of the
insects, and the seed is therefore totally injured.
Dr MacDougall gives the following description of the insect :—
“This insect, Megastigmus spermotrophus, was first received by
Wachtl, of Vienna, in 1893, and was described by him as a new
species. In the spring of 1893 Wachtl got some specimens of
Megastigmus insects that had issued from the seeds of the Douglas
fir. From these specimens
Wachtl described the male
and female of the species,
which description I now L§ v 4q ?
give, in translation, from
Wachtl’s paper :-—
“<The female (fig. 191)
is loam-yellow; the vertex
of the head and the fore- Q 7) 3 @
head to the base of the
Fig. 190.—Seeds of Douglas fir (Pseudotsuga Douglasii)
antenne are red-brown : injured by Megastigmus spermotrophus (slightly
reduced).
the central part of the face
(epistome), the inner edges of the eyes, and the palpi, yellow; the
ocelli red-brown, each edged with black, and sometimes connected
with one another by means of black lines; never, however, is the
entire inner surface of the ocellar-triangle dark-coloured ; the eyes
during life are shining coral-red, after death red-brown; antennz
blackish-brown, the scape, and the part between the scape and the
flagellum, reddish-yellow ; the pronotum with a more or less broad
yellow band at the hind edge; the scutum of the mesonotum gener-
ally red-brown ; the outer side of the shoulders and the furrows of the
parrapsides yellow; the surroundings of the bases of the wings to
a slight extent black ; the diaphanous wings finely black haired ; the
knob or club of the ramus-stigmaticus longer than broad, elliptical
and black ; the coxe of the fore-legs yellow; the pulvillus on all the
legs black; the compressed abdomen reddish-brown on the upper
196 FOREST ENTOMOLOGY.
side, with a larger or smaller black-brown or black spot at the base
of the first segment, and becoming paler at the edges. This spot is
sometimes wanting; on the other hand, the end of the body and
the under surface of the abdomen are somewhat light - coloured ;
the sheath of the ovipositor is intense black.
“<All the flagellum joints of the thirteen -jointed antenne are
longer than thick, and become gradually a little less towards the
apex of the antenne ; the first joint is the longest, the others prac-
tically agree in length ; the three-jointed club is egg-shaped, and as
long as the two foregoing joints taken together. The central part
of the face is obliquely wrinkled, the forehead longitudinally
Fig. 191.—Megastigmus spermotrophus (female). (Drawn by P. J. Brown.)
wrinkled; the vertex of the head, the prothorax, the mesothorax,
and the scutellum are transversely wrinkled; the post -scutellum,
outlined by a fine deep line, is glossy and smooth except at the base
and along the longitudinal middle line, where it is finely punctured ;
the metanotum is finely punctured, with a prominent longitudinal
keel in the middle, and in the case of most examples, with a trans-
verse ledge at the limit of its front third; the hind margin is glossy
smooth, without sculpture. The face, mesonotum, all the coxe, the
tibie and tarsi of the fore-legs and the middle and hind legs, are
white haired ; the vertex of the head and the forehead, the thorax,
especially both sides of the furrows of the parrapsides, the scutellum
other than the post-scutellum, the femora of the fore-legs and the
HYMENOPTERA—SAW-FLIES, ETC. 197
hind edges of the segments of the abdomen, are beset with longer
or shorter black bristles. The ovipositor is as long as the body.
The body length of the female measures from 3°25 mm. to 3°5 mm.
(= roughly | to 7 of an inch).
“<The male (fig. 192) is orange-yellow ; antenne reddish-brown ;
the pronotum has, in the middle of the front edge, a black transverse
patch, which is somewhat elongated behind, in streak-like fashion, in
the direction of the middle line, sometimes resolved into two spots or
reduced to two points; the scutum of the mesonotum is reddish-yellow,
and provided in front with a black-brown spot, paler behind, which
sometimes only shows through the hind end of the pronotum more
or less clearly; the bases
of the wings and _ the
metanotum are black ; the
ba
tarsi of the forelegs, as ae
well as the middle and | Gite =
hind legs, are reddish- <
yellow ; the strongly com-
pressed abdomen is brown-
ish-red above, with a
black longitudinal patch
at its base, gradually
j inc = Fig. 192.—Megastigmus spermotrophus (male),
narrowing behind and be (eee Ee
coming paler at the edges.
Sculpture, hairing, &c., as in the female. The body length of the
male measures from 2°75 mm. to 3 mm. (=1 to } of an inch).’
“So far as I know, the larva has not till now been described. It
is whitish in colour, and legless. The segments are well marked, and
indeed the general appearance, including the wrinkled and curled
form, is strongly reminiscent of a weevil grub. The marked horny
head of the weevil grub, however, is absent. Instead, in the mega-
stigmus larva, each of the two chitinised gnawing jaws is somewhat
sickle-shaped, the two jaws together reminding one of a pair of
callipers. The apex of each jaw is pointed, and on the concave side
is provided with marked teeth. These gnawing mouth-parts are red
or yellow-brown in colour.”
As regards the life-history of the insect, it of course hatches out
quite freely in confinement. Each infested seed contains a single
larva, and when the fully developed insect emerges from the seed
198 FOREST ENTOMOLOGY.
there is nothing left but an empty husk. The insects hatch out
freely in May and June, and no doubt the insect contains only a
single brood in the year. As the female flower or cone of the Douglas
fir is very open in the scales, the female insect can have no difficulty
in depositing an egg in each seed.
Having regard to the recognised value of the Douglas fir as a tree,
and to the unrecognised value as a shade-bearer, it is imperative that
this insect should, as far as possible, be kept in check. There
is, of course, no way of dealing with the perfect insect in the open
wood, and therefore remedial measures must be taken with the seed.
Hence Dr MacDougall’s remarks may be given in full :—
“The cones should be gathered as soon as ripe (the latter half of
October), and should at once be subjected to such treatment as will
permit of the seed being abstracted. This seed should without
delay be fumigated with bisulphide of carbon. The method is as
follows :—
‘“‘Place the material to be treated in an air-tight receptacle. Pour
the bisulphide of carbon into a saucer or saucers, or such shallow dish,
and lay these on the top of the material. Close the receptacle. The
bisulphide of carbon vaporises, and as its fumes are heavier than air,
they sink down through the material. The receptacle should be kept
closed for forty-eight hours. One ounce of bisulphide of carbon will
do for 100 Ib, of seed, or one ounce for every 50 cubic feet of air-
space. The treatment should be administered in not too cold a
temperature. Bisulphide of carbon fumes, being poisonous, should
not be inhaled by the operator, nor should a light of any kind be
brought near. If it is desired to store the cones during winter or
longer, these must be similarly fumigated directly they are gathered.
“The results to be looked for from fumigation are—
“1st. The germinative capacity of such seeds as have not been
infested is not interfered with.
“9nd. In infested seed, where the larvee may not have made much
progress in the destruction of the reserve in the seed, the larva will
be killed, and the seed may germinate.
“3rd. In infested seeds, where the contents have been altogether
or much destroyed by the larve, and which therefore would not have
germinated, the larvee will be killed, and the issue of the next year’s
brood of adults prevented.
HYMENOPTERA—SAW-FLIES, ETC. 199
“The light seed blown through by the fan at cleaning time should
be burnt at once, and where there has been attack, this will probably
account for many of the pests.”
As an insect-pest the Megastigmus is a very good case in point, as
showing that forest entomology is a very large and imperfectly worked
field. Though the insect had not been noticed until about 1897 or so
by Mr Crozier, still it has, no doubt, been in the country for a very
long period. At the same time, it is quite likely that its numbers have
been considerably increased with imported seed from Western North
America. It is possible that it may be very abundant on other
estates throughout the country, either as an insect-pest where the
seed of Douglas fir is available, or otherwise adapting itself as a
parasite, either on oak-galls or other suitable hosts.
MEGASTIGMUS STROBILOBIUS, Ratz.
Referring to the remarks on the previous species, and the probabil-
ity of other species of Megastigmus in the country, I received in the
early spring of 1906 a few seeds of silver fir containing larve from
Mr A. C. Forbes, of the Armstrong College, Newcastle-on-Tyne, who
had received a single cone from Longleat, Wiltshire. Fig. 193 is
a representation of the injured seed.
On July 15 three female insects emerged, and the specimens were
quite distinct in colour and other characters
from the previous species, and I made the
following note :—
Three specimens, all females. Black
marked with yellow, vertex of the head
black. Central portion of face yellow.
Eyes red-brown. Antenne blackish-brown
(entire length); whole pronotum black. 4... 193.— seeds of silver sir (Abies
Wings hyaline black. Fore-legs, coxa, —Pectinata) injured by Megastig-
and tibia yellow, tarsus blackish. 2nd
and 3rd pairs of legs yellow throughout, or darkish coxa, and other
parts yellow. Abdomen on dorsal surface black, with yellow
markings ; under surface yellow.
In ‘Forstinsektenkunde,’ by Judeich and Nitsche, there is a
note to the effect that Wachtl should not have priority for the
200 FOREST ENTOMOLOGY.
discovery of a Megastigmus species as a conifer-seed enemy, as
Borries had pointed out to Judeich by letter in 1887 an insect
of the genus Jorymus— viz, massive females, but no males, of
Megastigmus strobilobius, Ratz.
References to Literature consulted.
Cameron, P. A. Monograph of the British Phytophagous Hymenoptera. 3
vols. Ray Society.
Cameron, P. A. ‘The Galls of Mid-Cheshire ’— Manchester Microscopical
Society. 1892.
Carpenter, George H. Insects: their Structure and Life. 1899.
Judeich und Nitsche. Lehrbuch der Mitteleuropiiischen Forstinsektenkunde.
Berlin. 1895.
MacDougall, Dr R. Stewart. Megastigmus spermotrophus, Wachtl.
MacGillivray, Prof. Alexander Dyer. A Study of the Wings of the Tenthred-
inoidea, a Super-family of Hymenoptera. Washington. 1906. (This is a most
excellent work. )
Marlatt, C. L. Revision of the Nematine of North America. Washington.
1896.
Morice, Rev. F. D. ‘‘ Help-Notes towards the Determination of British
Tenthredinide ”—Entomologist’s Monthly Magazine for Jan. 1903.
Niisslin, Dr Otto. Leitfaden der Forstinsektenkunde. Berlin. 1905.
Ormerod, Miss. Manual of Injurious Insects. 2nd edition. 1890.
Trail, Prof. James W. W. ‘The Gall-making Hymenoptera of Scotland
(exclusive of those that live on Oaks). 1888.
CHAPTER VI.
COCCID (SCALE-INSECTS).
THERE is perhaps no class of insects more puzzling to the practical
husbandman, the economic entomologist, or the biologist who is
anxious to gain a general knowledge of insect structure and life-
histories, than the Coccide or Scale-Insects. The student must rely
almost entirely upon the microscope for the accurate determination of
these insects, which from their minute size present exceptional difh-
culties. Even for general field-work it is necessary to have recourse to a
strong pocket-lens ; as to the naked eye, they may be confounded with
as, for example, those on birch-twigs. They may also be
mistaken for certain micro-fungi on leaves or stems of various plants.
In the Introduction it was emphatically asserted that concentration
in the study of forest entomology was indispensable, inasmuch as
almost every natural order was represented, and thus as a branch
of forest science, to the forester in particular, general versatility in
entomology was impossible. Scale-insects, however, are to some
extent an exception to this rule. The arboreal-feeding species of
this important family are comparatively few, and therefore, in order
to thoroughly understand the salient characteristics, it 1s necessary to
glean information from all available sources. In other words, in order
to thoroughly understand the special part, it is essential to make a
general study of the available whole.
But though the arbereal species in this country ave comparatively
few in numbers, the forester, or student of forest entomology, can
always obtain an abundance of material from various plants cultivated
under glass—the amateur greenhouse often being a happy hunting-
ground.
Temperature and climatic conditions are important factors in the
distribution and regulation of scale-insects. Hence warm greenhouses
lenticels
202 FOREST ENTOMOLOGY.
afford several important advantages to the student. Thus where the
temperature is, comparatively speaking, perpetual summer, we find
several broods occurring throughout the year, as well as the creatures
in their various stages of metamorphosis. In the forest, on the con-
trary, many species are not only local in area but sparsely distributed,
and all are single-brooded. In hothouses, through importation, plants
are collected from various parts of the world, and thus, to some
extent, we get in private greenhouses and public botanical gardens
an approximate epitome of the scale-insects of the world. It is
therefore evident that, in order to understand the life-history of
many scales originally imported, but now acclimatised to our glass-
houses, recourse must be had to foreign and colonial literature. Not
only is it advisable to study the literature relative to foreign scales,
but it is essential to study the microscopical structure of the foreign
scales themselves which are to be found on our imported plants and
fruits. And as the dead females answer best for microscopical
examination, greengrocer’s stalls may be looked upon as a very
happy hunting-ground—more especially at a time of the year when
life is dormant, and when the working entomologist may use his
microscope as an instrument for original research in a comparatively
fresh field.
But the study of foreign scales and the literature bearing on them
has, in addition to its charms and pleasures, a very practical bearing,
inasmuch as we find that some species are quite cosmopolitan in dis-
tribution. We also find that many species which are practically
identical to the naked eye, and likewise in point of damage, prove on
microscopical examination and in their life-history to be quite distinct.
As regards the value of such knowledge bearing on the discrimination
between foreign injurious scale-insects and the apparent introduction
of any particular injurious species into this country, as recognised
only from naked-eye characters practically identical to the casual
observer, one important case may be cited—viz., the San José scale
(Aspidiotus perniciosus) from California, as compared with the
scurvy-bark louse (Aspidiotus ostreeformis) of this country. The
former is a sub-tropical insect, and would not likely withstand the
rigours of a Western climate. In fact, it has not even established
itself under glass in this country.
~ In the year 1898 it was thought the San José scale- eee had
established itself in this country, and so much was the scare felt
COCCID, 203
that the Board of Agriculture invited Mr Newstead to give evidence
before a special committee meeting at the House of Commons. As
the result of previous studies, he was able to dispel all fears, and
subsequent experience has amply justified his opinions.
As showing the wide geographical range of certain scale-insects and
their adaptability to varied food-plants, one species, namely, the com-
mon mussel-scale (Mytilaspis pomorum), may be cited. Newstead
says: “It occurs as a pest in almost every part of the world where
the apple is cultivated—in Europe, North and South, the United
States, New Zealand, Australia, North Africa, and probably many
other places.”
The Coccide or scale-insects belong to the order Hemiptera, which is
subdivided into two principal divisions—viz., Hemiptera-Heteroptera,
which includes the bugs; and the Hemiptera-Homoptera, which in-
cludes Aphididx, Cicade, Psyllide, and Coccide or scale-insects, ‘The
last are broadly distinguished from other families by the scv/e or cover-
ing which they spin to protect their bodies.
Hence the Germans call them by the express-
ive term Schildlduse (shield-lice).
Having often found that intelligent prac-
tical men designate scale-insects as a “very
low form of life,” it may be well to show
their close relationship with other families
which are grouped together in the same sub-
order. As in point of structure and life-
history they are very closely associated with
other families of the sub-order, it may be
well, even at the risk of repetition, to present
the more salient features of each family as
an educational advantage to the clearer dis- Cs Bye
crimination of the relationship which exists Fig, 194.—Cerataphis lataniz
(fringed aphis) on palm.
between them. All the insects of the natural Known, to horticulturists
; ; as the ‘‘black-seed scale.
order Hemiptera are characterised by the
possession of suctorial mouths, and therefore belong to that great
division of Insecta known as Haustellata.
The Aphidide or plant-lice are soft-bodied insects, usually green,
with long, rather slender legs, and not formed for leaping. They
occur in two forms—winged and wingless. The beak (proboscis), or
feeding-organ, is often very long, and the tarsus two-jointed. One
204 FOREST ENTOMOLOGY.
species of this family is often mistaken for a scale—viz., the fringed
aphis (Cerataphis lataniv), known to horticulturists as the “ black-
seed scale”: it occurs on palms, orchids, We. (see fig. 194).
The Psyllide very much resemble the Aphidide in general appear-
ance, but their legs are formed for leaping. The wings are clear, the
antenne conspicuous, long, nine- or ten-jointed, and the eyes large and
prominent. The tarsus 7s twojointed.
In general appearance the Aleyrodide are the nearest approach
to the scale-insects, more especially so in their nymphal or pupal
stages. Their bodies are of an
ivory-white colour, scaly-looking
in appearance; both sexes are
winged, and the tarsi twozjointed.
They often deposit a scale - like
secretion on plants (see fig. 195).
Aleyrodid are found on tomatoes, &c., in greenhouses, and on ivy,
lime, and hazel in the woods.
The closely allied Coccip# are broadly distinguished from the other
families of the Homoptera just referred to by the following character-
istics—viz.: In the females by being naked (Lecanium), clothed partly
with secretion and partly with moulted skins (Diaspine), or clothed
with white meal-like secretion (Dactylopius), and with wax-like plates
(Orthezia). The tarsus in all the British species but one! is composed
of a single joint ; there are also two foreign genera in which the tarsi
are two-jointed.
The larve are minute, and very active when young, usually naked,
and the sexes are inseparable in the first larval stage.
The female undergoes a semi-complete metamorphosis, is apterous
in all stages, has generally a well-developed rostrum, and, according to
the genus, the legs may be present or absent.
The adult male undergoes a complete metamorphosis, and may be
winged or apterous. It has no mouth or feeding-organs, but possesses
six legs, eyes, and antenne.
It is important to bear in mind that both sexes secrete a varying
quantity of waxy, horny, mealy, or resinous substances for the forma-
tion of their shield-covering or scwle, and that these secretions or
coverings vary in form and colour. In fact, those differences are so
1 Eacretopus formiciticola, Newst.
COCCIDZ. 205
clearly pronounced that they afford valuable data, not only for the
distinction of sex, but for the separation of the various sub-families
and genera. These remarks are applicable to the “scales” of both
sexes, but more especially to the male scale or puparium.
Maskell! gives the following microscopical characters :—
(1) The presence of only one joint in the tarsus, or fourth joint of
the leg, in males and females.
(2) A single claw terminating the leg in males and females,
(3) Two wings and two halteres in the males,
(4) Two or more eyes or ocular tubercles, in addition to an ordinary
pair of eyes.
With regard to the classification of scale-insects, it would be quite
superfluous under “ forest entomology” to give all those sub-families
at present known in the British Isles, but the following genera, ac-
cording to Newstead’s Monograph, are arboreal in their habits :—
SYNOPSIS OF SUB-FAMILIES.”
Males with Simple Eyes.
A. Abdomen of female terminating in a compound segment forming
a definite pygidium. Anal orifice simple.
(1) Insects with a separate covering scale (puparium) composed
partly of moulted skins (exuviz) and partly of secretion.
Adult females without legs; antennz rudimentary ; mentum
monomerous ; : : Diaspine.
B. Abdomen of female without detnite pygidium. Anal orifice
setiferous.
(2) Females with a posterior extremity cleft ; anal orifice closed by
a pair of dorsal plates. Larve with prominent setiferous
lobes within the anal cleft . : : Lecaniine.
(3) Adult females with cleft extremity and anal plates, as in
Lecanium. Larve with abdominal lobes, as in Dacty-
loplinee : : : Hemicoccine.
(4) Abdominal extremity not lene usually with a pair of more or
less prominent setiferous lobes at margin. Abdominal ex-
tremity of larve similar. ; : Dactylopiine.
1 Scale-Insects of New Zealand. 2 From vol. i. p. 67.
206 FOREST ENTOMOLOGY.
DIASPINZ.
The sub-family or group Diaspine may be defined, from a purely
entomological point of view, as insects covering themselves by a shield
or scale composed partly of discarded skins and partly of secreted
matter. Two very common scales—viz., the species on ash, &c.,
and the species on fruit-trees known as mussel scale—are very good
examples of this sub-family. As there are, however, other forms of
scale belonging to this group, it is often somewhat difficult to deter-
inine to what genus the scale really belongs. The first point to note
is the form of the scale—whether it is linear or circular. But this
in some cases is not always quite sufficient, as the male scale, or
puparium, must be looked for to determine the genus. Hence the
following characters may be given—viz. :
Female scale circular (fig. 196); male scale circular (fig. 197)
ASPIDIOTUS.
Female scale circular (fig. 198) ; male scale linear (fig. 199)
D1asPIs.
Female scale linear (fig. 200); male scale linear (fig. 201)
Curonaspis and Mytimaspis.
These are most important points to remember, inasmuch as it is
sometimes impossible to determine the genera until a male scale 7s
found.
In fig. 196, which represents a female scale of the genus As-
pidiotus, a represents the first larval moult, b the second larval
Fig. 196.—lemale scale of Aspidiotus. Fig. 197.—Male scale of
a, first larval moult ; b, second larval moult ; Aspidiotus.
c, portion representing sub-lying body of a, larval moult; b, secre-
female; d, outer secretionary portion of tionary portion.
scale.
moult, ¢ the underlying female, and d the outer “scale” which is
spun by the insect, and thus attached to, but extending beyond, the
COCCID.A. 209
ear-shaped (pyriform) and white, with exuvie at the anterior
xtremity. Under a pocket lens the two larval moults may be
istinctly recognised. The male puparium is elongate, and composed
{most entirely of a pure white secretion, with the yellowish larval
1oult at the anterior extremity. :
CHIONASPIS SALICIS (Linn. )
The scales of this species are very common on ash, willow, and
ther trees. In some parts of the country, notably in mid-Cheshire,
ve find young ash-trees from six to eighteen years
f age, and osiers from four years and upwards,
ompletely covered with these scales. They are
omparatively small, and if accurately measured
would probably be about
‘75 mm. in length.
A cursory examination
shows that two forms of
scale appear on the stems
—the male form (fig. 203)
and the female form (fig.
204). Sometimes we find
both sexes on the same
tree, at other times only
females are found. In
those cases where the
male form preponderates,
a whitish appearance is
Fig. 203. — Male scales of Fig. 204.—Female scales
Chionaspis_ salicis on of Chionaspis salicis
presented, as in fig. 203, bark of a@ young ash- on stem oF a Jive-year-
tree. old balsam poplar.
where the male scales, or
puparia as they are called, entirely cover the bark of the young stem.
Those two forms, as seen collectively by the naked eye in figs. 203
and 204, and individually magnified in fig. 205 (7 and 3), represent
the male and female forms of Chionaspis salicis.
If we lift a perfect female scale any time during the winter
months, turn it over, and examine the under side with a lens, or as
an opaque object with an inch objective, a considerable number of
beautiful red eggs will be noticed (fig. 205 (4)). In my younger days,
when working in the woods, I have often rubbed my thumb- nail
)
210 FOREST ENTOMOLOGY.
against the bark infested with Chionaspis, and sincerely designated
the squashed eggs as “blood.” Subsequent research with the micro-
scope has yielded many happy hours with what was originally
crushed in a careless and thoughtless manner. These eggs are of
a chocolate colour in autumn, just after oviposition, but become
Fig. 205.—Life-history of Chionaspis salicis.
1, egg; 2, larva; 3, dursal surface of female scale—(q) first larval moult, (6) second
larval moult; 4, under surface of female scale, showing dead female and eggs;
5, fully developed female at period of fecundation ; 6, form of female scale at period
of egg-deposition ; 7, male scale or puparium ; 8, fully developed male ; 9, pygidium
or anal segment of female as seen under }-inch objective.
lighter during the winter months. Now let us follow the develop-
ment of these eggs. Fig. 205 (1) represents a single egg. The larve
hatch out in Cheshire‘about the beginning of May, and by the middle
of that month the infested stems may be recognised at a considerable
distance, on account of the numerical strength of the larvee, imparting
quite ia red colour to the stem. These larve (fig. 205 (2)) are at first
COCCID. 211
very active, and measure approximately about the z}5 of an inch in
length. They possess six legs (the tarsus being single-jointed, and
terminated by a claw and knobbed hairs), comparatively long antenne
of five or six joints, two eyes, and two very long transparent hairs at
the posterior end of the body. Under imperfect magnification the seg-
mentation of the abdomen cannot be clearly traced ; hence I at first
hastily, but erroneously, concluded that ‘the posterior legs spring
from the abdominal part, which is a unique feature in insect
anatomy.” In the course of two or three days they assume a
quiescent state, and inserting their beaks (proboscis) into the bark of
the tree, suck up its juices. As soon as the larve assume this habit
they enlarge considerably, and the legs and the antenne disappear
beneath the body. After the larva has grown for a short time it casts
its skin, and it is after the first larval moult that the sexes are deter-
mined. The female scale develops into the form shown in fig. 205 (3),
and the male as shown in fig. 205 (7).
Now let us follow the development a little more fully, and first
with regard to the female. After the first larval moult, which is rep-
resented by fig. 205 (3 a), the creature develops and again moults, the
second larval moult being shown by 0 in the same figure. Up to this
stage the creature protects itself by means of cast-off skins, but the
female now commences to further protect herself by means of a cover-
ing or “scale,” which is spun by minute organs known as “ spinnerets,”
and represented in fig. 205 (9). After the second larval moult the
metamorphosis of the female insect is complete. The full develop-
ment is shown by fig. 205 (6), from which it will be seen she is simply
an inert slug-like creature made up solely of body and mouth.
The rostrum or mouth serves the double function of feeding-organ
and anchor, but in the latter capacity it is further assisted by the
long hairs, or ‘‘setez” as they are termed. And sometimes when the
females are loosened from their host-plant by birds, they may be seen
dangling in the air attached by the “sete” alone.
Prior to the deposition of eggs, which takes place in September,
the body entirely fills the ovisac, but as the eggs are deposited the
body gradually shrivels until it ultimately occupies but a very small
portion at the upper or anterior end of the scale. The female dies
shortly after the eggs are deposited, and during the winter months the
dead female and the eggs may be found under each scale.
1 British Naturalist, Feb. 1894.
BIA FOREST ENTOMOLOGY.
If a microscopical examination of the female be made in the winter
months, the well-developed rostrum will be observed, but a special ex-
amination of the anal segments forming the pygidium (fig. 205 (9))
shows five groups of spinnerets and other important structures.
It is well to bear in mind that the pygidium yields the main char-
acters which form the principal basis for the discrimination of species.
The anal lobes, hairs, and other characters, requiring the highest
powers of the microscope, are all taken into account by the specialist.
Hence at this stage it may be as well to give detailed characters of
the female and pygidium of this species, as given by Newstead in
his Monograph :—
“Adult female (fig. 205 (6)) elongate ovate ; cephalic, thoracic, and
abdominal segments strongly defined, the former being distinctly
trilobate. Colour dull crimson; cephalic extremity dull orange,
mottled with crimson ; pygidium bright orange ; the dorsal spinnerets
indicated by a double semi-elliptic series of dull crimson marks.
Eyes black. Rudimentary antenne normal. Lach of the three free
abdominal segments with about nine large tubular spinnerets at the
margin, of the same character as those of the pygidium ; and the last
segment presents a few stout, spiny plates. Pygidium (fig. 205 (9))
has five large groups of circumgenital glands.
“Dorsal tubular spinnerets, short and cylindrical, are in twelve
distinct series, forming three incomplete arches. Within the first
series, and immediately behind the lateral circumgenital glands, are
usually three other tubular spinnerets; anus and vaginal opening
opposite. The median and second pair of lobes are well de-
veloped ; the former have the margins rounded, or faintly and
roundly serrate or dentate; the second pair are bilobed, the anterior
lobule very small, and both have the margins rounded; third pair
are also divided or bilobed, the posterior lobule usually dentate, the
anterior lobule very minute, and sometimes both are wanting. There
is a spine-like projecting pore between the median and second lobes ;
an angular one immediately posterior to the third lobe ; and there is a
third midway between the latter and the last group of plates. Two
long spines at the base of the anterior lobule of the second pair of
lobes. Of the plates, there is a short one between the median and
second lobes; six others, long and spine-like, are arranged in three
pairs, and followed by a group of four or five others.”
It ought to be laid down as an axiom that only the full-grown
COCCID.. 213
female should be examined for specific points, as the spinnerets and
other microscopical characters are not fully developed till after the
second larval moult, and no doubt in a general way specific errors
have occurred, and are likely to do so, by several workers examin-
ing the same species in two distinct stages.
The male scale (fig. 205 (7)) differs from the female (fig. 205 (6)) by
having only one larval moult, by being lighter in colour, felted, more
linear, and carinated. The perfect male (fig. 205 (8)) contrasts with
the female, inasmuch as it has two wings (though apterous specimens
are often found), six legs, and two antenne, two eyes, and xo mouth
or feeding-organ. The male generally appears about the first week in
July, and only lives from about three to seven days, but during that
short space of time he has obtained the sole object of his existence—.
viz., the perpetuation of his species.
The genitovres are large in proportion to the size of the creature,
varying from about one-third to one-half the length of the whole
insect. We here see the adaptation to environment in the abnormal
development of the penis-sheath requisite, considering that the female
is stationary and helpless, and covered with a shell ; while we note in
her the absence of eyes and legs—hboth useless under an opaque shell.
Hence we have a beautiful illustration of the elaboration of one part
and the degeneration of others.
It may be as well to remark that previous to the publication of
Newstead’s Monograph this species was known as Chionaspis fraxini,
Sign., but this and several other so-called species have been sunk as
synonyms of C. salicis.
In order that the student may thoroughly understand the life-
history and structure of this important arboreal insect, it may be
advisable to give a short epitome of the foregoing description, as
illustrated by “figs.” in figure 205. In fig. 1 we have a single egg.
The eggs are found in winter as represented in fig. 4, and hatch out in
May. Fig. 2 represents a larva which is active for a short time; fig. 3
represents the dorsal surface of a fully developed female scale: a is the
first and } the second larval moult. The sexes cannot be distinguished
till after the first larval moult, and fig. 7 represents the male scale,
showing the remains of only one larval moult, together with the
secretionary portion ; and fig. 8 represents the fully developed male,
which appears in July, and copulates with the female, represented in
fig. 5. It should be specially noted that at this period the female is
214 FOREST ENTOMOLOGY.
relatively small and of a peculiar form: this stage of development is
known in Coccid study as the period of fecundation. After the act
of impregnation the female changes her form, as represented in fig. 6.
This change in form is due to the body being filled with eggs, and
up to the time when the eggs are deposited this stage is termed the
period of gestation.
Thus, in a female Diaspid scale we have several stages—viz., the
egg, larva (first and second moult), period of fecundation, and period
of gestation ; and in the male we have egg, larva (one moult), pupa,
and winged stage.
Genus MyTILASPIS.
This genus, of which we have here only one species to consider,
may be distinguished from Chionaspis by the mussel-shaped scale of
the female. The scale is highly rounded, of a uniform light-brown
colour, and the second larval moult is completely covered by secretion.
Male puparium rare, elongate, sides parallel, and there is a faint
hinge-like depression towards the middle. It somewhat resembles
the second stage female.
Myrinaspis pomorum (Bouche).
This scale-insect is unfortunately only too well known as a
garden pest. It infests apple, pear, and plum amongst our fruit-trees,
and hawthorn, mountain ash, cotoneaster, and wild-rose amongst
our forest trees and shrubs. Its common name “ mussel-scale” is a
very appropriate one, inasmuch as it resembles, when magnified, our
common mussel of the sea-shore. The scale differs from that of Chion-
aspis in being more elongate, less circular, of a brown colour, and
about an eighth of an inch in length. It is built up in the same
manner as the ash-bark scale, but the first larval moult is yellow.
Plant after plant may be found so thickly covered_by the female
scales as not to be able to get a pin-point down without touching them
(not only covered with, but killed by, the scales), and yet not a single
male scale is to be found. Hence the species was almost considered
as parthenogenetic, and Mr Maskell says, ‘Male unknown in New
Zealand and Europe, doubtful in America.” It was not until July
1896, after nine years of observation, that Newstead discovered the
male on broom at Bearstead in Kent. As the male had hitherto been
unknown, this was rather an important find. It may even now be
or
COCCID. yt
considered as analogous to some species of Aphidze, in which males
have only been found after an interval of several years, otherwise the
sex may have been determined (as sexes of insects often are) by the
food-plant. With regard to finding it on certain food-plants, New-
stead remarks, “ Here in England, however, I have met with it freely
on Cytisus and Vaccinium, and sparingly on heath.”
Its habits are much the same as the Chionaspis on ash, &e.
At the end of August or early in September the female lays her eggs,
which remain under the scale during the winter. They are white,
and hatch out in Cheshire about the end of May, but not until the
middle of June (June 16, 1900) in Northumberland. The males,
when found, have appeared in July.
Newstead gives the following detailed description of the pygidium
—viz.: “ Pygidium (fig. 202) with five groups of circumgenital glands,
subject to great variation in number. Dorsal tubular spinnerets,
small and cylindrical, are arranged in three series,—the first, opposite
the lateral ventral glands, form a long scattered band terminating near
the anus ; intermediate series in a single row forming an incomplete
arch, with an outward lateral series extending from the middle almost
to the margin ; third series following the articulation of the pygidium
with the segment. On each side of median lobes along the margin
are six tubular spinnerets, of which the second and third, and
fourth and fifth, are arranged in pairs. Anus a little in front of the
anterior group of ventral glands. Vaginal opening almost central.
Median lobes almost as broad again as long; lateral margins usually
straight ; posterior margin centrally lobate, with one or two notches
on either side. Second and third pair of lobes small, almost touching,
have their margins rounded and entire or bluntly and irregularly
dentate. Plates long and spine-like, usually one median and four
lateral pairs.” !
Genus ASPIDIOTUS.
Female puparium more or less circular, and either raised or com-
paratively flat in centre. Exuvie central or conspicuously to one
side of centre. Secretionary covering often very thin. Females show
oreat variation in the character of the pygidium. Hence, from a
microscopical or specific point of view, it is advisable to study every
available species on different host-plants.
Male puparium circular, but much smaller than the female scale.
1 Newstead, vol. i. p. 196.
216 FOREST ENTOMOLOGY.
Synopsis oF ARBOREAL SPecrss,!
A. Pygidium with four, rarely with five, groups of circeumgenital glands.
(1) Short serial group of lateral dorsal pores absent. Puparium
reddish-pink in the young, pie grey in the old examples.
On oak . : : : Zonatus.
B. Pygidium always with Sine groups a Sipeiigential ? glands.
(2) Serial group of dorsal pores present. Puparium flat, convex
grey with a darker central zone. Hitherto found on fruit-
trees . : Ostrezformis.
C, Pygidium with club- shamed anil
(3) Groups of tubular spinnerets connected, with pores on both
surfaces of pygidium ; circumgenital glands almost continuous.
Puparium bright-fulvous. On holly. . Britannicus.
ASPIDIOTUS ZONATUS (Frauenfeld).
This insect is found on oak, but, so far, it has been rarely recorded.
One of the first discoveries was by myself at Agden, in Cheshire, Sept.
1892. It has been found fairly often in Cheshire, but never occurs
in any great numbers.
As regards life-history, the egg-laying takes place early in May, and
the larve hatch soon afterwards. As soon as the first larval moult
takes place, the sexes not only assert themselves, but they separate,
the males moving on to the leaves, and fixing themselves to the
midrib and veins, and the females congregating on the stem. But
though separated, it is, after all, only in the metamorphic stages,
inasmuch as it is only for the requirement of pupal development on
the part of the male. As the males emerge from the puparia on the
leaves with fully developed wings, it is obvious they have no distance,
or difficulty, to move from the leaf to the stem for nuptial rites and
associations.
ASPIDIOTUS BRITANNIOCUS (Newstead).
This is a species which, so far, has only been found on holly and a
species of fern cultivated under glass in the immediate neighbourhood
of London. The scales are circular, of a dusky-brown colour, and on
the slightest disturbance fall readily from the leaf. The males can
be distinguished from the females by the smaller size of the scale.
1 Modified from Newstead’s Monograph, vol. i.
COCCID2. er
As the two preceding species are not very common except in one
or two special localities, it would be well for the student to study the
habits and structure of an easily procurable and closely allied species
—viz., Aspidiotus ostreeformis on plum, apple, pear, and cherry,
This species is very common in many parts of the country.
In the event of this species not being procurable, the student may
find several species of Aspidiotus under glass, as in fig. 206 on Lap-
ageria, and fig. 207 on Stephanotis.
Genus DIASPIS.
This genus has a circular female puparium, and the remains of the
larval moults lie between the centre of “scale” and its outer edge.
co)
Fig. 206.—Scale of Aspidiotus on Fig. 207.—Scale of Aspidiotus Fig. 208.—Scale of Aula-
leaf of Lapageria. on leaf of Stephanotis. caspis rose on dog-rose.
The puparium of the male is elongated and strongly ridged, closely
resembling the puparium of Chionaspis.
In this genus proper we have no arboreal species, and the species
on wild-rose, long known as Diaspis rose, has been named Awlacaspis
(Diaspis) rose by Cockerell, and Newstead has, somewhat reluctantly,
adopted the change.
AvLaAcasPIs (Diaspis) Rosx (Bouché).
This scale (fig. 208) is found on the dog-rose (Rosa canina), and
sometimes on species of Rubus (bramble). It is fairly common in
218 FOREST ENTOMOLOGY.
some districts, and entirely absent in others. I have, for instance,
never taken it in Northumberland. It is generally found on the
stems of very old plants, and then often so abundant as to completely
cover the bark.
The female scale is of circular form, slightly convex, and from 2
to 3 mm. in diameter. The central or larval exuvie generally lies
between the centre and the outer edge of the scale. It is of a dull
canary colour. The exuvie of the second moult is yellowish-brown,
and the scale proper is a dirty-white-looking colour. Collectively,
they give a sort of drab colour to the infested stem.
Prior to the deposition of the egg, the body of the female is of a
dull orange-crimson, and the pygidium, which is rather conspicuous,
is a bright orange. The body, though elongated, has a slight leaning
towards a rough circular outline, and the front portion is almost a
perfect semicircle. The outline of the body shows the segmentation
very clearly.
The male scale is elongated, and very much resembles the puparium
of Chionaspis. It is of a whitish colour, and the exuvia varies in
colour from bright-yellow to red-orange. Jf examined carefully, it
will be seen that the white portion possesses three linear ridges, the
centre one being more raised than the other two.
The male of this species, and also the male of the genus Diaspis,
resemble the male of Chionaspis, both as regards the form of the
scale and the perfect insect. The body is crimson, and the wings
whitish. The eyes are black, and the antenne long and slender, with
very delicate hairs. The legs are yellowish, and slightly pubescent.
There is an important point in connection with the life-history of
this species, as compared with the genus Chionaspis, and the advice
given by Linneus, ‘‘ Observe and compare,” is very applicable to the
study of scale-insects. It has been noted that the larvae of Chionaspis
hatch out early in May, assume a quiescent stage after a few days’
active existence, and that eggs are found underneath the scale from
September to May. The active larve and eggs of A. vos, on the
other hand, are found throughout the year. I have found active
larvee, together with eggs and females, in November of one year, and
also in January of the following. Newstead says that the eggs are
deposited in August, and that there is only a single brood in the year ;
and the apparently abnormal character of eggs and active larvee being
found together shows that where egg-laying extends over a consider-
COCCID A. 219
able period, the respective stages of the metamorphosis are often
variable in point of time, resulting in an irregular appearance of the
adults.
Hitherto I have dealt with a group of insects which spin a covering
or scale, in addition to using cast-off larval moults, to protect their
bodies. Now we come toa group in which the actual body of the
female is transformed into a covering or “scale” for the protection of
egos and larve. This group is known
as the Lecaniine, of which fig. 209
represents a typical example of a
Lecanium scale found on sycamore.
The scales of the genus Lecanium,
or “brown scales” of the gardener,
are found on _ sycamore, hawthorn,
hazel, and other plants. They have a
general resemblance to brown dead
buds. If a few of these scales are
placed’ in a glass-covered box about
the middle of July, we should find
that towards July 25 or so the box
would be literally swarming with small
chocolate-brown coloured active larve.
They are very small mite-looking crea-
tures, measuring about $5 of an inch
in leneth. ‘These small mite-like larve
are the first stage of the “brown
scales” referred to; and as there is a Se earep ain ne! of Sees
great difference in size and apparent
structure between the small active larve and stationary brown dead-
like scales, it would be well for the student to study the development
of a Lecanium scale.
Under the one-inch objective the structure of the larve will be
seen to resemble that of the larve of Chionaspis. In their natural
state they move about very actively for a time, and then settle down
and begin to imbibe the juices of the plant.
As it is rather difficult, more especially for a beginner, to follow out
the life-history of a Lecaniwm on a forest tree, it is best to have
recourse to stove or greenhouse specimens, and get a plant which is
220 FOREST ENTOMOLOGY.
badly infested with “brown scale.” For example, a comparatively
small specimen of Croton will often serve the purpose. In order to
understand the structural details, it is best to prepare and mount
a young adult, and examine it under the inch objective. It is then
advisable to carefully look for all the characters found in fig. 210.
In the first place, see the mouth and sucking-tube, as at a and 0.
The antenne (fig. 211) should be
well studied, as the number and
relative lengths of the joints often
afford important points in classifica-
tion. At c¢cccewe get the openings
leading to the spiracles or stigmata,
and these structures may be carefully
studied. At d we find the anal
plates or lobes; at e the anal cleft ;
and at f the marginal spines. All
these structures are clearly displayed
in the young adults. The legs, like
Fig. 210.—Adult female Lecanium after the antenne, should also be care-
treatment with potash x 20.
a, mentum; 0, rostral filaments, forming fully noted under the field of the
microscope.
the sucking-tube ; ecec, ventral chan-
nel leading to spiracles ; d, anal plates
or lobes (dorsal); e, anal cleft; f, mar- D 7 7eQr 1
Shel qphes. (kon Sere onion But while the microscopist thus
ograph of the British Coccide.’ Ray oging a ceneral idea of the struc-
Society.) =) 5
ture, the fully developed “ brown
scale” is nevertheless a puzzling
. organism to the practical man.
Dy Perhaps it may be best understood
oS
by adopting an illustration. In
= view, therefore, of making it in-
« telligible, it is to be hoped that a
very homely, if not grotesque,
Fig. 211.—Typical antennee of female STAT ; Wave
8 EES Tee Ee simile may be used. Most people
are conversant with the tortoise
creature moving along with short legs and hard body. Now suppose
this creature was born with fully developed legs, but after one or two
“moults” the body developed, say, fifty times its infantile size, while
the legs remain the same as at birth, and also as a natural consequence
the creature became absolutely helpless from such abnormal develop-
ment,—we should have exactly an analogous case to the development
a
COCCID 4. 221
of a brown scale. If, therefore, the fully developed creature be
boiled and mounted according to instructions given, we shall have
a more or less circular form, representing the outer edge of the scale,
and the internal appendages as represented in fig. 210. As already
stated, the body is transformed into a covering for the eggs and larve.
Thus, speaking generally, the eggs are contained in the enlarged body,
and when the larve hatch out, they may often be found in a group
underneath the scale.
When this stage of development is attained, the female is some-
times apparently, and often in reality, dead. In either case it shows,
on the part of nature, a very beautiful arrangement. The modifica-
tion of form and structure for the prospective requirements of her
own progeny is a beautiful adaptation ; but when we consider that
the dead body of the female is transformed into a protective cover-
ing for the offspring, it shows a form of altruism,—the application of
that law which reveals a struggle for the life of others, and which is
in itself, certainly, a very beautiful adaptation indeed.
In studying those creatures in a natural state, from an arboreal
point of view, it would be best to mark a badly infested plant
for examination, and make regular visits to the same. If, there-
fore, the attacked portion be examined during autumn, it will be
ascertained that the small larve are somewhat difficult to find. They
have, of course, lost the activity of early youth, together with (to the
naked eye) characters and their appendages. They are now trans-
formed into small scales, measuring perhaps approximately about '5
or zy of an inch in length, comparatively flat, and in colour harmon-
ising well with the food-plant. They are to all appearance lifeless,
and in this comatose state pass the winter. At the same time it
must be remembered that before winter sets in the larve will have
passed through their first moulting stage. In spring, glassy elongated
puparia of the male may be found (see fig. 212), and if collected in
late spring or early summer the perfect insect can be hatched
artificially.
After copulation, the females develop rapidly until they measure
about 4 to 58; of an inch in diameter. As males are not always found
associated with the female scales, it is quite possible they may at
times be parthenogenetic.
In Cheshire the females reached maturity by July 1. If a number
of specimens are placed under glass about the time referred to, it will
Pople FOREST ENTOMOLOGY.
be found that some of the scales will soon appear perforated, and the
case swarming with small Hymenopterous parasites. Hence, prob-
ably, the harmony of colour in the early stage was a means of
protection against natural enemies.
The salient characters of the sub-family Lecaniinz, according to
Newstead,! are: ‘‘ Adult females either naked or covered with secre-
tion, forming a test or ovisac. Abdomen in all stages with a more or
less defined cleft, and on the dorsal surface at the base of the cleft
are two more or less triangular lobes or plates. Legs and antenne
generally retained, but a few forms are apodous, and have rudimen-
tary antenne. Mentum generally monomerous or dimerous. Males
generally possessing wings, either with or without caudal filaments.
The puparium of the male is generally of a glassy nature.
“‘ Larvee with large setiferous anal lobes, placed within the posterior
anal cleft.”
SyNopPsIS OF GENERA (ARBOREAL).
A. Females naked. Ovisac behind and partly beneath the posterior
extremity of the body : : : . PULVINARIA.
B. Females naked—no ovisac.
(a) Females retaining legs and antenne. Old adults hollow
beneath . ; ; : ; ; LECANIUM.
(1) Females without antenne and legs; body with two internal
pouches . : : : : . PHYSOKERMES.
Genus PULVINARIA.
The male scale of this important genus cannot be separated from
the male scales of the genus Lecaniuwm or “brown scale.” In the
younger stages we cannot distinguish the female scales of the one
genus from the other. The adult species are, however, quite distinct.
We may define the adult female Lecaniwm as a brown scale proper,
and the adult female Pulvinaria as a brown scale with a white ovisac
attached to the scale itself, and extending behind and beneath the
insect proper.
PULVINARIA VITIS (Linn.)
