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New York
State College of Agriculture
At Cornell University
Ithaca, N. Y.

Library

ornell Universit:

ritish oak galls.

Cornell University

Library

The original of this book is in
the Cornell University Library.

There are no known copyright restrictions in
the United States on the use of the text.

http://www.archive.org/details/cu31924002883134

BRITISH OAK GALLS

“Mihi contuenti se persuasit rerum natura nihil incredibile
existimare de ea.” :
(Pliny the Elder, Nat. Hist., XI, 2.)

=

“The contemplation of Nature has convinced me that nothing
which we can imagine about her is incredible.”

FRONTISPIECE.

[PLATE L]

Galls caused by DRYOPHANTA SCUTELLARIS on under-surface of leaves of
Quercus pedunculata,

“THE CHERRY GALL,”

aAdlard § Son, Impr.

BRITISH OAK
GALLS

BY

EDWARD T. CONNOLD, F.Z.S., F.E.S.

AUTHOR OF ‘BRITISH VEGETABLE GALLS, ‘GLEANINGS FROM THE FIELDS
OF NATURE, ETC., ETC.

EDITOR OF ‘ BRITISH HYDROID ZOOPHYTES,’

FROM NOTES BY THE LATE P. J. RUFFORD, F.G.8., ETC.
(PUBLISHED POSTHUMOUSLY )

ILLUSTRATED WITH 68 FULL-PAGE PLATES, 21 INSETS
AND 17 SMALL DRAWINGS

London
ADLARD AND SON
BARTHOLOMEW CLOSE

1908
[ALL RIGHTS RESERVED ]

$&
658
0 |

67s
1'75140

PRINTED BY ADLARD AND SON
LONDON AND DORKING

JOREA

PREFACE

Tue British Oak is the abode of a vast concourse
of dependents. Nearly five hundred different species
of insects, and other creatures, find their needs amply
supplied, mainly by the leaves. Of this number

about two hundred are either parasites living upon

the larve of fifty-four species of Cynipide which
produce galls, or they are inquilines obtaining their
nourishment from the tissues of the galls. The Oak
is therefore of great importance to insect life.

The object of this volume is to describe and illus-
trate, in some measure, galls produced by the Cynipidee
and other causes of galls on the Oak. The insects,
with their parasites. and other occupants of the galls,
have been fully described by various writers ; several
pages will, however, be devoted to a few interesting
and unique features of the Cynipide. This volume is
also the fulfilment of an intimation contained in the
preface of my ‘British Vegetable Galls,’ explaining
the reason why galls on the Oak were not described
in that work.

I trust the information herein contained may be the
means of assisting many students to a further under-
standing of the subject ; that collectors of these most
interesting and dainty galls will be enabled to identify
any specimen obtained; and, that casual observers
will find in the illustrations and the text, such as will
influence them to pursue the study in a practical

manner.
There is much more to be ascertained concerning

vi PREFACE.

the growth of oak galls, and one purpose of the
following pages will have been accomplished if they
are the means of inspiring somebody to further unfold
the subject.

I shall esteem it a pleasure to endeavour to identify
any galls. Specimens should always be sent in a tin
bow.

I desire to acknowledge with much gratitude the
kindness and help received from my aged friend, the
Rev. E. N. Bloomfield, M.A., F.E.S., of Guestling Rec-
tory, Sussex, without whose stimulation and encourage-
ment I should probably never have studied galls.

To Mrs. M. J. M. Andresen of Hastings, I offer my
heartiest thanks for translating various Continental
treatises ; and to my wife, for valuable assistance from
the earliest contemplation of the work, and with the
proof-sheets; to Sir Archibald Lamb, Bart., for his
kindness in allowing me, at any time, to roam about in
Beauport Park in search of specimens; to Dr. Alfred
Nalepa of Vienna, for permission to reproduce Plate
LXIV; to Mr. W. H. Hammond for the photo-micro-
graphs divs. B and OC, Plate XXXII; to Mr. A. W.
Bawtree, F.L.S., for the insets on Plates XLVIII and
XLIX; also to Mr. H. Stone, F.L.S., F.R.C.1., and
Messrs. W. Rider and Son, Ltd., for permission to
include Plate II; to Mr. E. W. Swanton, M.C.S., for
specimens and notes of observations; and also to Mr.
W. W. Midgley for a valuable specimen.

EDWARD CONNOLD.

1, St. PETER’s Roan,
St, LEONARDS-ON-SEA
July, 1908.

CONTENTS

PREFACE
List oF Fuuu-pacre Puatss.
List oF Smatt [uiustRations

INTRODUCTION

CHAPTER I

Tue PRIncIPLES OF Oak GALL Formation

CHAPTER II

Some Frarvures or Oak Gatt GrowrH

CHAPTER III

Tore Numericat Aspect or Oax GALLs

CHAPTER IV

Tur CynIPIpD# AFFECTING THE Oak .

CHAPTER V

Tue British Oak

CHAPTER VI
Hints on Contectine anp Mounrine Oak GaLts
Terms EMPLOYED IN THE SynopricaL TaBLES .

TapLe or ALTERNATE GENERATIONS

20

26

33

40
46
49

Vill CONTENTS

PAGE

Tue Genus Andricus . , ; : ; : . 60
i Aphilothrix f : ‘ : . 8
is Biorhiza . ; : ‘ ‘ ‘ . 98
* Cynips.. ; : : , 102
Fe Dryophanta : , : 108
is Neuroterus. ; : : : : . 117
3 Spathegaster : : : : . 126
” Teras : : . . 187
” Trigonaspis_. ‘ ‘ . 139
Cynips tinctoria . : 5 i , . 141
i calicis 4 ; ; ‘ ; . 148
Curves oF Q. Ilex ; : 5 ‘ : : . 144
OrHeR Gattis on THE British Oaks NOT CAUSED BY
CyniPIpa— ‘
Asterolecanium variolosum . : : : : . 146
Diplosis dryobia : ; : : : ; ; . 147
Dichena quercina . : : ; ‘ : : . 148

Parasites anp INQUILINES MENTIONED IN THE VoLUME . 150

A TasLe or Montus In wHIcH THE British Oak GALLS

ILLUSTRATED IN THE VOLUME MAy BE Founp . . 153

A List or Mrp-Europzan Oak Gauls ‘ ‘ . 155
DEscripTion or Puatr XXXV . : ; ‘ ; . 159
‘ or Puars XXXVI. . . ...s «160

Pr or Prates XXXVII anp XXXVIII .. . 161

INDEX . 3 ‘ : ; : : 3 : . 163

PLATE

LIST OF PLATES

I.—Frontispirce, “THe CHerry Gat,” Dryophanta scutellaris.

II.—Sections of Oak Wood.

III.—Fruit and Leaves of Q. pedunculata and Q. sessiliflora.
IV.—Fruit and Leaves of Q. cerris and Q. Ilex.

Gatis CauUsED BY—
V.—Andricus Astivalis.

VITT.—
IxX.—

x.—
xXI—
XII.—
XIIT.—

amenti.

circulans.
clementine.

gemmatus.
lucidus.

curvator.

”

glandium.

”

nodult.
glandule.
inflator.
nodult.

nudus.
pilosus.

» Aphilothria quadrilineatus
XIV.—Andricus ramuli.

xV.— 7. solitarius.
XVL— 3 testaceipes.
XVII.— 5 albopunctata.
XVIII.—Aphilothriz callidoma.
xXIX.— 3 corticis.
xXxX.— » fecundatria.
XXI— ”

PLATE

XXII.—Aphilothrix fecunda-
triz, A. corticis.

XXTII.—Aphilothriz Malpighii.

” globult.
” 5 autumnalis.
XXIV.— marginalis.
” » seminationis.
XXV.— _,, quadriline-
atus.
XXVI.— - radicis.
XXVII.— 4% Sieboldi.
XXVIII.— s 2
XxIxX.— 2 re
xXxX.-— i _
a radicis.
XXXI.—Biorhiza aptera.
XXXII. 7 » Ova, &C.
XX XTII.— 3 » roots
of tree.
XXXIV.— » vrenum.

XXXV.— Cynips Kollari,ridges,
papille, ete.
XXXVI.—Cynips Kollari, aber-
rant examples.
XXXVII.—Cynips Kollari, geo-
metrical groups.

XXXVIIL.—Cynips Kollari, con-
glomerated clusters.

x LIST

PLATE

XXXIX.— Cynips Kollari,attacked
by Phoma gallorum,
parasites and inqui-
lines,

XL.—Dryophanta agama.

xXLI.— » disticha.
XLII.— sy divisa.
XLITI.— 2 longiventris.
XLIV.— ss scutellaris.
XLV.— ra _
XLVI.—Neuroterus fumipennis.
XLVII.-- ss laeeviusculus.
XLVIII.— Pe lenticularis.
XLIX.— “ numismatis.
L.— “y ostreus.