The specific name of this species would suggest that it may be
looked for only in the vinery. Such, however, is not invariably the
TSViolesite) Daas
COCCID.®. Jao
case, for though under glass it may be found on vines and peaches,
out of doors it may be found on various trees—viz., hawthorn, birch,
hazel, willow, alder, cotoneaster, and others.
Before the publication of Newstead’s Monograph this species was
known by a number of synonyms, according to the respective food-
plant—viz., Pulvinaria betule, P. salicis, P. populi, P. persice, &e.
It is therefore very helpful to find these specific names have now
been sunk as synonyms of P. vitis.
Whilst I have found it sparsely distributed on the various trees
enumerated, I might just add that the most common part of an old
tree to find it is on the young bark formed by occlusion either after
pruning or where the stem had been previously stripped of its bark
by accident.
If this scale be found just as the eggs are deposited (at the period of
parturition), the smooth, white, plump ovisac, together with the over-
lying scale of chocolate-brown colour and slight corrugations, makes
a very pretty object. But soon, however, it changes. The scale
grows darker, while the outer edges of the body curve inwards and
upwards, becoming detached from the ovisac, and only fixed to the
food-plant by the cephalic area. At this stage, also, the dermis is
very heavily wrinkled.
The antenne are generally composed of eight joints, though at
times there are only seven. The legs are ordinary, with simple digi-
tules to the tarsus.
PULVINARIA VITIS, var. ribeste (Signoret).
So far as the naked-eye characters of this insect are concerned, it
very much resembles the preceding species, but as it may often be
found in districts where P. vitis does not exist, it would be well to
study its life-history and microscopical characteristics.
Fig. 212 is from a photograph of this species on Ribes sanguineum,
found at Lyham, Northumberland.
Newstead gives a very full and interesting account of it, and the
following is his summary—viz. :
‘“We find that there is but one brood ina year. The larve hatch
in June and the early part of July, the first moult taking place from
the middle of July onwards ; the second moult is in August, when
a sexual difference is first observed. Pupation takes place towards
2a’ FOREST ENTOMOLOGY.
the end of August, the males appearing in September. They then
fertilise the females, when the latter moult again for the third time.
Hibernation commences shortly afterwards, and the insects remain
dormant until the spring. Ege-laying takes place at the end of April
and throughout the early part of May. In all probability the periods
here set forth may vary slightly, according to the season.”
The male (fig. 213), copied from Newstead’s Monograph, is described
as dusky reddish-crimson or blackish-crimson in colour, with black eyes;
Fig. 213.—Male of Pulvinaria. Species Fig. 212.—Male and female scales of Pulvinaria on flower-
found on flowering currant. ing currant, Ribes sanguineum (natural size).
long, slender, and ten-jointed antenne. ‘Two very long caudal filaments
at posterior end. Length, including caudal filaments, 2 to 3 mm.
Having in a general way referred to the characters and life-history
of the genus Lecaniwm, it may now be best to give the salient char-
acters of the arboreal species, according to Newstead.
Genus Lecanium.!
Adult females, some low, convex, others hemispherical above, hollow
beneath at the period of parturition.
1 Adapted from Newstead’s British Coccide, vol. ii.
COCCID A. 225
Synopsis of arboreal species,
1. Adult female highly convex, sometimes hemispherical, and more
or less rugose . . d . persice and var, corylt.
2. Adult female with a delicate marginal fringe, and usually with
a dorsal fusiform swelling, Coxa one-third the length of the
tibia. t : : : : , ciliatum.
3. Adult females more or less hemispherical, spheroid, or oblate-
spheroid.
(a) Dorsum with conspicuous tubercles; anal lobes
rounded . é : : bituberculatum.
(b) Dorsum rounded, with two to four short, deep, irreg-
ular grooves radiating from the anal cleft; sides of
body comparatively smooth. Legs and antennze
short ‘ t ; ; ; capree.
LECANIUM PERSICAH, var. coryli (Linn. )
I have only found this species in the adult stage—viz., on Coton-
easter microphylla, growing in a cemetery near Leamington, War-
wickshire. The colour is bright reddish-brown, more or less hemi-
spherical, of a very uniform pattern and size.
Lecanium ciLiatum (Newstead).
I found this scale fairly common on oak-coppice shoots at High
Legh, Cheshire. The female may be first recognised, about the latter
end of May or beginning of June, by the conspicuous fringe which
surrounds the body. This is the period of fecundation, and it may
be compared to a large specimen of “mealy bug” we find in green-
houses. The whole body is covered with a whitish farinose secretion,
including the two anal lobes which project beyond the body.
As this stage of the life-history of the species in question cannot
be called a starting-point, though in all probability the student may
also recognise them in the forest at the same stage, the following
note as regards life-history is taken from Newstead :—
“The larve hatch towards the end of July. At least one moult
takes place before winter, and the insect grows to some extent before
hibernating. In spring (March) the female appears, and is then about
P
226 FOREST ENTOMOLOGY.
3 mm. long, bearing upon its back the singular square-shaped excresc-
ences, which are composed partly of secretion and partly of the effete
skin of the previous moult. The latter is not cast off, but splits or
divides into squares, and these, as the insect grows, become more and
more widely separated. In May another moult takes place, the newly
cast skin carrying with it the marginal fringe and all the old exuvize
and secretion. After the final moult the insect grows somewhat
rapidly,” and the period of fecundation is therefore reached.
Later on the female at the parturition period assumes a chestnut-
brown colour, with a highly convex swelling in the central area. The
whole scale retains slight traces of the original waxy covering, with a
shining surface and a fringe of delicate hairs at the outer margin of
the scale.
The antenne usually consist of eight joints, but this number is not
always constant, as seven is often found. The legs are comparatively
short, with unusually well-developed coxe.
LECANIUM BITUBERCULATUM (Targioni-Tozzetti).
The adult female scale of this species is a large, brown, highly con-
vex scale, with two pairs of sub-dorsal shining tubercles projecting
considerably beyond the contour of the scale. It is found on haw-
thorn hedges, more especially in the eastern and southern parts of
England, but it is very local. It has several characters which go to
determine it as a distinct species, but these are of more importance to
the specialist in scale-insects than to the general student of forest
entomology. It is, however, one of the most beautiful and best
marked of all the British species.
LEcANIUM CAPRE# (Linn.)
This insect may be called the common brown scale of the forest, as
it is found on quite a variety of food-plants—viz., hawthorn, apple,
elm, sycamore, oak, alder, willow, hazel, lime, horse-chestnut, laurel,
wild sloe, &c. (see fig. 209). Careful observation and comparison of
similarly aged specimens will show that this scale varies very much
in form according to the food-plant. Thus on elm and horse-chestnut
the insects are smooth and spherical, while on lime and hawthorn
they are more flat, slightly elongated, and wrinkled. During life the
bo
bo
af
COCCID.
colour is of varying crimson shades, but after death the colour is
invariably chestnut-brown.
The antennz are variable, and may be composed of six, seven, or
eight joints. It is, however, possible that eight is the typical number,
but two or more joints may be so fused together as to lose all trace of
segmentation.
It is also considered that parasites have a peculiar influence in
determining the form of the scales.
The insect not only varies in colour during the period of parturi-
tion, but even more so during the period of fecundation. Hence the
variety of form in the two stages has given an endless number of
specific synonyms, and coccidologists and general entomologists must
be grateful to Newstead for placing them all under one species.
With regard to the life-history of this species, I found that the
larvee of insects from sycamore hatched out, in confinement, on May
25th. This was in Cheshire, and the
specimens having been kept in a warm pm
room, it is possible that this was rather
early.
The larve move about quite promis-
cuously for a time on leaves and shoots,
but early in the autumn they all betake
themselves to the shoots and moult.
1 |
They pass the winter in a comatose 4,,, Tie Glee
state, and the sexes assert themselves in Species found on sycamore, Por-
tugal laurel, goat willow, de.
early spring; but there is generally a
preponderance of females, and in some cases males cannot be
found.
In Cheshire Newstead found that males hatch about the end of
April or beginning of May, but in Northumberland I found, after
keeping puparia for two days in a cool room, that males appeared on
May 23 in 1901. Allowance must be made for the lateness of the
north, but it would seem as if twenty days to a month elapses from
the appearance of the males to hatching of the larve. The student
will be well repaid by following out the life-history of a Lecaniwm, as
it is in some respects a typical example of how variable in point of
time larval development and emergence may be.
Newstead thus describes the male (fig. 214): “ Pale crimson, with
the head, thoracic bands, and apodema crimson-black ; abdomen, legs,
228 FOREST ENTOMOLOGY.
and antenne paler and dusky. Eyes and ocelli black, shining, and
of the latter there are four dorsal and six ventral. Caudal filaments
comparatively short. Halteres pale red, turned back over the thorax
when the insect is at rest. Wings rather short, and suddenly widened
at base. Stylus nearly as long as the abdomen.”
I have found this insect sparsely distributed on all the food-plants
enumerated. As a veritable pest, however, I have found portions of
hedges near the city of Chester, and also in other parts of mid-
Cheshire, killed outright by this insect. It is also somewhat remark-
able that I’always found this scale most injurious where the hedges
were either cut twice in one season or on cottage-garden hedges cut
only once in a season, and more especially where the cutting was done
very early in the autumn.
Genus PHYSOKERMES.
The larve and early stages are quite identical with Lecandwm.
After this, however, the structural details differ from Lecaniwim, in-
asmuch as in Physokermes the body at egg-deposition is composed
of two chambers, both of
which are filled with eggs;
and also in the adult scale
no traces of antenne or
legs are found.
PHYSOKERMES ABIETIS
(Geoffrey).
This insect is always
9 found on spruce (Abies
a excelsa). The scale is
very much like a Lecan-
Fig. 215.—Scales of Physokermes abietis as found in the q 7 a =
“forkings” of the young twigs of common spruce. EM 18 general ejees
ance. It may be looked
for on the younger twigs of spruce, and more especially in the
“‘forkings” of the young twigs (fig. 215). The colour, generally
a dull chestnut, harmonises well with the food-plant, which may be a
means of protection against natural enemies. Newstead says he has
hatched from this scale a chalcid parasite, Hncyrtus scaurus, Walk. ; a
COCCID.4. 229
small beetle, Brachytarsus varius; and a small dipteron, Dizplosis
latibulorum, Winnz.
The life-history somewhat resembles that of a Lecanium, but the ana-
tomical structure is altogether different and quite unique. Newstead
says the eggs may be found in the pouches at the beginning of June,
and the larvee hatch towards the end of July. This observation was
made in Cheshire, and therefore differs from notes I have made here
in Northumberland—viz., to the effect that on August 2, 1900, I
found eggs, and on September 1, same year, I also found eggs, and
placed the insect containing them in a small box, but the observation
was neglected until September 21, when the larve jrom those of the
latter date which had hatched out were all dead. The larve hide
themselves rather effectually on the young twigs during the winter
months. Hitherto no males have been found. The creature has an
internal double-chambered marsupial pouch, into which she places her
eggs for incubation. This peculiar structure can best be seen by em-
bedding the body in paraffin wax and making sections by means of a
microtome. Legs, antennx, and other appendages are not found after
boiling the body in potash, but a peculiar rough tesselated surface
can be seen after the chitinous body has been prepared for microscopic
examination.
I found this species very plentifully at Pollok, near Glasgow. As
a rule, it is very common on sickly specimens which are considerably
injured by Chermes abietis. In healthy spruce-trees no appreciably
ill effect accrues from the presence of this scale, but the more weakly
trees, which act as shade-bearers, are often killed outright by this
species and the associated Chermes.
Sus-FAMILY DACTYLOPIIN A.
“Adult females active or stationary, naked or covered with mealy,
cottony, waxy, horny, or glassy secretion.
“ Antenne and legs either well developed, rudimentary, or entirely
absent. When present, the last joint of the antennz is usually
much longer than the penultimate. Anal lobes generally small or
rudimentary.
“Larvee, exhibiting anal lobes and setiferous anal orifice, similar
to those of the adult female.
“The females of this division are distinguished chiefly by the
230 FOREST ENTOMOLOGY.
character of the anal lobes, which, although varying in degrees of
development, are always present.
“Tn Dactylopius the ovisacs are usually formed of loose, white,
flocculent secretion, often quite devoid of form, and aggregated in
masses on the food-plant.
“In Cryptococcus the ovisacs are also felted, and often so thickly
packed together as to completely cover the bark of the tree.
“The males are characterised by the comparatively short and
somewhat complex structure of the genital armature.
“The male puparia are generally felted.” !
SYNOPSIS OF THE GENERA.
A. Adult females stationary, enclosed in a glassy or horny fringed
ovisac (test) . ; ; (I.) AsTEROLECANIUM (1).
B. Adult females active, covered with mealy secretion, not enclosed
in ovisac.
(a) Female antenne of eight joints . (II.) Dacrynoprus (2).
BB. Adult females enclosed within ovisac at gestation.
(a) Female antenne of nine joints. (III.) Pszupococcus (3).
(>) Female antenne of six, rarely of five or seven, joints
(IV.) Riperstra (4).
C. Adult females stationary, living from the earliest stage within the
ovisac ; antenne and legs rudimentary or absent.
(a) Anal orifice of adult female with four spiny hairs
(V.) Cryprococcus (9).
(b) Anal orifice of adult female with six long hairs
(VI.) Anronina (7).
CC. Antenne and legs present; anal orifice with six flattened hairs
(VII.) AprErococcus (8).
D. Anal lobes of adult female very large, body with long marginal
or dorsal spines : : . (VIII.) Ertococcus -(5).
FE. Body of adult female with numerous short conical spines
(IX.) Gymnococcus (6).
The above ‘‘synopsis” is copied in full from Newstead’s Mono-
graph, vol. ii.; and though all the genera are not arboreal in their
habits, it is important that the student, more especially a horticultural
student, should study at least a typical species from each genus.
1 Adapted from Newstead’s Monograph.
COCCID 2. Paid
The arboreal genera are: Asterolecanium, Pseudococcus, Crypto-
coccus, and Apterococcus. With the exception of Asterolecanium,
these genera are, so far as our present knowledge goes, exclusively
arboreal.
The remaining genera — viz. Dactylopius, Ripersia, Antonina,
Eriococcus, and Gymnococcus—are, as regards food-plants, very varied
indeed. Thus Dactylopius (‘‘ mealy-bug”), of which five species are
at present known, may feed on numerous greenhouse plants, grasses,
or sea-pinks ; Rzpersia on a hothouse fern, on Stephanotis, roots of
grass, and even subterranean birds’- nests; Antonina on bamboo ;
Eriococcus on gorse, grasses, or heath; and
Gynmococcus on stovehouse plants.
Genus ASTEROLECANIUM.
The females of this genus are completely
enclosed in a sac of opaque or semi-trans-
parent waxy or glass-like secretion. This
ovisac is usually termed a “test,” and the
margins are generally furnished with a fringe
of waxen rods or plates.
The adult females are apodous, and the
antenne are either absent or rudimentary,
ASTEROLECANIUM VARIOLOSUM (Ratz. )
This is a species which I found very
common in Cheshire, on the tips of the
young oak shoots. The female scale ad-
heres very closely to the young twig,—so
much so, that she actually causes a de-
pression to be formed, and where they ig. 216.—Depressions on twigs
of oak caused by Astero-
are numerically strong, often kill the twig. aay variolosum (nat-
% ral size).
The appearance presented may be compared
(if the simile is not considered too grotesque) to the features of a
person who has suffered severely from small-pox (fig. 216). The
ovisac is made up of a “test” or scale, which is of a circular shape,
and around the lateral sides a curious fringe may be seen under the
microscope. The colour of the scale varies according to age: thus
Wow, FOREST ENTOMOLOGY.
in summer it is green, and in winter brown. Underneath this
scale or ‘‘test” may be found the actual body of the insect,
but in the living specimens it is almost inseparable from the
scale, hence it is best to select dead specimens for microscopical
examination.
After treatment with potash, details of structure can only be
seen under high powers, of which the salient features are spin-
nerets and rudimentary antenne.
Genus PsEUDOCOCCUS.
The genus Psewdococcus is decidedly arboreal, and in many respects
resembles the mealy bug, more especially in the larval stage.
PsEUDOCOCCUS ACERIS (Signoret).
In fig. 217 a typical example of this scale is represented on horn-
beam. To the naked eye this scale appears as a small white speck
on the food-plant. It is found
on various forest trees and shrubs,
including sycamore, hornbeam,
mountain ash, elm, oak, and
gorse or other plants. On the
last-named food-plant it is some-
times very thickly coated on the
spring leaves, and at other times
only sparsely distributed. Though
never so numerically strong as to
be considered a pest, it has never-
theless an interesting life-history.
aS Speers RES on bark of The female insects, as seen in the
illustration, should be looked for
towards the end of May or beginning of June. They may be then
placed in a box, together with a very small portion of the host-plant
upon which the insect rests. The larve hatch about the middle of
June, and they are mere pin-points in size, and of a light-yellow
colour. The antennz at this stage are composed of six joints, the
terminal joint being as long as three succeeding joints. They have
large prominent eyes, of a brown colour, with just a slight tinge of
COCCID.. Zoe
blue. The legs are similar to those of other coccid larve. The body
at first sight appears to be in one piece, but the abdomen is segmented
and fluted, each flute terminating in a single hair.
The species illustrated on hornbeam, on which I tried to make a
few observations, was taken from a tree in my garden in High Legh,
Cheshire. I found the larve hatched out about the middle of June,
but I failed to discover their presence again until September. It is
true that the bark of the particular tree in question was very much
covered by the alga known as Protococcus viridis, and would thus
provide ample shelter and covert
for the creatures. By that time
they had enlarged considerably,
Fig. 218. — Antenna of
Pseudococcus aceris.
(Camera-lucida sketch.)
PN
iG)
\ y
v
fj
has
A
a
Sy
Fig. 220.—Rostruin of Pseudococcus Fig. 219.—Leg of Psendococcus aceris.
aceris. (Camera-lucida sketch.) (Camera-lucida sketch.)
and could be found in comparatively large numbers swarming
on the lower region of the trunk. At this stage they are still
larvee, but the sexes then assert themselves and separate. The males
remain in the south or lee side of the trunk, and the females
go higher up, on the branches, generally in the cleft. According
to observations made daily with this species, on a laburnum-tree,
Newstead says the females reawaken in March, a few days before the
males, descend the trunk, copulate, and return to the branches. This
seems all the more remarkable inasmuch as the males have wings and
well-developed legs, and could easily move in the direction of the
female residence. In May the females spin their cocoon, which
234 FOREST ENTOMOLOGY.
takes about three days. The eggs are laid during the construction
of the cocoon, and the larve hatch out, as previously mentioned,
about the middle or end of June.
I found larve of this species very plentifully in thorn hedges at
Prestbury, Gloucestershire, Sept. 10, 1906. In general appearance
they very much resembled the “mealy bug” of greenhouses. They
were yellowish, with a white dusty covering over the body. The
parent scales with their ovisacs were situated on the twigs, but the
young larve in question were congregated in a streak along the mid-
rib of the leaf, and generally on the upper side.
The female can be easily detached from the ovisac without the aid
of a lens. The body is simply an ovate sac of a yellowish colour.
If the body be boiled in potash we get rather an interesting object.
The antenne are composed of nine joints (fig. 218), of which the
second is usually the longest, but the antenne are often variable.
The legs and the outline of the rostrum can also be clearly traced.
Fig. 219 represents a camera-lucida sketch.
Fig. 220 is a camera-lucida sketch of the rostrum.
Genus CRYPTOCOCCUS.
“ Adult females stationary, living within a felted ovisac. Antenne
rudimentary. Posterior pair of legs rudimentary ; anterior and inter-
mediate pair absent. Anal legs normal. Larva with anal orifice, as
in the adult female. Antenne of five joints.” !
Cryprococous Fact (Barensprung).
This insect is very common in many parts of the country, and is, in
fact, one of the most dreaded pests of the arboriculturist. At the
same time, it may be noted that it often confines itself to compara-
tively small areas, or to isolated park trees. In general appearance
the trunks and larger branches of beech-trees infested with this pest
present the appearance of a shower of snow having frozen. This pest
has been graphically termed the “felt scale” by Miss Ormerod.
Fig. 221 is a representation of this scale on beech.
Where the pest is but sparsely distributed on the stem little
damage accrues ; but it is sometimes found about a quarter to half an
1 Newstead, vol. ii. p. 214.
COCCID 2. 235
inch in thickness, and when such is the case the bark separates from
the stem, and the tree ultimately dies in consequence.
This insect confines its attacks exclusively to the beech (Fagus
sylvatica), and, by reason of its whitish appearance, must not be con-
founded with the various species of Chermes (Aphidz) on larch, silver
Fig. 221.—Cryptococcus fagi on beech. (From F. V. Theobald’s ‘ Animal Pests of
Forest Trees.’)
fir, Weymouth pine, &c. It should also be noted that the “ copper
beech” is all but immune from this insect-pest. In fact, I have
occasionally seen cases where the copper beech was grafted on the
common beech, of the pest appearing fairly thick on the stock or
common beech portion, and the copper beech portion above having
only here and there the smallest possible specks on it.
236 FOREST ENTOMOLOGY.
On moving the white covering about midsummer, the insects may
be found in all their respective stages.
The adult female is of a sulphur-yellow colour, about half a line,
or 5's of an inch, in length, convex above and below. The creature is
both wingless and legless, and has, therefore, no power of locomotion.
The mouth-organs are placed on the under side of the body, and are
composed of long hair-like appendages, forming mouth or sucking-
tube and anchorage. She covers her body with the white waxy
secretion, which is impervious to rain, and here she lives, lays her
eggs, and dies.
The larve, in shape and appearance, very much resemble other
coccid larve, being active and yellow in colour. The eyes are rather
conspicuous, and of a purplish colour, The antenne are five-jointed,
and terminated by a forked bristle. The legs are short and stout.
As a rule, they are found under the living or dead bodies of their
parents or in the same felted mass, for the larvz also secrete a white
waxy covering, thus adding to the white materials, and also aiding in
the destruction of the tree. Occasionally the larve move to the fresh
portions of the bark, secrete a covering over their bodies, and thus
spread the injuries over the trunk.
The eggs are also of a lemon-yellow colour, and comparatively large
for the size of the insect.
As regards the life-history of this insect, it may be said that much
may yet be done by the inquiring and observant student, inasmuch as
eggs, larvee, living and dead female, may at various periods of the year
be found all huddled together. However, it is possible that the
majority of the eggs are deposited in July, and that some hatch out
in the autumn months and pass the winter as active larvee, whereas the
majority hatch out in spring and soon atter evolve into fully developed
females.
At various seasons of the year I have often found very active
specimens of acari amongst the insects.
Considering the alarming spread of this pest, preventive and remedial
measures ought to be taken in order to save many specimen trees in
pleasure-grounds, parks, the neighbourhood of villages, and forests
generally.
Some years ago, as a remedy, I tried a solution which proved very
successful. To make it, take about half a gallon of soft water, boil,
and dissolve about 1 lb. of soft soap and about 1 lb. of common soap ;
COCCID®. 237
add a handful of sulphur, one pint of paraffin, and about the same
quantity of turpentine. Then add about four gallons of soft water
to this mixture. Churn well with a syringe, and when cold, store
away in a stoppered barrel to prevent evaporation. Apply with a
whitewash brush about May, just as the larve are hatching out, but
before application churn well with the syringe, to ensure the mixture
of the ingredients.!
I did not measure out the ingredients in exact proportions, but
took care not to add too much paraffin and turpentine. I have, how-
ever, in practice, been fortunate enough to have been associated with
healthy beech-trees in Northumberland, and therefore have not had
an opportunity of putting this mixture to the test on a large scale, but
all those who have tried it maintain that it answers well. In fact, I
had several portions of beech bark sent from various parts of the
country showing the good effects accruing from the application of
this mixture.
A most interesting remedial measure has been brought under my
notice at Blagdon, in Northumberland. With an inch augur bore
three holes at about equal distance right into the centre of the trunk,
about three feet from the ground, and sloping slightly towards the
root of the tree. Into these holes place as much flowers of sulphur
as can be conveniently got in, and then cork them firmly up with a
plug of soft wood. This should be done in the autumn, and will be
found successful. It was first adopted about thirty years ago, and
the trees which were then operated on are now in comparatively good
condition.
Though this remedial measure may be adversely criticised by many
practical men, nature would seem to suggest some analogous form of
treatment by inference from the copper beech being all but immune,
and also from the fact that certain species of fruit-trees are immune
from American blight and scale-insects.
From an able and interesting leaflet of the Board of Agriculture the
following insecticides for this pest are recommended :—
(1) Paraffin emulsion.—Mix equal proportions of soft soap, dis-
solved in boiling water, and paraffin, and churn them up by means of
a force-pump or syringe. When required for use add twenty times
its bulk of water, and again churn.
1 This has been adopted by the Board of Agriculture. See Leaflet No. 140,
Remedy ‘‘No. 2.”
238 FOREST ENTOMOLOGY.
(3) Caustic alkali wash.—Dissolve 1 lb. of commercial caustic soda
in water, then 1 lb. of crude potash or pearl ash in water. When
both have been dissolved, mix the two well together; then add # Ib.
of soft soap, stir well, and add sufficient water to make up to ten
gallons. Caution.—Do not mix in painted vessels of any kind.
Genus APTEROCOCCUS.
Adult female stationary, living within the ovisac. Legs persistent.
Antenne six joints. Male apterous. Antenne seven joints. Male
puparium felted.
APTEROCOCCUS FRAXINI (Newst.)
In some parts of the country this scale is fairly common. I found
it frequently in Cheshire, and again in some instances in Northum-
berland. As a rule, it is gener-
ally found on isolated trees, or
otherwise extremely local on
hedgerow trees. It is found on
trees of varying ages, from fifteen
years upwards, but most abund-
antly on trees from thirty to
forty years of age with compara-
tively smooth bark. When it is
found on old trees, it is sparsely
scattered in the fissures of the
rough bark. The general appear-
ance of this scale somewhat re-
sembles the genus Dactylopius or
mealy bug, inasmuch as the bark
is spotted with numerous white specks (fig. 222). If an individual
sac be examined during the winter months, it will be found to
contain two or more female insects.
The adult female is of a bright-red colour, somewhat globular in
shape, with six-jointed antenne, short legs, and very long rostral
filaments. A microscopical examination of a prepared female insect,
under high power, reveals special rings of spines surrounding the anal
orifice, and a few tubular spinnerets on the dorsal surface.
The male is apterous, of a bright-red orange colour, with black
Fig. 222.—Apterococcus fraxini on bark of ash.
COCCID.© 239
eyes. The antenne show seven and sometimes eight joints, and at
the junction of the third and fourth joint a curious ball-and-socket
arrangement may be seen. The genital armature is comparatively
short. The males appear in considerable numbers during October and
November, and during the day may be seen actively moving on the
bark.
I found the larve hatching out in Derbyshire about the latter end
of June 1906, and about a fortnight later of the same year in North-
umberland.
References to Literature consulted.
Cockerell, T. D. A. Notes on the Geographical Distribution of Scale-Insects.
Smithsonian Institute. 1895.
Comstock, J. H. Report on Scale-Insects. 1881.
Douglas, J. W. Some British and Exotic Coccide,. E.M. M. 1891.
Fuller, Claude. Articles in Australian Papers.
Howard, L. O., and Marlatt, C. L. The San José Seale. U.S.A. Bulletin, No. 3. -
1896.
Hunter, 8. J. Scale-Insects Injurious to Orchards. University of Kansas,
Lawrence. 1898.
Lea, A. M. Scale-Insects. Western Australia. 1898.
Lewis, Richard. Papers on Scale-Insects.
Lounsbury, Chas. P. Coccidze or Scale-Insects. Cape of Good Hope. 1907.
Maskell, W. M. Scale-Insects of New Zealand. 1887.
Various papers from 1883.
Morgan, A. C. F. Scale-Insects. Portugal. 1888.
Newstead, R. Monograph of the British Coccide. Ray Society. 2 vols.
1900-1902.
Newstead, R. The Injurious Scale-Insects and Mealy Bugs of the British Isles.
Journal of the Royal Horticultural Society. Also separate papers from E. M. M.
1891.
Quaintance, M.S. American Aleurodide. 1900.
Sule, Karl, Studie 0 Coccidech. 1895.
Tryon, Henry. Scale-Insects. Queensland. 1898.
240
CHAPTER VII.
LEPIDOPTERA (Morus).
Tue Lepidoptera are undoubtedly the most favourite order of insects,
and, as far as ornament is concerned, they are the highest in the
insect world. The majority of entomologists begin their studies with
the Lepidoptera. They are very interesting in breeding, from the
larvee being associated with special food-plants, and more especially in
watching their development from the egg stage.
As regards the association of this order with arboriculture, it is of
course obvious that it is somewhat difficult to know what species to
adopt or reject, inasmuch as some of the rarest species are exclusively
arboreal feeders, and on the other hand, some of the most direful forest
pests belonging to this order may only appear in certain localities at
very long intervals of years. Perhaps, therefore, the best method will
be to simply give the more general species, with as few details of
generic and specific characters as possible, because the student will
find more available books on Lepidoptera, and probably more assist-
ance from local naturalists, than in any other order of insects.
With reference to general characters, the Lepidoptera have four
wings; body and wings covered with scales, which are usually varie-
gated in colour; venation more or less straight and without cross
veins. Imago with mouth only fitted for sucking, which is situated
at the extreme end of a long coiled proboscis, capable of protrusion.
The metamorphosis is complete, but abrupt ; the larva has a large
head and strong mandibles; the pupa often has the antenne ad-
pressed, and cemented to the body ; and the full development of the
moth takes place within the pupal case.
The head is in a large part made up of the compound eyes, the
simple eyes or ocelli which are usually concealed by the antennex, and
the proboscis or trunk.
LEPIDOPTERA. 241
The prothorax is small, the mesothorax large, and the metathorax
small.
The abdomen varies according to sex. In the female it may be
said there are seven segments dorsally and six segments ventrally.
But one segment is concealed ventrally, and other two segments are
modified in connection with the ovipositor, thus making in reality
nine segments. In the male the abdomen is also composed of nine
segments, and as a rule is more slender than in the female. At the
extremity the anatomy is somewhat complex, but the general design
shows two terminal claspers.
The /egs are long, slender, and covered with scales. The tarsi are
five-jointed, and terminating with two small claws.
The wings of the Lepidoptera are a remarkable feature of this
order, inasmuch as they owe their beauty to the often exquisite blend-
ing of colour which adorns their surface. This delicate colour is due
to the arrangement of minute scales, which overlap one another after
the manner of slates on the roof of a house. They form very fine
objects for microscopical mounts, and the young collector must always
remember their delicacy, as the slightest touch of the finger will at
once destroy the beautiful pattern of the wing.
A detailed study of the wings is of very great importance to the
specialist in Lepidoptera, and requires, as a subject, a good deal of
consideration to thoroughly understand. The most salient features
are the size and form of the scales, the arrangement of nervures, the
comparative size of the wing-cells, and the development of the wings
during the pupal stage.
The egg shows great variety in structure, and also in the manner of
deposition. In some cases the eggs are large, naked, and exposed ;
in other instances they are beautifully coated over with a substance
bearing so close a resemblance to the food-plant that it is with great
difficulty they can be found, while in other cases it is scarcely
possible to discover them at all. There is also great variation as
regards the interval of time between the deposition of the eggs and
the hatching out of the larve. Thus, some hatch out in the autumn
and feed for a short time, and then hibernate for the winter ; while
many, on the other hand, pass the winter in the egg stage, and hatch
out only slightly in advance of the development of the food for the
larve.
The larve of arboreal- feeding Lepidoptera show considerable
Q
242 FOREST ENTOMOLOGY.
diversity in apparent structure. They are generally composed of a
head and thirteen divisions or segments of the body. Those feeding
on the surface of foliage have generally well-developed legs, and
clothed with hairs, while those feeding within the tissues of the
plant are either footless or with partially-developed legs and smooth
surface.
In the pupe there is also great diversity as regards form and habit.
In some, all parts of the future perfect insect are visible, while others
are enclosed in a silky cocoon. Some bury themselves in the soil,
while others pass their pupal stage within the leaf or other portions
of the food-plant. From a structural and evolutionary point of view,
the complex changes taking place within the pupal stage of a Lepid-
opterous insect are most remarkable, and would require a long and
detailed study to thoroughly understand.
The mouth of a Lepidopterous imago presents a great change from
the mouth of the larva, inasmuch as the one is adapted solely for
sipping and the other for biting and masticating its food. As regards
special structure, the mouth of the fully developed insect is somewhat
difficult to understand, but the principal feature is a tube or proboscis
which is rolled up when the creature is at rest, and protruded when it
wishes to sip nourishment, as may be readily seen by the collector
when the moth is enjoying his prepared banquet of “sugar.” The
proboscis, and the exact mode in which it acts, present many sug-
gestive questions. Thus the length of the proboscis is adapted to
the needs of the creature, inasmuch as the essential food often lies
at the bottom of a floral vessel which could be reached in no other
way except through the medium of a long tube. On the other hand,
a short tube is often recognised on the mere surface-feeding moths,
and still further in many species the mouth is atrophied, and minute
anatomical investigation shows that the stomach is in a correlated
condition. ae
With reference to classification, it is obviously unnecessary, having
regard to the few species selected as arboreal Lepidoptera, to give too
many details of the larger-sized sub-families. Students, however, as a
general rule, may divide the order into two principal sections—viz.,
Macro-Lepidoptera and Micro-Lepidoptera. The former deals with
the larger-sized species, and the latter with the smaller or very tiny
creatures.
In the smaller-sized moths or MJicro-Lepidoptera it is essential in
LEPIDOPTERA. 243
some sections to give considerable attention to generic characters, as
in certain cases the whole genus may not only be arboreal in habits,
but as the characters are minute, microscopical examination of the
salient features is indispensable.
SMERINTHUS POPULI (Linn.) (Poplar Hawk-Moth).
This moth, as the name implies, is found on the poplar. It is not
so abundant as ever to be considered a pest, though fairly common as
an entomological specimen. ‘The larva lives on Lombardy and _ black
Italian poplars. The moth appears about midsummer.
The eggs are deposited on the upper side of the leaves. They are
Fig. 223.—Smerinthus populi (Poplar Hawk-Moth).
large and nearly globular, pale green in colour, and glued singly to
the leaves. The embryo may be seen before hatching.
The larve hatch out about the beginning of July, and the long
caudal horn projecting from the last segment is quite a conspicuous
feature. As development proceeds the horn is less conspicuous, but
stripes, spots, and markings on the lateral segments may be noticed,
and after the respective moultings the larve develop a short, stout,
yellow, caudal horn, and it is interesting to note the changed markings
in comparison with the green colour of the leaf.
The moth, fig. 223, is a large heavy insect of a stone-grey
colour, with a whitish spot on the fore wings and a _ brick-red
blotch on the hind wings. The wings are notched at the margins,
and the venation is fairly conspicuous. The body is soft and
velvety -looking. The antenne are serrated in the 6, nearly
filiform in the 2.
244 FOREST ENTOMOLOGY.
SMERINTHUS ocELLATUS, Linn. (Eyed Hawk-Moth).
The life-history and habits of this moth very much resemble the
preceding species, and the larva is said to generally feed on the
willow and apple, though I have found it feeding on the leaves of
the black Italian poplar.
The moth, fig. 224, is more beautiful than the preceding species,
and receives its specific name in consequence of having a large eye-like
spot on each of the hind wings. The fore wings present a beautiful,
Fig. 224.—Smerinthus ocellatus (Eyed Hawk-Moth).
glossy, velvety appearance, which renders the veins less conspicuous
than in S. populi. The hind wings are of a delicate rosy tint.
Trocuitium (SESIA) BEMBECIFORMIS, Hub. (Hornet
Clear-wing of the osier).
The larvee of this species are generally found in the base of stems of
the goat willow (Salix caprea). The holes which show whence the
perfect insects have escaped are often the first conspicuous indica-
tion of the damage. Such holes, however, are not always a sign
that all the moths have escaped, for if a few cuts be taken from such
stems and placed in a box, say in April or May, we may anticipate
moths emerging at the proper time for two consecutive years. The
dates on which I found them appearing in Northumberland were
July 10, 1901, and July 10-14, 1902. Fig. 225 shows a longitudinal
gallery, and cross section of several galleries.
The larva is whitish, a little over an inch in length; head brown,
tapering considerably behind ; legs dark-brown and small,
LEPIDOPTERA. 245
The pupa is of a bright chestnut colour, with the wing - cases
and antenne rather long and free from the body. In the in-
b
ey ie Sane sree!
Fig. 225.—Timber of goat willow injured by larve of Trochilium Fig. 226.—Pupal case of Trochilium
beinbeciformis. bembeciformis projecting from
a, cross section. b, longitudinal section. trunk after the escape of the moth.
terior of the wood it is encased in a strong cocoon of white silk
and gnawings of wood. After the moths hatch out, the empty
pupal cases may be found lying in
the hatching-box, or otherwise pro-
jecting from the stem, as in fig.
226.
The moth, fig. 227, has a wing
expanse of 14 to 14 inch. Wings
transparent, costal edge dark orange-
brown, and nervures dark - brown.
Head dark-brown. Abdomen dark- Pe ee iyinn ofthe alene
brown, with conspicuous yellow bars
across the abdomen. Antenne black, rather short and stout. Legs
an orange-brown.
CossUS LIGNIPERDA, Fab. (Goat Moth).
The larve of the goat moth are often very injurious to various
species of trees, as, for example, oak, elm, ash, willow, and poplar. In
Cheshire I twice hatched it from oak gate-posts. It may be termed
a south-country species, as it generally does not occur north of York-
246 FOREST ENTOMOLOGY.
shire, and it is said to be most abundant near London. Fig. 228 rep-
resents the injuries done to an oak stem or plank. I am indebted to
sind ue
Fig. 228.—Oak plank injured by larve of Goat Moth.
destroyed) to be a breeding - ground.
Mr E. G. Wheler, of Claverdon
Leys, Warwick, for this speci-
men.
Mr F. V. Theobald says :—
“The goat moth larve are
the cause of the damage, for
they are not only large but rav-
enous creatures, which tunnel
right into the heart of the hard-
est wood, and in from six to
ten years a large tree is com-
pletely killed by them, the
whole trunk becoming a honey-
combed mass. As many as two
hundred have been found in a
single tree. If once a tree is
struck by this pest, it continues
for years (usually until it is
It is quite erroneous to say
they only attack sickly trees: perfectly sound and healthy ash and
Fig. 229.—Cossus ligniperda (Goat Moth). (From ‘The Forester,’ by J. Nisbet.)
elm have been observed to be attacked and eventually killed, and
then the larve traced to the nearest tree that is unaffected. Nor are
LEPIDOPTERA. 247
solitary trees and those along wood borders only infested, for I have
found trees killed by the goat moth in the heart of dense woods.
‘“‘ Infested trees may easily be told by the holes
in the trunks, the dying limbs, the wood chips
thrown out of the holes, and the rough and
gnarled appearance of the trunks. Infested trees
are said to be easily recognised by the foul odour
they emit: this I have failed in every case to
notice, and some 150 trees that have been in-
fested, and have succumbed to the attack, have
been examined.” !
The moth, fig. 229, is a very large insect, with
pectinated antenne in both sexes. Head reddish-
brown ; fore wings ashy-grey colour, mixed with
a dash of brown, and hind wings more of a
smoky-grey. The sexes are somewhat similar,
but the female is much the larger, being some-
times 35 inches across. The moths appear in
June and July, and at once deposit their eggs
in the crevices of the bark.
The larva, fig. 230, is from 3 to 34 inches in
length, rather smooth and shining. Head small, ee ee of Goat
shining black, the body flesh-coloured, and the ester,’ hy J. Nisbet.)
legs yellow. They live for about three or four
years in the larval stage, and observers have re-
corded that it frequently has the habit of wan-
dering from its food-plant and pupating in the
soil. When it does pupate in the stems of trees,
it makes a cocoon with chips and frass.
The pupa, fig. 231, is very stout, shghtly curved
with rings of sharp spines, and rather prominent
wing-cases. The colour is a dark red-brown.
Collectors sometimes get the moth at “sugar.”
ZEUZERA HSCULI (Linn.) (Leopard Moth). SA Cne CMaree
2 . E ester,’ by J. Nisbet.)
The larva of this moth is destructive to various
species of trees—viz., poplar, horse-chestnut, ash, elm, sycamore,
birch, willow, hawthorn, and several species of fruit-trees. It may
1 The Animal Pests of Forest Trees.
248 FOREST ENTOMOLOGY.
be found feeding in the trunks, branches, or twigs. It is said to
live from two to three years in the larval stage.
The larva is about 14 to 2 inches in length, yellowish-white colour.
Head rather small, blackish-brown ; second segment has a broad dorsal
plate. Each segment of the body has black spots, so that the entire
larva has a spotted appearance.
The moth, fig. 232, is very handsome. The ground colour of the
wings is white, semi-transparent, with many large blue-black spots.
Antenne black; abdomen grey or blackish.
Fig. 232.—Zeuzera wsculi (Leopard Moth).
The expanse of wings is about 2} or 2¢ inches in the female, but
the male is rather smaller.
It appears on the wing from the end of June to the beginning of
August.
Mr A. Gallie, Ringwood, Somerley, sent me a sample of damage
done to young trees by the larvee, which bore into the stems, and then
they snap off.
Orey1a ANTIQUA, Linn. (Common Vapourer Moth).
This is a moth which may be almost termed a universal feeder, in-
asmuch as the larve may be found on almost every tree and shrub. I
have, however, not found it so numerically strong as to be considered
a serious pest, though I found it very abundant in Delamere Forest,
Cheshire, June 1895.
LEPIDOPTERA. 249
The caterpillars, fig. 233 a, are very noticeable from their peculiar
tufts and bunches of hair. It is quite parti-coloured—a mixture of
brown, grey, pink, yellow, &e. The head is black, and behind the
head two very long feathered bristles project, after the manner of
antenne ; the segments are brightened with red spots, hairy bristles
project from the segments, and four conspicuous yellow tufts spring
from the dorsal surface.
The pupa, fig. 233 b, is very stout, swollen in the middle, shining
dark-brown, hairy, and enclosed in a small cocoon within the balls of
leaves,
The male moth, fig. 233 ¢, which flies in the day, is of varying
Fig. 233.—Orgyia antiqua (Common Vapourer Moth).
a, larva; b, pupa; c, male; d, female. (Photo by A. Flatters.)
shades of brown or chestnut, and with a white half-moon-shaped spot
near the lower outer edge of the fore wing. The antennz are short
and pectinated.
The female, fig. 233 d, is almost wingless, having short abortive
wings, and of a uniform grey colour.
Dicoranura (CERURA) vinuLA, Linn. (Puss Moth).
The caterpillars of this moth are sometimes very injurious to willow
and poplar. I once found them eating hazel in Cheshire, and reared
several moths from the caterpillars. I have had them reported from
several places in the east coast of Scotland, and the reported injuries
coincide with the following account from Miss Ormerod :—
“In 1885 especially, I had notes from Mr J. Low, forester on the
250 FOREST ENTOMOLOGY.
Rothes Estate, Fife, of the caterpillars being at work in the middle
of summer on Balsam poplars, from some of which they had entirely
stripped the leaves. These trees had been planted in the previous
spring, and were from four to five feet high, and in another instance
the rapidity with which the caterpillars devoured the leaves was
specially mentioned. During the present year a very curious instance
was reported to me from Lincolnshire, in which the little trees were
so young and small that the quantity of woody material and bark
removed by the caterpillar for its cocoon had so weakened the slender
stem that the young poplar plant had broken off. In the specimen
sent me, the slender stem was completely bared of bark for some
little distance from the hard cocoon, and the young plantation was
reported to be practically destroyed.” 1
From the species above mentioned which I hatched out, I found
that the eggs were deposited about July 1. The eggs were brown,
circular, and about 2 mm. in diameter.
Buckler gives the following description, viz. :—
“The eggs are laid either singly or two or three near together,
on leaves of poplar, sallow, or willow. (I fancy poplar, any kind,
is preferred by the larve, when they have the choice.) The egg is
button-shaped, convex above, nearly flat underneath, fairly round,
with a small pit at the apex, varying from 1°6 mm. to almost 2 mm.
in wide diameter, slightly more than 1 mm. high, the shell hard,
glossy, but finely pitted all over, colour rich warm brown above, more
smoky beneath, the central pit blackish, but ringed with yellowish-
white. ‘There is a pale variety of the egg of a buff tint, the central
pit still blackish, with light ring.” 2
The larva, when full fed, is large, stout, and smooth. It may be
easily recognised by the position it assumes, of arched body and
forked tail, which, in fact, may be termed a fighting attitude. The
fourth segment is surmounted by an angular hump, head black, and
often partially withdrawn within the body. The prevailing colours
of the caterpillar are brown and yellow, the former an angular por-
tion along the back, and the latter conspicuous when viewed from
the side.
The pupa is enclosed in a very hard shell-like cocoon, which may
be found on the trunk of the food-tree, or, in fact, on any adjacent
1 Manual of Injurious Insects.
? The Larve of British Butterflies and Moths. (Ray Society.)
LEPIDOPTERA. Daya:
object. When glued on the stem, they display most excellent
examples of protective resemblance (fig. 234).
The moth, fig. 235, is a very large handsome insect, antenne pec-
tinated in both sexes, very broadly so in the
male. The female is the larger insect. It is
of a greyish colour throughout, and the body
is downy and soft in general appearance—
hence the name. Wings partially transpar-
ent, showing the venation, but more covered
near the base, where there are several
dark spots.
Py@@ra BUCEPGALA, Linn. (Buff-tip
Moth).
The larve of this moth often do consider-
able damage to various forest trees by feed-
ing on the leaves of elm, oak, and other
trees. In some cases oak-trees have been
quite defoliated, but as a rule the damage .
is easily recognised in early autumn, which Fig. 234.— Pupa of Puss Moth
consists of a defoliated bough, standing ea
out quite conspicuously from the otherwise fully foliaged trees.
The moth, fiz. 236, appears in May and June, and the eggs are laid
Fig. 235.—Dicranura vinula (Puss Moth).
in patches on the under side of the leaf. The moth may be found rest-
ing in repose during the day, with the wings folded narrowly across
aia ol FOREST
ENTOMOLOGY.
the body, and the pose so beautifully harmonises with a dead twig
that it may, in fact, be easily overlooked. There is a conspicuous
buff-coloured portion at the extremity of the wings—hence the name.
Fig. 236.—Pygera bucephal i (Buff-tip Moth).
The fore wings are of various shades of pearly grey or silvery grey,
with mottled whitish markings.
In fact, the wings may be briefly
described as sparkling with silvery powder of a frosty appearance.
Fig. 237.—Larve of Buff-tip Moth on twig
of oak.
The hind wings are whitish stone-
coloured in appearance. There is a
conspicuous raised crest on the
thorax.
The caterpillars, in their very
young stage, feed in company, but
after the first larval moult they
separate into parties of eight or ten,
but do not move far from their
birthplace—hence the damage is all
done in one place. When resting,
however, from feeding, they re-
assemble in comparatively large
groups, as seen in fig. 237. When
full-grown they are about 12
inch in length, rather soft and
limp. Head black, body downy.
The prevailing colour is a mixture
of yellow and black. In the first three segments behind the head
those two colours are blended in squares, but on the other segments
LEPIDOPTERA. 253
the darkish colour is in fairly large patches, and the yellow colour in
longitudinal lines. The yellow colour prevails to such an extent as
to brighten the whole body, and thus the caterpillar is a very pretty
creature.
As this is often a very injurious insect, it is at times essential to
adopt some remedial measures. This can best be done in the cater-
pillar stage, by shaking them down on a spread sheet, or otherwise
collecting the larve and placing them in paraffin.
The pupe may in some cases be kept in check by spreading gas
lime or hot lime round the roots of a previously infested tree.
Famiry GEOMETRINA.
The family of moths known as GxomETerS are of considerable
importance in forest entomology, inasmuch as many species may be
readily recognised on the foliage of trees by the peculiar habit of the
larve, known as “looper grubs,” This peculiar habit arises from
the method of the larva walking in the form of a “loop.” <A short
observation of the creature will give a rapid demonstration. The
larva of a “looper grub” has six well-developed true legs in the
fore part of the body, and four well-developed claspers at the abdom-
inal end of the body. When at rest the creature may be perfectly
straight, but when it wishes to exercise locomotion it brings up the
claspers against the true legs, and thus the greater portion of the body
rises upwards in the form of an arch or loop. Then the creature
adheres by the abdominal legs, and projects the whole body forward,
and again draws the claspers against the true legs, thus making the
loop and moving the length of its own body forward each time.
The moths are not quite so easily recognised, but as a general rule
they have well-developed wings (though in some cases the females
are partially wingless), and the wings are generally folded ridge-wise
when at rest.
Fiponta pryzaria, Linn. (Bordered White Moth).
This moth is very common in Northumberland during the summer
months. In the Scots pine woods they fly very abundantly amongst
the heather and rough herbage. The larva is not particularly con-
254 FOREST ENTOMOLOGY.
spicuous in the foliage to the naked eye. The caterpillars may be
beaten from the foliage in September and October.
The eggs are deposited on the needles of the Scots pine.
The caterpillars are lightish-green in colour. In the early stages
they may be compared to thread-like worms, beautifully harmonising in
colour with the foliage. - When full-grown they change in colour, but
still harmonise with the foliage. The prevailing colour is sea-green,
with a whitish longitudinal line down the back, and a yellow line
along each side of the body, running parallel with the dorsal line.
The caterpillar (fig. 238) is from 14 to 1} inch in length. They are
full fed about October. They pupate in the soil.
The pupa (fig. 239) is light dark-brown in colour, It may be noted
Fig. 238.—Larva of Bordered White Fig. 239.—Pupa of Bordered White
Moth. (From ‘Forest Protection,’ Moth. (From ‘ Forest Protection,’
by W. R. Fisher.) by W. R. Fisher.)
Fig. 240.—Fidonia piniaria (male), (From Fig. 241.—-Fidonia piniaria (female). (From
‘Forest Protection,’ by W. R. Fisher.) ‘Forest Protection,’ by W. R. Fisher.)
that in this insect the pupal period is of comparatively long duration,
nd Altum points out! that full-fed caterpillars and pupa are subject
to being attacked by several natural enemies, both fungi and insects.
The male moth (fig. 240) has very strongly pectinated antenne,
whilst those of the female are quite simple. The body is slender,
whitish-grey, and approaching to yellow at the extremity. The. pre-
vailing colour of the wings is a mixture of dark-brown and white.
The apical portion of the fore wing
a space about equal to one-half
of the wing—is a brown-black colour, and the remainder of the wing
is practically white, with brown streaks. The under wings are of a
similar colour, but the white portion is more mixed with the brown
colour, and sometimes roughly divided into white and brown spaces.
1 Forstzoologie.
LEPIDOPTERA. zg
or
or
The female (fig. 241) is, as a rule, slightly larger than the male,
being a little over an inch in expanse of wings. In colour both
sexes are very unlike, the female being of a nearly uniform orange-
brown tint above.
Both sexes fold their wings erect when in repose.
CHEIMITOBIA BRUMATA, Linn. (Winter Moth).
To the fruit-grower in many parts of England this is a dreaded pest.
It is also a most injurious forest insect, inasmuch as it feeds on several
species of hardwood trees. In nursery-rows, in early summer, young
Fig, 242.—Foliage of lime-tree eaten by larve Fig. 243.—Leaf of wych elm eaten by
of Winter Moth. larve of Winter Moth.
lime-trees—more especially those of a comparatively large size which
have just been transplanted the previous spring—are often defoliated
by the voracious larve of this species (fig. 242). The foliage of the
wych elm and sycamore, also, is often much destroyed by the larvee of
this species (figs. 243 and 244). The injuries done to the foliage
are very similar to the ravages of certain species of Tortrices, and it is
therefore very important, for purposes of verification, that the moths
should be reared from the larval stage.
The moths appear about November, hence the name of “ winter
moth,” and the males fly about in the evening. The males are winged,
but the females are furnished only with abortive wings, which are
practically useless in the service of flight (fig. 245 B).
256 FOREST ENTOMOLOGY.
The male moths (fig. 245 a) have a wing span of about 1 to 14 inch.
The fore wings are of a light brown-grey colour, and marked by sev-
eral faint transverse bands or bars. The hind wings are a pale greyish-
white colour. The antenne are simple, and the body very slender.
The abortive wings and body of the female are of an ashy-grey
colour. The fore wings are brightened by irregular white markings.
The colour harmonises very beautifully with the lichen covering the
bark of the trees, on which it may be found. The abdomen is very
large in proportion to the thorax, and thus the creature when at rest
may, as Miss Ormerod remarks, be mistaken for a spider.
I have not found the eggs on the trees, but have examined them
Fig. 244.—Foliage of sycamore eaten by larvee of Fig. 245.—Winter Moth (natural size).
Winter Moth. A, male; B, female; c, caterpillar.
(From ‘The Forester,’ by J. Nisbet.)
when deposited in confinement. At first they are a light-green colour,
and later on they change to a beautiful light-orange. Prior to hatch-
ing they are a dark-green colour, from the colour of the encased cater-
pillar, and after hatching the empty shells are glassy and transparent.
The approximate measurement would be about jth of an inch in
length, oval, blunt at both ends, and beautifully pitted over the sur-
face. The hatching-cases were placed in a cool shed, and the eggs
hatched very irregularly. The first larvee were recognised on Febru-
ary 10, 1905, and a few appeared every week until the beginning of
April, when the bulk then hatched out. At first the larve are of a
dirty-green colour, with dark heads. When full fed they are about
an inch in length, green, with a dark dorsal line, and three yellow
stripes along each side, and a dark-brown head.
LEPIDOPTERA. 257
The pupa is a light-brown colour, and slightly encased in a very
loose flimsy cocoon. In this species the pupal stage is a comparatively
long one, and some specimens do not appear till the following spring.
There is only one generation during the year.
As regards remedies, when the insect is very destructive to young
trees or special trees in a park, the method adopted by fruit-growers
may with advantage be copied. This consists in intercepting the
female moths from climbing up the trees to deposit their eggs. The
fruit-grower simply ties a band of grease-proof paper around the stem
of the tree, and then smears the paper over with tar and cart-grease or
other viscous substance, into which the female becomes embedded, and
therefore cannot extricate herself. This prevention, however, is often
overcome by the insects, inasmuch as the male frequently performs
the apparently chivalrous action of carrying the female in cop. to the
tops of the trees.
HYBERNIA DEFOLIARIA, Clerck. (Mottled Umber Moth).
The larve of this moth are often very injurious to various species
of trees, as, for example, hornbeam, white-thorn, hazel, oak, and
sycamore. The worst attack I ever saw was in Sherwood Forest,
May 26, 1896, when the larve were actually hanging by threads in
shoals from the trees.
Newman thus describes the caterpillar :1 “The head is rather large,
and not notched on the crown; the body is uniformly cylindrical, and
without humps; the head is without gloss, and brown; the body has
a broad dorsal area, of a clear brown colour: this area is bounded on
each side by a very distinct, but narrow-waved, black stripe, and is
also adorned with grey markings, which are particularly conspicuous
at the interstices of the segments where they approach the black
boundary stripe; below the boundary stripe the body is bright
yellow ; the spiracles are white, and the region surrounding each
spiracle brown ; the belly is greenish-yellow ; legs and claspers pale.
A beautiful but very abundant caterpillar.”
The moth appears in October. The female is wingless, and the
male has large wings and pectinated antennew. The fore wings are of
light-brown colour, usually with two dark-brown bands. The hind
wings are paler, and have a dark spot in the middle of the wing.
1 British Butterflies and Moths, p. 105.
R
258 FOREST ENTOMOLOGY.
TRACHEA PINIPERDA, Panz. (Pine-Beauty Moth).
This is the only species selected from the very large family of noc-
turnal moths generally known as Noctue. There are other species of
arboreal habits belonging to this group, but this will probably be
sufficient for the purpose of this work.
This species is exclusively an arboreal one. The larve feed on the
twigs of Scots pine trees, and may be beaten from them in June
and July. In colour the larva has a pale-
brown head, and the body varies from
dark-olive to rich oil-green. It has five
longitudinal white stripes. It is not often
recorded as being numerically strong, and
PS: Gata ern therefore cannot be considered as a pest.
vuty Moth).
The moth, fig. 246, appears in April,
and may be found adhering to the bark. The antenne of the male
are serrated and those of the female simple. The head is compara-
tively small. The fore wings are of a bright
reddish-brown colour mixed with orange, and
the hind wings are grey-brown.
DiIoRYCTRIA ABIETELLA, Zinck.
The larve of this species are injurious to the
cones of the spruce fir (Picea excelsa) and silver
fir (Abies pectinata), fig. 247. As the larve live
within the cones during the latter part of
summer and early autumn, the affected cones
may not at first be recognised. When very
much eaten, as represented in fig. 247, they are
of course easily noticed, but in the early stages
Big. 247.—Cone of silver of the injuries it is best to collect the cones ‘and
jiv (Abies pectinata)
partially eaten by larve ¢ ino , ¢
SP Diontotrid abiotalin lay them out singly on a clean floor or on a
paper, and then select those from which the
frass may be seen escaping. They may then be put aside in
a vessel, and wait till the perfect insect appears in the following
July.
The larva is of a dirty reddish or greenish colour, with darkish back
and slightly side-striped. Head and shield brown.
LEPIDOPTERA. 259
The moth (fig. 248) may be described as follows: Fore wings long
and narrow, glossy dark-grey, with several wavy black transverse
lines. Basal and first lines preceded by a white fascia ; first line very
distinct on costa; second
line angulated and bordered
on its outer margin with a
white line; an _ indistinct
shaded grey line between
it and the hind margin; a
pale central spot on dise of
wing. Hind wings concol-
orous. Length 22 to 25 mm.
This species belongs to the
family of Crambites, and typical moths of the same may be seen fly-
Fig. 248.—Dioryctria abietella (full size). (Drawn by
P. J. Brown.)
ing, or rather leaping on the grass fields, in a summer evening walk.
Famity TORTRICIDA.
The moths of this family are comparatively small, and some natur-
alists have proposed for systematic considerations, as regards external
anatomy, to merge it with the Tineide. This suggestion, however,
has not met with much support, and from an arboreal point of view
the two families should be considered as quite distinct. The name
Tortricide refers to the general habit the larvee of those moths possess
of rolling up leaves, or twisting and distorting shoots and buds. The
mode of rolling leaves by small larve has been much discussed, and
is probably due to definite operations of the larve, together with
assistance derived from silk threads spun by themselves. These silk
threads are rolled round the leaves, and they harden and contract
from exposure to the air. After the leaf is thus bound by the tiny
thread, the rol/ is still further perfected by the growth of the vege-
table organism accruing from the interference of the caterpillar agency
acting within the prescribed limits of the silken thread.
As a great many species of this family are arboreal feeders, a large
field for investigation is presented to the student of forest insects.
The prospective interest is still further intensified, as their life-history
is involved in considerable obscurity, more especially in the egg
stage, inasmuch as the moth often effectually conceals her eges. The
injuries are done just when growth is most active, and it is obvious,
260 FOREST ENTOMOLOGY.
therefore, that this must have a very appreciable effect on the
increment.
The imago stage is, as a rule, of short duration. Many examples
may be found on the wing from March to November, but the majority
of arboreal species are most abundant from May to July.
The general characters of the imago may be given as—head tufted
with hairy scales, often partially hiding the eyes; the compound eyes
usually large and spherical; antennz invariably simple, and never so
long as the anterior wings; thorax usually short; abdomen moder-
ately stout in both sexes, more especially in female, and often
terminated by a tuft of bristles in the male.
The larva is from $ to # inch in length, usually with sixteen feet,
head and shield horny, and the anal segment generally has a horny plate
on the dorsal surface. The duration of life and habits vary according
to the food of the species. Thus, for instance, those living on the
foliage of deciduous trees must be fully developed prior to the fall of
the leaf, or even before the leaves become too hard, while those feed-
ing under bark can live comfortably throughout the winter months.
The pupa is either enclosed in a cocoon or web spun by the larva.
The abdominal segment is often armed with minute spines. The
pupal stage, like that of the larva, is also very variable.
TORTRIX VIRIDANA, Linn. (Green Tortrix Moth).
There is perhaps no species of insect whose injuries are more
conspicuous than those of the green Tortrix, or oak-leaf roller moth.
Often as early as the end of May, or beginning of June, the larvee
are so abundant as to almost completely defoliate the trees. As this
occurs just at the time when the tree is actively growing, it is obvious
that in consequence of defoliation the loss of increment is enormous.
By way of revenge, as it were, the tree subsequently produces a crop
of late green shoots— Lammas shoots, as they are termed, —and
though to some extent amendment may be made, yet it is just
possible that there may be such a physical difference between the
spring and autumn formed cells as to cause technical depreciation
of the timber.
It is generally asserted that this species confines itself entirely to
the oak. Such, however, is not always the case, as I have often bred
it in comparatively small numbers from hazel and ash. It has been
LEPIDOPTERA. 261
asserted by several German writers that when the oak does not yield
sufficient food for the larve, they often leave the oak, and complete
their full development on other species of trees—viz., lime, ash, beech,
mountain-ash, maple, and other species of hardwoods. I have never
found it on Turkey oak.
It is also worthy of note that while generally distributed over the
Fig. 249.—Foliage of oak destroyed by larve: of the Green Tortrix Moth.
country, it is not a common species in Northumberland. One or
two woods, however, on Tyneside are often badly attacked, and in
Co. Durham it is frequently very common. Fig. 249 is a photograph
of an injured oak-shoot.
The eggs are laid the season preceding the larval attack. They
are doubtless deposited on the immediate vicinity of the buds, but
opinions differ as to the precise spot, and I have not actually dis-
covered them.
262 FOREST ENTOMOLOGY.
The larvee are a slaty colour. The head is a dark-bronze colour, a
shade darker than the body, but not so dark as the shield of the head.
On each segment may be found four minute black spots, which become
more pronounced as they get older. When full fed they measure
about +¢ of an inch in length. They curl up the leaves for shelter,
feed most voraciously, and when disturbed lower themselves by a
slender thread.
The pupa is of a uniform dark-brown colour. Pupation takes
place in the folds of the leaves, and the moths appear in swarms
about the end of June.
The moth is easily identified, as it is the only pure green Tortrix
we have. The fore wings are pure green, hind wings grey. Head,
antenne, and body yellowish-white. Wing-span about 22 to 24 mm.
This species, as has been asserted, is very injurious to the oak,
but it should be noted that it is more injurious to the pedunculate
than the sessile variety. As regards the discrimination of those two
varieties, practical men as well as botanists do not quite agree; but
it may be said that distinct types are easily determined. The par-
tiality of the insect for the pedunculate variety was pointed out to
me by my friend Mr J. F. Annand in the Chopwell Woods, Co.
Durham. In this case the pedunculate variety was entirely
defoliated, whereas the sessile variety was untouched. This
peculiarity is noted by Mr Elwes, in his magnificent work on ‘The
Forest Trees of Great Britain and Ireland,’ in the following
remarks :—
‘‘ Another peculiarity of the sessile oak is referred to in a letter
from the Hon. Gerald Lascelles to Mr Stafford Howard, in which
he says: ‘I doubt whether there is much difference between the
timber of the sessile and pedunculate oaks, but I think that the
sessile is straighter and cleaner in growth, and one thing is certain,
that it is almost immune from the attacks of the caterpillar (Tortrix
viridana) which so often destroys every leaf on the pedunculate oak
in early summer. Whether this does any real harm or not is a moot-
point, but I think it must be a check to growth, and that the trees
would be better without it. I have seen a sessile oak standing out
in brilliant foliage when every tree in the wood around was as bare
of leaf as in winter.’
“Mr J. Smith, in the paper above referred to, pp. 29, 30, confirms
Mr Lascelles’ observations, and says that in 1888, which was the
LEPIDOPTERA. 263
worst year for these caterpillars that he remembered, he passed
through a wood composed of Q. sess//fora in which, though it had
been attacked by the caterpillars, they had left off, evidently either
poisoned or starved. He also quotes a resident in the Forest of
Dean, who, writing in 1881, says: ‘It was strikingly evident last
summer that the Q. robur pedunculata, or old English oak, was
attacked by blight (? caterpillars) more severely than Q. 7. sessi/7-
flora,’ and Mr Baylis, who now has charge of Dean Forest, writes
to me on the subject as follows: ‘I can confirm the statement that
the larva of the green oak moth defoliates Q. pedunculata very much
more than Q. sessiliflora, and I think the reason is this: the latter
is the first to come into leaf, and the leaf has time to get fairly tough
before the caterpillar has reached its most destructive stage, which
is about the time that Q. pedunculata is coming into leaf. I have
frequently noticed this fact, that the oak with more decided pedun-
culate characters is almost invariably attacked rather than the
other.’ ”
As regards remedies for this species, it is most difficult to know
what to suggest, and it therefore affords a very good case in point as
showing how difficult it is to cope with a real forest pest on a large
scale,
ToORTRIX RIBEANA (Hub.)
This species is a general feeder on many kinds of trees, and fig. 250
on hazel may be taken as a typical example of its injuries. The
foliage is often entirely eaten by the larve of this species. At first
they riddle the leaves very much indeed, and take advantage during
the day of the uneaten portions of the under side of the leaf for
shelter. Finally, they often denude the trees of the entire foliage,
and pupate in the soil.
The larva and moth of this species are often very variable in
colour and markings, and as there are several species doing similar
damage, it would be well to verify the respective species by hatching
out the moths from larve making injuries on hazel after the manner
of the illustration given.
PENTHINA PRUNIANA (Hub.)
It often happens that isolated specimen thorns on lawns, and also
patches of trimmed thorn hedges, show almost complete defoliation
264 FOREST ENTOMOLOGY.
about the end of May and beginning of June. This is due to the
voracious feeding larvee of Penthina pruniana. The larve commence
feeding just as the foliage develops, so that the infested patch re-
mains naked until the larve pass into the pupal stage—about the
middle of June.
The moth may be looked for about the beginning of July lodging
amongst the foliage, and with a little patience may be easily boxed
during the daytime.
The moth has fore wings blackish for two-thirds of their length, a
Fig. 250.—Foliage of hazel injured by larve of Tortrix ribeana.
space before middle of wing white, between basal patch and central
fascia, sometimes crossing the wing, but always distinct on inner
margin ; apical third white, clouded with grey, with about four small
tooth-marks on costa; hind margin dark-grey. Expanse 18 to 20 mm.
All the species of this genus have similar markings, and are not easy
to determine ; but the short broad form of the wings will separate it
from its allies.
LEPIDOPTERA. 265
HeEpDYA OCELLANA, Fib.
This species is very common in many parts of the south of Eng-
land, and the larva is injurious to numbers of trees. Mr E. T.
Connold sent me the specimen from which fig. 251 is taken, as show-
ing typical injury to the variety of white-leaved poplar known as
Populus argentea. It will be noticed that when
the larva injures the leading shoot, as seen in
the illustration, considerable damage is done to
young woods.
BATODES ANGUSTIORANA, Haw.
It often happens that many of the extreme
twigs on the common yew are dead through-
out the early part of summer, and having the
appearance of being damaged by frost. This,
however, is the result of the larva of this species. Re Ie Teach eioLler
The larve hibernate during the winter in cocoons ane Deere oh
of hair and leaves of the yew-tree. They eat
the woody portion of the twig, and thus cause it to wither (fig. 252).
In early summer they may be beaten from the yews.
The larva is about half an inch in length, of a green or yellowish-
green colour, with black markings on the sides, and having a dorsal
line of a lightish-yellow colour.
The pupa is about 3 lines long, and of a pale-brown colour.
The moth has fore wings brown with reddish-brown markings, the
basal blotch reaching disc of wing; central fascia broadest on inner
margin, gradually narrowing to costa, and oblique by crossing the
wing. On its outer margin on the costa is a pale-yellow spot. Then
follows the ocellated blotch which extends to the anal angle ; in the
middle of it are some darker scales. Hind wings uniform dark-grey.
Description from a @ specimen. Expanse 12 to 16 mm.
PxpDIscA OcoULTANA, Dougl.
I have only found this insect once, and that was an attack on
Pinus cembra in Northumberland, on plants which had been pur-
chased preceding the attack from a public nursery in the Midlands.
266 FOREST ENTOMOLOGY.
The plants in question were from 3 to 4 feet high, and the injuries
consisted in the top shoots being arrested in their development.
Every practical man knows that conifers in general make but a very
short leading shoot the year following transplanting, and that in the
early stages of growth the whorl of lateral branches stands erect and
surrounding the leading shoot. In this particular case the injuries
inflicted by the larve resulted in not only eating the young leaves,
Fig. 252.—Shoots of English yew (Taxus
baceata) injured by larvee of Batodes Fig. 253.—Shoot of holly injured by Pedizca
angustiorana. ophthalmicana.
but in soldering the whole of this whorl together, so that in many
cases the leading shoot and lateral branches were either very much
weakened or otherwise killed outright.
PapiIscA OPHTHALMICANA, Hub.!
If the holly hedges are examined about May or June, it will be
found that the leaves of the terminal shoots are often drawn to-
gether by a small silken thread, thus forming a sort of rosette
(fig. 253). It will be found that each rosette is tenanted by a single
small caterpillar, and in many cases they are very abundant on hedges
! Tt is possible there are several closely allied species doing similar damage, so
that implicit confidence should not be placed in the name of this species from the
damage alone.
LEPIDOPTERA. 267
which are switched or clipped annually. The rosette is not con-
spicuous until the larva is nearly full fed. It is of dirty-green colour,
with black head and shield.
The pupa is about 4 lines long, of a rich brown colour, and slightly
shining.
The imago appears about the end of June or beginning of July.
The fore wings are of a dark smoky-grey colour. The hind wings are
of a light-green colour. Eyes intense brown, and with a velvety
appearance. Antenne dull brown. Abdomen shining grey colour.
Length about 6 to 7 lines.
This species cannot be regarded as very injurious, yet it does a con-
siderable amount of damage to the surface of the hedge, inasmuch as,
being often numerically strong, it appreciably affects the growth of the
shoots. As the surface is the all-important point in an ornamental
hedge, it would often be well to check this pest by simply cutting or
nipping off the tender shoots while they contain the larvee, and either
burning or throwing them into a bucket containing paraffin. This
operation, though rather tedious, would have the effect of reducing
the number of perfect insects, and therefore diminishing the attack
for the following year.
STIGMONOTA REGIANA (Zeller).
If the loose projecting bark on very old sycamore-trees be
lifted up during the winter months, small cocoons, sometimes
quite a number together, may be recognised. In each cocoon
there is a small larva, of a dirty- white colour, and about 4 or 5
lines long.
The pupa is about 34 lines long, and of a light-amber colour.
The imago, which appears in June or July, is about 6 or 7 lines in
expanse of wings, and when unfolded is certainly very pretty. The
prevailing colour of the fore wings is chocolate, whilst on each wing
there is a semicircular patch of yellow, which, when the wings are
closed, forms a beautiful circle in the middle of the folded wings.
The effect of this marking is somewhat lost when the wings are
spread out.
This species cannot on any account be considered injurious. It is
quite possible, however, that the action of the larve causes the old
bark to fall off sooner than it otherwise would do.
268 FOREST ENTOMOLOGY.
Genus RETINIA.
The genus Retinéa is found amongst fir-trees, and in certain localities
some species are quite dreaded enemies. In fact, it is possible that
a consulting entomologist may receive more specimens of Retinia
buoliana than almost any other insect for identification. This species,
being fairly well distributed, may be studied as a type form of the
genus. It is very easily hatched out artificially, more especially as it
is generally full fed before it asserts itself.
Lepidopterists recognise seven or eight British species, but the
following is a synopsis of the important species :—
(a) In buds of Scots pine, with brownish-grey fore wings
R. turionana.
(>) In leading shoots of Scots pine, with yellowish-red fore wings
and silvery cross lines. : ‘ R. buoliana.
(c) Forming a gall of resin as a fee al chamber. Fore wings dark
brown-green, with grey dusty covering ; R. resinella.
(d) Making a “running” side destruction of leading shoot of larch
or Scots pine. Fore wings brown, with dark-buff tip
R. duplana.
Retinta TURIONANA, Hb. (Pine-bud Tortrix Moth).
This species has only once come under my observation as a pest—
viz., in Delamere Forest, Cheshire. The infested pines were from
ten to twelve years of age, and the injuries were in the leading bud,
as shown in fig. 254.
The moths hatched out early in June. They were from 16 to
18 mm. in expanse of wings. The fore wings were of brownish-grey
colour, with transverse lines. The hind wings were whitish. Head
and thorax ferruginous, and abdomen grey.
The larve are a yellowish-red colour, and rather less than half an
inch in length.
RETINIA BUOLIANA, Schiff (Pine-shoot Tortrix Moth).
The habits of the larva are very much like those of &. turionana,
except that in buoliana the leading bud or whorl of buds are
not arrested in their early development, and therefore all begin to
LEPIDOPTERA. 269
grow at the same time ; but the centre one soon droops and finally
dies, in consequence of the centre of the shoot being entirely destroyed
Fig. 254.—‘‘ Leading ” bud of Scots pine Fig. 255.—‘‘ Leading shoot” of young Scots pine
injured by larva of Retinia turionana. injured by larva of Retinia buoliana.
by the larva. Fig. 255 represents a photograph taken from a two-
year Scots pine plant in the nursery-line. The affected shoot, which
contains a single larva, is lying to the
right, and the normal shoots are very
vigorous, but they are not shown in
full length. In addition to injuries
being done in nursery-lines, we often
find young Scots pines and Austrian
pines from six to ten years of age
very much destroyed by this species.
As a rule the injured shoots die,
but a few exceptional cases are
found on young trees with dis-
torted or deformed leading shoots,
accruing from the damage done by
this insect.
The moth (fig. 256) is from 18 to 22 mm. wing span. The fore
wings are of yellowish-red colour; the red is brightened by silvery
Fig. 256.—Retinia buoliana.
a, male; b, female.
270 FOREST ENTOMOLOGY.
cross-lines, which are very variable in pattern. The hind wings are of
a uniform dark-grey, being fringed with light pale-grey cilia. Head
and thorax a pale-yellow colour; antennze brownish; eyes black ;
abdomen dark-grey.
The larva is from 6 to 7 lines long, dark-brown in colour. Head
and thorax black ; legs small and black, very sluggish.
The pupa is about 5 lines long. The head, thorax, and wing-cases
are a dark-brown colour, and the abdomen a light-chestnut colour.
As regards the life-history, the moths appear about the end of July,
and deposit their eggs at the tip end of the shoots. The larve hatch
out late in summer, and gnaw the side of a bud, so as to cause a flow
of resin, which covers the caterpillar over for the winter, and here
they hibernate. In spring they wake up, attack the leading bud, giv-
ing rise to the injuries already referred to, and feed till about the
latter end of June or beginning of July. They pupate within the
infested shoots, and the pupal stage lasts from ten to fourteen days.
With regard to remedies, very
little can be done except pick the
injured shoots, together with the
incased larva or pupa, about the
middle of June, and then destroy
the same. This would have the
effect of diminishing the attack for
the following year. The moths
may be found lodging in the young
shoots, and if collected shortly after
hatching out, egg-laying might be
checked.
RETINIA RESINELLA, L,
This insect is said to be confined
to certain localities in the north
Fig. 257.—Gall of resin on Scots pine of Scotland, and the only time I
caused by Retinia resinella.
have ever seen it in numbers was in
Belgium in 1905. There is no mistaking it when seen, as it is simply
a large gall of solid resin on the shoots of Scots pine at a spot repre-
senting what practical men would term the commencement of the
growth the year before last (fig. 257). This spot at once suggests an
LEPIDOPTERA. PAT bah
important factor in the life-history of the insect—viz., that the gall
takes two years to reach maturity. The generation is therefore a bien-
nial one. The eggs are laid in May, just under the whorl of buds,
which are bursting, or about to burst, into the growing shoots. The
caterpillar bores into the pith, and this being the most active period in
the life of the plant, causes the growth of a hollow gall resinous mass,
about the size of a pea, and in this abode the larva passes the winter,
In the following spring the larva
continues feeding, but meanwhile
the gall rapidly increases in size to
that of an average gooseberry. A
section of a gall shows that it is
divided into two chambers by a strong
vertical partition: in one the larva
lives and pupates, and the other
contains its excrement. The pupal
period is very short, and the moth
flies about May—the generation thus
Fig. 258.—Retinia resinella.
extending over two years.
It generally attacks trees from six to ten years of age, but, as a
rule, the injury to the forest, or even to individual trees, is very
trifling.
The moth (fig. 258) has a wing expanse of 16 to 18 mm. Head,
antennee, thorax, and abdomen dark brown-green, or lightish grey
dusty covering. Fore wings dark black-brown, with shining grey
transverse lines; hind wings grey-brown ; fringes pale.
The larva is about 11 mm. long, and of an orange-brown colour.
Famity TINEA.
Genus HyYPONOMEUTA.
In many parts of the country, more especially in lanes, we
often find bushes defoliated and covered with a sort of net, in
the interior of which are a large number of small larve of
the genus called Hyponomeuta. They are popularly known as
the small “ermine moths,” but they are comparatively large for
‘* micros.”
Die FOREST ENTOMOLOGY.
HyYpPoNoMEUTA EVONYMELLUS (L.)
The genus contains a number of species. The one generally
found in the north of England is H. evonymellus. It is found on
bird-cherry and spindle-tree, and the conspicuous feature of the
damage is the defoliation of the
bushes, together with the gauze-
like spun webs, which protect the
eregarious larve.
The moth (fig. 259) measures
about # inch from the tip of the
wings. The upper surface of the
Fig. 259.—Hyponomeuta evonymellus. wings is a lustrous white colour,
and shows five rows of black
spots (over forty in all). The hind wings are dark-grey. The
head and antenne are white, eyes black, and abdomen grey.
The caterpillar is about # inch in length, and of a yellowish-grey
colour. The head is black,
and there are black spots on
the segments.
After the caterpillars are full
fed they congregate within the
web, and pupate in a mass,
for the mass of pupal remains
may be found even in the
following year, reminding one
of the empty cases of the
wasp or honey-bee. (Fig.
260.)
As regards the life-history
of this species, I have only
made observations in North-
umberland. The moths ap-
pear about the first week in
Fig. 260.—Webb and empty pupal cases of Hypono- Sc ne
i meuta evonymellus. July. They deposit their eges
in clusters on the twigs, just
immediately below a bud, and they are most beautifully concealed by
a delicate covering, the colour of which harmonises with the tiny
stem so well that it is only after a most careful search they can be
LEPIDOPTERA. 273
found at all. So far I have not been able to ascertain the approxi-
mate date at which the larvee emerge from the eggs and betake them-
selves to the opening buds, but they do not assert themselves on the
foliage until well on the middle of May. [By this time the leaves are
well developed, and thus afford plenty of food for the larvae, which
live gregariously, and spin a veil-like web over the colony. They are
full fed by the middle of June, and the pupal stage completes their
life-history.
As this species is in many cases very injurious, and as its host-plant,
the bird-cherry or hackberry, has some claims as an ornamental tree,
on account of its beautiful white flowers, it would be well in very bad
cases to adopt some remedial measures. It is obvious that we could
only apply remedial measures in its larval and pupal stages.
As regards checking the larvie, they may be (1) shaken down from
the trees during the day on to a sheet, or (2) hand-picked by cutting
off the web containing the larve, or (3) they may be sprayed with a
paraftin emulsion. With regard to the last method, the following
note is taken from the Board of Agriculture leaflet, No. 65 :—
“The Board know of one case in Perthshire where, in an extremely
severe infestation, the proprietor, dissatisfied with the result of a
paraffin spray, made up a strong solution of an arsenical sheep-dip, and
by this means killed thousands of caterpillars. The caterpillars that
had not been killed, or which on disturbance had let themselves down
from the web by their threads, collected at the foot of the trees, and
were easily destroyed. Great care, however, had to be exercised, as
any leaves touched by the material turned black and dropped off.”
With regard to checking the pest in the pupal stage, this can best
be done by simply cutting off the webs when they are in the cocoon
stage ; but as this stage is a comparatively short one (about ten days
or a fortnight), no time would have to be lost in order to make it
effectual.
PRAYS CURTISELLUS, Don. (Ash-bud Moth).
This species seems to entirely confine itself to one food-plant—viz.,
the common ash (Fraxinus excelsior), and is certainly very injurious
indeed to plants in the nursery-lines from three to six years of age.
It attacks the terminal bud, and thus causes the young ash to fork,—
a feature we do not by any means wish to see in young ash plants.
S
Th pa FOREST ENTOMOLOGY.
Kaltenbach says! that he ‘never found the larve in free-standing or
healthy ash, but more abundantly on young over-shadowed or thick-
standing small trees.” The result of the larval damage first asserts
itself in the terminal bud, which does not develop along with the
lateral ones (fig. 261), and as time goes on the leading bud dies, and
we have a forked young tree, as in fig. 262. As soon as the leaves
begin to grow the larva leaves the bud and bores itself into the leaf-
stalk, and in consequence the leaf-stalk, together with the leaves,
wither and die off. One larva goes from stalk to stalk, and thus kills
several of them. After the larva is full fed it spins itself into a
Fig. 261.—Leading bud of young ash-tree Fig. 262.— Young ash-tree ‘‘ forked”
injured by larva of Prays curtisellus. by larva of Prays curtisellus.
silken cocoon, pupates, and appears in the imago form about July 1.
Specimens sent from Chatsworth, Derbyshire, and those in Northum-
berland, hatch out simultaneously.
The moth is a pretty whitish-grey insect. Head white and hairy ;
eyes black ; thorax white ; abdomen brown-grey. Fore wings when
closed showing a white line in centre, and brown at sides, a kind of
magpie colour. Fore wings when spread, whitish with brownish
patches. Hind wings brown-grey with light fringe. Wing span 14
to 17 mm.
Larva with black head, and neck shield ; body of a dirty ashy-grey
colour, streaked with reddish-green, tapering at both ‘ends, and the
1 Die Pflanzenfeinde aus der Klasse der Insekten.
LEPIDOPTERA. 275
belly dark-green. Length 12 mm. Viewed with a lens, the colour
very much resembles a healthy young ash stem.
Pupa dark-brown in fore part, and latter part of a very light
greyish-yellow, enclosed in silken threads.
As regards the life-history of this species, I find there is a great
difference between the account given by Judeich and Nitsche, as seen
from fig. 263, and what I have found in Northumberland, inasmuch
as the species is double-brooded in Germany, and only a single gener-
igvle
My,
“eemun minetorepee wlices meer“ « x
Ae =
i.e sai eee
Fig. 263.—Prays curtisellus.
a, moth ; 6, bud injured in autumn by young larva; c, the young larva has left the bud in
spring and spun a protection for itself; d and e, the young shoots destroyed by spring
larve; f, g, and h, leaves eaten by summer Jarvee—i.e., larvee of second brood. Copied
from Judeich and Nitsche.
ation in a year in the north of England. It is, however, possible that
the species may be double-brooded in the south of England, and it
will be well, therefore, for students in forest entomology to verify
this. Hence the illustration from Nitsche may be very helpful. In
the accompanying illustration it will be seen that the spring brood
destroys the leading shoots and the leaf-stalks, as seen in d and e.
The larve of the second brood eat the leaves, as seen in f, g, and h,
and then deposit eggs in the leading buds.
With regard to remedies, it is scarcely possible to do anything
except collect the larva when they are feeding in the leaf-stalks.
DIG FOREST ENTOMOLOGY.
This could easily be done in the nursery-lines, and also in a young
plantation, though it would obviously be more practical in the
nursery. Pruning by checking the worst of the double shoots should
be done during the summer following an attack, as an ash is a tree
which is very much depreciated in value if allowed to become forked.
In glens or valleys where ash has been planted in a very con-
genial position, much good may be done by cutting down the young
damaged trees to the ground and allowing them to spring up again,
which in sheltered spots they do very rapidly.
Genus DEPRESSARIA.
The genus Depressaria is the largest of the sub-family Gelechiide,
numbering just over forty species. They are remarkably character-
istic from the broad flat appearance of the moths in repose. Wings
two and a half times as long as broad, tip rounded, hind margin
nearly parallel to anal angle ; hind wings nearly as long as fore wings,
with the hind margin indented
near anal angle ; palpi long, ascend-
ing, curved, aud often furnished
in middle with dense tufts of
scales.
DEPRESSARIA CONTERMINELLA,
Zeller.
Fore wing reddish - ochreous ;
base of wing pale yellow, rather
sharply defined. A pale ochreous
Fig. 264.—Leaves of osier (Salix viminalis) spot on dise, and near it an
drawn together by larva of Depressaria oblique, crescent-shaped, black
streak. A series of short black
marks along the costa; hind margin before cilia narrowly bordered
with a black line. Head and often thorax pale ochreous ; hind wings
uniform dark-grey. Length 18 to 20 mm.
If osier-beds are examined during the latter end of May, it will
be found that many of the leading shoots present the appearance
shown in fig. 264. If the whorl of leaves be unfolded, it will be
found that a small wriggling larva has been protecting itself within
LEPIDOPTERA. Dit
the folded leaves and injuring the leading bud and shoot. This is
the larva of Depressaria conterminella.
It should be noted that several species of Lepidopterous larve
do similar damage, so that the injury represented in fig. 264 should
not be taken as solely due to the species given. The species in
question, however, was most injurious in Cheshire to osier rods
(Salix viminalis). I am obliged to Mr J.
Collins, Oxford, for the identification of
this species.
DEPRESSARIA ASSIMILELLA, Tr.
Jf an inspection of broom be made from
March to the beginning of May, it will be
found that the twigs are often very much
drawn together, as in fig. 265. If the
twigs are separated at the points where
they overlap, it will be found that a small
brown larva lives within the folds, and has
injured them very considerably. ‘This is
the larva of Depressaria assimilella.
The moth appears in June and July.
The fore wings are of a pale ochreous colour,
and about 9 lines in expanse. The antenne
are dark-brown.
It cannot be said that this species is of
any great economic importance, but it
often happens that broom is grown for
ornament or covert purposes, and in such
cases the insect may be considered a | | |.
pest. In order to effect remedial meas- Tegner lem of Depron
P assimilella.
ures it would be well to top the broom
while the creature is in the larval stage, and burn the prunings.
When broom is cultivated it is well to prune off the tops in any
case, either in early autumn Jefore the frosts appear, and thus
prevent the winter winds from blowing the bushes about, or after
the spring frosts and prior to the vigorous growth of early summer.
Thus the adoption of practical work is a remedial measure against
the pest.
&
278 FOREST ENTOMOLOGY.
Genus ARGYRESTHIA.
Stainton! gives the following characters for this genus —viz,
“Imago, head rough; the face smooth; no maxillary palpi; labial
palpi rather short, the terminal joint blunt or slightly pointed ; fore
wings elongate ; hind wings lanceolate, with long fringes.
“The insects of the genus Argyresthia are distinguished by their
position in repose, as the hind pair of legs are laid alongside the body,
which is elevated at a considerable angle, the insect’s head being
almost in contact with the sub-
stance on which it rests.”
ARGYRESTHIA LEVIGATELLA
(H. Sch.)
In all probability this is a
forest insect which has escaped
attention for a considerable time.
The first record of it in this coun-
try is given by Dr Somerville and
Mr John Bennett so recently as
July 1907.2. The insect was not
difficult to determine, from its
: o damage to the larch, as a very
Fe, ane Top young lartras tured ty good figure is given by Niiselin
and though not hitherto recorded
in this country, it is just possible that it may have been overlooked,
owing to the close resemblance of the damage accruing from the pine-
weevil (Hylobius abietis). At all events, I now find the creature
fairly common in Northumberland, and that I mistook the injuries
as suggested. The larval action is that the leading shoot is killed, as
shown in fig. 266.
Dr R. S. MacDougall gives the following description of the insect :>—
*“* Moth.—The moth is very small, measuring only 4 to 5 millimetres
(less than one-fifth of an inch) in length and 10 to 12 millimetres in
spread of wings. The fore wings are silver-grey and silky, with a
1 Manual of Butterflies and Moths.
2 Quarterly Journal of Forestry, vol. i., No. 3.
® Journal of the Board of Agriculture, vol. xiv., No. 7.
LEPIDOPTERA. 279
gloss like lead; the fore edges are somewhat darker ; the fringes of
these fore wings are grey or brownish-grey.
“The hind wings are dark-grey, and not so glossy. The face is
white ; the base of the antenne is white, and the rest of the antenne
dark and light-ringed. There is a tuft of hairs on the head ; the
colour of the hairs is given differently by different Continental author-
ities, —in my own specimens the colour is yellow. The abdomen of
the moth is dark-grey.
“ Caterpillar.—The larva is pale yellow when young, but later is
pale grey with a dash of red, and is dark striped towards the hind
end of the back. The head and the three front pairs of legs are black.
The length, 6 to 7 millimetres.
“ Pupa.—The pupa is dark-brown, with a black head ; its hind end
is distinctly pointed.”
As regards the /ife-history of this insect, the moth appears in the
latter end of May or beginning of June. The eggs are deposited in
the lower part of the shoot of the current year. The egg soon hatches,
and the tiny caterpillar bores below the epidermis. Meanwhile the
shoot develops, but when winter overtakes the larva it hibernates in
the hollow made by itself. In early spring it awakes, and commences
eating where it left off, with the result that the shoot is very much
weakened, and thus the injury not only arrests development but finally
kills the twig, as shown in fig. 266, which was photographed in the
latter end of June 1907.
The caterpillar is full fed about the end of April, so that the pupal
stage is comparatively short.
As regards remedies for this pest, it is perhaps well to remember
that the creature has only been recently recognised in this country,
and therefore the full extent of the damage is not thoroughly under-
stood. If the damage be done to twigs on trees from ten to twenty
years of age, little could be effected ; but if (as I have from preliminary
observation discovered) on young trees the second year after planting,
something might be done. One rarely sees larch plants in the nursery-
lines affected. The inference, therefore, is that weakly shoots are
selected, as dead twigs are obviously a necessity for the final trans-
formation of the creature. Hence the greater vigour accruing from
careful planting would to some extent act as a check. When, how-
ever, the young shoots are attacked, the dead or dying twigs in the
recently planted wood should be recognised as early as possible in
280 FOREST ENTOMOLOGY.
April, and then, together with the larva or pupa in the shoot, cut off
and burned. This method is apparently tedious, and when the lead-
ing shoot is removed considerable disfigurement ensues, but as a tree
the larch has wonderful recuperative powers of taking a lead from a
side branch, so that the labour would be well repaid.
GRACILLARIA SYRINGELLA, Fab.
This species is often very injurious to the foliage of lilac (Syringa
vulgaris). The larve live gregariously within the epidermal skins of
the leaves, and cause very conspicuous blotches, as seen in fig. 267.
Mr Collinge has worked out the life-
history of this species, and the following
account is given by him :!—
“The observations and experiments were
made on nine trees about five feet in height
and growing five or six feet apart. °
“The moths of the first brood were noted
on May 24, rather later than in 1904. The
eggs were noticed on both the upper and
under surfaces of the leaves a few days
later, 27th and 28th, and the caterpillars
hatched out on June 4. They at once made
their way into the leaves, and commenced
to feed upon the soft parenchymatous
tissue between the upper and lower epi-
dermis. The largest number found in any
one leaf was thirteen.
“‘Sometimes the whole of one side of the leaf was tunnelled; in
other cases the basal half was blistered before the apical ; whilst in
others the blisters were irregular and scattered over the leaf.
“The young larve are almost transparent and glossy; a little later
they have a faint yellowish tinge, with a narrow median green line,
caused by the green chlorophyll in the intestine. After feeding in the
leaf for about three weeks, they creep out on to the surface and
commence to feed on the epidermis, the leaves rolling up laterally or
from the apex. About ten days later they become full fed, and are
slightly over a quarter of an inch in length, with a prominent brown
Fig. 267.—Leaf of lilac (Syringa
vulgaris) injured by the min-
ing larve of Gracillaria syrin-
gella.