LI.—Spathegaster albipes.

LIT.— os aprilinus.
” is similis.
” 9 Taschenbergi.
LUI— i baccarum.

OF PLATES

PLATE
LIV.—Spathegaster tricolor
LV.— a vesicatrix.

LVI.—Teras terminalis.
LVII.— ,, 5
LVIII.—Trigonaspis crustalis.

LIxX.— i i
LX.—Neuroterus fumipennis.

» Cynips tinctoria.
LXI— ,,
» Cupules of Q. Ilex.

LXII.—<Asterolecanuwm variolo-
sum.

LXIII.—Diplosis dryobia.

LXIV.—Epitrimerus cristatus.
LXV.—Dichena Quercina.

LXVI.— a 5

LXVIL—Q. pedunculata
at Guestling.

LXVIII.—Q. pedunculata
at Guestling.

calicis.

LIST OF SMALL ILLUSTRATIONS

FIG.
1.—A pair of Nippers .
2,—A Pruner
3.—A Fern-trowel
4.—Mm., Cm., and Inch Scale

5.—Galls caused by Andricus glandule: a, young x 24;
B, mature x 23; c, section x 23
6.—Galls caused by Andricus ae on patil and mid-
rib of leaf .
7.—Galls caused by Aphilothriz pee sensi
variability in situation, form, and marking .

8.—Galls caused by Aphilothria collaris: a, in situ, nat.;
B, enlarged, x 4; c, scales removed, x 4

9.—Galls caused by Aphilothriz Malpighti

10.—Galls caused by ees Sieboldi, mE shaes and
situations

11.—Sections of galls caused is A, Dae agama ;-

B, D. disticha ; co, D. divisa .

12.—Three aspects of the same specimen of D. disticha:
A, side; B, top; c, end

13.—Sectional aspect of specimen of D. neta : A, CYOSS;
B, longitudinal; o, transverse ,

14.—Galls caused by Neuroterus leviusculus on upper-surface
of leaf; variations in form, etc.

15.—Diagrammatic sections of N. lenticularis, N. fumipennis,
N. leviusculus
16.—Section of gall caused by N. Fevioutort

17.—Galls caused by Spathegaster verrucosus

PAGE

45
45
45
48

62

72

74

80
88

98

109

111

114

119

121

121
135

INTRODUCTION

Tue beautiful colours, diversity of sizes, and the
peculiar shapes of many British oak galls impart an
unusual interest and charm to their study. It, how-
ever, possesses an additional interest to the student of
Natural History. The gall-makers, with the numerous
Parasites, Inquilines, and other creatures which
emerge from the galls, invite the student to extend
his research in another direction, and when he does
so Entomology becomes inseparably associated with
Botany.

Collecting oak galls is a most fascinating occupation.
It does not require a greater amount of time than is
devoted to gathering material for an herbarium.

The principal British oak gall-producing insects are
the Cynipide, a family of the Hymenoptera. Flies
with two wings, or Diptera, are represented by a few
species; there is also one species of Coccus, and one
Fungus.

A few species of flies producing galls on other
plants, are of medium size. Tephritis bardane, and
Urophora solstitialis, which produce galls in the seed-
heads of common burdock, and in thistle stems
respectively, are typical examples. The alar extent
of these species is about 8-10 mm. But the majority
of gall-flies (including those on the oak) are very
diminutive, many species not measuring 2mm. To
these the name of gall-enats, or gall-midges, may
appropriately be given. They produce galls in a great

Xiv INTRODUCTION

variety of forms on numerous plants. One form is
illustrated on Plate LXITI, and others are referred to
elsewhere.

Of the Cynipide there are-many species. They
attack various plants, but they are found principally
on the oak. They have four wings, and to distinguish
them from other gall producers may correctly be
known as gall-wasps, and henceforth they will be
referred to as such. They are briefly described in
Chapter IV.

While the Diptera are comparatively free from the
attacks of other insects, the gall-wasps are not; they
are extensively preyed upon by parasites, and hyper-
parasites, and the gall tissue around the larva is often
the welcome abode of a host of other creatures which
play the parts of imquilines, commensal tenants, or
casual occupants. They seldom cause the death of
the rightful inhabitant except in the case of inquilines
living gregariously around the larval cell of Cynips
Kollari. The number of lodgers in oak galls is very
great (more than 180), a good many occurring in
several kinds of galls. Hurytoma rose occurs in four-
teen different galls, Megastigmus dorsalis in eleven,
Synergus facialis in ten, S. vulgaris in nine, and five
other parasites each in eight galls. There are many
more of similar habits.

It will be found that thirteen species are without
alternate generations, viz.: Andricus exstivalis,

amenti, = clementine, = glandium, = glandulez, =
lucidus, = solitarius, Aphilothrian albopunctata, =
marginalis, = quadrilineatus, = seminationis, Dryo-

phanta agama, and = disticha. At present these are
unknown; and of two other species there is yet some
doubt. In this, however, our British species are not
alone. According to Beyerinck the sexual generations
of twenty-six continental forms are unknown (p. 152).

A very large number of oak galls occur in Mid-
European countries. The various species and varieties
of oak are also numerous, consequently a great many

INTRODUCTION Xv

of the galls cannot be expected to occur in England,
and several of our English forms do not appear in
those countries. It is not improbable, however, that
some of the continental species do occur in England,
and that they will be found when more workers are
engaged upon the subject. I have therefore prepared
a list of Mid-European oak galls with fullest details
obtainable, as a guide to the collector. The list must
not be regarded as complete (pp. 155-158).

The history of British oak galls dates from a very
early period.

The word “ gall” appears first in English literature
in ‘ Trevisa,’ Barth., De P. R., XVII, civ (Tollem MS.),
where the following occurs: “ The mall (Mandragora)
hap white leuse . . . and apples growep on pe
leues, as galles growep on oaken leues.” In 1481
Caxton uses the word “ gall.” Turner, in his ‘ Herbal,’
ii, 109 (1562) describes a gall as “the fruite of an
oke, and especially of the leve.”’ In 1616 Surfl. and
Markh., in ‘Country Farme,’ p. 28, remark: “ He
shall know a fruitfull and fertile yeare if he see the
Oke apples, commonly called Gals.”

In the last case the reference is to the oak-apple,
Teras terminalis. Probably very few other oak galls.
had then been observed. In 1668, however, several
kinds were recorded. In a volume published in 1902,
(‘Notes and Letters on the Natural History of
Norfolk, more especially on the Birds and Fishes;
from the MSS. of Sir Thomas Browne, M.D. [1605-
1682],’ by Thomas Southwell, F.Z.S.), there are two
references of much value in showing the circumstances
under which these galls were introduced to literature.
The fact is also revealed that Sir Thomas was aware
of galls on foreign oak trees.

“The fourth letter to Dr. Merrett, Decemb. xxix
(1668). (Fol. 42 verso) . . . .

“A paragraph might probably be annexed unto
Quercus. Though wee hawe not all the exotic oakes,
nor their excretions, yet these and probably more

s

XV1 INTRODUCTION

supercrescences productions or excretions may bee
obserued in England.

Viscum—polypodium—Juli pilulee—

Gemmee foraminate (formicate P) foliori—
excrementum fungosum verticibus scatens—
excrementum Lanatum—

Capitula squamosa jaceeze emula.

Nodi—melleus Liquor—Tubera radicum

vermibus scatentia—Muscus—Lichen-—
Fungus—vare querine.”

In the volume the Rev. E. N. Bloomfield, M.A., of
Guestling Rectory, Sussex, suggests the ‘following
explanatory notes :

“1, Viscum, is doubtless the Mistletoe.

“2. Polypodium, the Common Polypody Fern.

“3. Juli pilule, ‘little balls on the flower catkins,’
the Currant Gall (Newroterus baccarum, which is the
spring form of N. lenticularis, Oliv.).

“4, Gemme foraminate (formicate?) foliorum,
‘pimple-like buds on the leaves.’ Leaf-galls such as
the Silky Button, N. numismatis, Oliv., and the
common Spangle, N. lenticularis, Oliv.

“5. Excrementum fungosum verticibus scatens, ‘
spongy secretion bursting out from the ends of seta
The Oak Apple, Biorhiza terminalis, Fab.

“6. Excrementum lanatum, the Woolly Gall,
Andricus ramuli, L., a somewhat rare gall, resembling
a ball of cotton wool.

“7. Capitula squamosa jacez emula, ‘little scaley
(or imbricated) heads resembling the heads of Jacea’
(Black Knapweed). The Artichoke Gall, Andricus
fecundatriw, Htg.

“8. Nodi, probably swellings of any sort, whether
caused by insects or not.

“9, Malleus liquor, honey-dew, a secretion of
Aphides.

“10. Tubera radicum vermibus scatentia, ‘ swollen
tubers on the roots containing grubs’; without doubt
the Root-gall, Andricus radicis, Fab. Polythalamous

INTRODUCTION XVil

Galls, often very large at the roots or on the trunk
near the ground.

“ How wonderfully observant Sir Thomas Browne
must have been to distinguish the various galls, etc.,
and to point them out so distinctly —E. N. B.”

The second reference is :

“Letter No. 5. Dr. Browne to Merrett (Dr.
Christopher Merrett), . . . .

“TI made enumeration of the excretions of the oake
which might bee obserued in england because I con-
ceived they would bee most obseruable if you set them
down together, not minding whether there were any
addition by excrementum fungosum vermiculis scatens
_ I only meant an vsuall excretion, soft and fungous at
first and pale and sometimes cowered in part with a
fresh red growing close vnto the sprouts, first full of
maggots in little woodden cells which afterwards
turne into little reddish browne or bay flies. of
the tubera indica vermiculis scatentia I send you
a peece, they are as bigg as good Tennis-balls and
ligneous.”

The Oak-apple and the Truffle-gall are the kinds
here referred to.

It was not until Withering’s ‘ British Plants’ was
published (1776-1796), that galls were again definitely
treated of. In Edition 8, vol. ii, p. 388, it is stated
that “the balls or galls upon the leaves are occasioned
by a small insect with four wings.” It would appear
from this that the galls of Spathegaster bacearum and
others were well known to botanists, and the cause of
their origin understood.

In ‘The Entomologist’ for the years 1874-1878
there appeared a translation from Dr. G. L. Mayr’s
‘Die Mitteleuropaischen Hichengallen,’ with numerous
wood-cuts of the galls. Francis Walker, E. A. Fitch,
and others, added notes as to the occurrence or other-
wise of the species in Britain, and a most valuable
compilation was thus made of the knowledge of those

days.
y b

xvii INTRODUCTION

Several interesting and informative papers on the
same subject have been published in various Trans-
actions, etc,

But the study of the causes of oak galls remained
greatly neglected, and although several British ento-
mologists worked out the life-history of some of the
Cynipide it was not until Peter Cameron published
vol. iv of his excellent ‘Monograph of the British
Phytophagous Hymenoptera’ (Ray Society, 1892)
that there was a comprehensive account in the English
language of the gall-producing species.

_In 1894 Charles R. Straton, M.D., translated from
the German Dr. Hermann Adler’s ‘ Alternating
Generations’ (“A Biological Study of Oak Galls and
Gall Flies”), and himself added many pages of very
valuable information. .

_In drawing up the descriptions of some of the galls
IT have added éxtracts from these works; the character-
istics of the specimens are so excellently described by
these authors that I feel sure the student will be
grateful for their reproduction. In addition I have
meorporated the results of fifteen years’ practical
research in the field and in the study. I am also
glad to be able to describe several galls not mentioned
in any other English publication.

With a very few exceptions the illustrations are
entirely new and original, and are my own production.
The specimens were collected expressly for this work,
and great care has been exercised in their selection
and arrangement that they may as far as possible be
representative.

For several reasons it has been found desirable to
arrange the species in alphabetical order. In depart-
ing from the classification set forth in my other work,
‘ British Vegetable Galls,’ I have been animated with
the desire to present the subject in as simple a form
as possible.

BRITISH OAK GALLS.

CHAPTER I.

THE PRINCIPLES OF OAK GALL FORMATION.

THE part of the tree from which the material is
supplied to build up the substance of a gall is that
known as the cambium layer or the cambium region.
“The cambium itself is a clammy secretion, formed in
the spring; a highly viscous fluid elaborated by the
internal organs serving to nourish several parts of the
plant ” (Henslow, ‘ Dict. Bot. Terms,’ p. 32).

“The cambium layer is a tissue in which a very
vigorous formation of new cellsis carried on” (Kerner
and Oliver, ‘The Natural History of Plants,’ vol. 1,
p- 475). It may also be described as “a series of
formative cells lying outside of the wood proper and
inside of the inner bark. The growth of new wood
takes place in the cambium, which is very soft”
(‘Webster’s International Dictionary,’ p.207). The cells
of which it is composed form a complete thin cylinder
concentric to the pith throughout the whole of the
plant, but separated from the pith by the xylem
inwardly, and from the cortex, by the phloém out-
wardly.

The xylem is that portion which has developed, or
will develop into wood cells; the phloém is that portion

2 BRITISH OAK GALLS.

of fibro-vascular bundles which corresponds to the
inner bark.

The activity of the cambium layer begins in the
spring and increases throughout the summer, the cells
dividing continually, until by the autumn the layer is
ten or twelve times thicker than at the commencement
of activity. The result of the multiplication of these
cells, which are formative, is to produce a new ring of
xylem on its inner and a new layer of bark on its
outer surface. The whole life of the plant springs
from this cambium layer; it is the part in which
active metabolism takes place, and it alone possesses
the necessary conditions for gall production.

One essential condition for gall formation is that
the egg must be laid in, or in closest contact with, the
cambium layer. Another condition is the birth and
growth of the larva.

It should be borne in mind that the act of oviposition,
7,é, a wound caused by a simple puncture, does not of
necessity give the impetus to gall formation. There
are, however, exceptions to this. They are supplied
by several species of the aculeate Hymenoptera. To
name but one instance, the gall caused by Aulax
hypochevidis in the flower stalk of the Cat’s-ear
(Hypocheris radicata, L.) is well developed before the
larvee hatch.

It is somewhat difficult to understand why this
should be so. Ifit were merely a question of providing
a sufficiency of food for the larve before they hatch,
then the same reason would be expected to hold good
with regard to the gall of Aphilothria radicis; the
more so, because the number of larvz of the latter
species (normally about sixty), is about five times
greater than that of the former.

But as regards galls on the oak, it is only when the
larva emerges from the egg that active metabolism
begins and the seat of increase of plant.tissue is mani-
fested. Both Cameron and Adler, the two principal.
writers on galls, whose works are in English, are very

THE PRINCIPLES OF OAK GALL FORMATION. 3

definite on this point. ‘What is the first factor in
gall formation ? This, the growth of the larva, as has
already been pointed out. The second is that the egg
must be laid in, or in contact with, the cambium layer ”
(‘ Brit. Phyto. Hymen.,’ vol. iv, p. 21). “ Whena gall-
fly has inserted its egg into the neighbourhood of this
(cambium ring) tissue, what follows? In the first
place the act of oviposition itself has no effect.

IT am convinced that the simple prick of the gall-fly
does not set up gall formation ; this, I hold, only begins
when the larva emerges from the egg” (‘ Alternating
Generations,’ p. 99).

In comparison with the opinions of such specialists,
supported by those of recent observers, and confirmed
by many who have devoted years of research to the
subject, the theories of gall origin advanced by very
early writers have but little value. They must not,
however, be entirely omitted. It was thought by
several of the early observers that the production of
cell activity was caused by a glandular secretion of an
irritating nature, introduced with the egg at the time
of oviposition. Others advanced a theory that the
action of oviposition caused irritation to the plant.
Another suggestion was made, viz. that the egg pos-
sessed a higher temperature than that of the plant, and
thus the cells were warmed into activity. Several
writers have also maintained that infection, in the
form of disease, was the sole cause of galls.

That a secretion of some kind emanates from the
gall-wasp when ovipositing is well known, and it can
be seen, especially if a number of imagines develop from
galls kept in a glass bottle or glass-topped box. They
will place their eggs on the glass, and at the same time
the minute drop of fluid can be seen also. Andricus
nudus will provide a good example. It would appear
that the purpose of the secretion is to seal the hole
caused by the ovipositor. That it does not stimulate
the plant to action the following will demonstrate.
The imagines from galls of Trigonaspis crustalis make a

A BRITISH OAK GALLS.

row of punctures in the veins of young and tender
leaves in May or June. The marks are very distinct,
and the eggs may be easily detected in the tissue of
the leaf, but no change takes place until the larva
hatches late in August, or early in September; then
the galls of Biorhiza renwm quickly develop.

Since oak gall formation does not begin until the
larva hatches, it is certain that the influence of the
larva ig necessary, not only for the early stage of
development, but also for its completion. Rapid cell-
multiplication results from the irritation caused by the
larva feeding, and very soon the gall acquires a vascular
system of its own, and becomes a more or less indepen-
dent structure.

The cells nearest the larva are very rich in starch
granules, while those of the exterior contain tannin, or
colouring pigments, or become transformed into hair-
lets, papillee, etc.