1 Report on the Injurious Insects and other Animals (Midland Counties), 1906.
LEPIDOPTERA. 281
head. Here they remain for about ten days, then leaving the rolled
leaves and pupating in the axils of the leaves or branches, or even
leaving the trees and crawling to fences, &c. After fourteen or six-
teen days the moths of the second brood make their appearance, and
the life-cycle is again repeated, the pupal condition continuing through
the winter.
“ Preventive and Remedial Measures.—Picking off the leaves had
but very little effect. Spraying with paraffin emulsion in May proved
beneficial. There were very few blistered leaves on the two sprayed
trees, whilst the remaining seven showed little else but blistered ones.
“Spraying with soda and potash in January killed or injured many
of the pupe, but as these trees were near a fence, many of the larvae
had left the trees, and were pupating in crevices and cracks in the
fence.”
Genus COLEOPHORA.
Hitherto this genus has not received such special attention from
economic entomologists as to assure us that the habits given by
naturalists are over-reliable. At all events, it is a genus that would
well repay special attention.
The perfect insects appear from the end of May to the beginning of
August. The larve hatch out in autumn, and in the early stage
many species feed as leaf-miners, and after mining the leaves the
individual larva forms a small case, within which it passes the winter
in the larval stage. In the spring they recommence feeding by suck-
ing the juices of the leaves, and each larva makes a larger case for
itself in which it lives and pupates. The larva never moves out of
its case, and never exposes its body beyond the anterior (or true)
legs, which are used in walking,
In the perfect insect the head is smooth, and the antenne are
always erected in repose. The antenne are slender, the basal portion
smaller and covered with scales. The anterior wings are smooth,
narrow, elongated, and pointed with long ciliz. The posterior wings
are very narrow, and fringed with long ciliz.
CoLEOPHORA LARICELLA, Hub.
The larve of this species are very injurious to the foliage of larch
in spring,—so much so, that on account of the invisibility of the
282 FOREST ENTOMOLOGY.
insect, and the conspicuousness of the damage, the injury is often
attributed to frost. The general appearance, however, very much
resembles the action of frost or singeing by fire, imasmuch as the
leaves are half withered up, and practical foresters have therefore
often associated this appearance with the commencement of “larch
disease.” It is, however, possible that this insect may play a very
important, though indirect, part in connection with the larch disease
ce
Sie
wad
as
; : i
= fee we
“ bes
ee
1
Si)
R.
=
teen bee
mS
/s 3
4 Ss ‘
Ns a 4
\ Mi ei:
Fig. 268.—Normal foliage of Fig. 269.—Foliage of larch injured by larve
larch. of Coleophora laricella.
fungus (Peziza Willkommii). The fungus is most active in spring
months, and as the injuries caused by C. laricella on the foliage,
together with the obvious effect of checking the rate of growth, have a
tendency to reduce the plant below par, it follows that the fungus is
materially assisted in its action, and can therefore do greater damage.
Fig. 268 represents the normal foliage, and fig. 269 the injured shoots.
The small caterpillars which do this damage hatch out in July, and
feed on the leaves of young trees from six to thirty years of age, but
as a rule they are most destructive to trees of the latter age. At first
LEPIDOPTERA. 283
the very tiny larve bore into the leaves or suck the juices. The
damage is done from apex to base, for about half the length of the
leaf. The injured portion shrivels up, is light in colour, and therefore
very conspicuous. Meanwhile the larve, when resting, bury them-
selves in the middle of the cluster of leaves, but they soon change their
mode of protection, as each individual larva forms a case for itself out
of the injured leaves. At first the case is very lightly coloured, but
it becomes darker with age. The interior is lined with silk. When
the caterpillar is feeding, the case stands erect, with the head of the
larva downwards. The larve go on feeding in this way throughout
the season, so long as nourishment remains in the leaves, and then
hibernate for the winter. Many of them go into cracks and crevices
of the bark, or bury themselves
amongst the lichens. A consid-
erable portion of them lay them-
selves quite flat on the twigs,
and butt against the natural
ridges of the young twigs. The
light-coloured cases harmonise 7) A
well with the light-coloured ;
bark. In this way they pass A
Carcurot =
the winter, being perfectly 1m- Fig. 270.—Coleophora laricella. (From F. V. Theo-
a 6 a ets Nores ’
mune to the effects of frost. bald’s ‘ Animal Pests of Forest Trees.’)
A, pupal case; B, moth.
As soon as the young larch
needles burst forth in spring the larvee wake up, carry their cases
back to the needles, and commence feeding in real earnest, thus giv-
ing rise to the characteristic withering already referred to. The
larvee now grow very rapidly, and the original cases become too small.
The tiny caterpillar then makes a fresh case.
The larve are a dark red-brown colour, and still darker head. Only
the anterior pair of legs are at all moderately developed, and, with
the exception of one anal pair of pro-legs, with which they fix them-
selves in the case, the pro-legs are also but poorly developed. There
is a black plate on the anal segment. The larva is about 5 mm. long.
The pupa is small and brownish-black.
When the wings of the perfect insect are expanded they measure
about 4 or 5 lines across. The head and anterior wings are grey, the
posterior wings of a paler grey, and the abdomen of a blackish grey.
(Fig. 270.)
284 FOREST ENTOMOLOGY.
COLEOPHORA FUSCEDINELLA, Zell.
This species is, as a rule, very common on alder, and is termed the
alder-bud moth, in consequence of the larve feeding on the buds and
destroying them prior to forming its case, and then on the leaves.
COLEOPHORA Sp.
Some years ago I received from my friend, Mr Elder Cholmondeley,
Cheshire, a quantity of birch twigs which had been utterly destroyed
by a species of Coleophora. So far this species has not been defin-
itely identified. Fig. 271 is a representation of the damage, and the
fi ae * x
Fig. 271.—Coleophora sp. on birch.
normal leaf at the bottom was added for the purpose of identification.
The larvae were very injurious, as the twigs were stripped of their
entire foliage. After the larvee had made their final cases, they de-
stroyed the foliage by boring a hole into the leaf from the upper side
and entirely eating the contents of the leaf, which lie within the two
epidermal skins. Taking the hole as a centre, the larva eats all round
the same, thus making a circular patch, but, as a rule, always keeping
itself attached to the case by means of its anal hooks, and on the
slightest approach of danger drawing itself within its case. Some-
times it goes on feeding within the epidermal skins away from its
camp, but, as a rule, it moves to a fresh spot, after eating the circular
patch referred to, and then going on a fresh spot, until finally the
whole of the green portion of the leaf is destroyed.
The imagines are considerably larger than the species on larch.
bo
CO
Or
LEPIDOPTERA.
LITHOCOLLETIS.
This genus is very common on the leaves of several forest trees.
The larva mines the leaves of trees and shrubs, sometimes simply
creating a flat blotch on the under side of the leaf, at other times mak-
ing the blotch in such a manner that a pucker is produced either on
the upper or under side of the leaf. The larva never quits the mine.
Some species make no cocoons ; others, cocoons of various kinds.
The perfect insects are very small in size. They have a rough head
and smooth face. The antennz are rather
long, but not so long as the anterior wings.
The larve have only fourteen legs and one
pair of ventral pro-legs.
The pupa is either naked or enclosed in a
cocoon, and in the former the wing-cases are
quite free.
As regards artificial hatching, many species
can be picked up in autumn, as the blotches
appear quite conspicuous on the fallen leaves.
They may be collected and placed on the
ground in a canvas bag for the winter months.
In early spring they may be removed from the
bags and placed in glass cases. The imagines
appear In May.
LITHOCOLLETIS MESSANIELLA, Zeller.
The larvee of this species are very injurious
to the foliage of the evergreen oak (Quercus
ilex). In the evergreen oak we find several
distinct varieties of the tree, and it may be said,
eae ra 1 . Fig. 272.—Typical blotch of
though the injuries of this species of moth are —_Lithocolletis on species of
evergreen oak.
practically identical so far as the physiology
of the damage is concerned, yet the general appearance of the damage
itself is somewhat different. In the case of the holm oak proper, the
leathery leaves are blotched “brown” and withered-looking. In the
case of the other variety, the injuries are not so conspicuous on the
upper surface, and on the under surface we get a delicate white patch,
and prior to the eruption of the skin it looks as if a very fine piece of
tissue-paper had been pasted on the under side of the leaf (fig. 272).
286 FOREST ENTOMOLOGY.
The first time I found this species in abundance was on a holm oak
(fig. 273) close to Checker House Station, when walking with the Man-
chester Microscopical Society to Sherwood Forest, and after finding
the respective stages of the insect I made the following note :—
“May 9, 1896.—Leaves considerably damaged ; effect of damage
shown on both sides of leaves, but most conspicuous on under side.
Larva mines between under epidermis and thick fleshy part of leaf.
The parenchymatous part of leaf not eaten, therefore upper surface
appears brown and leathery, but not showing ‘thin’ as under side.
Fig. 273.—Injuries to foliage of holm oak (Quercus ilex) by larvee of Lithocolletis messaniella.
“ Larva.—Full fed are rare to find at present,—now principally
pupe. Length 4mm. When young flattish, and round when full-
grown. Colour of first four segments white, with darkish head ;
remainder of segments saffron colour. The six thoracic legs short,
and first pair longest. Pseudo-legs not very conspicuous.
* Pupa.—5 mm. long ; dark-brown colour. Passes pupal stage in
leaf. Very active, wriggling about at posterior end. Antenne nearly
full length of chrysalis. The projection beyond attachment, and
active anal end shows irregular ‘forked’ end. Side view shows pupa
has pointed horn and bent awl-shaped.
LEPIDOPTERA. 287
“ Imago.—Length about 4 mm. to 4°55 mm. Fore wings saffron
colour, folded ridgewise. Under wings fringed.” !
This is rather a difficult species to check. However, one suggestion
may be made. As regards the holm oak, every gardener dislikes it as
a lawn tree, in consequence of its shedding its old leaves, about the
end of April or beginning of May, just when every place is tidy and
spring work very abundant: hence the hatred to the tree. It would
be well, therefore, to burn all the leaves as soon as they fall off, or, if
desired, the trees may be shaken to bring them off. Provided the fall
is in April, many moths would be destroyed, but it is obvious that if
not done till May the moths would have hatched out, and the burning
operations consequently useless.
There are several other species of Lithocolletis found on forest
trees, but none of them can be considered as injurious, though they
are, of course, interesting from a collector’s point of view.
L. salicicolella causes blotches on the under side of the leaves of
sallow bushes. The injured leaves may be looked for in September
and October. ‘The insect may also be found in May, so that there
are two broods in a year.
L. coryii is found on the leaves of hazel bushes. The blotch starts
from the midrib, and the tip portion of the blotch is a sort of
pucker, so that it is seen from the upper side. Imagines in May
and August.
L. carpinicolella is found on the leaves of hornbeam.
L. faginella is found on beech.
CEMIOSTOMA LABURNELLA, Heyd.
This species is responsible for the blotches caused on the upper
surface of the leaves of the laburnum (fig. 274). This species is
very common in many parts of England, so much so that it is scarcely
possible to examine a laburnum-tree without finding its leaves heavily
blotched with a dirty green-whitish appearance. This is caused by
the larve mining the leaves. It is not so abundant in Scotland,
more especially as we proceed northwards, as it is in England.
Again, it may be mentioned that it is far more common on the
English variety of laburnum (Cytisus Laburnum) as compared with
the Scotch variety (Cytisws alpinum). The latter variety has very
1 Trans. Manchester Microscopical Society, 1896.
288 FOREST ENTOMOLOGY.
much larger leaves, and a brighter green bark, in younger stages,
than the former.
If we examine the sheltered side of a laburnum-tree, or any
adjacent palings, about the latter end of April or the beginning of
May, we are sure to see a brilliant, little, white moth, with a few
yellowish markings towards the apices of the wings. This is the
imago of C. laburnella. It measures about 3} lines across the
expanded wings. The head and face are white, and the antenne
fuscous. The anterior wings are white, with yellow spots or bars
across. The posterior wings are also white, with long cilix. The
thorax is white, and the abdomen pale-grey. The legs are also white.
When carefully examined under the microscope, this tiny moth is a
Fig. 274.—Foliage of laburnum injured by larve of Cemiostoma laburnella.
very beautiful object,—so much so, that it seems to vie with the
rich colours and brilliant markings of tropical insects.
The larva is about 3 lines in length, of a pale greenish-white colour,
with sometimes a bright-green dorsal line,—due, of course, to the
food taken from the green colouring under the leaf.
The pupa is encased in a white cocoon, pointed at both ends.
The life-history may be thus briefly described : The moths appear
during the latter end of April or beginning of May, and deposit their
eggs on the under surface of the leaf, generally near the midrib.
There are two broods in the year. In the first the larve are full fed
about the early part of July. Then they leave their feeding-ground
on the upper surface of the leaves and pupate on the back of the
LEPIDOPTERA. 289
leaves, more especially on the younger leaves, which have been form-
ing throughout the summer season. The pupe are long whitish
objects, pointed at both ends, and encased within a very beautiful
white cocoon. About the beginning of August, or after about ten
days to a fortnight in the pupal stage, the moths appear. This brood
deposits eggs in the same way as the moths of the second brood
which appeared in spring. The larve feed as before, on the newly
formed leaves. They are full fed about the middle or latter end of
October, when the caterpillars let themselves down by a slender
silken rope to the ground, where they pupate, and appear as perfect
insects about the latter end of April or beginning of May. About
the latter‘end of October the tiny larve may be seen on a sunny day
dangling from the laburnum bush, They may be collected and put
in a small box, as this species hatches very well in confinement.
References to Literature consulted.
Carpenter, G. H. Various papers on the Injurious Insects of Ireland.
Collinge, W. E. Reports on the Injurious Insects observed in the Midland
Counties.
Kaltenbach, J. H. Die Pflanzenfeinde aus der Klasse der Insekten.
Kollar, V. A Treatise on Insects injurious to Gardeners, Foresters, and
Farmers.
Meyrick, Ed. A Handbook of British Lepidoptera.
Newman, Ed. Natural History of British Butterflies and Moths.
Ormerod, E. O. Manual of Injurious Insects. 2nd edition.
Stainton, H. T. A Manual of British Butterflies and Moths.
Theobald, F, V. Various papers on Economic Entomology.
Wilkinson, 8. J. The British Tortrices.
290
CHAPTER VIII.
APHIDID A! (GREEN-FLY).
THRovuGHOUT the whole country no class of insects is more universally
distributed or more deserving of the appellation ‘injurious ” than the
Aphidide or ‘‘Green-fly.”. The term blight is adopted for the de-
struction accruing from this class of insects, which are individually
small in size but collectively most injurious. They are to be found
on almost every plant, and are soft-bodied insects, with comparatively
long legs which are but poorly adapted for leaping. They are always
found in two principal forms—viz., winged and wingless; and the
largest are never more than a quarter of an inch in expanse of wings.
The body of the aphis is pear-shaped. The head, which is small
in comparison with the rest of the body, has two compound eyes, and
in the perfect stage ocelli or supplementary eyes are often present,—
a feature which is well worth special consideration from a physiolog-
ical point of view. During the larval stage the eyes are very con-
spicuous. In fact, they are often quite obvious in the embryo stage,
before the larve quit the eggs. They vary in colour from ruby red
to brown or even black.
The beak, which is always an important organ in insect structure,
is peculiarly adapted to the destructive demands of the creature, and
just shows that all insect anatomy is a modification of similar parts
to meet the needs of the creature. The beak proper is composed of
three joints, which vary in length according to genus and species.
Thus in the Stomaphis, a species living on oak, the beak is longer
than the body, while in the genus Chermes it is very small indeed,
the mouth being adapted to the food-plant. The former lives on oak
deeply furrowed; the body reposes on the outer hard bark, while
the long proboscis is a necessity to reach the bottom of the narrow
fissure, where the juice can only be found. On the other hand, the
APHIDID®. 291
short-beaked Chermes lives on smooth bark, on which the slightest
tap would yield the necessary juice.
The antenne are from three- to seven-jointed, and form good points
for classification. They are very variable in length according to
genera, and are also variable in the larve as compared with perfect
insects of the same species. Hence it is essential in the discrimin-
ation of genera to know that we are dealing with adults.
The wings are thin, and of a beautiful transparent iridescent colour,
folded ridge-wise over the body, but possessing poor powers of flight.
In the wing of a typical aphis (fig. 275) the cubitus or post-costal
nervure gradually expands into a semi-coriaceous stigma, whence
proceed the veins of the wing. Fig. 275 is a camera-lucida sketch of
the wing of Aphis sambuci, and may be considered as a very good
example of a typical wing.
The following is an explanation of the characters :—
. Costal cell.
a. Cubitus or post-costal nervure. 1
b. Posterior marginal. 2. Basal cell.
ec. Costal nervure. 3. First discoidal.
d. Cubital nervure. 4. Second discoidal.
e. First furcal. 5. Infra-marginal.
f. Second fureal. 6. Marginal.
g. Second oblique. 7. Second cubital.
h. First oblique. 8. First cubital.
z. Insertions. 9. Stigma.
k. Apical marginal.
Z. Stigmatic.
p- Hooklet.
The above is adapted from Buckton’s Monograph, but in that work
the wings of Siphonophora are used as a typical case.
The third vein, counting from the body of the insect, is twice
forked in the tribes of Aphidine and Lachnine (fig. 275); once forked
in the tribe Schizoneurine (fig. 276); and not forked in the tribe
Pemphigine (fig. 277), and also in Chermesine (fig. 278). In the
lower wing of the typical aphis the post-costal vein gives off two
oblique veins only. The wings are carried vertically when at rest,
with the costal vein downwards. In the foregoing sketches we have
typical wings represented, and the student would do well to study
the wing venation of the family, more especially as it is not infrequent
to find different venation on each side in some forms.
292 FOREST ENTOMOLOGY.
The abdomen is composed of several rings, and is capable of much
distension, this being dependent on the amount of food taken. The
Fig. 275.—Wing of Aphis sambuci, with third vein twice forked.
number of rings or somites is variable. On the sixth segment many
genera have two important tubes or appendages, called cornicles,
es ee
Fig. 276.—Wing of Schizoneura ulmi, with third vein once forked.
t=} ‘J
which serve for the exudation of a liquid substance known as “honey
dew”; others have none.
Fig. 277.—Wing of Pemphigus pallidus, Fig. 278.—Wing of Chermes abietis,
with third vein straight. with third vein straight.
The honey-dew itself is a substance which has given rise to a good
deal of interesting thought and speculation. It is of a saccharine
nature, and is consequently sought after by other insects, more
APHIDIDA, 293
especially ants, which not only sip the juices but extract the honey-
dew from the aphis by squeezing it from the cornicles. I have often
observed ants doing this on the aphides on elder.
The honey-dew is very injurious to vegetation, for not only does it
have a tendency to choke up the stomata or breathing-pores of the
leaves, but the injury is still furthur increased by the honey-dew
forming a lodgment for soot, dust, and dirt.
The tail, though not an important appendage in the discrimination
of genera or species, must not be forgotten in generic distinction, inas-
much as it is long in some, and short or entirely absent in others.
The life-history of an aphis presents many interesting points, either
considered biologically or as evidenced by the mysterious appearance
and disappearance of the so-called “blight” or “ green-fly.”
The aphis generally appears in numbers simultaneously with the
ereen foliage. The first brood of the season originates either from a
female which has hibernated during the winter months, or from eggs
—that is, generally true eggs, resulting from male fertilisation. In
the former case, the ‘“‘stem-mother” (Stamm-mutter), as the Germans
call her, very much resembles the queen wasp, inasmuch as she is the
mother or founder of a whole summer’s colony. As a rule, she is
considerably larger and less active than any of her offspring.
The eggs of Aphidide may sometimes be seen in autumn as small
white specks on the stem, though generally they are green-brown or
bottle-green. They become dark in winter, and, of course, are not so
conspicuous as in the autumn months.
The brood arising from eggs which had been deposited in autumn,
or from the ‘“stem-mother” in spring, give rise to insects which are
generally all females. These may be found in two forms — viz.,
winged and apterous. In many genera, when but a few days old,
both forms are capable of giving birth to living young. Each in-
dividual insect produces from 90 to 100 progeny, and so on until
about twenty generations are produced in a single season. Hence it
will be seen by a progressive calculation that the numerical strength
of the progeny produced by a single insect certainly becomes ap-
palling, and the number just given is under rather than over the
average.
In order to realise the numerical strength of aphis reproduction,
Professor Huxley made some remarkable calculations, and has there-
fore put them in his own inimitable way. He calculated that if an
294 FOREST ENTOMOLOGY.
aphis weighs zoo Of a grain avoirdupois, and a stout man not more
than two million grains,—about twenty stones,—then the tenth brood
formed (exclusive of all the preceding broods, supposing that the
multiplication had been altogether unchecked by the various causes
which generally influence it) will exceed in weight five hundred
million men, or about one-third the entire population of the globe.
This calculation is made on the assumption that each individual
member could turn the scales at 280 lb., and also that each aphis is
capable of producing only twenty young, whereas, according to
Latreille, the average rate of production of a viviparous aphis during
the summer months is twenty-five per day,—but this is greatly in
excess, as far as this country goes.
Fortunately for vegetation, the aphis has several natural enemies
to keep the enormous reproduction within bounds. Heavy rains act
as a check, but, entomologically considered, the small Chalcidide,
Hymenopterous parasites which pass their metamorphic stages in the
interior of the aphidian bodies, are of inestimable value in keeping
them down. Throughout the summer months the dead bodies of the
Aphididz may be found adhering to the food-plant. These bodies are
mere chitinous shells, with a small hole whence the tiny Hymenop-
terous. parasites have emerged. Ladybirds, horse-flies, Chrysops, and
birds are natural enemies.
At the end of the season the last brood for the year is generally
composed of males and females. In certain species males have not
been discovered for a few years. But investigation seems to show
that sooner or later males will appear — verifying what Andrew
Knight said in 1799 regarding self-fertilisation, viz., that it is a “law
of nature that organic beings shall not fertilise themselves in per-
petuity.” Subsequent research has borne out this statement in other
animals. It is well known to every entomologist, collector, or econ-
omist that the number of insects depends very considerably on the
conditions of the weather and the supply of food. The Aphidide are
certainly more susceptible to those external influences than any other
class of insects. Should the weather suddenly become colder, a
great number of winged specimens will appear, as they do also in the
event of the food-supply becoming scarce.
It is neither by chance nor latent ability that apparently apterous
individuals suddenly become winged, but apterous specimens give
birth to young which develop wings. Hence the change from wing-
APHIDIDA., 295
less to winged specimens is the result of the short period necessary
for the ushering in of a fully developed fresh brood, which will adapt
themselves to natural changing conditions. In other words, the
newly born brood will move to new quarters either in search of food
or warmth. And here comes in a very common but erroneous notion
—viz., that the sudden appearance of “blight” is due to “east
winds.” Now the fact is that the proverbial east wind has simply
assisted the winged aphis, which, after all, is but poorly adapted for
locomotion, to move from his native land to ‘‘ fresh fields and pastures
new.”
Winged forms are known at an early age as apterous larvee, the
“pupal” stage being that period when the wings are half-grown.
Some species pass through these metamorphic stages before their life
cycle is complete. Thus apterous larvee, semi-winged pups, and
winged imagines may be constantly found throughout the summer
season on the food-plant.
In many species both apterous and winged females produce living
young, but, according to Buckton and other observers, the pups never
give birth to young. There are two classes of females apart from
apterous and winged ones—viz., oviparous and viviparous, the first
reproducing themselves by eggs, the second by living young. It is
asserted by many practical workers that the oviparous never becomes
viviparous, or vice versa, the same individual aphis never producing
eggs and living young.
The difference between the deposition of eggs and the production of
living young on the part of the respective female insects would appear
to be simply a question of time and stage of reproduction, but it affords
a subject for actual investigation by dissection and serial section-cutting,
in order to ascertain the morphological difference between oviparous
and viviparous organs.
To the student of forest entomology it is not only essential to make
a detailed study of the life-history of the various species as found
on trees, but it is indispensable to study the species found on almost
every plant, inasmuch as we get migratory species and dual or
multiferous food-plants of certain species. Thus, for example, we get
the hop aphis, the larch and spruce aphis, mealy plum aphis, together
with root and trunk forms constantly changing from food-plant to
food-plant. It is therefore obvious that this is a good case in point,
showing that it is most essential for the economic entomologist to
296 FOREST ENTOMOLOGY.
become, as far as possible, well acquainted with the structural details
of the systematic student.
As regards terms for the family or sub-families, Buckton says—
“The Aphides have the following synonyms:
Aphides, Linneeus.
Aphide, Curtis, Westwood.
Aphidina, Burmeister, Walker, Hartig.
Aphidine, Rondani.
Aphidide, Passerini.
It is therefore rather difficult to know what precise term to adopt for
the family or sub-family.”
The family APHIDIDA may be divided into six tribes—viz.,
Aphidine, Lachnine, Schizoneurine, Pemphigine, Chermesine,
and Rhizobine.
The following are the principal tribes and genera which are arboreal
in their habits :-—
Tribe Aphidine.—Upper wings with cubital vein twice forked ;
lower wing with two oblique veins. Antenne long, with seven
joints: 7th joint long, 3rd usually longest.
The following are the principal genera belonging to this tribe
which are arboreal in their habits—
Myzus. APHIS.
DREPANOSIPHUM. CHAITOPHORUS.
MELANOXANTHUS. CALLIPTERUS.
Tribe Lachnine (woolly).—Wings same as in Aphidine. Antenne
six joints, 7th rudimentary. Genera—
PTEROCALLIS. STOMAPHIS.
PHYLLAPHIS. Dryosius.!
LAcHNUS.
Tribe Schizoneurine.— Upper wing, cubital vein once forked;
lower wing with two oblique veins. Antenne six joints, 7th rudi-
mentary ; 3rd ringed, 4th often ringed. Genus—
SCHIZONEURA.
Tribe Pemphigine (gall-forming).—Upper wing, cubital vein not
forked ; lower wing with one or two oblique veins. Antenne short,
six joints; 7th rudimentary. Genera—
PEMPHIGUS. TETRANEURA.
1 The above is adapted from Buckton, as it is rather difficult to reconcile his
classification ; see vol. i. p. 94 and vol. iii. p. 11.
APHIDID®. 297
Tribe Chermesine (/ermes, a red dye).—The genera of this tribe are
varied in their habits, inasmuch as they are coccus-like, bark-feeders,
gall-makers, or wool-spinners, and sometimes subterranean. Genera—
CHERMES. PHYLLOXERA.
Tribe Rhizobine.—The genera of this tribe are root-feeders, and
hitherto have not been much investigated in the forest. There is a
species very common on the dead leaves of Scots pine which may be
found throughout the whole of the year, but hitherto I have not dis-
covered any name for it.
In giving an account of the more common and destructive genera and
species of arboreal Aphidide, it may be suggested to the student that
much valuable information on the habits and structure of these insects
might be gained by studying many species of the genus S¢phonophora,
which are found on many varieties of plants. Thus, for example, Siphon-
ophora rose is abundant on roses ; S. bi on raspberry ; S. avellanee on
hazel ; and various other species of this genus are found on our com-
mon plants.
Trine APHIDINZA.
Genus Myzus.
The chief generic characters are antenne about equal to the length
of the body. Cornicles long, tail prominent. Wing venation much
the same as in a typical
aphis.
Myzvs cerast (Fab.)
This species is very com-
mon on wild cherry or gean
of the forest, as well as on
the cherry of gardens and
orchards. The damage done
by the insect is very easily
recognised. The injured
shoots form a sort of rough
rosette of leaves (fig. 279) Fig. 279.—Terminal shoot of wild cherry injured by
5 z Myzus cerasi.
and the absorbing action of
the insects, coupled with the exudation of honey-dew, add a sort of
sooty appearance to the damaged shoot.
298 FOREST ENTOMOLOGY,
The apterous viviparous female is wholly black in general appear-
ance. Antenne not conspicuously long. The abdomen is of a
very shiny black colour. The cornicles are rather long. The eyes
are a darkish-brown colour.
The winged viviparous female is wholly and conspicuously black,
with rather long antennze and broad wings.
It is somewhat difficult to prescribe a remedy for this species. It has
been suggested to cut off the infested shoots or rosettes and destroy
the same, but as the leading shoot is the portion generally attacked,
this would obviously destroy the young tree, so that it would be better
to adopt some spraying measure, or otherwise shake the aphides into
a vessel containing paraffin.
Genus DREPANOSIPHUM.
Rostrum short; antenne very long, third joint longest ; seventh
joint very delicate ; cornicles large; tail inconspicuous. Wings long
and narrow ; cubital vein twice forked.
DREPANOSIPHUM PLATANOIDES (Schr.)
This is a common aphis which lives on sycamore, and may be
found simultaneously with the appearance of the foliage. It simply
injures the plant by sucking the juices, and does not cause any mal-
formations.
The eggs of this species may be found very plentifully on the bark
of sycamore during the winter months. They are black in colour,
and, when abundant, their glossy appearance on lichen and Protococcus
viridis renders them conspicuous to the naked eye at some distance.
The larve are found on the young leaves just as the latter are
bursting. When hatching they are of a bright-green colour, with
very long antenne and conspicuously red eyes. In general appear-
ance the body is so slender that the creature may be said to be all
‘legs and arms.”
The pupal form, or stage between larva and winged insect, is very
variable both in colour and general appearance.
The winged insects are also variable in colour, but the prevailing
hue is bright green. The head is rather flat, the eyes are very
prominent, and being of a golden-green colour, contrast very strongly
APHIDID®. 299
with the head and body. ‘The antennz are black, long, and slender,
and consequently liable to injury. There are two vertical black
markings and five or six transverse bars on the abdomen, as well
as similar markings on the under side. The legs are variable in
colour. The tail is short and not very conspicuous. The cornicles
are comparatively long.
This is altogether a handsome-looking aphis, and is suggestive of a
lobster. It may be shaken in showers from the leaves. This species,
however, is so very variable in colour that Buckton gives several
varieties in both larval and perfect forms.
About the middle of April, just before the winged insects appear,
large apterous specimens, very much larger than the general larvae,
and of a mahogany colour, may be found. Contrasting with the
larvee just referred to, it may be observed that in proportion to the
size of the body, the antenne, cornicles, and tail are all comparatively
short. The abdomen is large, warty, and bristly. At first sight
this insect may be taken for a “stem-mother” or for some other
species, but if kept in confinement for a few days it will be found
to be a bloated parasitised form, whence parasites are hatched.
It has been asserted by several observers that the larve of this
species always assume wings, and that consequently the wingless
specimens never give birth to young. In other words, only the fully
developed female, which in this case is the winged specimen, gives
birth to young. I have not fully verified this, but so far as my
observations go, I am inclined to endorse this view.
The apterous oviparous female may be found in the autumn on the
under side of the leaves, just before they fall. It is easily recognised
by its darkish colour and elongated abdomen prolonged into a tail.
The eyes are bright red.
This insect rather lends itself to a study of ovarian characters.
Genus MELANOXANTHUS.
As this genus was founded by Buckton, it is best to give his own
description :—
“ Body elliptical, rather flat, vertex flat between the antenne.
“Antenne short. The third joint double the length of the fourth.
The seventh equal to the sixth. Frontal tubercles inconspicuous.
“ Nectaries short and pear-shaped, with trumpet-like mouths.
300 FOREST ENTOMOLOGY.
Prothorax marked by two lateral teeth. Abdomen oval. Legs strong
and short.
“Tail inconspicuous or none. Wings moderately long. Stigmatic
veins with their apices reflected.”
In this genus it would be well for the student to carefully
study the generic characters, inasmuch as the genus may be con-
founded with Lachnus.
MELANOXANTHUS SALICIS (Linn. )
This insect may be found very abundantly on the two-year-old
shoots of the common osier (Salix viminalis). They are gregarious
in their habits, and may be found clustering on the rods they select.
The attacked rods may
be afterwards known by
the deposition of a white
mealy substance on the
infected portion of the
stem. They are very
common in Cheshire
about the latter end of
June.
The apterous female
Fig. 280.—Melanoxanthus salicis. (From Buckton’s : alan : t
“Monograph of British Aphides.’ Ray Society.) iS a very iarge insect.
The body is of an oval
shape, and of a sooty greyish-black colour. Along the dorsal
surface there is a faint median line of rudely diamond-shaped
spots of a greyish-heliotrope colour, and also similar spots on the
abdomen. The two largest spots are situated near the middle of the
body. The basal half of the antenne is of a terra-cotta colour, and
the apical portion is blackish or dark brown. In proportion to the
size of the body, the antenne are comparatively short, the third joint
being the longest. The legs are slightly pubescent, and similarly
coloured to the antennz. The cornicles are small and of a bright-
orange colour. ‘The rostrum is fairly long, but appreciably longest in
the young stage. The tail is not very long or conspicuous.
The pupa is somewhat similar to the above, except that the thorax
is a more slaty colour.
The winged viviparous insect (fig. 280) is very large, but not so
a
APHIDID®. 301
plump or oval as the apterous specimens, and the spots are not so
pronounced.
On the whole, this is a very pretty aphis, the spots giving the
entire body a very bright-looking appearance.
Mr Theobald in correspondence says—
“The curious staining of the wood where they have been is
interesting. I have found them in masses over a foot long in Hunts
and Kent.”
Genus Apuis, Linn.
The genus Aphis, according to Buckton, contains 45 species, and
it is a very important genus. In the first place, the name Aphis
to a novice in entomological knowledge is very apt to be confounded
with the whole family of Aphidide, and may therefore in a general
sense be used to refer to every individual species. As there are 45
species in the genus, with food-plants ranging from the small weed to
the tall trees, it is obvious that some care must be taken in tabulation.
As regards the main points in the genus, Buckton gives the
following—viz. :
“Rostrum moderately long, the last joint skittle-shaped, and as
long as the preceding. Antenne shorter than the body. Frontal
tubercles none or rudimentary. Seventh joint setaceous, and as long
as the third. Cornicles cylindrical, and equally thick throughout.
Cauda short, sometimes hardly visible. Legs moderately long. Wings
generally shorter than the preceding genera, but veining similar.”
APHIS CRATHGI (Kalt.)
In several districts in Cheshire during the season 1893-94 very
much damage was done to young thorn hedges and young quicks by
the Aphis crategi, young thorns in many cases being killed outright.
There is no mistaking this pest. In consequence of growth being
arrested, the shoots are comparatively short, the leaves curl up, and
in general appearance the infested plants look as if the leaves and
young shoots are covered and killed with fresh soot (fig. 281).
If infested plants are examined during the winter months, the top-
most portions will be found studded with dark-brown eggs. These
eggs hatch out as soon as the leaves burst, and throughout the summer
the insect pest in all its various stages may be found.
302 FOREST ENTOMOLOGY.
It is very variable in colour and appearance. Hence Buckton re-
marks that “it is exceedingly difficult to reconcile the descriptions
of various insects named Aphis cratagi by authors.”
The apterous viviparous
female is a_ bright -green-
coloured insect with brown
eyes. The antenne are
shorter than the body. The
third and seventh joints are
the longest. The cornicles
are comparatively long, cylin-
drical, and equally thick
throughout. The tail is
short but conspicuous.
The pupa in many respects
resembles the apterous speci-
mens, but on the whole is
very much smaller in size.
As I have not made any
Fig. 281.—Eggs of Aphis crategi on thorn in s LS eeae
2 Aoi Se descriptive notes on the
winged form (fig. 282) when
examining the living insect, and mounted specimens lose all colour,
ITappend Buckton’s description :—
“Head, neck, ring, thorax, and its lobes black, head broad and
convex, abdomen shining bright-
green, with the same marked carin-
ation and minute pore marks of
the larve. Cornicles Iong and
straight, colour olive-green, an-
tennee and legs ochreous, pale, and
hairy. Rostrum reaches to the
second coxa. Tail conspicuous
2 wea 2] n, ”
Fig. 282.—Aphis crategi. (From Buckton’s and geek Eyes bright red.
‘Monograph of British Aphides.’ Ray With regard to vemedies for
Society.) . ) : k ‘
this pest, we must either kill the
insect in the stages of its metamorphoses or destroy the eggs. The
insect form may be considerably checked by syringing the foliage
with a mixed solution of soft soap and quassia chips. On the other
hand, the eggs may be got rid of, so far as young hedges are concerned,
APHIDID&. 303
by simply “cutting down” the young thorns and burning the prun-
ings. In transplanting such thorns previously cut down, care must
be taken to lift plants with the best possible roots, and encourage as
much as possible by attention and good management. This plan I
have adopted with considerable success. However, under ordinary
circumstances, it is certainly not advisable to cut down quicks the
same year as they are planted, inasmuch as the shoots produced are
not so strong as from those grown for a season prior to cutting off.
When the young thorns are cut off the same season, or, perhaps,
rather the same day, as they are planted, they are exposed to con-
siderable,risks. In the first place, the shoots are weak, and not able
to withstand insect attack, as for example the aphis on the shoots
during the summer, and also prior to the commencement of growth
by the clay-coloured weevil (Otiorrhynchus sulcatus). The shoots,
being comparatively weak, are more apt to be destroyed by rabbits
or choked by weeds. Hence it is better to cut off the second year,
wherever this method coincides with good local husbandry.
If young thorns in nursery-lines are very badly attacked with this
species, and if such attacked quicks are not strong enough to go out,
or otherwise not convenient to put out,
it would also be well to cut them down
in the nursery-lines, burn the tops, and
dig in manure between the rows, so that
a strong bushy thorn may be produced
by another year.
ApuHis PapI (Reaum.)
This insect is very common on the
young shoots of Prunus padus (bird-
cherry). Fig. 283 shows the injuries,
or rather the gregarious habits, of this
species ; but later on in the year, say
about the middle of July, nearly every terminal twig of the bird-
cherry bush has been killed. It is therefore evident that severe in-
juries accrue from this species, as the development of the bush has to
depend upon growth being produced in the latter end of the season.
The apterous viviparous female is of a yellowish-green colour, some-
what variegated with oval stripes, and more or less stained with a
Fig. 283.—Aphis padi on bird-cherry.
304 FOREST ENTOMOLOGY.
coloured mealy powder. yes black; antenne, legs, and cornicles
yellow, the last being rather dilated at the base.
The pupa is of a greenish or black colour. The prothorax is
partially green, varying to light olive, and the abdominal portion is of
a shining black colour, Eyes and cornicles black ; antennz and legs
olive-green.
In the winged viviparous female the whole body is of a shining
black colour, and brightened here and there with lightish spots.
Antenne, eyes, and legs lightish-brown. Wings rather large, with
somewhat conspicuous dark stigma.
APHIS EUONYMUS (Fabr.)
This insect causes the shoots of Ewonymus europeeus to form a sort
of rosette, very much after the manner of the shoots on wild cherry,
The insects cluster under the rolled leaves, and both apterous and
winged forms are either a very dark-brown colour or otherwise wholly
black.
APHIS HEDER# (Kalt.)
This insect is often found very plentifully on ivy, and clusters of
them may be discovered during the winter months where the position
is rather warm. It is dark-brown or blackish colour, and it is said
that the species found on holly is precisely the same insect.
APHIS ABIETINA (Walker).
This insect is often found very plentifully on spruce from May
onwards throughout the summer. The apterous form is a bright-
green colour. The abdomen is somewhat elongated, and the cornicles
rather long. The eyes are red. The winged form is rather small,
and also of a light-green colour. The colour of this insect is some-
what variable, but it is easily recognised from being associated with
the spruce, and by the seven-jointed antenne and the forking of
the wings.
During the winter months the apterous females of this species,
which give rise to the summer’s brood, may be found amongst the
leaves of spruce-trees.
APHIDID. 305
APHIS VIBURNI (Schr.)
This is another species causing the tip shoots to form into a rough
rosette of leaves on Viburnum opulus, and the shining blackish insects
may be found underneath the leaves.
APHIS SAMBUCI (Linn.)
This insect is very plentiful on the young shoots of elder. They
are very gregarious, and often cluster two or three deep, and thus
form a covering from three to six inches in length on the shoots.
There are many species of the genus Aphis on forest trees and
shrubs, but they may be all recognised as belonging to this genus
from their structure, and in nearly all cases the specific name coincides
with the name of the host-plant.
Hence the specific name of the
insect may be almost anticipated ;
but this species is a migrant,
and does not live all the year on
elder. Fig. 284 is an illustration
of the winged female.
Genus CHAITOPHORUS.
As this Seis NEA be con- Fig. 284.—Aphis sambuci. (From Buckton’s
founded with) Drepanostpl um, dhe. ooosaDa Oks British °phides: shay
Society.)
is well to give full characters of
the same, according to Buckton. Rostrum fairly long; head with
tufted bristles ; antennze much as in Aphis, and short compared with
Drepanosiphum, very hairy ; abdomen studded over with tubercles,
each of which is surmounted with a tuft of bristles; cornicles
very short, and in mounted specimens projected at right angles
to the abdomen. Legs comparatively short and hairy. Wings
veined as in Aphis.
CHAITOPHORUS ACERIS (Linn.)
Anaphis is found on the sycamore which may be readily con-
founded with Drepanosiphum platanotdes previously described. This
U
306 FOREST ENTOMOLOGY.
is Chaitophorus aceris or “hairy aphis.” It is common in many
districts, but I first discovered it in Sherwood Forest on May 25,
1896. }
The general difference is that this species is more hairy, and is
altogether smaller. The antenne, legs, wings, and cornicles are all
respectively shorter. The abdomen is studded over with tubercles, and
each tubercle is surmounted by a tuft of bristles. The legs are com-
paratively short, and the wings are veined as in Aphis.
There is a unique interest attached to this species on account of
its special dimorphic forms. Its peculiar and interesting life-history
may be briefly told. During the winter months the apterous oviparous
female, which is the foundress of next year’s broods of insects, may
be found in the crevices of the bark, together with the dark shining
egos she had deposited in the crevices of the bark. From those eggs,
which hatch in spring, we get the apterous viviparous females, which
are comparatively small, of a greenish colour, and produce light-
yellowish or darkish larve. The latter are rather variable in detailed
colour.
The pupe are smaller than the apterous viviparous females, and
have rather lightish-coloured legs and dark-coloured wing-cases.
Arising from this brood there are two varieties of winged viviparous
females. The first variety to be considered is one with black head
and thorax and greenish abdomen, which is ornamented with a few
cross-bars. The cornicles are small and black, and the whole insect
more or less hairy. The second variety is rather larger than the first,
with comparatively larger wings, and the creature is more pilose than
the former variety.
It is, however, with regard to the young produced by those two
varieties of female insects that the chief interest is attached. The
first variety produces normal insects, which in turn give birth to other
insects, and so on throughout the summer season. The second variety
produces a class of insects so distinct, and differing so much from all
other Aphidide, that it has not only received several synonyms, but a
suggestion has been made to relegate this variety to a separate family,
between Coccide and Aphidide. I found several specimens on the
common sycamore in Sherwood Forest, and tried to induce them to
live in Cheshire, but without success. They are born in the early part of
summer, and live until autumn, never moving from their early habitat
or respective leaves, and, with the exception of moulting, undergoing
APHIDID®. 307
no metamorphoses. In addition to these characteristics, the creature
develops. a strange morphological structure, inasmuch as_ peculiar
flabellae are attached to its dorsal surface.
In short, it is a peculiar form of neuter
gender, and contemporary with ten or
twenty parthenogenetic generations (fig.
285).
I have found it common in Northumber-
land, on the under side of the leaves of the
purple varieties of sycamore, and also on
Acer coléhicum rubrum. As the green colour
of this creature contrasts with the species of
those plants referred to, it may be fairly io 955. cChaitophorus aceris
: : : Bs (special peculiar form). (From
easily recognised, though it must be remem Buckton’s ‘Monograph _ of
bered they are only mere pin-points in actual mae) Aphides. Ray
size, and often difficult to find.
Mr Theobald informs me that it is common in Cambridge, Devon,
and Kent.
Genus CALLIPTERUS.
This genus is rather important in forest entomology, inasmuch as
the species are all arboreal in their habits. Hence it may be well to
state the generic characters as given by Buckton—viz. :
* Rostrum stout, short, does not reach to the second coxe.
* Antenne very long, often tipped with black; third joint much
the longest. Seventh joint variable in length, but rarely less than
the sixth.
“ Head large, vertex flat, frontal tubercles none.
**Cornicles very short.
‘Legs moderately long ; longest in the males.
“Wings generally ample, iridescent, usually clouded with pigment
at the extremities of the veins. Stigmata long. Stigmatic cells
trapezoidal.
‘Abdomen : in some species the apterous females are hirsute. The
last abdominal ring is provided with two anal valves or papille.”
In habits of life, however, they are quite distinct from other genera
belonging the tribe, as those hitherto considered are all gregarious,
while the Calliptera, especially in the winged stages, are more or less
solitary. When they approach anything like gregarious habits, it
5308 FOREST ENTOMOLOGY.
will generally be found that they are the progeny of a single parent,
congregated, as it were, together before leaving “home.”
CALLIPTERUS BETULARIUS (Kalt.)
This species is very abundant on birch-trees, more especially birch
coppice, during the summer months, and great numbers of it may be
beaten from the foliage. The winged specimens are rather sluggish
in their motions, and do not take willingly to flight.
The apterous viviparous female is linear in form ; the body is almost
entirely green, with slight yellowish colouring in the anterior parts.
The head is shghtly covered with hairs; eyes red; antenne are very
slender.
The winged viviparous female is of a light pea-green colour, and
more smooth on the body than the apterous specimens ; antenne very
long and slender, and of a slightly brown colour. The third joint is
very long. The middle portion of the thorax is yellow-orange spotted
with brown. The front portion of the thorax is of a lght-yellow
colour ; eyes beautiful light chocolate; legs uniformly light green,
except the tarsus, which is dark brown. Wings moderately long
and clear; stigmatic portion yellow ; veins dark brown, and slightly
clouded at the tips.
CALLIPTERUS QUERCUS (Kalt.)
This species is found fairly common under oak leaves. The apter-
ous oviparous female is a light-yellow colour. Antenne shorter than
the body. Eyes brown. The winged viviparous female is of a pale-
green colour, leaning towards yellow. The antenne comparatively
long, and the joints marked with a blackish colour,—a character
which is well maintained in mounted specimens.