In every case, except one, on the death of the larva
cell-multiplication ceases. Growth also ceases if the
gall be removed from its place of attachment before it
has reached a certain stage. It will also die, sooner or
later, if the twig or leaf it is upon is severed from the
tree. The larva will then either perish, or, if possible,
pupate ; the resulting imago, however, is almost always
poor and undersized.

But many of the autumn galls, especially the Newro-
teri, fall from the leaf, and also with the leaf while
attached, so soon as the frosts commence, and pro-
viding the galls lie in moist situations, slow expansion °
continues, accelerated by the returning warmth of
spring, until pupation takes place; then growth finally
ends.

The exception to the rule, that gall growth ceases
with either the death of the larva or its pupation, is
presented in English galls by Andvricus inflator. This
gall develops from a bud. It is largely composed
of fibro-vascular tissue, and forms an enormously
thickened and shortened shoot, with a central longi-

THE PRINCIPLES OF OAK GALL FORMATION. 5

tudinal cylindrical cavity, at the lower end of which
is a little, partly-attached larval cell. This cell is
undoubtedly amenable to the laws controlling other
oak galls, but not so the outer structure. That con-
tinues its growth, throws out buds from which leayes
of normal size expand, and not infrequently a shoot
will grow from the apex, upon which, in the next
summer, a gall of the same species will develop (see
Plate XI, div. C.)

The gall of Andvicus curvator, when upon a twig or
leaf petiole, exhibits similar peculiarities, but not to so
great an extent; when a leaf is involved in its growth
there is no comparison. This gall is also bilocular;
the larval cell, however, is loose within the external
gall growth, while that of Inflator is attached.

In the compound gall of Aphilothria feeundatrix
the inverse is exemplified. The inner gall, when
pushed out in the late summer by the dying leaf
scales, falls to the ground, and continues growth in a
manner similar to that of the Newroterus galls. The
leaf scales, although dead, persist for many months,
and only disappear from the twig when pushed off by
new growth in the following spring.

The component parts of galls are variable.

The simplest forms are those of Spathegaster bac-
carum and Trigonaspis crustalis, in which the tissue is
very loose, filled with a copious thin fluid, and the
exterior merely a thin epidermis with chlorophyll.

After the emergence of the imago it withers and
shrivels to a condition sometimes beyond recognition.

The next form is that of galls such as Andrirus
nodult, A. nudus, Aphilothrie fecundatriz, A. quadi-
lineatus, A. solitarius, in which the inner layer is
moderately thick, and is composed of cells containing
nutritive materials for the larva, and surrounded by a
thin layer of hard woody cells filled with colour pig-
ments. The same is found in Aph. globuli, with the
addition of an outer sappy green rind. Aph. Siebolda
partakes of the same nature, but the rind, instead of

6 BRITISH OAK GALLS. .

being green, is red or crimson, and from it exudes a
sweet sticky substance. In Dryophanta scutellaris
there are three distinct layers. Surrounding the
larva are the primitive nourishing tissues; next is a
thin layer of bundles of hard cells, these being sur-
rounded with a thick coating of palisade-like cells,
with a thin epidermis containing colouring matter.

Three galls, although plurilocular in growth, are
widely dissimilar in the covering which surrounds the
cells when the galls are in perfection of growth. Aph.
radicis not only has the appearance of a truffle, but
when cut is very much like one; it also resembles a
potato, and has the same solid but sappy consistence.
Although usually below ground, decay is slow. In
Teras terminalis the texture is looser, but contains
more sap in proportion; it ultimately becomes spongy,
and, except the cells, decays during the following
winter. Andricus ramuli is perhaps unique. The
little larval cells, massed together to the number of
ten or twelve, are entirely concealed by a dense mass
of long white simple hairlets, neither the origin nor
the structure of which appears to be known.

A more complex structure is that of Neurvterus
lenticularis. When examined in September it is found
to consist of a central mass of cells, full of primitive
nourishment for the larva which occupies the centre ;
these the larva consumes before the gall falls. Outside
these cells are bundles of palisade-like cells, which are
surrounded with a thick layer of other cells containing
starch granules, and upon these the larva feeds before
it pupates. A thick epidermis with chlorophyll
granules forms the exterior, from which there grows
numerous hairlets arranged in a stellate manner.

Cynips Kollari is not only the most complex of British
galls, but also the most durable. According to Beye-
rinck (‘ Beobachtungen iitber die ersten Entwicklung-
sphasen einiger Cynipidengallen,’ p. 142 et seq.), when
the gall approaches maturity the cellular tissues
become differentiated -into eight layers: (1) The

THE PRINCIPLES OF OAK GALL FORMATION. 7

' exterior, consisting of epidermis with unicellular hairs
containing red pigment in their cell contents ; (2)
colourless hypodermal cells, beneath which is (3) a
layer of small meristematic cells; then (4) a thick
layer of large cells rich in tannin, below which follow,
(5) the cambian ring, (6) primary starch cells, (7) cells
containing crystals, and (8) a thin layer of primary
nee tissue composing the walls of the larval
cell.

re colours in many oak galls are very varied and
rich.

They range from white and cream through all
tints of yellow, from very pale to deep orange, and
from a very pale green to a rich dark hue, and through
almost every shade of red, some of the tints of which
are very attractive. Only one kind of gall yields a
purple, and that colour is in the hairlets with which it
is clothed (Spathegaster Taschenbergi). The browns
vary from very pale, through various shades of reddish-
brown, to chocolate.

No English gall student appears to have published
results of investigations into the origin of the colours.
This is rather remarkable, because the colours are
always so prominently before the collector, and in
many instances it is the colour which gives the charm
to the gall.

Dr. Marion Newhbigin’s researches (‘Colour in
Nature,’ 1898) have shed much light upon the
physiology of pigments and colours in plants and
animals. But the colours of vegetable galls do not
appear to have received her attention. Since most
galls are almost as complex in their structure as the
plant on which they grow, and as it has already been
shown, are so indissolubly associated with the ener-
gising functions of the tree, and also built up of the
same materials, may it not be inferred that the
coloration of galls is produced in the same manner
as in other parts of the plant ?

Chlorophyll-green is, of course, the supremely im-

8 BRITISH OAK GALLS.

portant pigment, and with it are associated lipochrome
pigments, whose nature and amount determine the
exact shade of green displayed by the vegetable
organs.

“The fixed or lipochrome pigments occur in the
form of solid particles in the cell, and the free or
anthocyan pigments, in solution in the cell sap” (loc.
cit., p. 70).

Galls, which during their median or final stages of
growth are yellow or orange, obtain their tints from
the lipochromes, which take the place of the
chlorophyll-green.

A series of pigments known as anthocyans, i in a
soluble condition, are blended with the cell-sap; they
form the colouring materials and manifest themselves
most prominently in the epidermis and underlying
tissue.

Anthoxanthin is the yellow pigment; it is common
and widely distributed. In the case of galls it appears
to manifest itself as soon as the chlorophyll-green
diminishes, and becomes intensified until the orange is
reached. Red is the most prevalent, and all the tints
are due to lipochromes or to anthocyans. Much of it
can be dissolved out in water.

It may be remarked that red is more common in
galls maturing in late summer and in the autumn than
those of spring time—a feature paralleled in the
autumnal tints of fohage and fruits.

Dr. Newbigin is of opinion that, in plants, tannin
plays the part of a brown pigment. This is more than
probable in oak galls since very few of those which
develop in the spring and mature in early summer
change to brown, whereas almost all the autumn forms
assume that colour at a comparatively early age.

The formation of tannin and its oxidation are most
active during the time these galls are growing.

CHAPTER II.
SOME FEATURES OF OAK GALL GROWTH.
THe Common Oricin: Tae Camsrum Recion.

I. Duration or Growre:
(a) Rapid; a few days. (b) Slow; several
months.

IT. Posirions Occupixn :
(a) Root. (b) Stem. (c) Leaf. (d) Flower.

IIT. Sruinariry or Growve.

TV. Dissimizartry or Swaps:
(a) Globular. (b) Ovoid. (c) Reniform. (d)
Lenticular. (e) Aberrations.

V. Variations in Sizz, Texturz, Cotour:
(a) Girth. (b) Length. (c) Succulent. (a)
Woody. (e) Green. (f) Red.

VI. Monirications In DEVELOPMENT:
(A) Due to Hvternal Influences ;
(a) Overcrowding. (b) Environment.
(8) Due to Internal Influences ;
(a) Parasites. (b) Inquilines.

VIT. Smet.
VIII. Taste.