The young of this insect are at first very small and light-coloured,
with conspicuously darkish or reddish eyes. These characters can be
very well ascertained with the aid of a pocket-lens against the leaf
as a background.
The more common species which may be looked for are the fol-
lowing — viz,: Callipterus coryli, Goetze, on hazel; Callipterus
carpint, on hornbeam; and Callipterus castanee, Buckton, on sweet
chestnut.
APHIDID 2. 309
Trine LACHNINA.
We now approach the second tribe of the family, known as
Lachnine. The venation is the same as in the preceding tribe, but
the antenne are six-jointed. This character as revealed by the
microscope is important to the systematist. To the economic ento-
mologist, however, there is no general character as revealed by the
injuries in the forest which can suggest a marked line of classifica-
tion. The term Lachnus means “woolly,” and this character is well
pronounced in the genus Phyllaphis, which is often very abundant
on beech; but unfortunately many members of the genus Lachnus
have xo wool.
Genus PTEROCALLIS.
The characters of this genus may be described as rostrum short and
stout ; antenne shorter than in Callipterus, the difference in length
being specially conspicuous in the apterous form ; six-jointed, but the
sixth joint has a break in the middle, which might on indistinct
examination be mistaken for a seventh joint. Cornicles small and
stout. Wines shorter and narrower than in Callipterus, and most
beautifully clouded ; hence the term Pterocallis is derived from the
Greek, and means beautiful wing.
Buckton describes three species as belonging to this genus, all of
which are arboreal in their habits—namely, Pterocallis alni, on alder ;
P. juglandicola, on the walnut-tree (Juglans regia); and P. tilia,
on various species of lime, which, however, is so abundant on the
ordinary lime-tree (Tilia ewropea) that it may be taken as typical of
the genus.
PrEROCALLIS TILIA (Linn.)
The apterous viviparous female is of a uniformly lightish-yellow
colour, with most beautiful light-red eyes. The antenne, more
especially in the young stage, are light and dark, the basal portion
of each joint being light in colour, and the apical portion of the same
joint being very dark. The contrasting colours therefore make the
antenne rather beautiful objects.
The winged viviparous female is of a uniformly light colour on the
under surface of the body, and on the upper surface she is of a
yellow colour, with short dark bands reaching half-way across the
Bem) FOREST ENTOMOLOGY.
abdomen. The thoracic portion of the body is also yellow, with two
longitudinal dark bars on the lower portion of the thorax. The legs
are variable in colour: the first two pairs are of a yellowish colour,
with darkish tarsi. In the hind pair, the portion adjoining the body
is also a light- yellow colour, and the middle portion of the whole
is conspicuously black, and the tarsal portion light brown. Eyes
same as in apterous form. The wings are comparatively long and
narrow; veins light brown, and broadly clouded at their apices.
Genus LACHNUS.
This genus is rather interesting from a sylvan point of view, inas-
much as the species are all arboreal feeders. According to Buckton,
one species lives on willow, while the others prefer the oak or conif-
erous trees.
As regards the leading points which characterise the genus, it may
be said that the rostrum is very long and slender; antenne six-
jointed ; small cornicles ; inconspicuous tail; very long legs and large
wings, with the cubital vein twice forked.
Perhaps the most conspicuous species are L. pini, on Scots pine,
and L. longipes, on oak,—the former, from the damage done to young
Scots pine in early spring, and the latter, as conspicuous by the eggs
in autumn.
The insects are very heavily bodied, and the winged specimens are
but poorly balanced for flight.
Lacunvs Pini (Linn.)
This species is found on Scots pine (Pinus sylvestris), and is fairly
common, more especially in smoky districts, where the young trees
do not thrive over-well. During the winter months the eggs, which
are comparatively large and black, may be found scattered amongst
the leaves or on the bark of the shoots.
In late spring or early summer, when the insects hatch out, they
make their way to the very tips and there congregate themselves,
and when an attempt is made to collect them they become very active
in their motions.
The apterous form is very large, of a dull brownish-grey colour,
black eyes, slender antenne, long legs, and the body rather hairy, but
APHIDID®. Foe Ee
soft in structure. In mounted specimens the rostrum is often very
conspicuous, and as a rule the front pair of legs are much more
prominent than the antenne.
The winged specimens are much the same in colour as the above.
They may be beaten from
Scots pine trees throughout
the summer, and as_ the
wings are often folded flat
over the body, they might
be mistaken by a beginner
in entomology for a species
of ant.
LACHNUS LONGIPES, DUFOUR.
This species is found on
oak, and often on young
shoots from oak stools. The
eggs, however, as represented
in fig. 286, are the most
conspicuous. They may be
looked for in late autumn or
during the winter months.
In early summer the apter-
ous viviparous females may
be found in masses on the
shoots of oaks which grow
as suckers from the stools
or stumps of previously
; np 4 Fig. 286.—Eggs of Lachnus longipes on oak. Photo-
felled trees. They ate ‘graphed in winter; leaf added for identification.
fairly, large in size, of
oval form, and of a uniformly deep-brown colour. Eyes black, and
cornicles small.
LacHNUS VIMINALIS (Fonsc.)
This species is found fairly common in some parts of the country
on willow or osiers, and very harmful to willows and osiers in parts
of South England. Wasps are greatly attracted to where they occur.
ey FOREST ENTOMOLOGY.
It is apt to be confounded with Melanoxanthus salicis, one of the
most salient points of difference being the joints of the antenne.
The other species described by Buckton in his Monograph are
L. picew, which is said to be very abundant on silver fir and also
on spruce near London ; LZ. pinicolus, on larch and Scots pine ; and
L. macrocephalus, on spruce.
Genus PHYLLAPHIS.
The following generic characters are from Buckton :—
* Rostrum very short.
“ Head convex, smooth.
“Antenne moderately long, the third joint about double the
length of the fourth; the fifth and sixth joints equal, the sixth
furnished with a representative nail.
“Cornicles hardly visible, and lying flat to the body.
“ Cauda almost obsolete.
“Body furnished with
long flocks of wool-like fibre
3 of a waxy nature.
“Wings long and broad.
Stigma long and trapezoidal.
Nervures not clouded,
“Legs moderate in size.”
PHYLLAPHIS FAGI (Linn.)
During early May the
leaves of beech-trees may
be found covered with a white woolly coating, produced by insects
known as Phillaphis fagi. In some cases large beech-trees are so
badly attacked as to be partially defoliated in midsummer, and this
being the growing season, the increment of the tree must be appreci-
ably affected.
The apterous female is a light-green or yellowish colour. The
general colour is, however, rather variable, as the abdomen is marked
with spots or bars. The cornicles are rather small, and the joints of
the antenne are about equal thickness throughout.
The winged female (fig. 287) is best examined by first dissolving the
Fig. 287.—Phyllaphis fagi.
APHIDIDA., ile
white fluffy matter, but this, unfortunately, rather spoils the colour.
The general colour is yellowish-green, with darkish legs and
antenne,
Fig. 288 is from a photograph of the leaves of copper beech ; and
there is only one species in the genus which confines itself exclusively
to the beech.
In the older writings of ‘The Transactions of the (Royal) Scottish
Fig. 288.—Foliage of copper beech (under side) covered with Phyllaphis fagi.
Arboricultural Society’ several accounts of this insect are given under
the name of Chermes fagi.
This species is particularly harmful around the London area.
Genus STOMAPHIS.
As this genus, according to Buckton, contains only a single species,
namely, S. guerciis, which is said to be comparatively rare in England,
it may be well, for the advantage of students, to simply give the
following generic characters according to Buckton—viz.:
“Head and eyes small. Antenne slender, moderately long, six-
jointed, third joint the longest, the sixth as long as, or longer than,
314 FOREST ENTOMOLOGY.
either the fourth or fifth, the aborted seventh joint longer than in
Lachnus.
‘**Cornicles very inconspicuous,
“Tess shorter than in ZLachnus, and less stout. Tarsus bi-
articulate, tail none, rostrum very long in the apterous females, but
shorter in the winged forms.”
I have not found Stomaphis, and therefore only give the generic
characters.
Genus DRYOBIUS.
The following generic characters are taken from Buckton :—
“Rostrum rather long and thick, projecting beyond the post-
sternum—much longer in the young.
“ Antenne slender, six-jointed, with an unciform process in the
sixth joint. Third joint more than twice the length of any other,
the fourth and fifth joints about equal—the sixth less than half the
length of the fifth.
**Cornicles conical, and very short.
“Cauda inconspicuous and rounded.
‘Legs, the first two pair moderately long, the hinder pair dispro-
portionately long; tarsus composed of two distinct joints.
‘Wings moderately long in the males, but very short in the
viviparous females. Stigmata rather long; cubital and first furcal
veins issue from the same point, which is at some distance from the
cubitus. The membrane of the upper wings variegated with brown,
smoky fascize.”
Buckton in his Monograph describes three species, but they appear
to have been found either on the Continent or in the south of
England ; and as I have not found either of the species myself, I
must simply refer the student to the generic characters.
Trine SCHIZONEURINZ.
This tribe contains the dreaded “ American blight ” found on fruit-
trees, and the damage done to stem and roots is unfortunately only
too well known to require description.
The species belonging to this tribe differ in two ways from insects
belonging to the previous tribe, both as regards the structure of the
insects and the nature of the injuries.
APHIDID®. ob
Genus SCHIZONEURA.
As regards the structural details, the following generic characters
are given by Buckton—viz. :
“ Rostrum moderately long in the adult, much longer in the young,
‘‘ Antenne with six articulations, omitting the terminal unciform
process.
“The first and second joints very short, the third much the longest,
and in all cases either ringed or cupped ; the fourth and fifth about
equal, and also usually ringed ; the sixth joint rather shorter than the
preceding, and ending with a rudimentary joint, a small tubercle
sometimes separating the two parts.
“‘Cornicles rudimentary or none; legs short. ‘Tarsi furnished with
two claws. Body either powdered with a mealy substance or fur-
nished with wool-lke tufts.
“Wings moderately long, cubital, with a single furcation, and in
Fig. 289.—Leaves of wych elm rolled by Schizoneura ulmi.
most species springing at some considerable distance clear from the
cubitus. The post-costal nervures of the hind wings nearly straight,
and giving rise to the usual two oblique veins.”
With regard to the damage, it may be noted that in this tribe we
find a reaction of the vegetable organism against the insect attack.
In other words, we get gall structure and its modification. The
various figures given by Réaumur and others would seem to suggest
that those features have been recognised for a very long time.
The arboreal species chiefly confine their attacks to the foliage.
The curling of the leaves of elm (fig. 289) is a very conspicuous
feature throughout the country. If the curl arises from the gnawing
of one stem-mother, then a single straight roll of half the leaf is
the result, but if the same leaf is seized by more than one stem-
mother, then the deformed leaf assumes various distorted shapes.
316 FOREST ENTOMOLOGY.
ScHIZONEURA ULMI (Linn.)
The arboreal species most injurious in this country and throughout
Europe is the Schizoneura ulmi (Linn.), and the most injurious
arboreal species in America is known as Schizoneura americana
(Riley)."
The description given by European writers was suggestive of the
two species being identical; but Professor Riley, on closer examina-
tion, found that the two species differ from each other in their
methods of damage and structural details, thus showing that while
we may deplore specific hair-splitting, hasty grouping is far from
commendable.
Riley maintained that, considered as a pseudo-gall, the chief differ-
ence in the two species is that the stem-mother of S. ulmi attacks the
upper side of the leaf, and the injured leaf in consequence rolls over ;
whereas the stem-mother of S. americana attacks the under side of the
leaf, and the injured portion rolls under, This observation was based
by Prof. Riley on a specimen sent from England by Mr Buckton, but
it certainly does not coincide with our own species, S. w/z, Inasmuch
as the queen-mother attacks the under side of the leaf and rolls under
(fig. 289).
Hence it is evident that we must have recourse to foreign literature,
for though the various species may be more or less local, the genus
may often be cosmopolitan. A more comprehensive view of the
genus will give a better grasp of the species.
The queen-mother may be found about the middle of May. She is
apterous, of a dark-olive colour, mottled with dark-bluish tints, like the
gloss on black grapes. The creature is considerably larger than any
of her offspring, which may be found either along with her or after
her death. The body is slightly covered with a cottony exudation
arising from a series of pores on the back. In comparison with the
body, the head and thorax are very small. The antenne and legs are
short, hence the creature is very helpless. The antenne are composed
of six joints, the third being nearly half the entire length. It is
highly probable that those stem-mothers hatch from eggs laid the
previous autumn.
The winged specimens may be found very plentifully by the middle
of June in the rolled elm leaves. The body of the female is wholly
black in colour; the eyes are also black. The third joint of the
1 Insects Injurious to Forest Trees. Packard, U.S.A. 1890.
EEE
APHIDID®. 317
antenne is very long, being considerably longer than all the other
joints put together, and beautifully ringed. The wings are moder-
ately long, and the cubital vein is but once forked, which is an
important point in generic classification.
Trine PEMPHIGINA.
Closely allied to the preceding group are the Pemphigine or gall-
forming aphides. The insects live sociably, but instead of rolling
leaves, form galls,—growths which, from a structural point of view,
may be considered higher in the scale of organisation than rolled
leaves. The curious abnormal growths, caused by insects belonging
to this tribe, appearing on the leaf-stalks or midribs of leaves, often
displaying beautiful colours, have received a great deal of attention
from various workers. The galls themselves, differing from one
another in appearance and position, give rise to specific characteristic
distinctions, apart from the structural points of the respective insects
themselves.
In comparing the characters of the two genera, it will be ascertained
that the rostrums are alike, and the antennz similar, viz., six-jointed ;
but the sixth joint in Pemphigine is larger than in Schizoneurine.
It is, however, in the wings that the most salient structural difference
may be recognised. The cubital vein in Schizoneurine is forked
once, whereas in Pemphigine it is not forked, but in both genera the
cubital vein is unattached to the cubitus.
Genus PEMPHIGUS.
The following are the generic characters according to Buckton :—
“Rostrum as in Schizoneura. Antenne short, with six joints,
omitting the nail-like process. Third joint about equal to the three
following taken together. The third, fourth, and fifth joints com-
monly ringed; the sixth joint longer than that of Schizoneura.
*‘Cornicles wanting.
“Wings with no furcated cubital vein,—this vein, as in the last
genus, being unattached to the cubitus ; stigma large and trapezoidal ;
the two oblique veins usually start from the same point. The post-
costal nervure of the hind wing somewhat angular, from which angle
the two oblique veins spring.
“Legs short, particularly in the apterous forms.”
318 FOREST ENTOMOLOGY.
PEMPHIGUS BURSARIUS (Hart.)
This species is found on the leaf-stalks of poplar (fig. 290), chiefly
on the black Italian species, the black burry poplar, and also on the
young woody twigs of the Lombardy pop-
lar. The gall is smooth, globular, highly
coloured, and with an opening at the side.
In July or August the leaves, with galls on
the foot-stalks, having fallen prematurely,
may be picked up, and the insects found
in all their respective stages of metamor-
phoses.
The stem-mother (fig. 291) is larger than
any of her progeny. ‘The legs are short,
and the creature comparatively helpless.
The antenne are four-jointed, and the corn-
icles absent.
HU URSA EO Te ay The larva (fig. 292) is of a very light-
poplar caused by Pemphigus gypeen eolour.
bursarius. ts)
The pupa (fig. 293) is of a pale-green
colour, with a slight mealy dusting, and shows signs of wings at a
very young stage. The antenne are longer than in the green aphis,
but the joints are not easily distinguished.
Fig. 291.—‘‘ Stem-mother”’ of Pemphigus bur- Fig. 292.—Larval stage of Pemphigus bur-
sarius. (From camera-lucida sketch.) sarius. (From camera-lucida sketch.)
The winged viviparous female (fig. 294) is black, and the body and
wings are dusted over with a white powdery matter. The antenne are
six-jointed, the third joint being the longest; and the third, fourth,
fifth, and sixth are ringed. Buckton says the sixth joint is smooth,
i i ee ee eee
APHIDID®. 319
but in the specimens I examined this joint was ringed like the
others.
Common and harmful in Kent.
PEMPHIGUS SPIROTHECH (Koch).
This species, like the preceding species, is also found on the leaf-
stalks of poplar of the black Italian species (fig. 295), but it makes a
corkscrew-shaped gall. It is far from
common, and very locally distributed.
While living in Cheshire, I only
found but one tree, growing on a
bank alongside a brook, which annu-
ally yielded me a good crop of galls.
The queen aphis punctures one side
of the leaf-stalk to obtain nourish-
ment, and the stalk in consequence
bulges on the opposite side. The
enawing and bulging causes the stalk
to form a corkscrew-shaped gall, His: 208.—Fupal stage of Pemphigus bur-
oOo”? sarius. (From eamera-lucida sketch.)
where the stem-mother and _ her
progeny find a home and shelter in the folds. As the fully devel-
oped insects are about to escape the galls become more elastic, and
Fig. 294.—Winged form of Pemphigus bursarius. (From camera-lucida sketch.)
open easily. The gall is of a dull-green colour, and may be looked
for from June to September.
The most abundant crop of those galls I have ever seen was at
Peterborough, on the Lombardy poplar.
320 FOREST ENTOMOLOGY.
The insects are smaller than those in the preceding species, and
differ in a few minor specific points.
PEMPHIGUS PALLIDUS (Haliday).
In fig. 296 an illustration is given of P. pallidus, which forms galls
on the midrib of wych elm. The specimen from which the photo-
Fig. 295.— “Corkscrew” gall on Fig. 296.—Gall of Pemphigus pallidus on midrib
leaf-stalk of poplar caused by of leaf of wych elm.
Pemphigus spirothecz.
graph was taken was found in High Legh, Cheshire, where it was
very common.
The fully developed insect is somewhat variable in size. The head
and thorax are black; abdomen yellow; eyes red; antenne darkish-
brown.
TETRANEURA ULMI (De Geer).
Closely allied to the Pemphigus, and belonging to the same tribe, is
the genus Tetraneura, with a single species, Tetraneura ulmt.
The galls of this species are found on the upper side of elm leaves
(fig. 297) about the middle of May. They are nearly one-fourth of
an inch in length. I have frequently found the galls projecting from
the folded portion of the leaves injured by Schizoneura ulmi. Thus
we get two species very closely allied entomologically, and practically
united botanically. The entrance to the galls of Tetraneura is well
closed, and guarded by hairs which doubtless act as a protection
against parasites.
APHIDIDA, Sk
As compared with the preceding genus, the rostrum is comparatively
short, the antenne short and six-jointed. The wings are similar to
those of Pemphigus, “except that there is only one oblique vein in
the lower wing.”
The gall attains its full size prior to the complete development of
the insect. The antenne are four-jointed, the rostrum rather long in
comparison with the body, and legs slightly hairy. Colour dark oak,
and the insects very sluggish. It is
very harmful to isolated elms, killing
the leaves*«in many parts of the
country.
Trine CHERMESIN A.
Perhaps in the whole realm of
forest entomology there is no tribe
of insects which presents such pecu-
liar difficulties as the Chermesine, ©
inasmuch as it is most difficult to
present the biological importance, as
revealed by the present state of Mis. 207.—Galls of rae ulmi on
our scientific knowledge, and the
exact discrimination of our so-called species in such an amalgamated
form as will be correct to the scientist, and also intelligible to the
practical man. In other words, we have, in this group, two problems
to face—viz., the alternation of a species from host-plant to host-
plant, and on the other hand the determination of the so-called species
on their respective host-plants as associated with their own peculiar
injuries.
First, let us consider the alternating generations as given by Judeich
and Nitsche,! and more recently by Niisslin? from Cholodkovsky. In
the former, two classes are given—viz., (1) Continuation or remaining
on spruce, with clear parthenogenetic reproduction ; (2) partly emi-
grating from the spruce to the larch, with parthenogenetic or sexual
reproduction. In the latter, which has been carefully worked out by
Cholodkovsky, the gist of it may be summed. up as follows :—
Typically the Chermes show five generations and an exchange of
host-plant. The principal host-plant is always the spruce ; but only
1 Forstinsektenkunde.
2 Leitfaden der Forstinsektenkunde.
x
322 FOREST ENTOMOLOGY.
one generation, the 3rd or emigrans generation, belongs exclusively to
conifers other than the spruce (such as Scots pine, larch, and silver
fir). This change of conifers referred to other than spruce is known
as the intermediate conifer (Zwischenkonifere) only in so far as the
Jormer brings about the transport of the species, through the laying of
eggs on the intermediate conifer, in order that they may return to the
spruce. Now this is a most important point, as it clearly implies that
this alternation is for the welfare of the species, though, as it were, on
the part of the insect, not altogether optional, but periodically (not
annually) compulsory for the welfare of the species. This shows that
it must have been difficult to discover and ratify by those Continental
workers, and even difficult for the student in this country to verify.
The following is a short account of the alternation as given by
Niisslin : '—
“The Ist generation (fowndress) is a parthenogenetic female, wing-
less, with three-jointed antennz, confined to the spruce and producing
the spruce gall. The 2nd generation (migrans alata) acquires wings
after the fourth moult, receives at the same time five-jointed antenne,
compound eyes, and three simple eyes. It develops in the gall on the
spruce, and flies usually to one of the ‘ intermediate conifers,’ where it
lays its eggs on the needles. From these eggs springs the 3rd genera-
tion (emigrans), which resembies its ancestor of the 1st generation (the
foundress). It remains on the alternate host (the ‘intermediate
conifer’) for hibernation, and lays eggs there in spring. From the
eggs emerge either forms resembling the parent (exulans) or the 4th
generation (secupara), which in every respect resembles the generation
before the last (its ‘grandmotherly generation’), the migrans alata,
only it remains smaller, and is less prolific. From the beginning it is
independent (/reilebend), and after the first moult varies somewhat.
It lives and develops on the needles of the ‘intermediate conifers,’
and flies back to the spruce, where it lays eggs on needles. Out of
the eggs come the two different forms of the 5th generation (seauales)
—the leaner males and the stouter females. Both are rather small,
but do not diminish in size, and have four-jointed antenne. The
female, after pairing, lays in midsummer a single fertilised egg on the
spruce, from which emerges the hibernating foundress. The fivefold
cycle requires, therefore, two years and two different coniferous species
for its completion.
1 Leitfaden der Forstinsektenkunde.
APHIDIDA. o2e,
* According to what has just been said, we have in the Chermes
eycle only three principal (chief or leading) forms—viz. :
1. The parthenogenetic (non-sexual or asexual) wingless form.
2. The parthenogenetic (non-sexual or asexual) winged form.
3. The sexual generation with male and female.
“But in reality the number is increased, as each of these forms
varies more or less in the 3-4 moulting stages. Especially does the
appearance of the insect change between the first and the last stage
of the parthenogenetic winged form (mzgrans aluta).”
The question of how to form a precise recognition of the different
species, and the various stages of the same species, is somewhat dif-
ficult to determine. It would be advisable to boil and stain the
respective mother Chermes, as found on different food-plants, and
compare their minute structure, such as chitin plates, wax glands,
antenne joints, legs, and so forth, together with the colour of the
eggs and general habits of the creatures.
Second, as regards the so-called species, it would perhaps be well
to consider them separately in the usual way, both as to their relation
with other closely allied insects and the damage on different trees.
Hence they may now be considered in the ordinary manner of genus
and species.
Genus CHERMES.
This genus is exclusively arboreal, and the respective species are
confined to conifers. They come near to the Coccide or Scale-Insects
in point of anatomical structure, and nearer in general appearance of
damage than any other tribe in the whole family. Thus the snowy
appearance presented by the felt scale on beech, and the white fluffy
matter on the stem of silver fir and Weymouth pine, are to the naked
eye practically identical. The difference between the two families
can only be decided by microscopical examination, and in fact,
between the respective species of this genus, can only be decided
by the most careful microscopical examination.
In structure the genus Chermes is characterised by the upper wing
having three oblique non-furcated veins, and the under wing a single
oblique vein, The antenne are normally five-jointed. The rostrum
is very short, being used exclusively as a feeding-organ, and not
specially for anchorage. The creature develops three or more long
324 FOREST ENTOMOLOGY.
hairs, or sete as they are termed, by means of which it maintains
a hold on ‘the bark. In this respect it very much resembles the
Diaspine, or scale-insects, on the ash, alder, willow, &c., as in both
families the creatures may be seen dangling in the air, after they
have been detached from the bark by birds or other natural enemies.
There are no cornicles. The parthenogenetic females secrete wax,
and for the most part show, on careful examination, clearly marked
chitinous plates.
Synopsis of the Species,
Producing comparatively large galls on the terminal and _ lateral
shoots of the spruce (Picea excelsa). The shoot often extends
beyond the gall : : : ‘ : C. abietis,
Producing comparatively small, hard, close galls on the terminal
buds of twigs of spruce, and always arrest subsequent
erowth . . : : : . C. strobilobius.
Producing a white covering on the Rene or foliage of compara-
tively young larch-trees . : : é C. laricis,
Producing a white covering on the twigs or branches of young
Scots pine or Austrian pine ; : a Cpe:
Producing a white covering on the branehies or stems of Wey-
mouth pine. : : ; : 2 6+ -corticales.
Producing a white covering on the stems or foliage of silver fir
(Abies pectinata) or Abies Nordmanniana ; C. picece.
CHERMES ABIETIS (Linn.)
This is a gall-forming species on the common spruce (Picea excelsa),
the gall being in appearance like a pine-apple or pseudo-cone of Scots
pine (fig. 298), each abortive shoot terminating in abortive leaves.
The structure of the gall varies, as in some cases it surrounds the
young shoots, and arrests or retards future growth. At other times
it may be found on one side of the shoot, thus doing only partial
damage. When the leading shoot is attacked, the young tree is often
very much injured.
The ‘stem-mother” hibernates during the winter months at the
extreme top of the young shoot, just immediately below where the
pseudo-gall will be formed next year. They are, however, very
difficult to find, as they are not only small but beautifully concealed.
pee
a ale wees te ae
coer Ss.
EE
Ge
bo
or
APHIDIDA,
Shoots in close proximity to the old galls of the previous year are
the most likely to yield specimens.
The first appearance of the gall may be looked for, according to
season, about the middle of April, This is recognised by a small
white speck at the tip of the shoot (fig. 299), in which the
mother Chermes may be found depositing her eggs. On examin-
ation about a month after recognising the white speck (my dates
were April 20 and May 18, and the locality Cheshire), the mother
Chermes was still surrounded by eggs, although none were hatched.
Meanwhile the cottony down had increased in quantity, the young
Fig. 298.—Gall of Chermes abietis Fig. 299.—Early stage of gall of
on spruce. Chermes abietis on spruce.
shoots had grown from 1} to 24 inches in length, and the pseudo-
cone or gall itself from 2 to $ inch in length, whence arose deformed
leatlets about 4 inch in length.
It is probable that constant irritation causes the gall formation in
question.
The young larve are hatched outside the pseudo-gall, which begins
to enlarge before the larve are hatched out, and it is not quite clear
how the vegetable structure reacts against the insect attack; but the gall
slightly opens at the slits, and the young larve creep in. Afterwards
the gall closes up, and the transformations take place within the gall.
It is computed there are about 2000 inhabitants to each gall.
eo
bo
(or)
FOREST ENTOMOLOGY.
Buckton remarks: “It is not quite clear if the queen-mother
dies outside of the developing gall, leaving thus the young which
hatch from the eggs to enter those chambers alone, or whether she
accompanies them in their retreat.”
From the middle of June to the end of August the winged speci-
mens may be found emerging from the gall. They are very sluggish
in their movements.
The “pupal” form presents a reddish-brown-coloured creature,
whose body appears ‘‘all made up of a piece.” The eyes are of a
darker brown colour than the body. The antennz and legs are short,
and the wing-cases slightly greenish ; but specimens differ very much
in colour. As might be expected, the insect is more or less covered
with a resinous exudation.
The winged imago is of a golden brown colour, which deepens very
much with age. The head is broad, and the eyes dark brown. The
antenne are short and five-jointed, the last three joints being pecul-
iarly straight on one side. The prothorax is comparatively broad and
large. ‘The abdomen is oval-shaped. Specimens mounted for some
time show the abdominal segment to have a rather broken outline,
and ending in a short ovipositor. The wings are comparatively broad,
and vary in colour from a light to delicate greenish tinge. The ven-
ation is typical of other Chermesine.
About the middle of September many insects will be found deposit-
ing eggs on the leaves, as seen in fig. 300. In some cases an insect is
found on almost every leaf. The head of the insect points towards
the base of the leaf, and she generally places herself fairly near to the
base of the leaf. After depositing the eggs the female dies, but the
dead body is so placed that it forms a protection for the eggs. It
should be noted, however, that the eggs are not thrust outside the
body, as Ch. laricis, but on the contrary the ovisac is slightly ex-
tended and placed bodily on the leaf prior to the death of the
creature.
These insects just referred to are, according to alternating genera-
tions, probably the return generation from the intermediate conifer.
CHERMES STROBILOBIUS (Kalt.)
It is quite possible that this species has, in this country, been
hitherto confounded with Ch. abietis. The structural features, as
APHIDID® 327
illustrated by Judeich and Nitsche, do not show any strong salient
points of difference, and in the absence of knowledge on the part of
the student regarding verification of the alternating stage, it would
be well to recognise the difference in the structure of the galls. In
C. strobilobius we find the galls smaller, globular in form, and in colour
resembling the unripe fruit of the wild strawberry. The develop-
Fig. 300.—Winged forms of Chermes abietis on spruce leaves (enlarged). Found in autumn,
This stage should be carefully studied, as it probably may be the sexupura stage.
ment of the gall is such that leaves do not project beyond the gall.
In the German literature it is said that there is a marked difference
as regards the “ over-wintering” (wherwintern) of the two species, in-
asmuch as in C. abietis the stem-mother (Fundatrix) passes the winter
at the base of the bud, whereas in C. strobilobius the creature winters
in the top of the bud. It is therefore suggestive that the initial action
of the respective insects produces the variation of gall structure.
328 FOREST ENTOMOLOGY.
CHERMES LARIcIS (Hartig).
This and the remaining species of Chermes differ from the preced-
ing, inasmuch as abdetds is gall-forming, and those about to be con-
sidered protect themselves by a woolly covering. The evidence of
the presence of addetis cannot in a general way be recognised by the
naked eye until we find a white speck in late spring. This speck
reveals the abode of the queen-mother. With regard to Chermes
laricis, on the other hand, considered as a distinct species, the queen-
Fig. 801.—Chermes laricis on bark of larch.
mothers may be found throughout the whole of the winter months on
the stems of young infected trees, their presence being indicated by
the cottony covering on the stems! (fig. 301). This is no doubt
the main harbourage, but many specimens may also be found hiber-
nating just underneath the leaf-scales.”
1 Mr Theobald, in correspondence, says: “ You cannot trace a single one on the
stems in South England, where laricis swarms. The trunk aphis is found in
Lincolnshire. There is no doubt it is different, and that there are two allied
species.”
2 The two forms—viz., those on buds and those on bark—are probably quite
distinct. The latter is termed C. viridis by some entomologists.
APHIDIDA. 329
In Cheshire, by about March 25, the queen-mothers may be found
just beginning to make ‘‘a move.” At this time they are very small,
and much resemble the larve hatched out from eggs later on in the
season.
If the infested trees be examined about three weeks later, it will
be found that the tufts of leaves have grown from about a quarter to
three-quarters of an inch in length. The queen-mother Chermes will
be found at the base of the leaf-buds, surrounded by eggs. Her
body is now very much enlarged, and of a dark-brown colour, with
conspicuous rows of tubercles and slightly
dusted with cottony down.
The antenne are very small, and partly
hidden. They are three- or four-jointed,
but the joints are not easily determined
by the inch objective. The rostrum is
short and stiff, with very long attached
sete. The legs are short, and naturally
not seen outside the bodily circum-
ference. The tail is short, but is
used by the insect in arranging her eggs,
with which she ultimately becomes half-
buried.
The eggs are greenish in colour, glued
together by a resinous turpentine, and
further attached to each other and to the
plant by delicate threads. Bite roliagelof larch arrested
The larval forms which hatch from the Gee a cnn a
egos are mere pin-points in size, and a
darkish colour. ‘hey spread themselves all over the tree, and do
immense damage by sucking the juices of the plant. When numer-
ically very strong, as in some local spots, they entirely defoliate, or
rather retard the development of the foliage—so much so, that the
severely affected trees may appear quite naked when others are in full
leaf (fig. 302). ;
Later on during the summer the green leaves are heavily dusted
with white—so much so, that they would appear as if covered with
a slight shower of snow (fig. 303). If each speck be examined in-
dividually, it will be found that it is composed of mother and eggs
covered by the white exudation.
330 FOREST ENTOMOLOGY.
CuHeRMES PINI (Koch).
This species is found on Scots pine and Austrian pine. The white
specks are generally found on the stems or branches of young trees,
and also on the shoots (fig. 304). To follow out the life-history of
this insect, the dark-brown queen aphis should be looked for in May ;
and by June she is covered with brownish-yellow pedunculated eggs,
Fig. 303.—Chermes laricis on foliage of larch.
which soon hatch out into very active larve. The insect protects
herself with long white silky filaments.
In early spring the white cottony matter covers the young shoots,
as seen by fig. 305. It will also be observed that in this case, which
is purely a typical example of severe damage, the shoot is considerably
bent as compared with unattacked shoots, which are perfectly straight.
In many cases, however, healthy trees recover from attacks of this
kind and no serious injuries accrue, but, on the other hand, as will
APHIDIDA. Bee |
be seen from fig. 306, many of the young shoots die from the
attack, This fig. was photographed from a plantation which was not
in a very good state of health. If, as a rule, the health of the crop
is fairly good, the trees “throw off” the attack, and no appreci-
able damage is done.
CHERMES CORTICALIS (Kalt.)
This species is very common in the south of England on Wey-
mouth pine,‘and is said to do very great injury to the trees. It has
Fig. 304.—Chermes pini on Fig. 305.—Chermes pini on terminal shoot of
stem of young. Scots pine. Scots pine.
been notably sent me from the sandy soils of Surrey, and I have
found it bad on one tree in Kent. Fig. 307 is taken from a branch of
Weymouth pine in a garden in Cheshire. I have not found this
species in Northumberland, so that I am unable to give any descrip-
tion of the creature.
(su)
Oo
bo
FOREST ENTOMOLOGY.
CHERMES PICE® (Rtzb.)
The bark-louse of the silver fir (die Tannenrindenlaus of the
German) is very destructive to young silver firs, comparatively young
specimens of Abies Nordmanniana, and even fairly old trees of Abies
nobilis. Fig. 308 is taken from the bark on a silver fir tree of about
Fig. 306.—Terminal shoot of Scots pine Fig. 307.—Chermes corticalis on branch of
killed by Chermes pini. Weymouth pine.
thirty years of age. Specimens of young silver fir trees in nursery-
lines are often killed outright by this insect.
It is to be hoped that the above account of the genus Chermes will
show that they are of very great importance from an entomological
point of view, and that much subsequent study is required in order
APHIDID. aoe
to fully clear up the life-history of this hitherto partially studied
genus. The aspiring student should therefore collect the various
species of what hitherto has been termed sfem-mothers on different
trees, boil them in caustic potash, and stain with Crawshaw’s magenta
penny dye, as recommended for scale-insects, and try to verify the
various minute points of structural difference as shown in fig. 309
from Judeich and Nitsche, carefully noting and tabulating the results
of his observations. Such a method would obviously be highly
interesting and important, as in searching for the various anticipated
alternating stages of the same insect on different trees, confirmation
of the same creature changing from host-
plant to host-plant would obviously be
ratified.
IMPORTANCE OF THE GENUS CHERMES
- IN FORESTRY.
This genus is exclusively arboreal, and
should be specially studied from a practical
and scientific point of view. To the
scientist the various species of insects
change from one tree to another, and thus
our so-called species are simply various
stages of the same insect. But the prac-
tical man, often indifferent to specific dis-
tinctions, recognises the injurious effects
on certain trees, and thus prefers to
identify the species as coincident with !"s gare rag has Ee
the food-plant. Thus Chermes laricis
may often be found very injurious to young larches of from ten to
fifteen years of age, more especially on those trees growing in hollows
or in damp spots; Chermes abietis on spruce-trees which are not
growing in suitable places, and often in young spruce-trees in the
nursery-lines ; and Chermes picee is often found on young silver firs
in the nursery, and on young trees of A. Nordmanniana. C. strobi-
lobius is perhaps more destructive to young trees in the wood, especially
those too much overshaded and not thriving well. ‘The dead galls
adhere very closely to the twigs, and can often be seen after the
infested tree is partially dead.
304 FOREST ENTOMOLOGY.
Now the question is, how are we to deal practically with those
pests, having regard to recognised systems of “mixing” with those
very trees which act as host-plants in the alternation of the species ?
Much has yet to be learnt from good sylvicultural conditions, careful
work in planting with well-rooted plants, and also from experiment
and observation. Take, for example, a suggestive case in point—viz.,
the growing of young silver firs. On many estates very fine examples
of old silver fir trees can be found, and the modern forester with his
high-class sylviculture cannot grow it. Without viving any definite
opinion, much might be done in the younger stages by growing under
shade of hardwoods in the nursery—say, plant a row of hardwoods,
Fig. 309.—Hibernating winter forms of four species of Chermes.
A, C. abietis ; B, C. strobilobius ; c, C. coccineus ; D, C. siliricus ; together with a highly
magnified single chitin plate of each species. Copied from Judeich and Nitsche.
two or three rows of silver fir, and again a row of hardwoods, and so
on throughout the nursery plot. Perhaps, also, an exception may be
made to the general rule of much transplanting in the nursery. This
tree should not be too often moved, but plants should be specially
carefully taken up when they are lifted. Again, when transplanted
in the forest, the silver firs should not be planted in the open, but
as shade-bearers in late filling up, or otherwise solely as under-
planting.
Then as regards the injurious effects of C. a/etis as compared with
Q. strobilobius, it may be said, so far as real injuries are concerned,
that the former is often injurious in the nursery-lines, more especially
to those plants standing in the rows for three consecutive years, and
APHIDID. ba,
the latter, as remarked, on young trees. As regards remedies for
C. abietis in the nursery, this is a very good case in point where
good husbandry is advantageous both to the seller and purchaser. A
general saleable age of the spruce plants is five years—namely, two
years in the seed-bed and three years in the rows,—2 yrs. 3 yrs. of
the nurseryman. When transplanting from the seed-bed they are,
of course, placed very thickly in the rows, and if they do well, are
useful stuff as 2 yrs. 2 yrs., but when unsold the nurseryman must
either leave the crop as it is or otherwise compromise matters by
interlining. «The latter method does not give relief between plants,
much to the
advantage of the Chermes. Again, three years in the nursery-line is
and the consequence is that they are afterwards weakly
conducive to bad roots, which, coupled with the depreciation from the
insect attack, means a very poor class of plant to the purchaser.
Hence, in order to maintain health and vigour, the practical remedy
is, at the end of two years, transplant again for another two years—
provided, of course, the seller could secure purchasers who recognise
that quality and not cheapness is the essential of success. By doing
so on suitable soil, we should get a better plant, and thus lessen
the attack of the Chermes. This could always be done on private
estates.
Another point in connection with the planting of spruce in the
young woods associated with Chermes may be mentioned—viz., that
in some parts of the country the spruce should not be planted in the
open amongst the more hardy species, but used more as an after-plant
for filling up. In the latter case it will thrive better, and though
attacked by C. abzetis, does not suffer to any appreciable extent,
inasmuch as on vigorous plants the galls are often considerably on
one side of the shoot, and thus the subsequent growth overcomes
the attack.
Another point in connection with Chermes and practical forestry
may be mentioned—viz., that it has been asserted by some observers
that the mother Chermes on larch inoculates! the tree with the spores
of Peziza, which is the fungus causing the well-known “larch disease.”
Hence it would obviously appear that a mixture of spruce and larch
would favour the insect, and consequently be conducive to the spread
1 Tt is just possible that the wounds caused by the insects form suitable spore-
beds, just as apple canker will develop in the wounds of S. /anigera, and can only
do so in wounds.
336 FOREST ENTOMOLOGY.
of larch disease. So far as the mixing of spruce with larch is con-
cerned, this theory does not square with actual results, inasmuch as
many instances of the ‘‘ mixture ” referred to may be seen throughout
the country, where, with spruce as an undergrowth, the larch is
practically free from disease, and likewise a very good commercial
crop. On the contrary, it is just possible that the under-crop of
spruce in a larch plantation, acting as a soil- protector, may have
proved a great stimulus to the larch crop, forming greater increment.
But while improved sylvicultural conditions may do much for the
prevention of insect or fungoid diseases, it must not be inferred from
the above remarks that spruce is the best mixture with larch, though
it must be borne in mind that larch is not a suitable tree to grow as
a pure crop.!
It might again be noted that this genus is, in general appearance,
practically identical with several other insect damage. Thus, for
example, Chermes corticalis may be common on Weymouth pine, and
Cryptococcus fagi abundant on adjacent beech-trees ; but the one is an
Aphis and the other a Scale—two quite distinct insects. Now this
is very important to the entomologist ; but it is often of far more
practical importance to the owner of trees, inasmuch as the imperfectly
trained entomologist is apt to make wrong deductions and prescribe
erroneous remedies, For example, I once knew of an expert ento-
mologist advising a landed proprietor to cut down Weymouth pines as
a remedy for the injuries of Cryptococcus fagi on beech, —a most
absurd remedy, seeing that the two insects have no connection
whatever.
Genus PHYLLOXERA.
Hitherto only one species has been found in this country,
and the generic characters may be characterised by moderately
long rostrum in the winged form, their jointed antenne, eyes small,
legs very short, and tarsi apparently single-jointed, with a double
claw and pad. In this respect they come very near in structure to
the Coccide or ‘scale-insects.” As regards the wings, they are
decidedly of aphidian structure, inasmuch as we get a well-marked
cubitus, whence spring their straight veins.
1 These remarks may be criticised by practical men, but in some cases the
success of this “ mixture,’ as showing the absence of “larch disease,” can be
seen in certain parts of the south of England.
APHIDIDA. 337
Phylloxera punctata (Licht.)
The damage accruing from this insect is often very conspicuous in
a general way, and, except to the searching eye of the naturalist, the
insect itself may be easily overlooked. During the latter half of the
summer the oak leaves begin to take
a very sere colour, and thus we often
hear it remarked that the drought is
playing havoe with the foliage, or that
winter is setting in early. Now the
cause of this is due to our aphis, Phyl-
loxera punctata, —a creature closely
allied to the dreaded pest of France,
and found abundantly on the under
side of the oak foliage (fig. 310).
The yellow spots are caused by the
mother aphis and her eggs or progeny,
which surround her in concentric circles.
The mother has a very long ovipositor,
by means of which she arranges her eggs.
The queen-mothers may be looked for
early in June or latter end of May
: Fig. 310.—Under side of oak leaf in-
under a very small pucker, which might —_/ested with Phylloxera punctata.
be mistaken for the beginning of some
species of gall.
The female (fig. 311) in the centre of
the yellow spot is a comparatively small
creature, with flask-shaped body of an
amber-yellow colour spotted with red. o ra
Head rather broad ; eyes small ; thorax @ *
hardly separable from abdomen, which
terminates in an obtuse ovipositor ;
antenn three-jointed.
Prior to hatching from the eggs, the
eyes of the larve are very conspicuous. When first hatched they
are of a yellow colour, with scarlet eyes and white antenne and legs.
It is said they moult four times before assuming the “ pupal” stage. -
They are of a long oval form, of a gamboge-yellow, becoming darker
with age, and variegated on the abdomen. The legs are short.
Y
Fig. 311.—Apterous female, eggs, and
larva of Phylloxera punctata.
338 FOREST ENTOMOLOGY.
Fig. 312 is a representation of the winged form.
My observations of this insect were made in Cheshire, where it
was quite harmful. I have never found it in north Northumberland,
Fig. 312.—Winged jorm of Phylloxera punctata.
but it is often met with in the south of the county, just on the borders
of Durham.
References to Literature consulted.
Buckton, G. B. Monograph of British Aphides. Ray Society.
Judeich und Nitsche. Forstinsektenkunde.
Niisslin. lLeitfaden der Forstinsektenkunde.
—
339
CHAPTER IX.
: DIPTERA (Two-wincep FL tres).
From an entomological point of view, the order Diptera is very import-
ant, inasmuch as it is, to a large extent, an unworked field, requiring
a good deal of careful study, and having admittedly an unsettled
question of classification. Viewed by the economic entomologist, it
traverses a very wide field. Thus we have the troublesome flea, the
annoying house-fly, and the irritating summer-evening midge. There
are several species which feed on carrion or decayed vegetables, and
destroy obnoxious matter, both in the animal and vegetable kingdoms,
and a number of species which take an active part in disseminating
some of the most direful diseases. From a husbandry point of view,
the familiar names of warble-fly, onion-fly, carrot-fly, Hessian-fly, and
many others, suggest the importance of the subject. In the forest
they are, as a general rule, not so destructive as some of the insects
previously dealt with, but their small size, minute characters, and
interesting life-histories suggest them as interesting studies to the
microscopist, the general biologist, and the practical man.
The structure of the Diptera can be best made out by taking a
house-fly as a typical insect. The chief character is, of course, the
“two-winged” structure. They are sharply marked off from all
other orders of insects by the reduction of the hind-wings to mere
knobs, “balancers,” or halteres as they are termed. The whole
mechanism of flight is entirely dependent on the two wings, but it is
patent that the creatures bound through the air with greater ease,
more gracefulness, and apparently, as it were, more command of will,
than any other group of insects.
The head is usually very convex in form, large eyes, and with so
slender and flexible a neck that the head all but turns round on a
pivot. The order shows that there is great diversity and modifica-
340 FOREST ENTOMOLOGY.
tion of mouth- parts. Thus the house-fly takes its food by a
sucker arrangement; and the equivalent of mandibles and maxille,
&e., of other insects are modified into organs for piercing in the
mosquito. The antenne of the order vary much in length and
structure.
The legs are usually very slender, and vary much in size. The
legs of the house-fly and ‘“ daddy-long-legs” are cases in point. The
feet end in two claws and a sort of pad. The wings are also variable,
and the venation requires the greatest attention, so far as detailed
studies are concerned.