The common origin of all vegetable galls is the
cambium layer, or region, of the plant. Unless the

10 BRITISH OAK GALLS.

egg is laid within or upon its tissues no gall formation
takes place. Taking this, therefore, as the main
feature upon which gall formation depends, it will
not be difficult to trace a few leading characteristics
relating to the development, environment, aberrations,
etc., in British oak gall growth.

They may be tabulated as shown on ‘page 9.

Duration oF Growrs.

(a) Rapid ; a few days.

The periods of duration of growth are either very
short or protracted. In point of rapidity probably no
other oak gall develops and reaches maturity with
such speed as does Spathegaster Aprilinus. Under
ordinary conditions three or four days are sufficient
for it to be completely formed and reach its maximun
of size. Spathegaster baccarum, S. tricolor and Trigon-
aspis crustalis are about equal with each other in the
same respect, and either may be mature within seven
or eight days. This does not imply that the inhabitant,
or inhabitants, have passed through the metamorphoses
and the imagines ready to emerge, although in the
case of 8. Aprilinus only a few days more are required
for its accomplishment.

(b) Slow ; several months.

The gall of Cynips Kollari doubtless requires a longer
time to attain maturity than any other. Beginning
growth early in April, it steadily progresses until
September before it ceases. But C. Kollar is a gall
by itself. It has been described as neither catkin,
leaf, bud, nor stem gall, belonging, indeed, to another
and separate category.

Aphilothriz radicis is the next slowest in growth,
five months being occupied in its development. Its
persistency and protracted decay are about equal to
those of C. Kollavi, extending to two or even three
years.

SOME FEATURES OF OAK GALL GROWTH. 11

Positions OccupPrE.
(a) Root. (b) Stem. (c) Leaf. (d) Flower.

This section presents the same features as are found
in all vegetable galls. The division of the plant into
four primary parts affords the only simple and com-
prehensive scheme of classification. The student
desirous of following this phase of the subject is
referred to the author’s previous work, ‘ British
Vegetable Galls,’ pp. 24-80.

Of those on roots there are two galls of distinctive
and definite forms, Biorhiza aptera and Aphilothrix
vadicis. While the former has never been found grow-
ing above ground, the latter is occasionally met with
on small twigs springing from the tree trunk, at a foot
or two above the soil (see Plate XXX, div. A).

The most characteristic gall on the main stem, or
trunk of the tree, is that of Trigonaspis crustalis, which
in reality is a transformed bud. Aphilothriv albo-
punctata is typical of an external gall on the twig,
and Andricus noduli of a gall concealed within the
tissues of the twig. Numerous examples could be
cited of galls attached to the leaf. The mid-rib, its
off-shoots, the under surface (mostly) of the blade,
occasionally the upper surface, the margin, and also
the petiole all have a gall or galls peculiar to them.

The staminate flowers are attacked, a typical
example being Aphilothria quadrilineatus. Seven
other galls are also found on the catkins. The acorn,
being a subsequent development of a fertilised flower,
is included in this sub-section, the only gall found
within the cotyledons being that of Andricus glandium.

SIMILARITY OF GROWTH.

There is a remarkable similarity in the appearance
of many galls of the same or allied genera, especially
in galls occurring on the continent, but not as yet
recorded for Britain. The collector of oak galls will
find upon looking over a collection of European oak

12 BRITISH OAK GALLS.

galls, or a series of illustrations, many forms which
resemble well-known British specimens; e. g. Dryo-
cosmus cerriphilus on twigs of Q. cerris, is very much
like Aphilothria corticis and A. Sieboldi, which do not
appear on Q. cerrvis in Britain; Cynips cerricola is like
Biorhiza aptera ; Andiricus crispator like Spathegaster
baccarum; Neuroterus saliens like N. ostreus; A.
cydome like A. inflator; N. lanuginosus, Cecidomyia
cerris, and C. circinnans all resemble NV. lenticularis
and N. fumipennis. Of British forms, Andricus cir-
culans, Spathegaster albipes, and S. verrucosus are
similar in form; so also are Andricus globuli, A.
autumnalis, A. acllavis and A. clementine. Further
illustrations might be given were it necessary. It is
also noteworthy that the positions these galls occupy
on the tree are very similar.

DISSIMILARITY OF SHAPES.

(a) Globular = spherical = globulose.—This is a
somewhat prevalent form, but subject to variation in
which the opposite poles are depressed, such galls as,
é.g. Dryophanta agama and D. divisa being termed
oblate. Examples of C. Kollart are not infrequently
seen which are as perfectly spherical as though they
had: been turned on a lathe. Aphilothrix globuli is
normally true to shape; denuded of its outer green
rind, it is an almost perfect sphere.

(b) Ovoid = oviform.—-This term is applied to those
galls whose long axis considerably exceeds that of the
short axis.

Spathegaster albipes typifies this form, although it
has a small style at the distal end.

(c) Reniform.—One gall is kidney-like in outline—
that is Biorhizarenum. Some specimens are very true
to form; others, however, approximate an ovoid, and
now and again a globular form will be found. NW. ostreus
occasionally approaches the reniform shape, and when
mature, and spots and basal scales are absent, it is

SOME FEATURES OF OAK GALL GROWTH. 13

difficult to determine. The larval cell of Andricus
curvator is also occasionally somewhat reniform.

(ad) Lenticular—This form of growth is confined, to
the three leaf spangles, and in N. lenticularis and
N. fumipennis it is very constant, except when the
galls are over-crowded. N. leviusculus, however,
departs from the true lenticular shape to a consider-
able extent.

(e) Aberrations.—Deviations from normal conditions
of both shape and situations.

The most remarkable examples of aberrations in oak
gall growth are found in specimens of C. Kollavi. On
Plate XXXVI a number of unique specimens are repre-
sented. Double, triple, and quadruple galls are due to
two, three, or four eggs being deposited in the same
leaf-axil, the distance between each being so slight that
as soon as the larve hatch they are in close contact,
and although they may each form a cell they are but
slightly separated from one another. Sometimes they
interfere with each other’s growth, and then only
one will survive to pupate. But supposing that all
reach the imago stage they may not all succeed in
emerging. One or more may commence to gnaw in
the direction of the longest axis and not have sufficient
endurance to reach the exterior, perishing in the
attempt to eat through double the normal amount of
gall substance.

Figs. 38 and 39 are scarcely recognisable as double
galls, yet each contained two larve; so also does Fig. 40;
a slight division is, however, noticeable. Figs 23-28
are double, but of very considerable unequal develop-
ment, showing that one larva lived for a short time
only. Figs. 29, 30, 33-47, 41, 42 all have a well-
defined constriction. All these specimens were attached
to the twigs at a point immediately above the figures.
But in Figs. 31, 32, 43, and 44 one sphere only is in
connection with the twig; the other sphere is united
to the opposite pole in a Siamese-twin union. They
are distinct from the common double form. In each

14 BRITISH OAK GALLS.

case, except that of Fig. 32, both sections have reached
maturity. Hach section possesses a larval cell.

Two or three galls of Andricus cwrvator frequently
grow together, forming but one cavity, with two or
three larval cells. Or the gall may develop near the
base of the petiole, and produce a swelling bearing a
strong resemblance to A. inflator. Neuroterus levius-
culus affords some interesting variations, a few of
which are represented in Fig. 14, where they are also
briefly described.

VARIATIONS IN Size, Texture, CoLour.

Sizp: (a) Girth.—The smallest of all known galls
is that of Neuroterus minutulus, Gir. It is not yet
recorded for Britain. “It is spherical, 1-2 to 1°5 mm.
in diameter, thickly covered with short conic-ovate
tubercles, and of a rusty brown colour” (‘ The Ento-
mologist,’ vol. x, p. 173).

To return to British galls. The dimensions attained
by Aphilothria radicis undoubtedly exceed those of any
other gall. The largest the author has found was on
a very old stump, on June 18th, 1902. It measured
32 cm. at its greatest girth. Had it not been removed
it would have increased considerably by the end of
August, at which time it would have attained maturity.
C. Kollari develops into the largest unilocular gall ;
specimens measuring 75 mm. in girth are not un-
common (See Plate XXXVI, fig. 1). The cherry-gall
occasionally attains 63 mm. in girth.

(b) Length—The genus of Andricus furnishes at
least nine examples of galls whose external measure-
ments do not exceed 2 mm. in length. Two of these
seldom attain that length. Both A. nudus and
A, pilosus are normally not more than 1:5 mm. long.
The latter species appears to be larger, but that is due
to the hairlets with which it is covered.

The stalked-spindle gall, caused by Aphilothrix calli-
doma, far surpasses all oak galls in its length. Specimens

SOME FEATURES OF OAK GALL GROWTH. 15

attain 80 mm. in length and 12 mm. in girth. 4.
seiminatiouis (thought by some writers to be the same
gall), which develops on the catkin instead of on a
twig,is the next in length, but it seldom exceeds 8 mm.
in length.

Texture: (c) Succulent—There is little difference
in the soft and juicy nature of Spathegaster baccarum
and Prigonaspis crustalis. A gall of either species
measuring 42 mm. in girth contains 12-14 minims of
fluid. A specimen of Dryophanta scutellaris will yield
a large amount of fluid, but not so much in proportion
to the gall-substance as the former species. From
Aphilothriv radicis and Teras terminalis a moderate
amount of moisture can be expressed. No other gall
contains a sufficiency of moisture worthy of remark.

(d) Woody.—This term, of course, applies only to
galls when mature. All are more or less soft during
the early stages of formation. Of simple structures,
those of Andricus curvator on twigs and _ petioles,
A. injlator, and A. solitarius are moderately woody.
Others of a harder texture are Aphilothriv corticis,
A. Sieboldi, Biorhiza aptera, and those of the Dryo-
phanta genus. The small hard cells of Andricus
vamuli, and the conglomerated cells with the sur-
rounding woody growth of Aphilothria radicis are,
however, surpassed by C. Kollari, which is the hardest
and most woody of all.

Couour: (e) Green.—Green is the prevailing colour.
It is due entirely to chlorophyll. From an exceed-
ingly pale shade, as in Spathegaster tricolor (denuded of
hairlets), or Aphilothrix corticis, various gradations of
this colour are to be found until as deep a shade as
seen in any oak twig or leaf is manifested in many
specimens. The most beautiful of all green shades is,
perhaps, that of the oak-marble, when in June and
July its epidermis is a beautiful golden green. Green
is generally succeeded by brown of various shades.
The brown pigment is probably due to tannin taking
the place of the chlorophyll.

16 BRITISH OAK GALLS.

(£) Red.—The same chromatic gradations are found
in this colour, from the most delicate suffusion of
pink, as in 7’. crustalis, until a deep crimson or rose-
madder is reached, as shown in A. Sieboldi. The most
charming example of a median red tint is that of D.
scutellaris when at the zenith of its glory. Teras
terminalis also often exhibits a wealth of beautiful
tints. The brilliant red spots or stripes on the green
ground of S. baccarum accentuate its resemblance to a
red-currant berry. The red stripes on Dryophanta
longiventris are worthy of remark. The pretty pink
and light red of D. divisa deserves notice ; it is, how-
ever, transitory—the brown soon asserts itself. The
crimson’ margin of many specimens of Neuroterus
leviusculus provides a charming contrast to the
greenish-yellow centre. The red and crimson stellate
hairlets of N. fumipennis and N. lenticularis clothe
these galls with rare and most beautiful effect. In
addition to these distinctive colours all tints of yellow,
also orange, both pale and deep, are to be seen in many
galls. White is somewhat unusual, Andricus noduli
giving the best example. Aphilothrix Sieboldi is often
cream coloured when shielded from the light by loose
earth or dead leaves.

MoprricaTions IN DEVELOPMENT.

(a) Due to external inflwences.—This division in the
study of oak galls should receive the attention of the
collector and the student, because from the examination
of affected specimens some very interesting facts can
be deduced, and much of the economy of gall-producing
agents and their allies understood. It is a section
which is very near that of “ Dissimilarity of shape due
to aberrations,’ yet sufficiently distinctive to be
separated.

Of the modifications in shape and size caused
by—

eh Overerowding not much need be said. The

SOME FEATURES OF OAK GALL GROWTH. 17

deformities thus produced are well illustrated in
Andricus estivalis, which normally is cup-shaped ; B.
wptera when solitary is globular. Three species of
Neuroterus are often much out of shape on account of
overcrowding, as may be seen on Plate LX, div. A;
and A. Nieboldi, B. renwm and C. Kollari are at times
subject to much distortion from the same cause.

(b) Hnvironment.—This also requires little more than
a passing notice. Those galls whose normal position is
on the under-surface of the leaf do not usually
attain their customary dimensions when on the upper
surface. A terminal, or nearly terminally situated,
specimen of Aphilothria callidoma is rarely as long as
when axillary. C. Kollari is sometimes badly pinched
in a forked twig (Plate XXXVI, figs. 9-14), or when
bunched together in clusters (Plate XX XVIII).

(3) Due to internal influences —(a) Parasites are the
principal agents in causing these modifications. They
destroy the rightful owner of the gall, and in all
unilocular galls growth is usually arrested ; the struc-
ture either remains a diminutive form of what it would
have been, or. some peculiarity is accentuated, such as
the style on A. solitarius and on C. Kollari (see Plate
XXXIX, div. C), or increase in the number of ridges
on Aphilothria callidoma.

(b) Inquilines do not usually destroy the larva, but
only live within, and feed upon, the tissues of the gall
in company with the owner, but not in the same larval
cavity. In the majority of galls tenanted by inquilines
no deviation from the normal dimensions are notice-
able. This is exceedingly well exemplified in speci-
mens of (. Kollart on Plate XXXIX, div. B. It is
in every way normal, yet from it there have emerged
the rightful owner and thirty-two inquilines, but their
combined depredations have been so great as to leave
the exterior a mere shell.

Of all galls, whether on the oak or any other British
plant, none appears to harbour more parasites and

inquilines and visitors than that of Teras terminalis,
2

18 BRITISH OAK GALLS.

the oak-apple. It is on record (‘ Alternating Genera-
tions, pp. 77-79) that Mr. Francis Walker reared
from a number of these galls specimens of Insects,
Arachnidx, and Acari, belonging to seventy-five species.
The effect upon this gall is to increase its rotundity
rather than to produce malformation in its contour.
A normal mature specimen measures about 8 cm. in
girth, whereas one containing a host of Inquilmes and
parasites measured 18 cm. in girth—an exceedingly
fine specimen.

SMELL.

Collectors of galls are aware that many species
possess a distinctive odour, which it would appear acts
asa means of defence against enemies other than
inquilines and parasites.

Cameron has ably summed up the subject in the
following manner: “This phenomenon is doubtless
accompanied by some noxious principles which make
the larve unpalatable to birds, etc., and is found
chiefly in the larger species which inhabit large galls
all the year round. Both the larva and imago may
give out an offensive odour. C. Kollari and Dryophanta
folii (= scutellaris of this work) are cases in point.
The smell given out is usually bug-like, but
Paszlavsky (‘ Wien. Ent. Zeit.,’ 1883, 1380) mentions
that D. folit has the smell of ripe apples, A. radicis
of lemon, A. Sieboldi and CO. tinctoria of caramel or
fresh malt, with a trace of bug-smell. According to
the same authority the foli individuals bred from
the Sessile-Oak have the smell much more intense
than those from the pedunculated species” (‘ Brit.
Phyto. Hymen.,’ vol. iv, p. 15).

TASTE.

The taste of oak galls to the human palate does not
appear to have been described in any writings. That,

SOME FEATURES OF OAK GALL GROWTH. 19

when disagreeable, the taste is in some instances due
to the larva within will readily be understood from the
previous quotation.

Spathegaster baccarwm on catkins has the least taste
of any kind. It is soft and very juicy. The larva
itself 1s but slightly acid in taste. Andricus curvator
is sappy, but somewhat bitter; A. glandulx, A. soli-
tarius, Aphilothriz albopunctata, and A. fecundatriz are
not disagreeable, but they are devoid of a distinctive
flavour. The rind of A. Sieboldi is slightly sweet, but
the woody part is unpleasant.

All the species of the Dryophanta and Neuroterus
genera are insipid. That is probably due to the fact
that although rich in starch they are poor in tannin.
Trigonaspis crustalis is the most unpleasant of any
kind. It is bitter and very disagreeable, which is
probably due to tannin and gallic acid. These flavours
may have a deterrent effect upon the appetites of
Lepidopterous and Coleopterous larve, since rarely
are galls seen that have been attacked by them,
Teras terminalis being an exception. -Birds also may
be warned off most kinds by the same cause. One
kind, however, is greedily devoured by ground-birds
in the North. The galls of Neuroterus lenticularis are
extensively eaten by game-birds, notably Black-game
(Tetrao tetriz, L.) In the crop of many of these birds
large quantities of the galls were found along with
other food. The crop of one bird contained a number
estimated at “not less than 500” (‘ Trans. Ento. Soc.,’
1907, pt. iv, p. 84). Doubtless pheasants, partridges,
and other ground-birds thoroughout the country feed
upon these galls.

CHAPTER III.

THE NUMERICAL ASPECT OF OAK GALLS.

THE great abundance of many species of oak galls is
often commented upon by field naturalists, but the
phenomenon is seldom referred to in publications. It
is, however, a feature which annually manifests itself

~in a most pronounced manner.