The abdomen is generally made up of eight segments, indicated by
numbering from the base—that is, the part attached to the thorax. The
last or anal segment is of peculiar shape, and contains the generative
appendages, and consequently the sexes are very easily determined in
many tribes of the Diptera. These characters are, of course, variable,
but in the male they may be either a sort of double forceps with
central penis, or lamelle and penis sheath. In the female the last
segment is prolonged into an ovipositor or vaginal sheath, and has
two basal lobes.1
With regard to classification, the order may be divided into two
sections—(1) OrTHORRHAPHA and (2) CYCLORRHAPHA.
(1) The larva in this section has a more or less perfectly developed
chitinous head, and the pupa escapes by a 7-shaped rent in the larval
skin.
(2) In this section the larva has no chitinous first head, but is
quite acephalous, and the pupa escapes from the larval skin by a
circular opening.
The OrTHorRHAPHA are divided into two sub-sections—viz., the
Nematocera and the Brachycera, the former having threadlike and
many-jointed antenne, the latter having the antennze composed of
two or three segments with a lateral bristle or arista.
The principal families of Diptera which cause injuries in the forest
are Cecidomytide, Phytomyzide, and Agromyzide.
The first-named is numerically considered the strongest, and the
following characters of the family are given by Mr Theobald : 7—
1 The student who wishes to pursue the special structural details of Diptera
would do well to consult a very detailed chart by the Rev. W. J. Wingate, in the
‘Transactions of Nat. Hist. Soc. of Northumberland and Durham,’ vol. 11., 1906.
2 An Account of British Flies, by Fred. V. Theobald, pp. 50, 51. 1892.
DIPTERA. 341
Famity CECIDOMYID-.
“Ocelli often absent. Thorax with no transverse suture. Antenne
long, composed of many segments (10-36). Wings with only few
nervures. Coxz not elongated, femora not thickened, no spurs on
tibia. Delicate midges or gall-flies whose larve are provided with
an anchor process beneath the head end.
Genus CECIDOMYLA.
‘
‘Antennz long and moniliform or cylindrical ; generally verticillate,
13-36 joints. Wings hairy, and have densely pubescent margins.
Three or four longitudinal veins. There are two types of wings. In
the first type the third vein is forked, thus representing the third
and fourth veins, which have united for most of their length. In
some rare cases this fork may become obliterated. In the second type
of wing the four veins are separate and simple. We must note in
these insects a curious longitudinal fold between the second and
third longitudinal veins, present in most Cecidomyide.”
The following are the more important as regards arboreal insects
-—VizZ. :
Dasyneura, Rd.
“‘Crcipomyia, Lw. =
j ) RuaspopHaca, Westw.
‘‘Same number of joints in the # antenneas inthe 2. The joints
may be pedicelled or sessile. The second longitudinal vein reaches
the margin of the wing before its tip.
( Payropaaca, Rd.
| Bremra, Rd.
“The antenne of ¢ =26 to 27 joints; that of the 9 =14 to 15.
The joints are pedicelled. The second longitudinal vein reaches the
margin beyond the tip. The joints of the antenne of the f double
the number of those of @.
“Drenosis; Lew. =
“Hormomyra, Lw. = ANcEnInia, Rd.
“This sub-genus is distinguished by the gibbose thorax, which is
often drawn over the head. The second longitudinal vein ends as
in the preceding sub-genus. Wings without lustre.
342 FOREST ENTOMOLOGY.
CyLinprocera, Lioy.
“ ASPHONDYLIA, Lw. =
: | PuyttopHaaa, Rd.
“ Antenne with short hairs of equal length ; joints cylindrical and
sessile ; no verticils. Same number of jointsin f~ and 2. Second
longitudinal vein reaches the margin of the wing, beyond its tip.
Wings shiny.”
As the insects in the family are so very small in size, it might be
best for practical purposes to consider them according to the injuries
they inflict on the respective arboreal food-plants—viz. :
(1) Foldings and rollings of leaves.
(2) Galls on leaves.
(3) Galls on stems or stalks.
(4) Various injuries or deformities of shoots, We.
It is, however, not practicable to attempt reconciling this arrange-
ment with systematic classification.
Hitherto this family has not been very carefully studied in forest
entomology, and the chief points for the discrimination of species are
very minute, so that recourse must be had to the microscope. The
main points are, the “ breast-bone” in the larval stage—an “ anchor
process” found on the first thoracic segment; the venation of the
wings; and the genitalia of the males.
By stupefying the insects with chloroform we can very easily
examine with the inch objective. It is necessary to do this, how-
ever, In order to carefully note all the characters, more especially as
they change colour rapidly after death, and they are most fragile to
mount as microscopic slides.
Crcipomy1A (DasyNEURA!) MARGINEMTORQUENS, Winn.
This insect is found on the common osier (Saltx viminalis), and
forms galls on the edges of the leaves,—often on both sides of the
leaves,—and rolled from the base to nearly the apex (fig. 313). These
galls or foldings are on the under side of the leaves, and rolled towards
the midrib. The rolled portion of the leaf is generally smooth, and
of varying shades of colour, from pale-green to purple and chocolate-
brown. The galls appear early, and may be found from June to
1 The generic names given in parentheses are those usually adopted at the
present time. I am indebted to Mr Theobald for this improved arrangement.
DIPTERA. 343
October. It is quite possible there are several broods, as I have
hatched them out in confinement in Northumberland from the begin-
ning of July to the end of October; and as the larve pupate within
the galls, artificial hatching is very simple, provided we see that they
are in the pupal stage prior to being placed in a glass-covered box.
By stupefying the insects with chloroform we can very easily examine
them with the inch objective.
Male.—The body and antenne are darkish-brown colour; antenne
15- to 16-jointed, as long as the body. The thorax slightly reddish ;
abdomen yellowish- brown; wings covered by darkish hairs. The
Fig. 313.—Leaves of Salix viminalis rolled by Cecidomyia marginemtorquens.
legs are of a lightish colour, and slightly tinged with red at the joints.
Length 1 tol} mm. (Fig. 314.)
Female.—The body is of a dark-grey colour, with rather com-
paratively longish halteres. Face light-grey ; the wings are clear,
but hairy, more especially at the edges. Eyes large, deep velvety-
black. The head and thorax black, with stiffish erect bristles ;
abdomen dark-grey above, light-grey beneath. The antenne light-
grey, with a darkish tinge throughout. The legs are light in colour;
oviduct long and slender. Length 1-2 mm. (Fig. 315.)
The conspicuous difference between the antenne of the male and
344 FOREST ENTOMOLOGY.
female, together with the small size and fascination of getting good
mounts, make this an interesting microscopical object.
Crcrpomyia (DasYNEURA) CRAT#GI, Winn,
This species is found on the common thorn, but more especially on
clipped hedges. The gall (fig. 316) isoften a common and familiar
roadside object. It is formed of a tuft or rosette of leaves on the
tips of the young shoots, and generally on shoots at the top of the
hedge, which grow after the previous year’s cutting. There is gener-
ally only one gall on the top of each shoot, but they are often found
Fig. 314.—Cecidomyia marginemtorquens Fig. 315.—Cecidomyia marginem-
(male). torquens (female).
so numerous that scarcely a twig is left untouched. The larve live
gregariously within the cluster of the deformed sessile leaves. Each
leaflet is thickly studded with short, stiff, blunt, erect hairs, which
provide protection for the larve.
“Imago black, with yellowish palps. Antenne 16-jointed in d,
15-jointed in 2. Oviduct long, and yellow at the tip. Sides of
thorax and metathorax flesh-coloured. Abdomen flesh - coloured,
with black bands. Halteres white. Wings hyaline; black pubesc-
ence and costa. Second long. vein bends forward at its junction
with the transverse veinlet, then, passing in an almost straight
line, joins the costal a little distance from tip of wing. Length,
3 lin.” }
1 An Account of British Flies, by Fred. V. Theobald, p. 67.
DIPTERA. 345
Crecipomy1a (DasyNeurRA) TAXI, Inch.
This species is found on both the English and Irish varieties
of yew. It forms a cone-shaped gall of tufted leaves (fig. 317).
There is only one larva in each rosette, and it lives and pupates
within the gall. The imago emerges either in the last week of May
or first week in June. This species is difficult to rear artificially,
therefore it is important to place them in confinement about May 20
or so; and as the galls shrivel up very quickly, it is advisable
to gather fresh specimens every two or three days about the date
mentioned. So far as this species is concerned, dates are important,
Fig. 316.—Shoot of hawthorn hedge Fig. 317.—Twig of yew injured
injured by Cecidomyia crategi. by Cecidomyia taxi.
having regard to the difficulty of rearing. I have gathered them for
artificial hatching about the middle of May, and they have all
shrivelled up so much that they never hatched; and again I have
gone to the trees about June 10, and the “bird had fled,” leaving
the empty pupa-case on the extreme tip of the rosette.
Male.—Antenne 15-jointed ; joints verticillate pilose ; basal joints
red, others light-grey. Eyes large, black ; thorax orange beneath,
dorsum black. Halteres bright orange; abdomen light-grey, with
dorsal orange streak ; genital armature light-brown ; wings light-grey,
slightly hyaline, legs of a uniform light-grey, anterior pair slightly
orange-coloured.
Female.—Antenne light uniform grey, very pilose, 18 - jointed.
346 FOREST ENTOMOLOGY.
Thorax light yellowish- orange beneath, above pilose dark. Wings
as in male; abdomen orange, with paler oviduct, and covered with
black hairs; legs uniformly dark-
brown, with greyish pubescence.
CECIDOMYIA(RHABDOPHAGA) ROSARIA,
Lw. (Willow Rose-gall Midge).
The galls caused by this insect
(fig. 318) are fairly common in
Northumberland, more especially in
the hilly districts, where there is
an abundance of scrub of the goat
willow (Salix caprea). The galls
may be found throughout the winter
months after every leaf has disap-
peared, and as many of the larve
Fig. 318.—Shoots of Salix caprea injured | pupate within the gall, it is well to
A ee collect them when dry for artificial
breeding. The insects appear about the middle of May, and deposit
their eggs in the terminal shoots. The gall very soon forms, as I have
found it by the first week in June. The gall itself is simply a rough
rosette of leaves formed in conse-
quence of growth being arrested.
Adult insect, female.—Expanse
of wings about 6-8 mm. Anten-
ne lightish, inclining to grey on
upper side. Thorax greyish,
“~~ very hairy. Abdomen flesh-col-
Ley | \ oured, telescopic portion of seg-
< ments very elastic, other por-
tions dark and hairy, under side
o/ uniformly flesh-coloured, with
greyish silken hairs. Eyes black,
wings greyish, veins dark-grey.
Halteres light. Legs greyish, with red foot.
Male.—Antenne greyish-black, and joints very hairy. Eyes black.
Base of wing flesh-coloured. Thorax darkish grey, hairy. Abdomen
uniformly grey, and hairy. Legs same asin 2. (Fig. 319.)
Fig. 319.—Cecidomyia rosaria (male).
DIPTERA. oan
CrcipoMy1a (RHABDOPHAGA) SALICIPERDA, Duf,.
(Willow-wood Midge).
This species injures the stems, from two years old and upwards, of
several species of willow, and can therefore be readily distinguished
from C. sa/icis, which confines
its attacks to young twigs.
In figs. 320 and 321 we have
a representation of the damage
done to a species from Kew
Gardens. Fig. 320 represents
a cross section of the stem,
showing the depth of the — Fig. 320.—Section of willow stem showing injuries
caused by Cecidomyia saliciperda.
injuries; and fig. 321 repre-
sents the damage as revealed by a very thin shaving or “slab”
taken off.
As I received the specimens after the insects had hatched, I give
the following account from Dr R.
Stewart MacDougall : !—
“This is a tiny fly, 2 to 3 mm. long (the
female is a little larger than the male),
with head and thorax black or black-
brown, and with black hairing. The
wings are milky white, with whitish hairs.
“The eggs, rounded and _ orange-
yellow, measure 0°40 mm. in length.
“The larva is rounded at both ends,
or somewhat spindle-shaped. It has a
well-marked anchor process, and on
magnification little projections can be
seen on the edge of the body, and warts
on the top of the body.
“The pupa is bright yellow, the
limit of the wings reaching to ring 4 and
the feet to ring 8. At the base of the
antennz two brown horns can be seen.
“The females lay their eggs on Salix alba, S. fragilis, S. caprea,
S. purpurea, S. viminalis, and exceptionally on white poplar.
domyia saliciperda.
1 Journal of the Association of Economic Biologists.
348 FOREST ENTOMOLOGY.
‘The parts chosen for egg-laying are most commonly about two
years of age and more, with twigs up to three inches in diameter.
“ Life-history.
“The female does not bore (her ovipositor is too weak), but lays
her eggs in chains or rows on the bark.” The larvee bore into the
bark, but by the time they enter below it the cambium has already
made the first layers of wood. Owing to the irritating presence of
the larve, the cambium gives rise to irregular streak-like growths,
through which the pests make longish excavations ; the galleries are
irregular. Between the larval galleries the wood is normal in con-
dition. It is possible that the larve may not really need to bore in,
as the activity of the cambium, with its wood formation, may be
sufficient to enclose them.
‘For a time the bark stretches, accommodating itself to the in-
creased thickening, so that only spindle-shaped swellings show ; but
ultimately it ruptures and hangs down in shreds. For pupation the
full-fed larva betakes itself to the periphery, pupation taking place
under only a thin external layer, which is easily broken through by
the two horns of the pupa. The empty pupa skin, with its ‘forehead
horns,’ may be seen jutting from the round hole until the weather
removes it. The bark from which flies have issued may be seen
riddled with small holes.
“There is one generation in the year, the larve tunnelling from
June or July till the next April, May, or June.
“ Measures of Preservation and Remedy.
“1. Cut off and burn infested shoots before issue of the brood. A
very observant forester will recognise the swelling before rupture of
the bark, and should remove it. Another sign of larval presence is
the poor leafage. The cut-away parts must not be left lying, else
development and issue may be completed.
“9. Streak over with tar the places attacked, as though the pupa
may push its way through, and the fly will be caught in the sticky
material.”
CrctpoMyIA (RHABDOPHAGA) HETEROBIA, Lw.
This species, which gives rise to the malformations as seen in fig.
322, is, I have found, often very closely associated with C. marginem-
DIPTERA. 349
torquens. Both species were found in the nursery. C. marginem-
torquens was in great evidence on the leaves of Salix viminalis, but
no terminal buds were infested. On the other hand, the terminal
buds as represented in the figure were infested on the species of
willow known locally as the Wentworth seedling golden willow, and
some of the leaves were rolled as in Salix viminalis (fig. 322), but
not to any appreciable extent.
The male is about 5 to 6 mm. in expanse of wings. Colour
blackish on back, and grey on belly side. Eyes black. Antenne
*
Fig. 322. —Leading shoots of a species of willow injured by Cecidomyia heterobia.
darkish-brown. Palpi lightish-grey. Thorax clothed with greyish
hairs. At base of wings a yellowish-orange. Wings hyaline, and
clothed with greyish hairs. Veins dark-grey. Legs lightish-grey.
Abdomen uniform dark-grey. Gentalia dark-brown.
Crcrpomyra (RHABDOPHAGA) SALICIS, Schrk.
(Willow-twig Midge).
The gall which is formed by this insect is found on various
species of willow throughout the latter part of the summer and
winter. The gall is formed by the gregarious larve feeding upon
350 FOREST ENTOMOLOGY.
the pith, and thus causing the woody cells which surround it to
swell out, as in fig. 323, The galls are always found on the twigs
of the tree or bush, and between the
internodes.
The perfect insects hatch out about
the middle of May (May 10, 1905, in
Northumberland), and deposit their eggs
in the twigs of last year’s shoots. The
larve soon hatch out, and by their united
action, which creates a form of symbiosis,
stimulate excessive growth at the affected
part. The larve feed right on through-
out the winter, and pupate within the
gall about April. The exit of the flies
may be recognised either by the flight-
holes or by the empty pupal-cases pro-
jecting from the gall.
The fly is about 6 mm. in expanse of
wings. Eyes black. Antenne dark.
Wings hyaline, and at the base they are
of a light vermilion colour. Halteres
white on the knob portion, and same colour as wings at base.
Thorax darkish, with two yellow-grey longish strips. Abdomen
variable in colour, sometimes dark
Fig. 323.—Twig of Salix caprea in-
jured by Cecidomyia salicis.
. above and red below, but as a rule
, darkish-grey above, and light with a
covering of silvery-grey hairs below.
Fig. 324 is a representation of the male.
The larve and pupe are of a light-yel-
low or orange colour, and, as a rule, from
12 to 30 are found in a single chamber.
CrcrpoMy1A (DASYNEURA) TILIAM VOL-
ENS, Rubs. (= C. sauicis, Schrk.)
Fig. 324.—Cecidomyia salicis (male). This species forms galls on the ter-
minal shoots of lime-tree branches and
the base of the leaf-stalk, about the size of a pea. The leaves are
deformed and disfigured, and growing with the point of the shoot
DIPTERA. avail
spoiled, but are found principally on shoots growing as suckers from
old stem. (See figs. 325 and 326.)
Larva yellow-orange colour, 2 mm. long. Head long, thin, and
pointed, footless. Has habit of anchoring anal end, raising head, and
making a motion or two in the air, then placing head to tail end, thus
making body a sort of loop, and then giving a high and clear leap off
the table to a distance of two or three inches. Mr Theobald says:
Fig. 325.—Leaf of lime-tree injured by Cecidomyia Fig. 326.—Shoots of lime-tree injured by
tiliam volens. A normal leaf is placed behind Cecidomyia tiliam volens.
the injured leaf for identification.
“T have found this very harmful on clipped and trimmed limes used
as ‘blinds’ in suburban gardens.”
Dipnosis (CLINODIPLOSIS) BOTULARIZ, Wtz.
This species is shown by the photograph (fig. 327). The larvae
live in a sort of pea-pod-shaped recess formed by rolling the leaf
inwards, and stimulating the growth of the leaf in thickness. The
larve secrete a liquid and, as it were, half swim in it. They are
white with a central streak of green in the body. It is said they fall
to the earth, pupate, and appear as flies in the following May. I
found them very common at Bellingham, in Northumberland, about
352 FOREST ENTOMOLOGY.
the middle of June every consecutive year, but have not succeeded
in hatching the insect.
Miiller, in ‘Gardener’s Chronicle,’ 1870, gives the following descrip-
tion of this insect: “It. is reddish-yellow, with a white beak. Its
thorax shows three narrow, short, pale-brown streaks ; the poisers are
pedunculated and whitish ; in the segments the abdomen is brown,
each segment with a fine brownish lateral streak ; the head border of
the segments beneath is fringed with long whitish hairs. The six
legs are long and slender, brownish, and clothed with a white pubesc-
ence. The wings are comparatively large, and sparse greyish hairs,
and suffused with a weak iridescent violet ; their veins are brownish.
Fig. 327.—Foliage of ash injured by Fig. 328.—Edges of oak leaves
Diplosis botulariz. folded by Diplosis dryobia.
The feelers are brownish, 26-jointed in f and 14 in 2. The latter
furnished with a short ovipositor.”
Dretosis (MacroDIPLosis) DRYOBIA, Lw.
This species causes the leaves of oak to fold over, as depicted
in the illustration (fig. 328). The folded portion is of a light-yellow
colour, and the larve live within the folded portion. They pupate in
the ground.
I found this species very common in Cheshire in the hedges. It
often happened in that part of the country that young oaks grew up
in the thorn hedges, and were of course switched with the thorns, and
this species was generally found on the foliage of those hedge oaks.
Os
or
Os
DIPTERA,
Dipeiosis (HARMANDIA) TREMUL&, Wtz,
>)
Theobald says: ‘The larvie of the ‘aspen gnat’ seem to form two
kinds of galls: the first are formed on the leaves of Populus tremula—
these are red galls, the size of a pea; the second kind is the well-
known gall formed on the leaf-stalk: each gall is inhabited by a
single larva, which pupates in the ground (Winnertz).” !
I found what I now suspect to have been the first form, in June
1897, in High Legh, Cheshire, but the latter I have never found, and
am indebted to Mr E. T. Connold for the form as shown in fig. 329.
Fig. 329.—Galls on leaf-stalks of aspen poplar caused by Diplosis tremule.
(From photo by E. T. Connold.)
Theobald thus describes the fly : ‘‘ Imago—dorsum blackish-brown,
with two rows of whitish-yellow hairs; abdomen dark-brown, with
thin flesh- coloured incisions and white hair. Posterior half of
seventh ring and the rest of the abdomen flesh-coloured; % genitalia
black; 2 yellow. Wings large, grey, with thick blackish-grey hairs,
third longitudinal vein bending in an almost straight angle to the
posterior edge; 1 to 14 lin.”
1 An Account of British Flies, by Fred. V. Theobald, p. 75.
Z
304 FOREST ENTOMOLOGY.
HorMomyYIA (OLIGOTROPHUS) PILIGER, Lw.
The larve of this insect cause galls on the leaves of the beech
(Fagus sylvatica). The galls (fig. 330) are pilose, more or less gregari-
ous on the upper surface of the leaf, but as a rule generally arranged
near the midrib. The colour is somewhat variable—at first yellowish,
then gradually deepening to various shades of red or brown. They
may be found from the beginning of July right on to the end of the
summer. The larvee pupate within the gall.
Hormomyia (OLIGOTROPHUS) CAPREE, Wtz.
This is a pustule-forming gall, as it were, Imasmuch as it may be
compared to an eruption arising from a sting on the midrib of the
A
Fig. 330.—Galls on wpper surface of beech leaves Fig. 331.—Leaves of goat willow gatied
caused by Hormomyia piliger. by Hormomyia capree.
leaves of Salix caprea (fig. 331). The midrib itself is more or less
conspicuous, while the gall is simply the adjoining portion of the leaf,
transformed into a hard woody structure. The colour varies from
pale-green to pale-yellow. It may be found from June to October.
The larve pupate in the ground, and the flies emerge during the
spring.
Hormomyta (Mrxiona) Faai, Hartig.
The gall is formed on the upper surface of the leaf, and is a
glabrous cone-shaped structure about 4 mm. high. ‘The colour
varies from green to yellow, and reddish. It may be found from
OS
or
Or
DIPTERA.
July to September. When fully ripe it falls to the ground, where
the larvee pupate, and the flies emerge the following spring. I have
found it in Alnwick parks, but it is not so conspicuous on the leaves
as C. piliger.
ASPHONDYLIA SAROTHAMNI, Lw.
This insect is important from a collector’s point of view, but may
easily be overlooked, as the galls formed by the larve very much
resemble the unopened flower-buds (fig. 332). They are larger in
size, and comparatively hard in the outer struc-
ture, being lined with a greyish pubescence, and
containing a single larva. The metamorphosis
takes place within the gall.
The flies (fig. 333) hatch out from the begin-
ning to the end of June, and in order to follow
out the development they may be looked for about
the first of May, as they are then in the larval
stage. The pupal stage is comparatively short.
As compared with the Cecidomyia, the flies
are very much larger, and the venation of the
wings more distinct. Rody dark-grey, head dark,
and wings brown and hairy. Antenne of female
13- or 14-jointed, the three joints at the tip
being very small in size.
Fig. 334 is a photograph of the pupal form.
LaSIOPTERA RUBI, Heeg.
Fig. 332.—Galls on broom
The larve of this insect cause galls on the (use! Py Asphondylia
stems of the common bramble (Rubus fruticosus)
fic. 335), and it is of course more interesting as an entomological
ro) > co) ro)
specimen than a forest insect. I have only twice found it—once in
Cheshire, and very plentifully near Ville la Villiers, Belgium. It
is, however, said to be very common in some parts of the south of
England. It is harmful to raspberries, forming galls on the canes as
on the bramble. The size of the galls is very variable, inasmuch as
the gall may be simply a slight excrescence.
With regard to the description of the species, Theobald says: ‘In
fo) b)
their habits they resemble the Cecidomyide, infesting plants much in
356 FOREST ENTOMOLOGY.
the same way. The larve are much the same as in the Cecids,
having the same peculiar reddish hue and curious ‘ breast-bone.’”
The larve live in excrescences on the stems of various Rubi, and
metamorphose in the galls. They appear in May.
Imago.—Brownish-black ; antenne of 2 black, shorter than the
Fig. 334. — Pupa
of Asphondylia
Fig. 333.—Asphondylia sarothamni. sarothamni.
head, 22-jointed. Palpi white; head white and brown, Thorax
deep black with a silvery white band around the edge in front, with
two pinkish or golden stripes partly along the top; seen in certain
lights, in others the centre of
the thorax is black ; scutellum
tawny. Abdomen black, with
four silvery bands - slightly
broken in the middle. <Ab-
domen and ¢ genitalia covered
by white hairs. Legs also cov-
ered by silvery hairs and scales.
Wings clear; costa thick and
dark, in the middle a white
spot; root of costa also pale.
2 resembles ¢, only the
antenne are 24-jointed. Ovi-
Fig. 335.—Gall on stem of bramble caused by : : 0
2 Tas a eb positor yellowish-white ; long ;
no lamelle. There are beau-
tiful scales on the venter of the abdomen as well as the legs.
After death the colours turn browner, and the white hairs less
silvery.
DIPTERA. 357
Crcipomy1a (?) prce#, Henschel.
In the spring of 1906 I began to dissect a number of cones of the
common spruce, with a view to looking for the larve of Mevastigmus.
In one batch the cones showed a number of light orange-coloured
larve. These were put aside in glass jars, and from May 13 to May 20
the jars simply swarmed with specimens of Cecidomyia. Reference
to available English literature has failed in giving any account of
this species, but the more important, German text-books give two
species—viz., C. pice as living in the seeds of the common spruce,
and C. abietiperda, Hensch., me
as living in the shoots of
spruce. The species in ques-
tion would appear to coin-
cide with the former. A
careful dissection, however,
showed that not only many
of the seeds were eaten by
the larve, but also a very
large proportion of them had
hollowed out the thicker
portion of the bracts.
Famity AGROMYZIDZ.
The larve of this family are
said to mine leaves and do
other damage, but I have not
hatched out any of those
insects. - Fig. 336.—Galls on stem of species of willow caused
As regards family charac- by Agromyza schineri. (From photo by E. T.
2 Connold.)
ters, Theobald states: ‘“ No
costal bristles. First longitudinal vein short, the auxiliary connected
with it at tip; posterior transverse vein far distant from the border.
Front with strong bristles. Border of mouth with vibrissa on each side.
Third joint of antenne rounded, terminal bristle bare or pubescent.”
AGROMYZA SCHINERI, Gir.
This species is found on willows, and I am indebted to Mr E. T.
Connold, St Leonards-on-Sea, for the photograph as shown in fig. 336.
358 FOREST ENTOMOLOGY.
The gall is formed, through the agency of the cambium, on the side of
the twig. Growth is complete in September; the larva pupates in
the ground, and the fly emerges in spring.
Famiry PHYTOMYZID&A.
In this family the larve are leaf-miners, and, so far as the species
to be considered are concerned, they pupate within the leaf. The
puparia are barrel-shaped. According to Rev. W. J. Wingate, there are
several genera and species in the north of England, but as regards
identification of species and association with damage I have only
hatched two species.
As the species on snowberry leaves makes markings very much
after the manner of the larve of several micro-lepidoptera, it would be
well for the student not to be over-sanguine in naming insects from
markings without verification by hatching. It would be well to bear
in mind, also, that in those species where pupation takes place within
the epidermal skins of the leaf, specimens should not be placed within
the hatching-box until the creature has reached the pupal stage.
CHROMATOMYIA OBSCURELLA, FIn.
Phytomyza xylostet, Kalt.
The leaves of snowberry (Symphoricarpus racemosus) are often
thickly covered over with white trailing galleries, as in fig. 337. In
fact, in several parts of Northumberland in some patches this species
is so common that it was almost impossible to get a leaf without
markings.
The insect causing this damage has a double generation in a year.
The first generation appears in spring, probably in May, and the larval
markings appear in June. At first the larva moves very irregularly
around a common centre, but afterwards it ‘‘mines” more rapidly,
making long winding galleries. The larve pupate within the leaf,
and the flies appear in the last week in July. The flies of this brood
immediately deposit eggs on the leaves which have developed during
the summer, and the larve make similar markings to those of the first
generation, and pupate within the leaves, which of course fall to the
ground in autumn.
The flies, which are like small house-flies, are matt black. Eyes
dark red, wings hyaline.
DIPTERA. 359
CHROMATOMYIA ILIcIS, Curtis.
Phytomyza ilicis, Kalt.
(Holly Leaf-miner. )
In many parts of the country this pest, known by the name of the
Holly Leaf-miner, is very abundant. In fact, it is quite the exception
to find specimens of the common holly, Hodgkin, and a few other
varieties, to be quite free from it. (Fig. 338.)
The flies are very easily hatched out by artificial means, if the
infested leaves on shoots from the previous year are gathered, after the
larva has changed to the pupal stage, by the latter end of April or
Fig. 337.—Leaf of snowberry mined by Fig. 338.—Leaf of holly blotched
Chromatomyia obscurella. by Chromatomyia ilicis.
beginning of May. In Northumberland the flies hatch out in the
first week of June.
In general appearance the fly resembles a small specimen of the
common house-fly. Expanse of wings, 3} to 4mm. Eyes of a shining
chocolate colour. Body, as a rule, entirely black and hairy. Wings
hyaline ; veins black; halteres waxy white. Under side of abdomen
sometimes slightly yellow, and on upper side of abdomen there are
frequently narrow whitish bands across the segments.
The full-grown larva is about 3 mm. long, white and footless, and
the puparium is rather shorter, barrel-shaped, and of a leathery colour
and texture.
As regards the life-history of this species, I have several times tried
to work it out, and so far as my observations go, they coincide with
the following description from Mr Collinge, the University College,
Birmingham :—
360 FOREST ENTOMOLOGY.
‘Early in June the female fly deposits her eggs on the under side
of the leaves ; so far as my observations go, only a single egg is placed
on each leaf, and on the midrib close to the leaf-stalk. In seven or
eight days the larva hatches out, and makes its way into the vessels of
the midrib, and then commences to slowly travel forwards. In Sept-
ember, October, or November it leaves the vessels, and tunnels its
way into the soft green tissue of the leaf, forming galleries which give
the leaf a blistered appearance.
“ By the following April the larva is mature, and it now bites
through the epidermis in order to provide an exit for the fly. Like
many other flies, it retains its last larval skin as a protection for the
thin, white, pupal case. ‘The puparium is of a flattened oval form,
and marked by a number of regular transverse segments—the original
segments of the larval skin. Within this is a second skin, which is
the true pupa.”
As regards any remedial measures against this pest, it is certainly
very difficult to suggest anything which would be at all practical. Mr
Collinge advocates spraying the foliage with paraffin near the time
of the flies hatching out, so that the bushes may be made offensive to
the females about to deposit their eggs. Spraying with diluted
paraffin as a check against egg-laying is often productive of good
results in some garden and farm crops, but it is obviously more diffi-
cult to carry out in practice in the forest.
As the damage is always on the leading shoots, all prunings done
in autumn or winter to hedges or bushes should be burned. It may,
however, be remarked that only judicious pruning of trees or bushes
is intended, as the clipping of hollies into certain stiff forms is quite
an objectionable feature. Healthy hollies shed their leaves in spring,
and those may be burned; but this would not in any way check the
pest, inasmuch as the blistered leaves on the ground have discharged
their parasitic pests a year or two prior to falling off.
Famity BIBIONIDA.
The members of this family, many of which are of a good size, are
mostly black, or black and yellow. No one can fail to find several
species along the banks of our streams or in damp woods from May
till September. Larve phytophagous, on living plants, rotting veget-
able matter, dung, &c.
DIPTERA. 361
Brsto marct, L. (St Mark’s Fly).
This insect is known as a dune-fly, and has never been considered
as a forest insect. Its connection with forestry was introduced to me
through Mr Thring, Boughton Kettering, who sent me samples of one-
year seedling ash very much eaten on the thick portions of the root.
The damage varied in appearance, and was therefore suggestive of
being the work of different insects. Mr Thring kindly sent me some
larve on ash seedlings. They changed into pupe near the end of March,
and hatched" out flies (fig. 339) about the beginning of May, which
were identified by Rev. W. J. Wingate, Bishop Auckland, as Bibio
marc?. Judeich and Nitsche say they are not of much importance in
Fig. 339.—Bibio marci.
a, females ; b, males.
forestry ; but the roots in question were very much injured, and Mr
Theobald informs me that they are often very injurious to the roots
of hop and other plants.
References to Literature consulted.
Binnie, Francis G. On the Asphondyliz of the Glasgow District. Nat. Hist.
Soc. Glasgow. 1876.
Cambridge Natural History. Insects. Part II. 1899.
Collinge, Walter E. Report on the Injurious Insects of the Midland Counties.
1904-6.
Collinge, Walter E. The Life-history of the Pear Midge. 1905.
Frank. Die Krankheiten der Pflanzen. 1896.
Gardener’s Chronicle, various articles from. 1870.
a0 FOREST ENTOMOLOGY.
Judeich und Nitsche. Forstinsektenkunde. 1895.
MacDougall, R. Stewart. Proceedings of the Association of Economic Biolo-
gists. Vol. i., Part I. 1905.
Niisslin. Leitfaden der Forstinsektenkunde. 1905.
Theobald, Fred. V. An Account of British Flies. 1892.
Theobald, Fred. V. Various miscellaneous writings.
Verrall, G. H. <A List of the British Diptera. 1901.
Wingate, Rev. W. J. A List of Durham Diptera. Transactions of the Natural
History Society of Northumberland and Durham, vol. ii. 1906.
363
CHAPTER xX.
art. I,
PS YLLID &.
CoNSIDERED as a distinct group, this family of insects is very easily
overlooked, even by workers who have a fair knowledge of economic
entomology, inasmuch as they may be mistaken for the Aphidid or
green-fly on the one hand, and the Cicadide on the other.
The following may be taken as the chief characteristics of the
group: Head produced in front, but somewhat broad ; eyes-large and
prominent ; three ocelli present, one close to each eye and the third in
the middle of the forehead. Antenne inserted in front of the head,
usually ten-jointed, with two large basal joints, the remainder of the
joints filiform, and terminated by a slender forked bristle.
The thorax is well developed. The wings, when at rest, are folded
roof-wise over the body. As the wings are nearly all equally clear,
they may be termed four in number, and not elytra and wings. The
venation of the upper is very simple. The subcostal vein passes
obliquely across the wing, ending in a small indistinct stigma, and
top]
dividing the whole wing into seven distinct open cells.
The front pair of legs are rather shorter than the other two pairs.
All legs are well formed for leaping. The tibie in the second pair of
legs are somewhat longer than in the first pair, and still longer in the
third pair. In the hinder pair the tibie have a few blunt spines at
the apex. The tarsi are two-jointed, and terminated by a distinct
claw. In the hinder pair of legs, the second joint of the tarsi, like
the tibie, have also a few blunt spines. There is a very notice-
able peculiarity in the adult insects on the food-plant—viz., that
they take to flight very reluctantly from approaching danger, and
seem to depend almost entirely on their leaping powers as a means
of escape.
364 FOREST ENTOMOLOGY.
The abdomen should be carefully noted, both as fresh or prepared
specimens, as the genital segments are so clearly defined that the
sexes are very easily determined, more especially if a side view be
presented.
The development of the creature, from its early larval stages to the
winged insect, forms a most interesting study, and should also be
examined both as fresh and as prepared specimens. The former will
show the wax cells, the latter the structural features. Witlaczil
describes four distinct larval stages from embryo to 1mago, and the
student will be well repaid by following up the development.
As regards classification, it may be noted that Dr Franz Low, in
his paper “Zur Systematik der Psylloden, 1878,” divides the family
into four sub-families — viz., Liviine, Aphalarinz, Psylline, and
Triozine. So far, however, as forest insects are concerned, the sub-
family Psyllinz are the most important.
The Psylline are again divided into two genera—viz., Psyllopsis
and Psylla. In the former genus we have two species on ash-trees,
and in the latter there are several species found on different trees.
PSYLLOPSIS FRAXINICOLA (Fiirst).
If the foliage of our large ash-trees be beaten over an inverted
umbrella during the summer months, we shall find a very large num-
ber of green Psyllide, amongst other insects. These are Psyllopsis
Jraxinicola. They cannot be said to be injurious to the foliage to
any appreciable extent, inasmuch as they simply suck the juices, and
do not deform the leaves in any way whatever.
The whole body of the insect is of a pale-yeilow colour, the tips of
the antenne and the claws of the feet being often darkish-brown.
Length 3 mm.
PSYLLOPSIS FRAXINI (Linn.)
In early summer the foliage of the young ash-trees in the nursery-
rows is often rolled up, as shown in fig. 340, the main char-
acteristic feature of the damage being that the whole of the com-
pound leaf is injured. Sometimes a single compound leaf springing
from the stem may only be affected, and at other times the damage is
so bad that almost the whole foliage is injured. As this injury appears
most conspicuous just when the plant is most active, it is obvious that
the growth must be appreciably affected. A careful examination will
PSYLLID. 365
show that the individual leaflets are rolled towards the centre in a
somewhat oblique manner. The natural green colour of the leaf is
substituted by large brownish mottled streaks, As long as the injured
foliage is attached to the plant, the leaflets are comparatively stiff; but
if removed from the stem, they soon get as flabby and tender as
tissue-paper.
If the leaflets are unfolded we find a large quantity of ‘ cotton-
wool,” protecting larve and eggs. This diversity in the phases of
development is therefore suggestive of the adult insects subsequently
appearing at ‘Varying dates.
As regards larve and pupe, it is difficult to determine where the
one stage ends and the other begins,
except that after one or two larval
moults the wing-cases are more fully
developed, and the latter stages may
therefore be termed pupze.
Fig. 340.—Leaflets of ash injured by Psyllopsis fraxini.
The adult insect is somewhat variable in colour, he head is a
reddish-yellow, with dark projecting eyes. Thorax a variable yellow
with black markings; abdomen black above and yellow below.
Antenne ten-jointed, long and slender joints, becoming smaller
towards the apex; last joint very small, and terminated by a forked
bristle. Wings, smooth in cells, veins, and even edges. Clouded at
edges. Legs a reddish-yellow. Length 24 to 3 mm.
The clouded wings and brown markings of the body are quite
characteristic features of this species, inasmuch as the colour of the
insect harmonises in a very wonderful degree with the chocolate-
pinkish colour of the leaflets.
366 FOREST ENTOMOLOGY.
The life-history of this species does not appear to have been worked
out, but it would well repay any one to follow it out.
As regards any remedial measures, it would perhaps be best to
collect (by clipping off) the individual injured leaves while they
remain in the young stages, and such clippings should be burned.
In its younger stages the ash is a tree which is somewhat difficult
to grow to perfection in the nursery, but more especially in the young
woods. Hence it is well to encourage vigorous growth.. The seed-
lings should be transplanted at a year old and grown for two years
in the nursery-lines, and then either transplanted in the nursery or
otherwise in the young woods, under the protection of wire-netting,
and if possible also under the sheltering influences of more hardy
species planted in advance. If they are transplanted in the nursery-
lines as one year, two years old, or say 18 to 24 inches in height,
they should be quartered the following year—that is, the best plants
should be taken out, and so thin the crop that “spindling” is pre-
vented in those which remain. The latter class should then make
very useful trees for park planting, where a method of systematic
groups at regular intervals, for continuity of effect, is the object in
view. If, on the other hand, two-year
seedlings are transplanted in the nur-
sery, then it is often advisable to grow
for one season and cut the plants down
the following year close to the ground,
taking care that only one good, strong,
vigorous shoot will spring up. Atten-
tion to these practical points, together
with any improvement on them, is
the best antidote against any appreci-
able damage accruing from the in-
juries of the insect in question.
Psyiua BUXxI (Linn.)
Fig. 341.—Leaves of box injured by
Psylla buxi.
a, normal leaves ; b, injured leaves.
This insect in its larval stages, and
also in its early adult stages, causes the
leaves of the box to curl up, so as to give rise to a sort of pseudo-gall,
as seen in fig, 341. Fig. 341 (a) represents the normal twigs of box
leaves, and fig. 341 (>) shows the “galls” caused by the insects.
PSYLLID®. 367
The adult insects may be beaten from box plants, especially those
with rolled leaves, in showers throughout the summer months, and odd
specimens can also be beaten from
box-bushes during the winter months.
An examination with the pocket-
lens will at once give the impres-
sion that the bodies of the tiny
insects appear “to have been made ”
out of box leaves. In other words,
the colour of*the insect, as compared
with the box leaves, is about the
best possible mimicry in the whole
realm of forest entomology.
The prevailing colour of the insect
is sea-green. Head and thorax pale-
green; antenne varying in colour
from yellow to brown. Wings
hyaline ; abdomen green; legs yel-
lowish-green, with darkish tarsi.
Length 34 mm.
PsyLia cRaTHel (Schr.)
The injuries caused by this insect
are not of very much importance,
and they are very apt to be over-
looked. They may be found either
on a hawthorn-tree or otherwise on
a switched thorn-hedge, but more
especially on the latter. Just as the
young shoots begin to grow the
larve of this species (fig. 342) seize
hold of the extreme tip of the
shoots and fasten themselves to
it gregariously all round the tiny
twig. The result is that, through
Fig, 342.—Young form of Psylla crategi
on shoot of hawthorn.
Fig. 343.—Tip of hawthorn shoot injured
by Psylla erategi.
@ shows the injured portion.
sucking the juices, the inflated portion dies off, as in fig. 343 (a); and
meanwhile the tiny larvee remove themselves to the foliage, change to
winged insects, and remain on the foliage all through the summer.
368 FOREST ENTOMOLOGY.
The adult insect is greenish in colour, but head and thorax are
almost white, abdomen darkish. Antenne yellowish-green, legs
reddish-yellow.
PsYLLA ALNI (Linn.)
About June 1 on an average season the tips of the branches of the
common alder (Alnus glutinosa) are thickly covered with a white
woolly down, as shown in fig. 344. These are the larve of Psylla
alni, and may by inexperienced entomologists be classified as Aphididae,
similar to American blight. The woolly covering acts as a protection
for the creature during the early stages of its existence. At this stage
they are very easily disturbed, and set
off rapidly as large white moving specks.
The larval and pupal stages cannot be
very easily separated ; but considering the
more advanced stage as pupa, it is, when
divested of its white overcoat, rather a
handsome insect. The prevailing colour
is green, with several dark transverse
spots across the body. The anal segment
is dark. The body shows “wing humps”
at a very young stage. The head is not
conspicuously separated from the thorax,
nor the abdomen from the thorax. The
wax hairs at the anal portion of the body
are quite a conspicuous feature.
Bigs 344s elie) Of adder amjured The perfect insect may be found
by Psylla alni.
throughout the whole summer. The pre-
vailing colour is a light-green. Head and thorax yellowish-green,
and studded with reddish markings; abdomen green. Wings
perfectly clear. Costal and stigma veins green; other veins some-
times darker. Legs green, with dark tibie and claws. Length of
insect when wings are folded about 5 mm.
The sexes can be very easily distinguished—partly by the abdominal
structure, and also on account of the antenne of the male being longer
than the antenne of the female.
It cannot be said that this insect is very injurious, as the summer
foliage does not seem to have been injured from the effects of the larval
and woolly secretions in spring.
CICADIDA. 369
References to Literature consulted.
Board of Agriculture Leaflet, A ad
Edwards, James. The Hemiptera-Homoptera (Cicadina and Psyllina) of the
British Islands. 1896.
Riley, C. V. Notes on North American Psyllide. Proc. of Biol. Soc. of
Washington. 1884.
Witlaczil, Dr Emanuel. Die Anatomie der Psylliden. Wien. 1884.
Part II.
CICADIDZ.
This family of insects is generally overlooked by the practical man,
inasmuch as he groups them along with the Aphididz or “ Green-fly.”
The injuries are not so conspicuous as to arrest special notice. In
fact, the injuries done by these creatures are of such a nature as to
suggest asking the question, What is damage? As regards the damage
actually done, three very general examples may be given—the first
from the nursery, the second from the garden or orchard, and the third
in the meadow. With regard to the example from the nursery, a
walk alongside a plot of wych-elms, say from 3 to 5 ft. high, in
August or September, coupled with a little observation, will show that
the foliage has entirely lost its green hue, and is of a sulphury-yellow
colour. If the leaves are slightly shaken, a shower of tiny active
insects of a yellow colour, harmonising with the foliage, will dance
about in all directions. These are known as Typhlocyba ulmi, and
may be taken as the most injurious of forest Cicadide. <A similar
example on pear-trees, more especially those on walls, will suffice for
those in the orchard ; and as regards those in the meadows, the most
common example is that of the “ cuckoo-spit ”—that froth-like spittle
substance which harbours the larva of a common example of a Cicadid.
Many varieties of deciduous trees harbour their own special species
of Typhlocyba, and some of them are very beautifully marked, and
would therefore form an interesting collection ; but the following very
2A
370 FOREST ENTOMOLOGY.
brief account of them is intended only for a formal introduction to the
family as associated with forest trees.
It has been remarked that they are very closely allied to Aphidide,
hence Buckton adopts the term Tettigide. The following table,! which
is perhaps chiefly of a microscopical character as regards tarsal struct-
ure, may therefore be given—viz. :
ORDER RHYNCHOTA.
Sus-OrpER HOMOPTERA.
Section I. Section II. Section ITI.
MonoMERA (Westw. ) Dimera (Westw.) TRIMERA (Westw.)
|
ie al F |
Aleyrodine. Aphidinee. Psyllide.
Thripide.
CocciDz. TETTIGIDA.
In size the British Cicadide show a considerable resemblance to the
Aphidide, but the most striking contrast is with regard to the wings,
which are coriaceous, more especially the upper wings or elytra. This
characteristic almost obliterates the venation. The under wings are
also coriaceous, but not so dense as the upper.
The head is always more rounded than in the case of the Aphidide
—in fact, it may be termed frog-shaped. The antenne are never very
long: they are extremely slender, so much so that even under the
microscope the joints are very difficult to count.