In districts where hedge-banks are neglected, and
woods are not cut down more than once in twelve or
fourteen years, the gall-wasps have every facility to
multiply and spread unchecked—an advantage of which
they fully avail themselves.

The diminutive size of most species doubtless affords
them considerable immunity from the voracity of car-
nivorous insects, nor do they often become the food of
spiders. Ifthe snare of almost any sylvan spider be
examined, it will be found that captive insects are
very few whose wing expanse is less than 1°5 or 2 mm.
As the strands of most snares are from 5 mm. to 10 mm.
apart, and some much wider, it may be assumed that
numbers of the smaller Cynipide pass through the
meshes without detention, while larger insects are en-
tangled in the sticky threads.

Doubtless they are enabled to escape the notice of ,
many enemies on account of their lethargic habits, and
a tendency to simulate death.

The main factor, however, in the abundance of galls,
is the prodigious number of ova these tiny insects are
capable of producing, and also the leisurely and
effective manner in which they oviposit. An instance
observed and recorded by Dr. Adler is perhaps the
most enlightening concerning this. An imago of
Biorhiza aptera “was put upon a little oak, and soon
began to prick a bud; when it had finished the first

THE NUMERICAL ASPECT OF OAK GALLS. 21

bud, it went on without interruption to another, and
was altogether eighty-seven hours busily employed in
laying its eggs. In two buds I counted 582 eggs”
(‘ Alternating Generations,’ p. 72).

So accurately are the ova placed either within, or
upon, the cambium layer, that failure in gall-production
is rare.

The operation of ege depositing isa delicate one and
it demands much care and time.

When Neuroterus lenticularis settles on a bud, the
long and slender terebra is inserted near the apex and
pushed between the leaf-scales down to the base of the
bud; then it curves upwards, penetrating a part of the
bud axis, until it comes into contact with that part of
the embryo leaf which will be the under-surface when
expanded; the gall of Spathegaster baccarum then
develops. N. leviusculus, whose mode of oviposition is
similar, requires from fifteen to twenty minutes to
perform the same operation. But piercing the vege-
table tissues is only one part; the egg with its long
stalk has to be pushed along until it reaches the termi-
nation of the puncture. For each egg a separate
tube has to be made in the bud, because the egg-stalk
occupies too large an amount of space in the tube to
allow another egg to be pushed by the side of it.

Efficiency is aimed at by the Cynips, and she is
rewarded for her labours and care by a high percentage
of satisfactory results.

How it is possible for the insect to determine the
exact spot for the egg to he is beyond the scope of
the present consideration of the phenomenon, except
to mention that certain tactile hairlets, whose bases are
connected with nerves, are situated on the ovipositor,
which are also employed in the discrimination between
leaf-buds and flower-buds.

In comparison with the size of the abdomen the
ovaries are very large,and many species of the Cynipide
contain enormous numbers of ova.

The ovaries of Cynips Kollari have been shown by

22 BRITISH OAK GALLS.

Beyerinck to contain about 800 ova. It is quite
certain, however, that she seldom, if ever, lives to
deposit so many. Single galls of Aphilothrix radicis
commonly contain 60 to 80 larval cells, and not
infrequently 120 to 150. The gall, of which half is
shown in Plate XXVI, div. A, contained .180 cells.
A most careful examination of the gall, and the spot
from whence it developed, failed to show that it was
due to the energies of more than one insect.

Ova are more abundant in the species which cause
autumn galls than in those which cause summer galls.
The numerousness of autumn galls on leaves is very
remarkable, much more so in some years than in others.

For several autumns the author has given some
attention to this phase of the subject. The following
are amongst the most noteworthy examples of which a

record has been kept :
Length of leaf Breadth of leaf Number of

Galls of exclusive of from tip to tip galls on
petiole. of widest lobes. the leaf.

Dryophanta divisa. 11 cm. . 62 cm. . 82

» - 10 ei. xe, OPAC. “ss . d4

Neur onaries ostreus . 12:2 ,, 8 ra 27

” 2 85 a8 a] ? 28

20° 9s 9°4 ” 6 ” 3l

a ow ow LD CO a 42

Biorhiza renum =. 12'3_—==", 8 me 32

” ” 7 LE 38 ” 33

a 7) 72 ” Ad8 ” 35

= a 116 ,, 68, 48

” ” 14 ” 7 ” 48

3 . 68 ,, 420 ,, 51
Neuroterus Te

matis . 9 se. oe We a 358

7 a de MOBS 35. a 32 - 465

i » « AOS 4, Ove 518

8 yw « DA 4 Do ys 609

” 9 . 14 ” 9 ” 681

158 ,, - 10: dre . 698

(See also description of same - species.)

THE NUMERICAL ASPECT OF OAK GALLS. 23

Neuroterus fumipennis—
3453 galls on-15 leaves off one bush.

Fewest galls on one leaf . . 115
Most ” rr) ” 2 . 489
Average per leaf . . 230

Weight of the galls, 2 dr., a sc., 6 er.
“ Neuroterus lenticularis—
1944 galls on 12 leaves off one bush.

Fewest galls on one leaf . a
Most fo a AG eS . 288
Average per leaf . . 162°

Weight of the galls, 4 dr., a sc., 17 gr.

These leaves were gathered after twenty- -two days
without rain. The galls were removed from the
leaves, counted, and weighed at once, all the figures
being verified in several ways.

To ascertain if the galls of N. fumipennis would have
weighed more had the weather been wet, they were
spread in a shallow dish and exposed to rain for three
hours. They were then allowed to dry off superfluous
moisture. Upon weighing again it was found they
were 12 grains heavier than before.

So far as the author’s observations have extended,
the largest number of galls of a few other species on
single leaves are :

Dryophanta scutellaris . 9 on one leaf.
Spathegaster tricolor 12 cay a

4 baccarum . 8 yg,

5 17 ~—s«ysxg«~=Ss cattkin stalk.
Aphilothria quadrilineatus 35s, 6 és
Cynips Kollari . : On twig.
Aphilothrix Sieboldi . . 188

es corticis . . 82 within an area 4°5 cm.
in diameter.
Trigonaspis crustalis . 12 within an area 15 cm.

in diameter.
On one leaf, 14 x 9 cm., there were growing:
1 Newroterus ostreus . 2 Dryophanta scutellaris.

24, BRITISH OAK GALLS.

122 Neuroterus nwmismatis 21 N. fumipennis = 146
galls.

On another leaf, 14°5 x 7°5 cm.:

5 Neuroterus ostreus . 12 Dryophanta divisa.

37 . numismatis 123 N. fumipennis = 177
galls.

It is very remarkable that the abundance of the
spangle galls in particular upon a leaf does not affect
its normal size, shape, outline, or thickness. There is
therefore no detriment to the foliage on account of the
presence of hundreds of thousands of these galls on a
bush or tree, nor is the growth and development of
either hindered.

The galls on catkins undoubtedly prevent the growth
of thousands of acorns, but that is of small consequence
since thousands more are available for seedling oaks, or
for pig food and small rodents. The value of the tree
is in its timber and its bark.

In connection with the numerical abundance of galls,
two correspondents have kindly communicated the
following: “It may be of interest to you to know that
several oaks (pedunculata) which I specially noted in
May as having an abnormal number of red-currant
galls upon the catkins, are at the present time (August)
quite free from galls of any kind, but some little
‘shrubby’ oaks in their immediate vicinity have their
leaves covered with N. lenticularis. In other places im
the same wood the Turkey oak and our common oak
are growing side by side, so close that the branches
intermingle; the Turkey oak is quite free from galls,
the others have numismatis and lenticularis in large
numbers, chiefly on leaves at the apex of the branches ”
(E. W. Swanton, Haslemere, Surrey, in lit., September
4th, 1904).

This latter peculiarity has been noticed on several
occasions by the author. So also has the strange fact
that enormous numbers of galls of several species will
be found in one part of a wood and nowhere else in the
same wood.

THE NUMERICAL ASPECT OF OAK GALLS. 25

The other correspondent writes: ‘Several workers
in the West Riding of Yorkshire have noticed that the
oak trees which are much attacked by Aphilothrix
fecundatriv usually produce acorns having pink cotyle-
dons. So pink are they that the colour shows through
the seed covers. Of course this may be only a coinci-
dence, but several of us have observed it for some years ”

(In lit., W. P. Winter, Moorhead, Shipley, December
29th, 1907).

CHAPTER IV.

THE CYNIPIDZ AFFECTING THE OAK.