The insect feeds by means of a short proboscis, which is variable in
length but always three-jointed.
No cornicles are ever found on the body, nor any organs for secret-
ing special exudation as a protective covering.
The legs contrast with the Aphidide, inasmuch as they are well
adapted for leaping, the femoree and cox having powerful muscles.
The tarsi are three-jointed, but this is sometimes rather difficult to
determine by observation.
1 From Monograph of the British Cicade or Tettigide, by George Bowdler
Buckton, vol. i. p. xxxiv.
CICADID. og fk
With regard to the life-history of the Cicadide, they present some
important differences from the Aphidide. Males and females are pres-
ent throughout the whole season, and the latter are always oviparous.
The eggs, according to Westwood, vary in number from 300 to 400.
They are deposited in grooves of the leaves, cut by the female insect
with her saw or ovipositor. The incision being healed up by the
flowing sap, the eggs hatch out in due course into six-legged active
larvee, which feed by means of a proboscis, and after moulting change
into pupx, which are also active and show embryo wings. These
finally moult, and become active male and female insects. They feed
by means of a rostrum, which also forms an anchor when the insects
are asleep. The sap pumped up by this organ is ejected by the anus,
thus differing from the majority of Aphididee, which develop cornicles
for this purpose.
It will therefore be seen that the insects undergo incomplete meta-
morphoses, and are injurious in all stages.
With regard to typical specimens of Cicadide, I will simply take
a few of the most common species.
The most conspicuous species is that known as the “ cuckoo-spit,”
so called because of the white froth or spittle with which the larval
form protects itself. In early summer the froth is very common
indeed on grasses and low plants. In the midst of the froth the larval
metamorphosis is passed. The commonest species is known by the
name of Philaneus spumaria, sometimes referred to the genus Aphro-
phora ox “froth-bearer.” The species in this genus are relatively
large, and may be found plentifully on almost all kinds of bushes
when beating for other insects.
There is a curious opinion prevalent with regard to cuckoo-spit
among gamekeepers. They universally maintain that if a young
pheasant swallows this froth it always proves fatal to it. However
this may be, I cannot vouch for it other than on the strength of a
keeper’s opinion.
During the months of July and August a very beautiful and large
insect belonging to this group may be beaten in considerable numbers
from the oak branches. The insect is about 4 or 5 mm. in length.
The head is brownish or a light-chocolate colour, and the body pea-
green. It is called Macropsis lanio.
She FOREST ENTOMOLOGY.
Sus-FAMILY TYPHLOCYBIDZ.
Genus TYPHLOCYBA.
This genus is perhaps the most important as regards forest insects,
and kindred associations in several orchard or garden plants. These
may be beaten in showers from the foliage of pear-trees, roses, elm,
and alder. ‘They are small yellowish insects, about the usual size of
Aphidide, with elytra much larger than the body, but at once show by
their active leaping powers that they differ from them. On examin-
ation with the lens or microscope they appear beautifully marked,
with bright-coloured spots on the light-yellow bodyground.
TYPHLOCYBA ULMI (Linn.)
This species may be selected as a typical insect. The head is
yellowish or greenish-yellow, with dark conspicuous eyes, and slender
antennz which taper to the finest point. The thorax is also yellowish,
with dark transverse markings. The abdomen is divided into eight
segments or somites, each of which is ornamented with a dark trans-
verse marking, thus giving the insect a general appearance of being
black and yellow. The upper wings or elytra are coriaceous, and the
veins can only be slightly discerned with the microscope. The wings,
or under wings, are lighter in colour and less coriaceous. They are
longer than the body. The legs are yellowish, and slightly hairy.
(See figs. 345 and 346.)
Mr Fred. V. Theobald has recently worked out the life-history of
one of these insects, and the following extract is taken from his
writings :—
“THE Oak AND Fruit LEAF-HOPPER.
““TYPHLOCYBA QUERCUS, Fabr.
“ Typhlocyba flammigera, Amyot.
“Like all members of this family, the insect passes the winter in
either the adult or nymphal stages. Hibernation takes place in any
sheltered position. One may find them amongst fallen leaves at the
foot of hedgerows, in box hedges, amongst moss and lichens on
trees, and abundantly amongst conifers. In spring they appear
again, and feed upon the young leaves. In June they were first
noticed in numbers: possibly between their exit from winter quar-
ters and June a generation had appeared. It was not until July
CICADID. 373
that any marked damage was done to the leaves of apple, plum, and
damson ; then all stages of the insect could be found at once, and
the life-cycle easily followed. How many generations occur in the
year could not be decided, but apparently more than two. The
adult may be told by its beautifully marked anterior wings, with six
bright-orange and vermilion spots on a milky-white ground, and with
a large dusky network at the apex. They are subject to variation in
regard to the markings.
“Their length varies from 3 to 3°9 mm. Both nymphs and adults
feed mainly*on the under side of the leaves, but by no means always.
“They are not very active, and can easily be taken at rest on a
ial
: ae Sl
Cn
~s ~~
Fig. 345.—Typhlocyba ulmi. (Drawn by Fig. 346.—Typhlocyba ulmi.
P. J. Brown.) (Drawn by P. J. Brown.)
dull day. When disturbed they take a leap from the leaf, and then
use their wings, often flying a couple of feet away.
‘“‘Egg-laying seems a laborious task. By means of the saw-like
structure the female cuts a slit into the under epidermis, and places
one or more eggs just beneath it. A very minute and faint oblong
spot marks where they have been laid.
“The ova are very delicate, white, and oblong-oval in form, some-
what curved on one side, and blunt at each end. When nearly ready
to hatch they may be seen with a strong lens under the epidermis,
their position being plainly marked by the dark eye-spots of the
embryos. Length 0:04 mm.
374 FOREST ENTOMOLOGY.
“Egos under observation were found to hatch in four days, but
how long they had been laid was not known. Lingerland shows
that the American Grape-vine Leaf-
hopper (Zyphlocyba comes) remains
two weeks in the egg stage, and it is
quite likely this is about the period
taken by Typhlocyba quercis.
“The young emerge on the under
side of the leaf, and grow rapidly.
There are four moults in the nymph
stage. At first the young are very
pale, but gradually become yellowish
as the wing-buds develop. Towards
the end of nymphal life they are
most ravenous. The whole period of
growth lasts from five to six weeks,
the complete life-cycle probably tak-
ing fifty days. (See fig. 347.)
“They kept on breeding until the
first week in October, but in very
small numbers after the middle of
September.
‘“‘ Until they are mature these leaf-hoppers are very sedentary, and
even when adult do not jump as do other members of their tribe.” !
Fig. €47.—Young form of Typhlocyba ulmi.
fy
References to Literature consulted.
Buckton, George Bowdler. Monograph of the British Cicade or Tettigide.
1890.
Edwards, James. The Hemiptera-Homoptera (Cicadina and Psyllina) of the
British Islands. 1896.
Theobald, Fred. V. ‘‘New Hemipterous Fruit Pests in Britain’? — The
Journal of Economic Biology, 1907, vol. ii., Pt. I.
1 “New Hemipterous Fruit Pests in Eritain,’ by Fred. V. Theobald, M.A.
—-The Journal of Economic Biology, 1907, vol. ii., Pt. I.
Oo
CAP TE RXTE.
HINTS ON COLLECTING, PREPARATION, AND
MOUNTING.
In giving a few hints to those about to make a start in the study of
forest entomology, perhaps it may be assumed that students can be
divided into two classes—viz., those who wish to study the subject
partially as a branch of scientific forestry, and those who are anxious
to follow it out thoroughly as a division of economic entomology.
It is just possible that both classes may at the commencement be
undecided how they will follow it up, and it will therefore be advis-
able to begin in as simple a way as possible. Perhaps it may be said
that one of the charms of the study of natural history is to spend
as little money, and develop a taste and skill for making as many of
the necessary requirements, as possible. Unfortunately, this idea is
seldom put in practice.
As a walk through a forest in midsummer will appear to any one
not conversant with entomology simply a chaotic confusion of insect
life, it would be well for all aspiring students outside the guiding
influence of a college to join some local field club, or otherwise seek
the guidance of a local entomologist. Having done so, they may
begin to collect anything and everything within the forest, and solicit
the assistance of local naturalists for naming and classification.
To all those who have not had the benefit of any special course of
systematic training, it may be said that in this study, as well as in
many others, it is advisable to cultivate a general broad acquaintance
with the whole subject of entomology.
It is, of course, necessary to have a simple outfit of that class
generally recommended for boys about to begin the collection of
moths—viz., a net, chip-boxes, a pocket lens, two killing - bottles, —
376 FOREST ENTOMOLOGY.
cyanide of potassium and chopped young laurel-leaves,—a few setting-
boards, with the accompanying entomological pins and braces.
With regard to the killing-bottles, the cyanide should be prepared by
a local chemist ; and as regards the laurel bottle, only the young leaves,
about three-quarters grown, of laurel (Cerasus lawrocerasus) should
be used. To the rural student, or the young forester enthusiastic of
spending his spare time profitably, the above-mentioned outfit will
suffice for a season or two. And as regards storage of captures for a
time, the collected insects may be placed in store-boxes and labelled.
Having devoted some time to the study in general, it becomes
essential to begin the study of pure forest entomology. The student
must decide to do so in earnest, and to be prepared for difficulties and
failures. It will now be obvious that a more expensive outfit is
necessary, but again there will be no harm even if the more or less
wealthy student “make haste slowly.”
So far as the actual forester is concerned, the one on a small estate
has the advantage, inasmuch as he can supervise most of his work on
foot, and therefore have greater opportunities for observation, than
one on a large property, whose time is largely taken up in travelling.
It is necessary, first of all, to recognise the actual damage, and then
ascertain the cause of it. A little practice will soon enable him to
distinguish between insect and fungoid damage. It will be necessary
to take the damaged portion home, together with the injurious grub
or insect, and submit it to some arrangement for development and
observation. The observations should be most carefully tabulated in
a note-book.
It is, of course, essential to carry a simple outfit of boxes and
collecting apparatus in the pocket ; but they are so light that they will
not in any way interfere with clothing, nor will the placing of a
specimen in a box interfere with his duties. On the contrary, the
cultivating of this habit of observation will do a very great deal to
improve the individual. .
In addition to collecting the damaged portion during the actual
hours of duty, it is also advisable to go out in the evenings and beat
the larve or perfect insects from their respective trees. Thus we
should have a double method of study—viz., recognising the actual
damaged part, striving to ascertain the cause of it, and also discovering
the special insects which attack any particular tree. In the latter
method the comparatively young student may place all his captures
ON COLLECTING, PREPARATION, AND MOUNTING. 377
from one tree together in a specially prepared cage, and then finally
arrange the perfect insects according to the respective trees from
which they have been hatched ; but, on the other hand, the special
portion of damage should be most carefully kept by itself, and the
perfect insects arranged together with the actual damaged portions in
entomological order.
As time advances and the student makes progress, it will be ad-
visable to become more specific and less general. In fact, the correct
method of study would probably be to take a few special insects and
work them thoroughly out by means of study and observation. Having
regard to the shortness of human life, and the desire, or necessity, for
other subjects, the student of forest entomology must carry on simul-
taneously a number of observations with special insects and their
damage. Hence it is necessary to have separate hatching-boxes for
each species, but with regard to what is the best plan, individuals will
naturally differ from one another. The simplest plan, of course, is to
collect the larve just as they are about to change to pup, for then
they require little or no attention. However, this is in many cases
practically impossible, and it must therefore be remembered that
moisture is invariably the most important essential in insect life.
This may be obtained either from a bed of damp sand placed in the
hatching-case, or from the food-plant itself. Hence two simple
methods may be given. The first is, simply to collect as many old
glass jam-jars, from a pint to a quart capacity, as may be required,
place a little damp sand in the bottom, insert a fresh potato in the
sand, stick the stalk of the food-plant into the buried potato, change
the food from time to time, keep down the mould, and patiently await
the results. Where moisture is not so absolutely important, as, for
example, in bark - beetles, the following plan will often suffice—viz.,
get an empty negative or lantern-slide box, cut out a hole in the top,
leaving a little over half an inch of rim all round, get a spoiled
negative or lantern-slide (a by no means rare article in the hands of
an amateur), glue the cleaned glass to the rim left in the top, and you
then have a glass-covered box wherein you can place your specimen
and watch the results, noting daily all important points of develop-
ment, and tabulating the same in a note- and sketch - book kept
specially for the purpose. It may be well to remark that the
hatching referred to should, if possible, be kept in a shed or
outhouse.
92
318 FOREST ENTOMOLOGY.
Having hatched or collected the special insects, now comes the
question of setting and storing; and to follow this out properly, the
student unfortunately requires leisure and money. At the same time,
it is no exaggeration to say that the real charm of the study begins at
this stage.
With regard to the actual setting, it will, of course, vary with the
family of insects, and also with the size of the individuals. Suppose
we begin with any of the larger moths, the usual style of setting-
boards with braces and pins may be adopted, or the style of setting
with glass, suggested by Mr Newstead and recommended by Mr Day,
late of Knutsford, Cheshire. In lieu of the cardboard braces, I would
recommend strips of transparent tracing-paper as being lighter, and
also as showing the wing in position with more reliable accuracy. The
setting of the smaller moths (micros) is more difficult, and it would be
well to get a few practical hints from any worker in this group.
It is, of course, advisable to have the smaller moths well relaxed
before attempting to set them. They should be handled as carefully
as possible, and braced down either with tracing-paper, bristles, or silk
thread and pins.
As regards beetles, the larger-sized specimens—the set specimens—
may be often seen with a pin through the bedy, and slightly raised
above the surface of the store-box ; or otherwise the individual beetles
may be mounted on a small card, and a pin placed through the card.
The latter method is obviously the neatest. In either case, the setting
is practically the same. First of all, see that the insect is well re-
laxed, brush the legs and antenne carefully out with a delicate red
sable brush, and fix the body and appendages well down on paper
with gum-tragacanth or gum-arabic. When it has stood for a con-
siderable time, until the body is perfectly stiff, float it off in water,
and then finally transfer it to a clean card, and fix it carefully down
with seccotine squeezed out of the tube and thinned down with a little
glacial acetic acid.
The smaller-sized beetles are, of course, more difficult to deal with,
and the following hints may be given. First get the insect well re-
laxed, and place the creature, under side upwards, on a very soft bed,
with a slight depression to receive the insect. There are two classes
of beds which may be recommended—viz., a piece of sheet cork, or
perhaps better still, a well-dried portion of the white fungus from
dead birch, known as Polyporus. The small insect must be tempor-
ON COLLECTING, PREPARATION, AND MOUNTING. 379
arily, but firmly, held in this position by gentle pressure, either by an
entomological pin or stiff bristle inserted in cork, and used as a sort of
pressure-bar, or by the careful manipulation of a soft silk thread. Havy-
ing arranged matters so, brush out the legs and antenne with a delicate
sable brush, or the “sportsman’s feather” from a woodcock’s wing.
When in correct position, brush them over with a slight moistening
of absolute alcohol, and allow it to remain for a short time, say until
two or three more insects are similarly treated. The effect of this
Fig. 848.—Simple arrangement for dissecting specimens under a magnifying-glass, or for
mounting small specimens for the microscope,
brushing with alcohol is to stiffen the legs into their desired position.
Then remove the insect, and place it on a card in seccotine. It is of
course advisable to do the preparation referred to under a lens or
magnifying-glass, as in fig. 348.
Hitherto the setting of insects has been considered, but it must be
remembered that many of the specific characters are very minute, and
also that the major portion of forest entomology is purely a micro-
scopical study. Hence, though it is impossible to give anything like
380 FOREST ENTOMOLOGY.
a full account of microscopical manipulation, a few general remarks,
together with some practical hints as regards special insects, may be
helpful to the young student.
As regards the choice of a microscope, it is, of course, best to get
what is termed a good stand, as accessories can always be added.
The principal lenses required are the inch and quarter-inch objectives.
A power lower than the inch is very useful, but the greater portion
of practical work is always done with the inch objective. For the
examination of opaque objects a bull’s-eye condensor is required.
A small outfit of, say, a spirit-lamp, a pair of scissors, a small dis-
secting-knife, a few slips and cover-glasses, a bottle of balsam and
benzole, and a pair of forceps, are about all that are required for a
start.
Now let us prepare and mount a slide of some simple object. Take
a few slips and cover-glasses, and have them thoroughly cleaned :
then select a simple object, say a wing of a house-fly or the scales off
a butterfly’s wing, gently warm the slip over the spirit-lamp (this is
not always done even by experienced workers), place the object in
the centre of the slip, drop a little balsam on the object, and with the
forceps lift a well-cleaned cover-glass and let it just “feel” the flame
of the spirit-lamp, so that any natural moisture may be removed, and let
it fall with its own weight on to the balsam on the slip, gently press
it, and keep it in position with a clip, lay it aside for a short time,
and the operation is completed,—you have a mounted slide. Great
care should be taken to prevent air-bubbles, as they are the deadly
enemy of mounts. Such is the simple method of mounting—viz.,
to fasten the object between two glasses with Canada balsam, as
this resinous substance is highly refractive, and brings out the details
of structure.
It would, of course, be well for the young student in a rural dis-
trict to get assistance from a naturalist friend in mounting, &e. A
good useful microscope and simple outfit cost about £8. |
In setting the insects hatching out from oak galls, the following
methods, either for microscopic slides or cabinet specimens, may be
adopted. First of all, get the insects separated from the galls by the
usual method of stupefying by chloroform. When under the influ-
ence of the anesthetic, place them in a clean empty box with a glass-
covered top, and when they revive and become active in the box,
“tap” them rapidly into a saucer containing boiling-water. When they
ON COLLECTING, PREPARATION, AND MOUNTING. 381
touch the boiling-water, many of them will immediately spread out
their wings in the correct position for setting, —in fact, appearing
perfectly set on the surface of the water. Select the best-looking ones,
and float each insect on to a separate microscopical cover-glass, and then
place the wings, antenne, and legs in the correct position: remove
the moisture by means of clean blotting-paper, and then drop methyl-
ated spirits on to the insect: lay them aside, and cover them over
a large champagne-glass which has its
with a large inverted glass,
foot broken off is a very good thing for this. We have then the
insects well set either for microscopic slides or cabinet specimens ;
and it may be noted that the principle of the method adopted is to
make the delicate insects as far as possible set themselves.
If specimens are intended for the microscope, it will be necessary to
place the insect on the cover-glass with the wnder surface upwards,
place on it a drop of absolute alcohol, and allow it to evaporate under
the bell-jar glass,—which, by the way, should be so arranged as to
allow a little air to enter from below. When the alcohol has evapor-
ated, it will be found that the insect adheres firmly to the cover-glass,
and when in this condition, immerse it in oil of cloves for twelve
hours, and again remove the surplus oil of cloves with blotting-paper.
Then place a drop of xylol or benzole, according to the balsam which
is used, and allow this partially to evaporate; then place a drop of
balsam on the insect again, allow it to stand for, say, twenty-four
hours under the bell-jar; prepare a microscopic slip in the usual way,
place a drop of balsam on the centre of the slip, and then turn over
and press the previously prepared insect on the cover-glass into the
balsam on the slip. We have then a well-mounted slide for ordinary
purposes.
If, however, a more transparent object is desired, the following
method may be adopted: Prepare the insect as previously described,
and when it is well set on the cover-glass and thoroughly free from
moisture, separate it from the cover-glass and place it in liquor-
potasse. It should be borne in mind that when well set in this
way, the insect will, with careful handling, always remain in this
fixed position. Hence it may be allowed to remain in the liquor-
potassee for one or two days, then float it on to a cover-glass,
and place it (by careful floating) on to clean water. Thus it may
be gradually washed in this way in water, alcohol, and xylol re-
spectively, until quite transparent. Then float it on to oil of cloves
382 FOREST ENTOMOLOGY.
and prepare it for mounting, under side upwards, as in the previous
method. By this method we get a better slide for recognising special
structural points.
If a specimen of a gall insect be required for general entomological
cabinet purposes, the following method of mounting may be adopted :
In addition to preparing the insect as in the first method, get a piece
of clean white cardboard, punch a hole in it with a 2 in. or # in. punch,
then attach with seccotine a piece of thinner cardboard to the punched
portion, and lay the amalgamated cardboard aside to get thoroughly
dry. Thus we have a circular cell of cardboard; in this place the
previously prepared insects, and according to space fix them neatly in
the prepared cell with a very tiny drop of seccotine. Lay the insects
aside for a time, see that they are kept free from dust, and then finally
seal them over with a microscopical cover-glass, a shade larger than the
cell. The latter should be done with considerable care, and either of
two fixing mediums may be used—viz., Kay’s Coaguline, or “ brown
cement.” In either case place a series of tiny drops around the edge of
the cell, but not quite touching one another; then let a cover-glass,
well cleaned and warmed over a spirit-lamp, fall on the edges of the
previously laid drops, again lay it aside until partially dry, and then
warm a glass microscopical slip over a spirit-lamp and press gently on
the cover-glass, and finally run a ring of the medium round the edge
of the cover-glass, and the whole is completed. This method of prep-
aration makes an excellent opaque microscopical slide for revealing
the natural colours of the insect.
The small Cecidomyidz may also be made to “set themselves” for
microscopical slides. First stupefy them with chloroform, then pick
a single specimen, male or female, place it on a clean cover-glass,
place a drop of absolute alcohol on the insect, allow it to evaporate,
and then mount in balsam in the usual way. The placing of the
alcohol on to the tiny insect is, however, rather difficult. It should,
as it were, be allowed to creep under the insect, and so let the delicate
wings adhere gently and properly to the cover-glass. If, on the other
hand, the alcohol were allowed to drop on to the tiny insect, the
wings would double up, and, as a microscopical slide, we should have
a complete failure. The aleohol dehydrates the natural moisture
in the body of the insect, and as the insects are very delicate, it is
well to move them about as little as possible. As the Cecidomyide
change colour rapidly after death, it is best to examine the unpre-
ON COLLECTING, PREPARATION, AND MOUNTING. 383
pared insect while under the influence of chloroform for specific
characters.
In giving a short account of the preparation of Scale-insects for
the cabinet and the microscope, I am not only indebted to Newstead’s
valuable Monograph, but to personal assistance from Mr Newstead
himself long before the book was published.
For cabinet purposes, and for the study of external characters,
where the number and variety of species are the chief objects in view,
small cork slips of 3 inch x 1 inch, and covered with white or black
paper, according to the colour of the species, may be used. But
where it is intended to display the “scale” from an educational point
of view, together with the nature of the damage it causes and the
more salient details of structure, a suitable space should be allotted
to it in the cabinet.
As, however, the scales are almost exclusively a microscopical
study, it is indispensable to give a short account of the necessary
preparation. In scale-insects we have two great divisions, — one
where the body is protected by the scale, the other where the actual
body is the scale itself. The former class is well represented by the
Diaspine, Pseudococcus, &c. ; the latter by the Lecanitum and Pul-
vinaria. Now let us begin with the Diaspinz, and no better example
could be taken than.the Chionaspis on ash, willow, &c., as found in
winter. Under a weak lens, reading-glass, or arrangement as in fig.
348, lift up a female scale, and underneath this we find the dead
female surrounded by eggs. Collect a number of those female insects,
and place them in a saucer of water. De it remembered they are
mere tiny specks, and can only be lifted with a needle or woodcock’s
feather. Now we must boil it in, say, a ten per cent solution of
caustic potash (KOH). The strength need not be too accurate,—
about two penny sticks in a pint of water would do. Place the
insects in a portion of this solution contained in a very small tube,
and stoppered with cotton-wool. Place this small tube inside a
larger one, containing water, and boil the two tubes in a small
enamelled cup over a spirit-lamp for about fifteen minutes. Pour out
the boiled insects from the inner tube into a saucer of clean water,
pick them up with a needle, and re-boil them in clean water fora
short time, transfer them to dilute and then to absolute alcohol, and
from this again transfer them into another glass containing absolute
alcohol and a weak colouring of one of Crawshaw’s dyes, which
384 FOREST ENTOMOLOGY.
are sold in penny packets, and which form a very good medium for
staining scale-insects. Then with the aid of a large but weak lens
lift them out of the stain, on the tip of a woodcock’s feather, and
place them on to a prepared cover-glass. Arrange them as carefully
as possible, and absorb the moisture with a clean-cut portion of blot-
ting-paper. Then the specimens may be allowed to remain under oil
of cloves for a short time, which may in turn be replaced by a drop
of xylol, and this again further replaced with thin balsam and xylol.
The latter may be allowed to remain under an inverted glass for a
Fig. 349.—Proboscis of honey-bee. Fig. 350.—Tongue of house-fly.
(From photo by A. Flatters.) (By A. Flatters.)
short time, and then finally mounted on to a glass-slip by pressing
the cover-glass with the scales into the balsam on the slip.
This method may be termed mounting the object on the cover-
glass, and is certainly, for this class of work, better than mounting
on the slip. All workers, more especially beginners, know full well
that when an object is mounted on the slip and the cover-glass after-
wards applied, the valuable object has often been found outside the
cover-glass in the superfluous balsam, so that mounting carefully the
opposite way generally gives better results.
ON COLLECTING, PREPARATION, AND MOUNTING. 385
With regard to the preparation of the larger specimens, as, for
example, the female scales of Lecanium and Pulvinaria, they may be
boiled in caustic potash in a test-tube (not in an inner one, as with
the very small species), then boiled in clean water, then transferred
to absolute alcohol with stain for a day, oil of cloves for another
day, and finally mount in xylol balsam.
In addition to studying the more salient points of the anatomy of
forest insects, the student would do well to study the details of
minute insect structure as revealed by microscopical investigation.
There is obviously no end of objects outside forest insects, thus giving
Fig. 351.—Life-history stages of ‘‘Swallow-tail” Butterfly (Papilio machaon).
(From photo by A. Flatters.)
the student not only a wider outlook, but teaching him many a
valuable lesson from indirect subjects. Take, for example, the case
of figs. 349 and 350—the proboscis of the honey-bee and the tongue
of the house-fly. Not only do subjects like these show marvellous
mechanism, but they throw a strong sidelight on such delicate ana-
tomy as the mouth parts and feeding organs of scale-insects, green-fly,
&c. In the case of all insects which suck the juices from the food-
plant, as contrasted with those which eat the vegetable direct, it is
obvious that the vegetable cellular structure must be ruptured, and
therefore many disease spores may thus find a ready entrance into a
favourable host. Hence the obvious necessity of careful investigation
2B
386 FOREST ENTOMOLOGY.
in many diseases, and the incalculable value of trained laboratory
research work.
Such are a few “hints” to the student from the writer’s point of
view ; but it is possible that even advanced enthusiastic students may
show a greater desire for life-histories than minute investigation.
Hence fig. 351 may be taken as a typical case of the life-history of an
insect, inasmuch as we see the successive stages of larval develop-
ment. In the example given we have, of course, an excellent instance
of the correct method for cabinet purposes ; but in reality all insects
should be worked out on similar lines, and the various stages noted
and tabulated in a book kept for the purpose.
CHAPTER XII.
INSECTICIDES AND GENERAL REMEDIES.
WHEN dealing with forest insects and showing them in the cabinet
or life-history cases from an educational standpoint, one is generally
asked the question by practical men, What is the best way of getting
rid of them? It will have been noticed that throughout the whole
of this work general and not specific remedies have been given. As
regards the latter, or the insects considered, it will be obvious that,
while there are some very notable exceptions, as a general rule only
sickly or back-going trees are usually attacked. Hence it is apparent
that there are two practical methods to be adopted—viz. : (1) to main-
tain good health or encourage vigour either for trees or shrubs individ-
ually, and for woods or plantations when considered collectively ; and
(2) that where we do get certain insects attacking healthy trees in
nursery or plantation, special remedial measures must be adopted.
With regard to good cultivation, it may be said that in making the
following remarks it is not intended that the methods should be
usually adopted in order to lessen insect attacks; but, at the same
time, it is certainly true that in many cases bad methods of cultiva-
tion, together with careless workmanship or inattention to details, are
points very much to the advantage of insects. Hence the absence
of insects and good husbandry are often very closely associated. It
will perhaps be most practical to consider what may be done in the
nursery, the young plantation (ornamental or commercial), the middle-
aged wood, or in old woods prior to replanting.
As regards the nursery, more especially the estate nursery, for gen-
eral plants the first thing to consider is the selection of a good site.
The nursery should not, e.g., be in the neighbourhood of an old Scots
pine wood or where Scots pine branches are likely to lie unburned
after heavy falls, as this would endanger young Scots pine or Austrian
388 FOREST ENTOMOLOGY.
pine to be subjected to attacks of Hylurgus piniperda. Again, the
site ought to be considered as regards shelter, for while it is obvious
that too much shelter is not advisable for subsequent planting in the
open, still it is much better to err on the side of shelter, and then
never plant out before young growth is fully matured, as, on the other
hand, too much exposure results in an absence of constitution and
vigour; hence growth is often not in proportion to anticipations, and
insects have an advantage.
Again, it is possible that selection of seed is a point more important
than hitherto considered. It is perhaps true, as many scientists have
asserted, that the vegetable organism, unlike the animal, does not
“hand on” the disease of the parent. Still, there is in all probabil-
ity an inherent weakness from the parent, and therefore a natural
predisposition to disease,—another point in favour of the insect.
So far as the actual management of the nursery is concerned, too
many details cannot be given, as such would simply be an epitome of
nursery management. Great care should be taken as regards good
handling, as the very first thing to be considered is a good root on
the plant, and careful lifting of the stock; and as regards the trans-
planting of seedlings and young trees generally, it is in most cases
essential to transplant or sell out always following two years’ trans-
plantings.
Much may be done to maintain a good constitution in young trees,
as prevention against insect attacks by transplanting at the proper
age. Take, for example, beech seedlings. If they are transplanted
at two years of age, they grow strong and healthy without any insect
attack ; but if they are transplanted when only one year old, they are
often injured by the woolly aphis (Phyllaphis fagi). On the other
hand, ash seedlings are less liable to injuries from the tiny moth,
Prays curtisellus, when transplanted at one year old and left for two
years in the nursery-line, than when transplanted at two years old
and left two years in the nursery-line: besides, the former make the
better plants.
The question of cleaning in summer has to some extent a beneficial
influence, both as regards the stimulating of the growth and the keep-
ing down of the weeds. As regards the latter, it may be said that
weeds not only choke young plants, and therefore weaken them, but
it is possible that some species of green-fly may be assisted by weeds.
The method of digging between rows of plants in autumn has a
INSECTICIDES AND GENERAL REMEDIES. 389
very marked effect in producing greater growth, and thus lessening
insect attack. Mr J. W. Robson, nurseryman, Hexham,—a nursery-
man of nearly fifty years’ experience,—informs me that he has often
experimented with autumn and winter digging as a means of stim-
ulating growth and lessening insect attacks. By taking a plot of
plants, say thorns, and digging and leaving undug alternate patches,
he has found that the undug portions made less growth and suffered
heavily from green-fly, whereas the dug portions made long shoots of
growth and were practically untouched by insects. By autumn dig-
ging, too, the frost pulverises the soil, and facilitates the subsequent
summer cleaning.
It often happens that many plots of hardwood in the nursery are
very much injured by insects. For example, ash plants at three
years of age (that is, two years in seed-bed and one year in nursery-
line) are injured by Prays curtisellus and other insects—so much so
that, with forked and bushy tops, they are practically useless. This
may be got over by cutting down to the ground in early spring, and
then giving sufficient attention to see that the plants spring away
with only a single shoot. The result is that we get very good,
healthy plants.
There are several other points which may be attended to with very
beneficial results, as, for example, burning of all prunings of hedges,
holly bushes, yews, &c. In the growing of fruit-trees, certain var-
ieties assert themselves as being practically immune from such direful
pests as American blight and mussel scale, and perhaps this suggests
the advisability of attending to certain species or varieties as regards
ornamental trees, shrubs, or willows, &c. Much might also be done
in the way of green cropping, green manuring, and so forth, according
to local circumstances or the experience of practical men.
As regards preventive measures against insects in young woods, it is
even more important than in the nursery, inasmuch as the majority of
reports against forest insects (although perhaps due to better facilities
for observation) come from young woods. In the majority of cases the
real cause of injury is primarily due to careless or indifferent planting.
Practical men, or men who ought to be practical, will write to news-
papers stating that certain areas can be planted for sums which cannot
even raise the plants. Seeing that a plantation is for a period of a
hundred years, why should it not be properly done? Do what is
right in principle,—get the full return of work from the workmen,
390 FOREST ENTOMOLOGY.
making quality a leading feature,—and the insect pest will often dis-
appear. What are correct principles in planting? The answer may
be varied according to the class of planting. Thus we may have here
(1) planting on a large area, chiefly pure or mixed, only by grouping
according to soil conditions ; (2) a mixed plantation on previously
cultivated land; (3) clumps or groups of trees for landscape effect ;
and (4) replanting of old woods.
(1) Planting on a large area.—If the ground be quite bare and the
herbage not very rough, the usual method of notching may be adopted
with very good healthy results; but if, on the other hand, the sur-
face conditions are against using a small plant, then unless some extra
care in preparation be adopted, the results will not be so good, and
therefore much to the advantage of insect attack.
(2) As regards planting with the object of forming a new plot on
previously cultivated land, more especially in a pasture field, the plants
are rather difficult to get away, and often hang on for a considerable
time. It is from this class of planting that we often get very severe
attacks of Chermes on larch, and, in fact, many larch plants are killed
with the aphis. This attack might often be considerably reduced if
a little more attention were given to a few practical details. In the
viz., two
first place, the wrong size and age of larch plant is used
years two years, or four years old; and some use one year three
years, which is even worse. The plea is that a large plant is used to
save expense of cleaning. A smaller plant and attention in keeping
down the grass will give better results. The best results of planting
a mixed plantation, including larch for early returns, would be to
plant off ploughed land and keep the grass and herbage down for
two years. The planting could be cheaper done, both as regards
plants and labour; and even if following a green crop, it would pay
to allow for “unexhausted improvements,” inasmuch as being in
every sense better as regards soil conditions there would be compar-
atively no blanks and no insect attacks. As an experimental com-
parison, it may be noted that when planting on grass land it is often
essential to have fires when preparing for planting, as when burning
old hedges and so forth. The larch plants on the burned patches
do infinitely better than those on grass, and never show signs of
Chermes.
(3) In planting ornamental clumps for landscape effect, the best
remedy against insects is to trench the ground. Not only do the
INSECTICIDES AND GENERAL REMEDIES. 391
trees grow ever so much faster as compared with pitting, but the more
rapid landscape effect and the greater increment amply compensate for
the initial outlay in trenching.
(4) In replanting, it may be noted that careless or indifferent man-
agement of the woodland, in the period intervening between the cut-
ting of the old crop and the replanting, not only gives every advantage
to the dissemination of insects, but the essential conditions of soil are
often so much placed out of order that the next crop is weakened and
more liable to be injured by insects. All branches should either be
carted off the ground or burned on the spot, which of course destroys
the breeding-ground for many species of beetles. Then in many cases,
more especially pure Scots pine woods, the ground should be well
stocked with cattle or sheep three or four years prior to replanting.
The effect of this is that the soil is so much trodden away from the
old stools that the bark falls off, and the stools are more unfit for
breeding-places. Scrub bushes are prevented from getting up, which
also often serve for the propagation of many species.
As regards the advantage of “stocking ” with cattle or sheep, it
should be noted that, as a result of pasturing, the “spongy ” layer
underlying the rough turf disappears. This is a great improvement
to the soil, inasmuch as the spongy layer is acid in reaction, and con-
tains nitrogenous matter derived from the decayed plant residues of
which it is composed. In the rough state the nitrogenous matter,
however, is not directly available as a plant food, but must be con-
verted into a soluble and available form by the action of the nitrify-
ing organisms always present in the soil. It will therefore be obvious
that the ground can be more cheaply and successfully replanted ; and
as the plants will not only do better and give a more regular crop, as
compared with planting on rough unprepared ground, the young trees
get better over the most critical period against the attacks of insects.
With regard to the prevention of insects in young woods, it may
be said that again it is essential to adopt sound sylvicultural prin-
ciples, and as a rule the insects will not be troublesome. One notable
exception is the Retinia or pine-shoot moth, which does not disappear
under good management as many others do. In young plantations
it is well to see that they are planted “thick” and kept so. Secure
a rapid canopy, get all grass killed off as quickly as possible, and keep
the soil conditions right by having a covering of leaves from the
shade-bearers—beech and other trees—and growth will be very much
392 FOREST ENTOMOLOGY.
stimulated. It has been proved by the Woburn and other experi-
ments that grass has no place in an orchard ; and as the case of young
woods is practically analogous, it would be well for the health of
young woods if the grass could be got rid of as soon as possible by the
density of the young thick crops.
In the nursery-lines many species of hardwood trees which may be
doing badly, partially owing to insects, after being planted for a few
years could be cut down to the ground, and then come away as strong
young trees, provided they are well sheltered with the remainder of
the crop, or under the protection of netting, and receiving attention
for the first year.
In dealing with Insecticides, or the destruction of certain insects by
the application of special chemicals and mixtures in varying degrees
of strength, or otherwise by the application of special mixtures as sold
by respectable firms or individuals, it will be obvious that in a work
of this class it would be very improper either to support or condemn
any “mixture” in the market. It is therefore considered advisable
to simply give a few general principles.
In the first place, it should be remembered that the use of any in-
secticide should be, as far as possible, applied intelligently (1) as
regards the life-history of the insect ; (2) what is to be the actual or
prospective effect on that particular stage of the insect under the an-
ticipated remedy ; and (3) how far such remedies may be practicable.
It is important to bear in mind the structural and physiological
functions of an insect (1) as regards the structure of the mouth and
method of feeding ; (2) the method of respiration or breathing; and
(3) in some special cases the method of reproduction. The applica-
tion of effectual insecticides must be through one or other of these
mediums.
As regards the poisoning of the insect through feeding, it must be
borne in mind that there are three distinct methods of feeding—viz.,
biting, piercing, and sucking. The piercing and sucking forms, how-
ever, are not always easily separated. Now take a typical case of
general insecticide application—viz., spraying, and consider obvious
results. The biting form of mouth, as seen in the beetle, would take
the liquid along with the full structure of the leaf; or if the insect
only ate the upper surface of the leaf, leaving the veins and under
surface, it would obviously take more liquid in proportion than the
other insects. But if the insect were literally of the piercing type,
INSECTICIDES AND GENERAL REMEDIES. 393
the proboscis would pass through the smallest possible quantity of the
poison on the surface, and feed on the pure vegetable sap underneath.
It is therefore obvious that before any good results could accrue, we
should require to get the vegetable organism to incorporate the poison
with its own sap. How far this can be done is still to a large extent
a question for future scientists, but nature does give us some very
good suggestions in this direction. Take, for example, the case of
some scales with their piercing mouths—viz., Cryptococcus fagi or
felt scale on beech and Mytilaspis pomorum or mussel scale on fruit-
trees. In the former case the copper beech often shows itself as prac-
tically immune alongside the badly infested trees of the common
beech, and in the latter certain varieties of fruit-trees are practically
immune while the surrounding trees of other varieties are literally
killed. Hence the practical inference is to either raise immune
varieties, as in fruit-trees, or if possible to so feed the vegetable
organism as to contain some ingredient so amalgamated with the sap
as to be inimical to the animal parasite.
With regard to the breathing-apparatus of an insect, it should be
remembered that breathing is not effected through the mouth, but
through slits or openings termed breathing-pores or spiracles. If these
openings are varnished over, the insect will be asphyxiated. Thus,
therefore, we get the suggestion of applying insecticides in the form
of an emulsion or thick spray. Nothing answers this purpose better
than soft-soap, because it adheres to the skin, and other ingredients
may be added within certain limits and according to the species of
insect and nature of injuries. Such ingredients are quassia, paraffin,
tobacco, sulphur, turpentine, caustic soda, caustic potash, &c. The
addition of any of these ingredients has the effect of corroding the
skin, and so intensifying the action of the emulsion. The skin of
insects is composed of a substance known as chitine. This substance
is more or less of a horny nature, and has the chemical formula of
C,H,,NO,. It is practically unaffected by alcohol, ether, acetic acid,
alkalies, or even when boiled in caustic potash. It may, however, be
dissolved by concentrated mineral acids, but as the latter would in-
jure the vegetable organism, it follows that insecticides must be so
composed as to act on the insect without doing injury to the plant.
The reproduction of insects may to some extent be checked, as for
example in the Aphides. In this family the young are brought forth
alive, so that by using any insecticide which would so injure the
394 FOREST ENTOMOLOGY.
creature as to prevent it giving birth to young we should be checking
the pest considerably.
Insecticides are now employed with great success, especially in
horticulture ; but obviously they are more difficult to apply in for-
estry, particularly in the forest proper. It appears best, therefore,
to suggest remedies in a general way for the nursery and individual
or ornamental trees.
In the nursery remedial insecticides may be classified under four
heads: (1) fumigation ; (2) dressing the soil; (3) spraying; (4) mis-
cellaneous.
As regards fumigation, it may be done in an open shed when re-
moving from the nursery to the plantation, or when foreign plants
have been purchased, or with a costly preparation on groups or in-
dividual trees.
As fumigation has not been adopted to any great extent in this
country, the following account of Mr Lounsbury, Government Ento-
mologist, Cape of Good Hope,! may be given :—
“Fumigation with hydrocyanic acid gas is applicable for the de-
struction of scale insects on citrus-trees, and to a large extent on other
trees. It is without doubt the most efficient remedy for this purpose
yet brought into practical use. The eggs of the insect do not suc-
cumb to the gas unless this is used at a much greater strength than
what is necessary to destroy the insects themselves. One treatment
suffices for the destruction of those species in which the young are
produced alive. Successive treatments at the ordinary strength are
necessary to destroy all stages of egg-laying species, but it is more
advisable to give several treatments at this strength than a single one
which would destroy the eggs, because of the liability of seriously in-
juring the trees in the latter case.
“Tn general, the treatment consists in covering the trees with an
air-tight cloth made in the form of a tent or sheet. The gas is then
generated beneath this cover by acting on potassium cyanide with
sulphuric acid, the amounts of the chemicals used depending upon the
dimensions of the tree. The coverings are removed after the expir-
ation of half or three-quarters of an hour, by which time the gas is
largely spent. Great care must be taken in the use of the gas, as it
is highly poisonous not only to insects but also to the higher forms of
life. When proper precautions are taken, however, there need be no
1 Report for the year 1906, p. 130.
INSECTICIDES AND GENERAL REMEDIES. 395
more danger in its use than in the employment of arsenical sheep-dips
or strychnine for other farm purposes.
“Tt is desirable to have various sizes of the coverings ; and withal,
the initial outfit demands an outlay so considerable, that not every
orchardist will find it economical to provide himself with an equip-
ment for his-sole use. But by co-operation among a number of
growers, the expense per tree treated may be lowered to a figure
which leaves a handsome margin of profit in the benefits which accrue
from the operation. After the first expense for the equipment the
chief item of‘ cost is the labour, but this expense is not much, if any,
greater than the expense of spraying citrus-trees. When purchased
in large quantities the chemicals are not expensive. - The cyanide
may be procured in London at 10d. per Ib. in 224 Ib. lots, and the
sulphuric acid in Cape Town for 50s. per case of 168 lb. : one mer-
chant sells the acid at 26s. per case of 122 lb. Estimating the
cyanide to cost 1s. 6d. per Ib. and the sulphuric acid 4d., the expense
of the chemicals necessary for a tree ten feet in height would be
about 3d.”
With reference to dressing the soil, various mixtures have been
used, but the one which has recently found most favour with prac-
tical men is Vaporite. It should be sown broadcast in the soil prior
to digging, and when thus applied it gives off a vapour that destroys
the larvee of many insects, as, for example, wire-worm, leather-jackets,
and others which pass their larval stage in the soil.
As regards spraying in the nursery, various commercial washes may
be used, and of course it may be noted that practical men will differ
in their opinion. It will therefore, perhaps, be best to give what
may be considered a kind of mixture which can be used with the
knapsack spraying arrangement or the hand syringe.
Get an old boiler of, say, 16 gallons capacity. Boil about 7 gallons
of soft water; add and well mix in this about 10 1b. soft-soap, to-
gether with about 1 gallon of paraffin. Then boil in a separate vessel
about 5 lb. quassia chips. Strain and add to the above. This will
form a kind of stock solution, and when quite cold add and mix well
in about 100 gallons of soft water (three old paraffin casks), and apply
with syringe.
As it is very difficult to apply any insecticide to trees collectively,
it becomes therefore a question how far we can apply any dressing to
ornamental or special trees individually, together with the cost of the
396 FOREST ENTOMOLOGY.
same. The best report I have received bearing on this is given by
my friend Mr Thomas Bond, Lambton Park, Co. Durham, regarding
treatment on old beech-trees badly infested with Cryptococcus fagi.
Taking as his guide the Board of Agriculture leaflet No. 140, and the
treatment No. 2, which is the same as that given in chap. vi., p. 236,
of this work, and mixed on a fairly large scale, he says: ‘“‘ We secured
a 25-gallon portable boiler and placed in it the following quantities—
viz., 2 gallons soft water, 4 lb. soft-soap, 4 handfuls sulphur, 4 pints
paraffin, and 4 pints turpentine. After boiling and mixing these in-
gredients, we added 16 gallons of soft water, and then allowed it to
cool before application. Then after well churning the mixture we
placed some in a paint-pot and rubbed it on the stems and large
branches with a large paint-brush, which we found better to use than
a whitewash-brush. We had, of course, to use ladders, but we
brushed it well into all the crevices of the bark. In this way we
went over 60 trees at a cost of about 4s. per tree, including labour
and materials. The operation was begun on the 3rd of May, but
was not completed till the 28th of the same month, owing to wet
weather retarding the work. In the month of August we noticed
very small specks of the ‘felt’ appearing in the crevices of the bark,
possibly coming from larvee which had been secure from the reach of
the mixture. The treatment was certainly a success, and with another
slight application the following year we hope to be able to eradicate
the pest. Having regard to the size and value of the trees from a
park point of view, the expense was not excessive.”
There are, of course, many other practical points which might be
enlarged upon that go to keep down the injurious species of-insects
in this country. We rarely hear of any species becoming such alarm-
ing pests in this country as on the Continent or in America. This
is probably due to the major portion of our forests being ‘‘ mixed”
woods, as contrasted with “pure” woods abroad. The effect of this
is that there is no preponderating advantages to any single species of
injurious insect.
Another point of importance which should receive special attention
is the encouragement of the various species of birds that live, or
partially live, on insects. The destruction of certain species of birds
is perhaps necessary in order to protect our fruits, our field crops, or
our game-preserves ; but on the other hand, the preservation of certain
kinds of beneficial birds should be rigidly enforced. The question of
INSECTICIDES AND GENERAL REMEDIES. 397
interfering with the “balance of Nature” is always a serious problem,
and great caution, combined with intelligent forethought, should be
exercised. On the one hand we get certain animals preserved by
killing their natural enemies, but on the other hand we may have a
direful pest unexpectedly assert itself as the result of killing natural
enemies.
References to Literature consulted.
Board of Agriculture Leaflets, &c.
Theobald, Fred. V. A Text-Book of Agricultural Zoology. Chiefly chapter
on the prevention and destruction of insect pests.
398
CHAPTER XIII.
BENEFICIAL INSECTS.
In the foregoing chapters it will have been noted that all insects con-
sidered are injurious to a more or less extent, and the inquiring or
philosophic student will naturally ask, Are there no beneficial forest
insects? In a general way an affirmative answer may be given, but
in defining “ beneficial” insects it 1s necessary that some qualification
should be made. Thus we may divide our subject into three main
divisions—viz., (1) the question whether insects play any part in the
fertilisation of flowers ; (2) the part which insects may play in aiding
the rapid destruction of certain refuse in the woods; and (3) the
very great part played by parasitic insects—z.e., insects living on
other insects.
As regards the first division, it may be said that the majority of
our forest trees are wind-fertilised, but there are, of course, probably
others which are not so, together with many flowering-shrubs, and it
is just possible that this may be to some extent an unworked field.
With reference to the second division, it 1s obvious that we can
get into closer association with this part of the subject. Thus, much
dead wood is often left lying in woods, and the forester desires its
early destruction. Many species of insects may be found within
rotting wood which doubtless assist in the disintegration of the parts.
This, however, may be considered as having a very indirect bearing,
inasmuch as many of those insects found in rotting wood may be
looked upon as being there purely for shelter or moisture. One not-
able exception, however, may be given—viz., the case of any insects
which may aid in the destruction of roots left in the ground. In Scot-
land and the north of England it may be observed that in the roots
of Scots pine, after being cut for three or four years, very small, clear-
cut, gimlet-like holes can be seen in the solid roots. It will be obvious
BENEFICIAL INSECTS. 399
to the practical man that the effect of these holes is to let moisture into
the body of the root, and so hasten its decay. Thus the more rapid
destruction of the roots accruing from the insect may well be con-
sidered as an advantage.
The insect doing the work referred to is a beetle termed Asemum
striatum. The larva is about an inch in length, of a whitish colour,
broad at the thoracic portion, and tapering very much in the abdom-
inal segments.
The beetle is of an oblong shape, a dull-black colour, and deeply
sculptured. The legs are brownish-black, with deep-black tarsi.
With reference to the third division of our subject, it may be noted
that it can be divided into sub-divisions, as it were—viz., insects
which prey directly on other insects, and those which are parasitic, or
in many cases indirectly kill other insects.
As regards those which feed directly on injurious insects, perhaps
the best example is the Coccinellide or “‘lady-bird” beetles. There
are several species of them, and they live on insects, more especially
Aphides. They feed on these insects both in the larval and beetle
stages. Some species pupate on the leaves of trees, and to a beginner
in forest entomology the rolled-up pupa is a somewhat puzzling object.
These beetles should be carefully studied in every detail, for not only
are they very good friends, but the males often differ so much from the
females that they may at first be mistaken for distinct species.
Many of the Colonial writers give very interesting accounts of the
great advantages of introducing a species of lady-bird or Vedalia
(Novius cardinals), the notorious Australian bug destroyer. The
bug referred to has been kept in check in many parts of the world by
the Vedalia. So that a very good hint is given to encourage lady-
bird beetles.
The field of beneficial beetles in forest entomology is rather an
unworked one, and Mr R. 8. Bagnall has recently demonstrated this
by showing that the beetle Epurwa angustala is a parasite on the
genus Trypodendron, and this obviously suggests that the parasites of
the Scolytide are entirely an unworked field.
There are many other species of beetles which might be well con-
sidered as beneficial, as, for example, many of the ground-beetles,
which live on the larve of various insects, or other creatures, which
in turn feed on the roots of young trees in the nursery.
The larvee of some species of Diptera are very beneficial in
400 FOREST ENTOMOLOGY.
keeping down green-fly, &c., and may often be found amongst these
pests.
The most important parasite insects belong to the order Hymen-
optera, and the following concise account of the families which may
be considered as beneficial is taken from Professor Carpenter’s work
on ‘Insects, their Structure and Life’ :-—
‘“Tchneumonide.—The IJchnewmonide or Ichneumon-flies are an
exceedingly large family. The feelers are straight, long, and many-
jointed, tapering towards the tip; three ocelli are always present on
the crown. ‘The wings have for the Hymenoptera a complex neura-
tion ; a distinguishing character is the presence of two cells between
the cubitals and the second posterior cell (at the anal angle of the
fore-wing). Rarely wings are quite absent. The stalk of the elongate
hind-body is attached to the lower or hinder of the first abdominal
seoment, which is very large, while the metathorax is relatively short,
so that the middle and hind pairs of legs are inserted close together.
The trochanters have two segments. The females are provided with
ovipositors, which in some cases are several times as long as the
body: by means of these they lay their eggs in the bodies of cater-
pillars. The forms with exceptionally long ovipositors, such as
Rhyssa, prey upon wood-boring grubs: this species lays her eggs in
the burrows of Sirex, on whose grubs her larve feed as external
parasites. In most cases, however, the Ichneumon maggots feed in-
ternally on the juices of their victims. Over 6000 species of Ichneu-
monide are already known, and the family is distributed in all parts
of the world.
‘“ Braconide.—The Braconide are a large family, closely allied to
the Ichnewmonide, but distinguished by having only a single cell on
the fore-wing, between the cubitals and the second posterior cell. The
larve live like those of the Ichneumons, and the range of the family
is equally wide.
“‘Chalcidide.—The Chalcidide are a very large family of small
Hymenoptera, distinguished from all the preceding families of Petio-
lata by their elbowed feelers, which have from seven to thirteen
segments. The pronotum is partially free, and does not reach back
to the insertion of the fore-wings. The neuration is very simple: a
single thick nervure runs from the base of the wing to the costa,
giving off at its termination a very short branch. The trochanters
are divided. The Chalcidide are frequently of brilliant metallic
BENEFICIAL INSECTS. 401
colours. Over 4000 species have already been described, and they
occur in all parts of the world. The eggs are laid in galls, or in
nests of the higher Hymenoptera, so that the larva may feed on the
contained maggot. Some species attack the caterpillars of moths, and
others, like Chalcis ovata, feed in pupe.
“ Proctotrypide.—The Proctotrypide are a large family of small
Hymenoptera, distinguished from the Chalcidide by the pronotum
being closely fused with the mesothorax, and reaching back to the
bases of the fore-wings. The neuration varies greatly : in some genera
a few nervurés and cells are present ; in others, none. The hind-body
is pointed at the tip, and the ovipositor is tubular. The trochanters
are usually segmented, but in some genera they are simple. The
larve live parasitically within the bodies of insects ; those of some
very minute species find food enough in other insects’ eggs. In some
Proctotrypide the larva in its first stage is broad in front, and tapers
behind to a point whence spring several tail-processes ; this is ulti-
mately changed into the ordinary Hymenopterous maggot. Some
genera of the sub-family Mymarine, tiny and delicate insects with
narrow wings fringed with long hairs, are aquatic in their habits, and
their larve are believed to feed in the eggs of dragon-flies. The
Proctotrypide have a world-wide range, and must number many
thousands of species.”
The above remarks are given simply with the idea of suggesting
the field of study for the student. As a general rule, the student
will find sufficient scope, along with other subjects, in confining him-
self entirely to the injurious species. If, however, he can possibly
study “beneficial insects” as here indicated, he will find the best
method of doing so to simply collect the various species in the
hatching-boxes. In the case of some insects this is specially interest-
ing, as for example in the “‘oak-apple” gall, from which various
parasites hatch out nearly all the year round. Again, it may be
said that it is essential to know something of parasites, as, to a
beginner, they may often in the hatching-box be mistaken for the
real injurious species. It is also of considerable importance to study
parasites, as in certain cases they may change their habits, as, for
example, in Megastigmus, which has been long known as a parasite on
‘oak galls,” and recently has been discovered as a deadly enemy to
the seeds of Douglas fir.
bo
Q
LIST OF TREES
402
CHAPTER XIV.
WITH INJURIOUS INSECTS.
Tue following “list” is given in order that the student may more
to} fo)
readily identify the insect from the damage.
Almost every reader
will be able to determine different trees, and the insect may therefore
be recognised from the brief note defining the nature of the injury,
or otherwise guiding the student as to where to refer for descriptive
information.
Name of tree or
shrub affected.
Name of insect.
Nature of injuries.
Alder
Apple
Eriophyes levis
Cresus septentrionalis
| Psylla alni
Scolytus prunt
Mytilaspis pomorum
Eriophyes fraxini .
1 Tucanus cervus
Cryptorrhynchus lapathi |
Produces galls on upper
surface of leaf.
Larvee and beetles injure |
the bark of young trees. |
Larvee live in colonies, |
eating foliage.
Insects live within woolly
covering on extreme
end of twigs.
Female beetle makes a
perpendicular gallery
under bark, and larvee
irregular radiating gal-
leries.
Small brown scales on
branches of compara-
tively young trees.
Causes malformation of
flower.
Larvee burrow into old
stems.
214
1 Also found on oak, hornbeam, holly, and beech. -
LIST
OF TREES WITH INJURIOUS
INSECTS.
403
Name of tree or
shrub affected.
Name of insect.
Ash
1 Sinodendron cylindri-
cum.
Rhagium inquisitor
Hylesinus crenatus
un fraxint .
" oleiperda
Vespa Crabro (hornet) .
Chionaspis salicis .
Apterococeus fraxini
2 Zeuzera cesculi
Prays curtisellus
Diplosis botularic .
Bibio marci .
Psyllopsis fraxinicola
" fraxini
Doreus parallelopipedus
3 Melolontha vulgaris
4 Agrilus viridis
Nature of injuries
|
Page.
Larvee burrow in the bark
Larvee live under bark of
decayed logs.
Female makes short gal-
leries under thick bark
of old trees. Larvee
make irregular galleries.
Female beetle makes a
double - armed gallery
under bark. Larve
make galleries at right
angles to mother gallery.
Female beetle burrows in
small twigs and larvee
make irregular galleries.
Insect damages bark of
young trees.
Small white scales on
stems of comparatively
young trees.
White scales on bark of
old trees.
Larve burrow in young
stems or branches.
Larva lives in leading bud
of young tree, which it
kills, and thus causes a
forked stem.
Insects form pea-pod-like
galls through foldings
of leaf.
Larve eat roots of young
plants in nursery.
Insects found on foliage
during summer.
Insects cause leaflets to
roll. The rollings are
of a brown variegated
colour.
Larve bore into back-
going trees.
_ Larvee feed on roots
Injures the bark of stems —
of young trees.
1 Also on beech and holly.
2 Also found on elm, syeamore, hawthorn, and several other trees.
3 Tnjurious to practically all nursery stock.
43
103
Ad
48
4 Rare ; found only in south of England.
404
FOREST ENTOMOLOGY.
Name of tree or
shrub affected.
Name of insect.
Beech
ii
Birch
Bird-Cherry .
Blackthorn
'" .
Box
Bramble
Orchestes fagi ; :
Rhopalomesites Tardyt .
Cryphalus fagt
Cryptococcus fagr .
Phyllaphis fagi
Hormomyia piliger
" fagi
Eriophyes rudis
Deporaiis betule
Strophosomus capitatus .
1 Pulvinaria vitis .
Callipterus betularius
Trypodendron domesti-
cum.
Hyponomeuta — evony-
mellus.
Aphis padi
Otiorrhynchus picipes
Monochetus sulcatus
Psylla buxi .
Lasioptera rubi
Nature of injuries.
Larvee injure the foliage .
Larvee eat timber of par-
tially decayed trees.
Female beetle makes bur-
rows in small branches.
White scaly covering on
bark.
The insects cover them--
selves with a white
cottony secretion, gen-
erally on the under
side of leaves.
Produces small hairy galls
on upper surface of
leaves.
Produces smooth galls on
upper surface of leaves.
Causes swollen abortive
buds.
Female beetle cuts and
rolls up the leaves.
Beetle eats foliage of
young trees.
Large brown scales, with
attached white ovisac.
Insects may be found on
trees, more especially
in a coppice, through-
out the summer
months.
Female beetle burrows
into sapwood towards
centre of tree. Larve
make short “ladder”
galleries.
Larvee often defoliate trees
and protect themselves
by a web.
Aphides often kill ter-
minal shoots.
Larva feeds on roots;
beetle eats bark of
young stems.
Causes leaf-rolling .
Insects cause leaves to
bend inwards.
Produces hard rough ex-
crescences on stems.
1 Also on hawthorn, hazel, willow, alder, &c.
127
LIST
Name of tree or
shrub affected.
Broom .
Cherry (wild)
Clematis
Dog-Rose
"
"
Douglas Fir .
Elder
Elm
OF TREES
Name of insect.
WITH INJURIOUS INSECTS.
Nature of injuries.
405
Page.
Phleophthorus — rhodo-
dactylus.
Depressaria assimilella .
Asphondylia sarothamni
*
Myzus cerast .
NXylocleptes bispinus
Ihodites eglanterie
" TOS
Aulacaspis rose
Megastigmus
trophus.
speriio-
Aphis sambuct
Orchestes alni
Scolytus destructor
" multistriatus .
Hylesinus vittatus
Cheimitobia brumata
Beetle burrows under the
stems, and larva makes
irregular galleries.
Larvee live on terminal
shoots, and knit shoots
together for protection.
Produces galls on young
twigs.
The Aphides injure the
foliage by causing a
rough rosette of leaves
on terminal shoot.
Female beetle burrows in
twigs.
Producessmall round galls
on under surface of leaf.
Produces “ moss” galls on
shoots.
Produces white scaly
covering on stems.
Larvee feed on kernel of
seeds.
Insects live in clusters on
young shoots.
Larvee injure the foliage,
and beetles perforate
the leaves.
Female beetle makes a
perpendicular gallery
under thick bark, and
larvee irregular radiat-
ing galleries,
Female beetle makes a
perpendicular gallery
under thin bark, and
larvee irregular radiat-
ing galleries.
Female beetle makes a
double-armed horizon-
tal gallery under bark
of branches, and larvee
make short galleries at
right angles to mother
gallery.
Larvee eat foliage in early
summer.
113
305
96
106
406
FOREST ENTOMOLOGY.
Name of tree or
ehanhiattacted! Name of insect. Nature of injuries. Page.
Elm Schizoneura ulmi . Aphides roll the leaves | 316
and live within the
foldings.
" Pemphigus pallidus Insect forms gall on mid- | 320
rib of leaf.
" Tetraneura ulini Insects form galls on | 320
upper surface of leaf.
" Typhlocyba ulmi Sulphur-coloured insects | 372
may be beaten in
showers from foliage
during the summer.
Field Maple . | Eriophyes macrochelus . | Produces conical galls on | 28
upper surface of leaf.
" n . macrorhynchus | Produces small galls on | 28
upper surface of leaf.
Hawthorn " gontothorax Causes leaf-rolling . 31
" Priobium castaneum Larva lives in dead stems | 51
in hedges.
" Otiorrhynchus picipes Larva feeds on roots, and | 68
beetle eats bark of
young stems.
" Trichiosoma tibialis Larva eats foliage 173
" Mytilaspis pomorum Small brown scales on | 214
branches of compara-
tively young trees.
" Penthina pruniana Larvee often injurious to | 263
patches of trimmed
hedges and_ isolated
lawn-trees.
" Aphis crategi The insects do consider- | 301
able injury to leading
shoots of young thorns
and hedges.
" Cecidomyia crategi Insects form a rough | 344
rosette of leaves on ex-
treme twigs, more es-
pecially on hedges.
" Psylla crategi Extreme end of terminal | 367
shoot often killed by
the young close-adher-
ing insects.
Hazel Eriophyes avellance Causes swollen abortive | 24
buds.
" Balaninus nucum . Larva eats the kernel of | 83
the nut.
" Dryocetes alni Female makes burrows in | 120
dead twigs.
| LIST
Name of tree or
shrub affected.
OF TREES WITH
INJURIOUS
INSECTS.
407
Name of insect.
Nature of injuries.
Hazel
Holly
Hornbeam
Ivy
Laburnum
Larch
Tortrix ribeana
Aspidiotus britannicus .
| Pedisca ophthalmicana
s
Chromatomyia ilicis
Dryocetes coryli
1 Pseudococcus aceris
Aphis hedere
Cemiostoma laburnella .
Strophosomus coryli
| Nematus Erichsonii
| Argyresthia levigatella .
Coleophora laricella
Chermes laricis . :
Gracilaria syringella
a Eriophyes tilie
Cryphalus tlie.
Larvee often
bushes in early sum-
mer,
Dusky brown scale on
leaves.
Larva lives on tender
young shoots of clipped
hedges and draws ter-
minal leaves together.
Produces large blotch on
leaf.
Female burrows in small
branches.
Large white scaly mass on
bark.
Aphides live in clusters
on leading shoots.
Larvie injurious to foliage
by living within leaves
and creating large ugly
“blotches.”
Beetle eats young devel-
oping foliage.
Larvee eat the foliage
Larva lives on and kills
terminal shoot of very
young tree.
Larve live in cocoons
and eat the foliage in
early summer.
Aphides live on _ shoots,
and may often be re-
cognised by a white,
woolly covering.
Larvee live within the
leaves, and therefore
cause large blotches.
Produce long tapering
galls on upper surface
of leaf.
Female beetle makes a
horizontal gallery under
thin bark of branches.
Larve make irregular |
galleries.
1 Also on sycamore, oak, ash, elm, gorse, &e.
defoliate | 2
287
70
186
278
281
328
280
408
FOREST ENTOMOLOGY.
Name of tree or
shrub affected.
Name of insect.
Nature of injuries.
Lime
Mountain-Ash
Oak
Cheimitobia brumata
Prterocellis tilice
Cecidomyia tiliam volens
Eriophyes aucuparie
Phyllobius maculicornis
1 Prionus corarius .
Attelabus curculionides .
Polydrusus micans
Orchestes quercas .
Scolytus intricatus
Dryocetes villosus .
Trypodendron domesti-
cum.
Xyleborus dispar .
Neuroterus lenticularis .
Larvee eat foliage in early
summer.
Aphides common under
foliage.
Insects roll leaves, or
otherwise form galls
on extreme tips of
twigs.
Causes surface injuries
to leaves.
Beetle feeds on foliage
Larve bore into living
trees.
Female beetle makes
“thimble case” by roll-
ing up the leaf.
Beetle feeds on leaves
Larve injure the foli-
age.
Female beetle makes a
short horizontal gallery
under bark, and larvee
make long galleries at
right angles to mother
gallery.
Female burrows in thick
bark of old dead trees
or under bark of dead
standing trees.
Female beetle burrows
into sapwood towards
centre of tree. Larvee
make short ladder
galleries.
Female bores into stem
of young tree. Larve
make galleries at right
angles to mother gal-
lery.
Produces “spangle galls”
on under side of leaf.
Galls raised in centre ;
flat at outer edge, and
covered with stellate
hairs.
120
128
140
1 Rare ; confined to south of England,
LIST OF TREES
Name of tree or
shrub affected.
WITH INJURIOUS INSECTS.
409
Name of insect.
Oak
Spathegaster baccarum .
Neuroterus fumipennis .
Spathegaster tricolor
Neuroterus leviusculus .
Spathegaster albipes
Neuroterus numismatis .
" ostreus.
Spathegaster aprilinus .
Aphilothriz radicis
" corticis
" globuli
Andricus inflator .
" curvator .
Nature of injuries.
Produces “currant galls”
on flowers or leaves.
Galls globular, — soft,
and succulent.
Produces galls on under
side of leaf. Centre of
gall concave, edges con-
spicuously turned up.
Produces galls on under
side of leaf ; in clusters,
and hairy.
Produces galls on under
side of leaf. Galls are
nearly smooth, white
or yellowish, the outer
edge turned up.
Produces spindle-shaped,
smooth galls, causing
fairly deep indenta-
tions of leaf.
Produces “button galls”
on under side of leaf.
Galls are depressed in
centre, surface covered
like silk velvet.
Produces small, spotted,
pellet-like gall on mid-
rib of leaf.
Produces “thin” galls, pre-
senting the appearance
of an undeveloped bud.
Produces large many-
chambered galls at
base of trunk near
surface of roots.
Produces galls in young
bark around a pruned
branch.
Produces globular green
galls, projecting from
bud _ scales,
Produces galls in inflated
portion of the terminal
twig.
Produces galls on leaf,
causing an irregu-
lar globular swelling.
These galls have al-
ways an inner gall.
Page.
143
144
145
146
146
147
147
148
148
149
150
410
FOREST ENTOMOLOGY.
Name of tree or
shrub affected.
Name of insect.
Nature of injuries.
Oak
"
1 (evergreen)
Aphilothrix quadrilin-
eata.
" albopunctata
Andricus ramuli
Aphilothrix fecundatrix
Dryophanta scutellaris .
" longiventris
" divisa
Biorhiza aptera
Teras terminalis
Biorhiza renum
Cynips Kollart
Aspidiotus zonatus
Asterolecanium vario-
losum.
Cossus ligniperda .
Orgyia antiqua
Pygera bucephala
Tortiia viridana
Lithocolletis messaniella
Produces small, ovoid,
ribbed galls on flowers.
Produces ovoid, green,
smooth, hard galls in
buds.
Produces gall like a ball
of cotton on flowers.
Produces gall wholly en-
veloped in leaf scales.
Produces cherry-like gall
on under surface of
leaf.
Produces a hard, reddish,
striped gall on under
surface of leaf.
Produces small, hard galls
on under surface of
leaf.
Produces irregular clus-
ters of galls on roots
of old trees.
Produces large, soft,
apple-like galls on_ter-
minal or lateral buds
or terminal shoots.
Produces kidney-shaped
galls on veins of leaf.
Produces marble - like
galls on twigs of young
trees.
Circular brown scales of
female on stems and
small scales of male on
leaves.
Scales produce pitted de-
pressions on extreme
twigs.
Larvee burrow in stems
of old trees.
Larvee eat foliage
Larve live gregariously,
and often defoliate
isolated branches or
whole trees.
Larvie often defoliate
trees in early summer.
Larva lives within a
“blotch,” generally on
under side of leaf.
LIST
Name of tree or
shrub affected.
Oaix
"
Pinus cembra
Poplar . :
4! .
=
! (white-
leafed)
W .
" .
" (aspen) .
Scots Pine
OF TREES
Name of insect.
Callipterus quercis
Lachnus longipes .
Phylloxera punctata
Diplosis dryobia .
Peediscu occultana
Saperda carcharias
" populnea
Melasoma popult .
Cladius viminalis .
Smerinthus populi
l Zeuzera eesculi.
Dicranura vinula .
Hedya ocellana .
Pemphigus bursarius
" spirothece
Diplosis tremule .
Melolontha hippocastani
WITH INJURIOUS INSECTS.
Nature of injuries.
Aphides may be found
under leaves.
Eggs may be found in
winter, and large
brown females in
summer, on the twigs.
Insects may be found on
under side of leaves.
Larvee cause portions of
outer edges of leaf to
roll downwards.
Larvee live in developing
shoots, and often arrest
development by eating
young foliage and
soldering the whole
whorl of shoots to-
gether.
Larvee burrow in stems
of standing trees.
Larvee produce swellings
in young trees.
Larvee eat the foliage
Larvee feed on the under
skin of the leaf.
Larve live on leaves
Larve burrow in young
stems or branches.
Larvee eat foliage, and
much injury is often
done to young twigs
by deep depressions
scooped out for large
pupal cocoons.
Larvee often destroy lead-
ing shoots of young
trees.
Insects live within gall
on leaf-stalk.
Insects live within “cork-
screw” gall on leaf-
stalk.
Insects produce — small
galls on leaf-stalk.
Injures the roots.
411
308
311
337
352
265
265
1 Also on elm, sycamore, hawthorn, and several other trees.
412
FOREST ENTOMOLOGY.
Name of tree or
shrub affected.
Name of insect.
Nature of injuries.
Page.
Scots Pine
Rhagium bifasciatum
Hylobius abietis
Pissodes pint
" notatus
Hylastes ater
Hylurgus piniperda
" minor
Pityophthorus pubescens
Tomicus sexdentatus
" acuminatus
Pityogenes bidentatus
Lophyrus pint
" rufus
Fidonia piniaria .
Trachea piniperda
Insects often found in
very dry dead stand-
ing trees.
Larvee live in roots. The
beetle is very destruc-
tive to shoots of young
trees.
The larve live under bark,
and pupze form cocoons
in dead or back-going
young trees.
Larvee burrow under bark
of stem close to roots
of young trees.
Female beetle makes short
gallery under bark and
close to stem of young
trees.
Female beetle burrows
under bark of newly
felled or back - going
trees. Larvee make ir-
regular galleries. The
beetle also bores out
the young shoots.
Beetle burrows under
bark. Larve make
short galleries.
Female makes burrows
in stems of young
plants.
Female said to burrow
in dead trees near
London.
Beetle burrows in bark.
Both beetle and larvee
make irregular gal-
leries.
Male burrows under thin
bark and makes a cir-
cular chamber, whence
female beetles make
radiating galleries and
larve irregular gal-
leries.
Larvee feed on foliage
Larvee feed on foliage
Larvee live on foliage
Larvee live on foliage
76
100
107
112
119
121
123
175
178
253
258
LIST
OF TREES
WITH INJURIOUS
INSECTS.
413
Name of tree or
shrub affected.
Name of insect.
Nature of injuries.
Scots Pine
Silver Fir
Snowberry
Spindle-tree .
Spruce .
Retinia turionana .
un buoliana
n-restnella
Lachnus pint
Chermes pint
Cryphalus picee
Sirex gigas
Megastigmus strobilobius
Dioryctria abietella
Chermes picee
Chromatomyia obscurella
Aphis euonymus
1 Ernobius mollis
Hylastes palliatus .
Cryphalus abietis .
Larva lives in terminal
bud and arrests de-
velopment.
Larva lives in terminal
shoot, which generally
dies as the result of
the injury.
Larva makes a gall of
resin on side of young
shoot.
| Black eggs may be found
in winter, and Aphides
in summer, amongst the
foliage.
Insects live within woolly
covering on shoots or
young stems.
Female beetle is said
to make burrows in
branches.
Larvee bore into back-
going trees or recently
felled timber.
Larvee feed on kernel of
seeds.
Larvee feed on cones
Insects live — within
woolly covering on
bark,
Produces winding mines
on leaves.
Aphides often kill lead-
ing shoots and form a
rosette of leaves.
Larvee make burrows
under bark of dry
poles.
Female beetle and larvee
make irregular gal-
leries under bark.
Female bores under bark
generally at knots of
the branches, and
scoops out a sort
of recess from which
the larval galleries
radiate.
117
189
199
258
332
116
1 Also under bark of larch paling.
414 FOREST ENTOMOLOGY.
Name of tree or
shrub affected. Name of insect.
Nature of injuries.
Page.
Spruce . . | Lrypodendron lineatum
tye ae . | Lygeonemetus saxeseni .
ue . | Strex juvencus .
af x . | Physokermes abietis
ie . | Dioryctria abietella :
HS eA . | Aphis abietina
" “ . | Chermes abietis
Sycamore . | Phyllocoptes acericola
" . | | Lecanium caprece
" . | Cheimitobia brumata
" . | Hybernia defoliaria
" . | Stigmonota regrana
" . | Drepanosiphum platan-
ovdes.
" . | Chaitophorus aceris
Wayfaring- Eviophyes tetanothrix
tree.
" . | Aphis viburnt é
Weymouth Chermes corticalis .
Pine.
Whin . . | Phleophthorus — rhodo-
dactylus.
Willow (goat) | Eriophyes tetanothrix
Female beetle burrows
into sapwood towards
centre of tree. Larvee
make short ladder gal-
leries.
Larve live on _ foliage,
often defoliating the
extreme twigs.
Larvee bore into back-
going trees or recently
felled timber.
Brown scales in forkings
of twigs.
Larvee live on cones ,
Insects often found plen-
tifully amongst foliage.
Insect forms pseudo-gall
on shoots.
Causes small galls on
upper surface of leaf.
Large brown scale on
twigs.
Larve eat foliage in
early summer.
Larvee live on foliage
Larvee underneath flakes
of old bark.
Insects may be found
under the leaves
throughout the whole
summer.
Insects may be found
under leaves during
the summer.
Causes galls on upper
surface of leaf.
Insects form a _ rough
rosette of leaves on
terminal shoot.
Insects live within woolly
covering on stems.
Beetle burrows under the
stems, and larvee make
irregular galleries.
Causes galls on upper
surface of leaf.
126
188
191
228
1 Also on hawthorn, apple, oak, elm, chestnut, lime, &c.
LIST
OF TREES WITH INJURIOUS INSECTS.
Name of tree or
shrub affected.
Name of insect.
Willow (goat)
" — (osier)
n (Salix
capred)
" W
" (Salix
viminalis)
1 (golden
variety )
" (Hunt-
ingdon)
! "
n (Salix
caprea)
"! "
'" "
nu (Salix
viminalis)
1 Aromia moschata
Phyllodecta vitelline
Euura pentandre .
Pontania salicis
" bel. la
" prozima
" gallicola
" ischnocerus
Pteronus salicis
Smerinthus ocellatus
Trochilium bembeci-
formis.
Depressaria contermin-
ella.
Melanoxanthus salicis
Lachnus viminalis
Cecidomyia =marginem-
torquens.
" TOSATIA
" saliciperda
" heterobia .
415
Larvee
shoots.
folds.
Nature of injuries. Page.
Larve bore in old de- | 55
cayed stems.
eat the foliage, | 64
and beetles destroy the
terminal buds of rods.
Produces galls on twigs 181
Produces galls on under | 181
side of leaf.
Produces galls on under | 182
side of leaf.
Larve bore in pith of | 183
Produces galls on both | 183
sides of leaf.
Produces longish galls on | 184
both sides of leaf along
the midrib.
Larvee eat the softer por- | 184
tions of leaves, leaving
the veins untouched.
Larvee live on leaves 244
Larvee burrow in stems | 244
generally at the base.
Larve eat extreme tips | 276
of shoots, and draw
terminal leaves to-
gether for protection.
Aphides congregate them- | 300
selves together on rods.
Aphides may be found in | 311
clusters on shoots.
Insects cause edges of | 342
leaves to roll inwards,
aud live within the
Insects form rosette of | 346
leaves chiefly on ex-
treme end of twigs.
Conspicuous through-
out the winter months.
Insects cause injuries by | 347
eating into stems.
cause longish | 348
Insects
galls of rolled leaves
at extreme end of
twigs.
1 Also attacks lime-trees.
416
FOREST ENTOMOLOGY.
Name of tree or
shrub affected.
Name of insect.
Willow (Salix
viminalis)
WY '"!
Cecidomyia salicis
Hormomyia capree
Agromyza schineri
Eriophyes psilaspis
Batodes angustiorana
Cecidomyta taxt
Nature of injuries.
Insects produce galls by
swellings on twigs.
Produces hard galls on
midrib of leaves.
Produces irregular galls
on stems.
Cause swollen abortive
buds.
Larvee live throughout
the winter in rough
cocoons on under side |
of foliage. In summer
injuries of larvee are
conspicuous by dead
twigs.
Insects form rosette of
leaves chiefly on ex-
treme end of twigs.
265
s
Note. —The names of insects given as synonyms throughout the book and
names not at present generally adopted are printed in italics.
Abdomen, 11
Abnormal buds, 20
Acanthocinus edilis, 58
Agrilus viridis, 48
Agromyzide, characters of family,
357
Agromyza schineri, 357
Aleyrodidez, 204
Andricus curvator, 150
Secundatrix, 152
gemmatus, 148
inflator, 149
noduli, 148
ramuli, 152
Anobiide family, 50
Anobiina, generic
characters of, 51
Antenne, typical, 10
Aphidide, general characters of, 290
honey-dew of, 292
oviparous and viviparous, 295
sub-families of, 296
Aphilothrix albopunctata, 152
collaris, 149
corticis, 148
fecundatrix, 152
globuli, 148
quadrilineata, 151
radicis, 147
Aphis, characters of genus, 301
abietina, 304
crategi, 301
euonymus, 304
hederz, 304
padi, 303
divisions and
»)
-
sambuci, 305
viburni, 305
Apterococcus fraxini, 238
Argyresthia, generic characters of,
278
levigatella, 278
Aromia moschata, 55
Arthropoda, divisions of, 3
Asemum striatum, 399
Ash-bark beetles, 101
Ash-bud Moth, 273
Asphondylia sarothamni, 355
Aspidiotus, generic characters of, 215
britannicus, 216
zonatus, 216
Asterolecanium, generic characters
ofa
variolosum, 231
Astinomus cedilis, 58
Attelabus curculionides, 66
Aulacaspis rose, 217
Balaninus, generic characters of, 83
nucum, 83
Bark beetles, descriptive characters
of, 85
Batodes angustiorana, 265
Beech Agrilus, 48
Beetles, descriptive details of, 37
classification of, 40
Beneficial insects, 398
Bibionidz, characters of family, 360
Bibio marci, 361
Biorhiza aptera, 154
renum, 157
D
418
Blind bud of currant, 19
Bordered White Moth, 253
Braconide, 400
Breathing organs, 12
Buff-tip Moth, 251
Butterfly, development of, 7
Callipterus, characters of genus, 307
betularius, 308
quercis, 308
Cecidomyidx, characters of family,
341
‘Cecidomyia, characters of genus, 341
crategi, 344
marginemtorquens, 342
pice, 357
rosaria, 346
saliciperda, 347
salicis, 349
taxi, 345
tiliam volens, 350
Cemiostoma laburnella, 287
Cerambycide, 55
Cerataphis latanize, 204
Ceratoneon vulgare, 34
‘Cerura vinula, 249
Chaitophorus, characters of genus,
306
abnormal form of, 306
aceris, 305
Chalcididz, 139, 400
Cheimitobia brumata, 255
Chermesinz, characters
321
Chermes, characters of genus, 323
importance of genus in forestry,
333
abietis, 824
corticalis, 331
laricis, 328
piceze, 332
pini, 330
strobilobius, 326
Chionaspis, characters of genus, 208
salicis, 209
Chromatomyia obscurella, 358
ilicis, 359
Chrysomelina, 62
Cicadidze, 369
Cimbicides, 172
Cladius viminalis, 180
Clay-coloured weevil, 68
Clinodiplosis botularie, 351
-Clytus arietis, 55
of tribe,
INDEX.
Coccid, general characters of, 201,
205
synopsis of sub-families, 205
Cockchafer, 44
preventive and remedial measures
against, 46
Coleophora, generic characters of,
281
fuscedinella, 284
laricella, 281
sp., 284
Coleoptera, 37
Collecting, 375
Cossus ligniperda, 245
Croesus septentrionalis, 185
Cryphalus, characters of genus, 115
abietis, 116
fagi, 118
pice, 117
tilie, 117
Cryptocampus pentandre, 181
Cryptococcus fagi, 234
Cryptorrhynchus lapathi, 82
Cynipidie, details of structure, 138
groups of, 140
Cynips Kollari, 158
Dactylopiine, 229
Dasyneura marginemtorquens, 342
crategi, 344
taxi, 345
tiliam volens, 350
Deporaiis betule, 67
Depressaria, characters of genus, 276
assimilella, 277
conterminella, 276
Diaspinz, 206
Diaspis, 217
Dicranura vinula, 249
Digestive organs, 13
Digging in autumn, 388
Dioryctria abietella, 258
Diplosis botulariz, 351
dryobia, 352
tremule, 353
Diptera, general characters of, 339
Dorcus parallelopipedus, 43
Drepanosiphum, generic characters
of, 298
platanoides, 298
Dryobius, characters of genus, 314
Dryocetes, generic characters of,
120
villosus, 120
INDEX. 419
Dryoczetina, 114
Dryophanta divisa, 154
longiventris, 154
scutellaris, 153
Dryophanta folii, 153
Eccoptogaster scolytus, 93
Eggs of insects, 4
Elm-bark Beetle, 93
Entomology, principal orders, 3
Epura angustala, 399
Erineum, 19
Eriophyes, life-history and micro-
scopical characters, 21
fastidious as to food, 35
physiological functions, 22
species causing malformation of
flowers, fruit, or leaves, 30
species living in buds, 23
species living in galls, 27
aucupariz, 32
avellanze, 24
axillaris, 29
fraxini, 30
goniothorax, 31
leevis, 29
macrochelus, 28
macrorhynchus, 28
psilaspis, 26
rudis, 25
tetanothrix (Jevis), 29
tiliz (typicus), 27
tiliarius, 30
Eriophyide, 19
Eriophyine, sub-family, 23
dissemination of, 36
Ernobius mollis, 52
Euura pentandre, 181
Eyed Hawk-Moth, the, 244
Eyes of insects, 9
Fidonia piniaria, 253
Forest Entomology, definition of, 1
Fumigation, 394
Gall-flies, setting of, 380
Gall-mites, 19
Geometrina, 253
Goat-moth, 245
Gracillaria syringella, 280
Green Tortrix Moth, 260
Harmandia tremule, 353
Head of insect, 9
Heart of insect, 14
Hedya ocellana, 265
Holcocneme Erichsonii, 186
Hormomyia capree, 354
fagi, 354
piliger, 354
Hornet, 192
clear-wing of the osier, 244
Hybernia defoliaria, 257
Hylastes, characters of genus, 98
ater, 100
palliatus, 99
Hylesinina, 98
Hylesinus, characters of genus, 101
crenatus, 101
fraxini, 103
oleiperda, 105
vittatus, 106
Aylesinus piniperda, 107
Hylobius abietis, 72
preventive and remedial measures
against, 74
Hylurgus, generic characters of, 107
minor, 112
piniperda, 107
piniperda, preventive and remedial
measures against, 111]
Hymenoptera—oak-galls, 130
characters of, 164
miscellaneous, 192
saw-flies, 164
Hyponomeuta evonymellus, 272
Ichneumonid, 400
Insect, general definition of, 3
Insecticides, 387
Insects, relative position in the
animal kingdom, 2
Lachnine, characters of tribes, 309
Lachnus, characters of genus, 310
longipes, 311
pini, 310
viminalis, 311
Lamiide, 58
Larve, typical forms of, 5
Lasioptera rubi, 355
Leaf-wasps, 172
Lecanium, general characters of, 219
generic characters of, 221
bituberculatum, 226
caprez, 226
ciliatum, 225
persice, var. coryli, 225
420
Leg, structure of, 11
Leopard Moth, 247
Lepidoptera, general characters of,
240
Lithocolletis,
285
carpinicolella, 287
coryli, 287
faginella, 287
messaniella, 285
salicicolella, 287
Longicornia, characters of, 53
family divisions of, 54
Lophyrides, 175
Lophyrus, characters of genus, 175
pini, 175
rufus, 178
Lygzonemetus saxeseni, 188
Lucanide, 42
Lucanus cervus, 42
characters of genus,
Macrodiplosis dryobia, 352
Macropsis lanio, 371
Marble gall, 158
Megastigmus spermotrophus, 194
strobilobius, 199
Melanoxanthus, characters of genus,
299
salicis, 300
Melasoma populi, 62
Melolontha, characters of genus, 44
preventive and remedial meas- _
ures against, 46
hippocastani, 47
vulgaris, 44
Mikiola fagi, 354
Monochetus sulcatus, 33
Mottled Umber Moth, 257
Mounting, microscopic, 380
Musk Beetle, 55
Myelophilus piniperda, 107
Mytilaspis, generic characters of,
214
pomorum, 214
Myzus, generic characters of, 297
cerasi, 297
Nail-galls, 27
Nematine, 178
generic divisions, 179
Nematus abietinus, 188
bellus, 181
gallicola, 183
ischnocerus, 184
INDEX.
septentrionalis, 185
vallisnerii, 183
Nematus Erichsonii, 186
Nervous system, 12
Neuroterus fumipennis, 144
leeviusculus, 145
lenticularis, 140
numismatis, 146
ostreus, 146
Novius cardinalis, 399 -
Oak-apple, 156
Oak-galls, 130
alternating generations of, 141
development of, 132
relation to theory of evolution,
134
synoptical table of, 159
their economic interest and teach-
ings, 162
Ocelli, 9
Oligotrophus capree, 354
puiger, 354
Orchestes, generic characters of, 80
alni, 81
fagi, 80
quercts, 81
Otiorrhynchus picipes, 68
sulcatus, 69
Peedisca occultana, 265
ophthalmicana, 266
Pemphigine, characters of tribe, 317
- Pemphigus, characters of genus, 317
bursarius, 318
pallidus, 320
spirothece, 319
Penthina pruniana, 263
Philaneus spumaria, 371
Phleophthorus, characters of genus,
113
rhododactylus, 113
Phraiora vitelline, 64
Phyllaphis, characters of genus, 312
fagi, 312
Phyllereum, 20
Phyllobius maculicornis, 71
Phyllocoptine, 33
Phyllocoptes acericola, 34
Phyllodecta, characters of genus, 64
vitelline, 64
Phylloxera, characters
336
punctata, 337
of genus,
INDEX. 421
Physokermes, characters of genus,
228
abietis, 228
Phytomyza xylostei, 358
ilicis, 359
Phytomyzid, characters of family,
358
Phytoptide, 19
Phytoptus aceris, 34
calycophthirus, 25
myriadeum, 28
ribis, 19
rudis, 25
taxi, 26
Pine-bud Tortrix Moth, 268
Beauty Moth, 258
shoot Tortrix Moth, 268
Pine weevil, 72
Pissodes, characters of genus, 75
notatus, 78
pini, 76
Pityogenes,
122
bidens, 123
bidentatus, 123
Pityophthorus, characters of genus,
118
pubescens, 119
Polydrusus micans, 71
Pontania bella, 182
gallicola, 183
ischnocerus, 184
proxima, 183
salicis, 181
Ss
characters of genus,
_ Poplar Hawk-Moth, 243
Poplar-leaf Beetle, 62
_ large Longicorn Beetle of, 60
small Longicorn Beetle of, 61
Prays curtisellus, 273
Priobium castaneum, 51
Prionus corarius, 54
Proctotrypidz, 401
Pseudococcus aceris, 232
Psyllide, 363
Psyila alni, 368
buxi, 366
crategi, 367
Psyllopsis fraxinicola, 364
fraxini, 364
Pterocallis, characters of
309
tilize, 309
Pteronus, characters of genus, 184
salicis, 184
genus,
Pulvinaria, characters of, 222
vitis, 222
var. ribesix, 223
Pupa, typical, 6
Puss Moth, 249
Pygera bucephala, 251
Reproductive organs of female, 15
organs of male, 17
Respiratory organs, 12
Retinia, characters of genus, 268
buoliana, 268
resinella, 270
turionana, 268
Rhabdophaga heterobia, 348
rosaria, 346
salicis, 349
Rhagium, characters of genus, 56
bifasciatum, 57
inquisitor, 56
Rhodites eglanteriz, 193
rose, 193
Rhopalomesites Tardyi, 84
Rhynchophora, characters of, 66
Rhynchota, 370
Saperda, generic characters of, 59
carcharias, 60
populnea, 61
Scale-insects, 201
Scarabeeidee, 44
Schizoneura, characters
315
ulmi, 316
Schizoneurine, 314
Scolytide, descriptive characters of,
85
Scolytine, characters of sub-family,
92
Scolytus, characters of genus, 9
destructor, 93
Geotiroyi, 93
intricatus, 97
multistriatus, 96
pruni, 96
Sesia bembeciformis, 244
Sinodendron cylindricum, 43
Sirex gigas, 189
juvencus, 191
Siricidee, 189
Smerinthus ocellatus, 244
populi, 243
Spathegaster albipes, 145
aprilinus, 147
of genus,
—
432 INDEX.
baccarum, 143
tricolor, 145
vesicatrix, 146
Spraying in nursery, 395
Stag-beetle, 42
Stigmonota regiana, 267
Stomaphis, characters of genus, 313
Strophosomus, characters of genus,
69
capitatus, 70
coryli, 70
Structure of insects, 8
Taphrina, 20
Tenthredinidx, 172
Teras terminalis, 156
Tetraneura ulmi, 320
Thorax, 10
Tinex, 271
Tomicus, characters of genus, 121
acuminatus, 122
sexdentatus, 121
Tortoiseshell butterfly, development
Ot, 7
Tortricide, 259
Tortrix ribeana, 263
viridana, 260
Trachea piniperda, 258
Trachee, 13
Trichiocampus viminalis, 180
Trichiosoma, characters of genus, 172
tibialis, 173
Trochilium bembeciformis, 244
THE
Trypodendron, characters of genus,
125
domesticum, 127
lineatum, 126
quercts, 128
Two-winged flies, 339
Typhlocyba ulmi, 372
flammigera, 372
querciis, 372
Typhlocybide, 372
Typical insect, 4
mouth parts, 9
Vapourer Moth, 248
Vedalia, 399
Vespa Crabro, 192
Volvulifex aceris, 34
Washing large trees, 396
Wasp Beetle, 55
Willow Beetle, 64
twig midge, 349
wood midge, 347
Winter Moth, 255
Wood-Wasps, 189
Xestobium tessellatum, 52
Xyleborus, characters of genus, 128
dispar, 128
Xylocleptes, characters of genus, 119
bispinus, 119
Zeuzera vesculi, 247
PRINTED BY WILLIAM BLACKWOOD AND SONS.
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