Since the Cynipide are such interesting and remark-
able insects, a few pages will be devoted to a very
brief description of the imagines and their early stages.
More than a mere outline of these facts is not desir-
able, since the present volume is designed to treat of
the galls they produce; nor, indeed, is it possible to do
this much without quoting largely from two works
frequently mentioned in previous and subsequent pages,
both of which works contain exhaustive and detailed
information concerning these gall-wasps. There is
practically no feature of great importance that can be
added.

But there may be many collectors, students, and also
readers who have not access to other works on the
subject of oak gall producers, and they would welcome
some information concerning the Cynipide. For their
assistance this chapter is inserted.

The name of Cynipide was given to this group of
the aculeate Hymenoptera by Linneus.

They are very interesting insects in several ways.
Almost all of them are either gall producers or are
parasitic upon other insects. The distinguishing
features of the family, according to Cameron (‘ Brit.
Phyto. Hymen.,’ vol. ii, p. 142), are shown in eleven
particulars, an important one being that the
abdomen is petiolated and laterally compressed.

The imago has many points of great interest. So

THE CYNIPIDH AFFECTING THE OAK. 27

far as is known the species which produce galls on the
oak do not take food, nor frequent flowers for nectar ;
they, however, occasionally imbibe water. Many kinds
when alarmed fold the wings, tuck their legs and
antenne close to the body, and remain motionless for
some time.

They seldom fly more than a very short distance,
their distribution being accomplished more frequently
by the wind than by their own efforts.

Several observers have recorded the fact that Cynips
Kollavi is a most lethargic insect. Hundreds of
imagines may be reared, and only very rarely will one
be seen on the wing. Nor is this peculiarity confined
to that species ; it is common to most.

On one occasion the author opened a gall of
Dryophanta disticha which contained a mature imago.
It at once ran about the table, and when a glass was
placed over it it ran up the side and expanded its
wings completely, but neither then, nor when the glass
was reversed, did it attempt to fly.

Almost all the species cling with remarkable tenacity
to leaf or twig, or even one’s finger, and it requires a
sharp and strong puff of wind to dislodge them.

‘The imagines of most kinds are difficult to rear,
because it is not easy to maintain the natural con-
ditions of life. But even when it has been possible to
accomplish this, success does not often follow. Some
remain in the larval stage for many months (e.g.
Andricus glandium, Aphilothrix fecundatriz), and for
many months more in the pupal condition, and then
perhaps they will die before the imago ‘stage is
reached. Doubtless, in their natural surroundings of
hedges, woods, trees, etc., innumerable multitudes
never complete their metamorphoses. A few species
are able to endure great cold. Cameron states that
Biorhiza aptera appears during frost and snow in
winter time and deposits ova (loc. cit., vol. iv, p. 3).

Immediately after leaving the galls the Cynipide
begin to lay their eggs, and speedily-die. The act of

28 BRITISH OAK GALLS.

oviposition—seldom or frequent, as the case may be
is carried out with remarkable certainty in the
right part of the plant. As is shown on another
page, error of judgment means the loss of progeny.

The study of the imagines will be found very
puzzling to the general entomologist, as there is a
very general likeness amongst the species. The
inquilines, especially, greatly resemble the true gall
producers.

The bodies of the Cynipide are of very beautiful
and bright metallic colours. Red, green, orange and
blue predominate. The wings also are exceptionally
iridescent. The imago of C. Kollari is the prettiest,
having a bright metallic yellow, orange and purple
body, and highly iridescent wings. All the species
are small, varying from 2 mm. to 5 mm. in length.
Many are very agile, and all are graceful in their
movements.

They have four wings. The two anterior wings are
about the same length as the body; the other two are
about half the size; the margins are usually fringed
with minute hairlets. Some species are wingless.

The antenne are long in comparison with the size
of the insect. In the males there are generally one or
two joints more than in the females; they are also
thinner.

The abdomen of the male is differently shaped from
that of the female, but there is no difference in the
coloration of the sexes. The difference in the size
and form of the ovipositor depends upon the genera-
tion of the insect. In those species which appear
in the spring it is much shorter and less curved than
that possessed by those which oviposit in the autumn.
The process of egg-laying on the part of gall producers
is somewhat complicated ; it is therefore necessary that
the instrument with which it is performed should be
elaborate. It is known as the terebra, or ovipositor.
It consists of three portions: the seta, and two
serrated spicule. When-at rest the entire instrument

THE CYNIPIDH AFFECTING THE OAK, 29

is concealed within the abdomen. The seta is a very
stiff bristle united to the interior of the abdomen and
controlled by five distinct sets of muscles. If a
transverse section of the terebra be examined it will
be seen that the seta occupies about half the area,
which is circular. The spicule are alike in outline
and serration, and occupy the remainder of the area.

The action of the ovipositor when making a hole for
the imsertion of an egg is very similar to the move-
ments of the puncturing or stinging apparatus of other
aculeate Hymenoptera; e. g. wasps and bees.

So deeply and firmly do the organs penetrate the
plant tissues that the insect is sometimes unable to
withdraw them, and they are either broken off or torn
away from the abdomen together with the mechanism
which controls them.

Some of the oak gall Cynipide require from fifteen
to twenty minutes to deposit one egg (e. g. Newroterus
leviusculus).

The actual process of oviposition can be divided into
three stages, which, according to Adler (‘ Alternating
Generations,’ p. 119), are these: (1) The canal is
bored, the ovipositor gliding under the imbricated scales
to the base of the bud, and then being driven into the
centre of the bud-axis. (2) The egg passes out of the
ovarium to the base of the ovipositor, where the egg-
stalk is pinched between the two spiculz, and the egg
is pushed along the ovipositor. (3) After the point of
the ovipositor is withdrawn the egg-body enters the
pierced canal and is pushed forward by the ovipositor
until it reaches the bottom.”

The number of eggs deposited by a single individual
varies. Those of the summer generations produce from
200 to +00 eggs, the agamous generations several
hundreds more.

The eggs of this family are remarkable in having
what is known as an egg-stalk which is attached to the
anterior part of the egg. It is a continuation of the
yolk sac, and has the function of a respiratory organ

30 BRITISH OAK GALLS.
conveying to the embryo a supply of oxygen which
otherwise could not reach it.

The larve are fat, fleshy, and legless, white or
cream colour. When removed from the larval cell and
placed ona flat surface they will remain almost inactive.
They lie within the larval cavity with head and tail
directed slightly towards each other along the ventral
surface. The body has thirteen segments. The
mandibles are short, broad, and sharply cusped. They
pupate in the galls without exception. The length of
time required for development is variable. Nothing
passes through the body.

The pupa is the same colour as the larva, until
shortly before the emergence of the imago, when it
changes to a deep pink, the eyes become distinct and
the appendages also. The antennz and legs are
enclosed in pellicles, and are placed along the ventral
surface of the thorax; the wings are like small bags
placed on the sides of the thorax.

The most wonderful features connected with the’
life-history of this family of gall producers are the
alternations of generations, sometimes also called hetero-
genesis, in which the young do not resemble their parent,
Dut their grand-parent ; and parthenogenesis, or virgin
production. Thus these insects, although somewhat
insignificant in appearance, are of extreme scientific
interest on account of the alternations which the
various broods present of winged or wingless, and
sexual and sexless, individuals at different times of the

ear.
y The phenomenon of alternating generations is not
confined to the Cynipide. It occurs in the Salpinide ;
among some species (the liver-fluke) in the parasitic
Entozoa; it is also one of the means of propagation
among the Hydromedusz and the Polyzoa.

Dalbert de Chamisso was the first to observe this
phenomenon, when in 1815 he accompanied, as natura-
list, an expedition round the world.

His observations, published in 1819, were not believed,

THE CYNIPIDA AFFUCTING THE OAK. 31

but as years passed investigations made by other
naturalists (Sars, Siebold, and Lovén) proved that he
was correct.

In 1842 J. J. 8. Steenstrup published (‘Uber den
Generationswechsel’) all that was known on the sub-
ject. The essay was translated into English by George
Rusk, and published by the Ray Society, 1845. Steen-
strup quaintly describes this mode of reproduction as
“a peculiar form of fostering the young of the lower
classes of animals.” The preface (loc. cit, p. 1) contains
the following paragraph: “ Alternation of generations
is the remarkable, and till now inexplicable, natural
phenomenon of an animal producing an offspring,
which at no time resembles its parent, but which, on
the other hand, itself brings forth a progeny, which
returns in its form and nature to the parent animal, so
that the maternal animal does not: meet with its
resemblance in its own brood, but in its descendants
of the second, third, or fourth degree or generation.”

The bi-sexual, therefore, gives rise to the asexual or
agamic, and the agamic in its turn to the bi-sexual.
Moreover, the: two generations produce galls which
differ entirely in shape, size, and situation.

One generation consists of females only, the other
includes both males and females, The bi-sexual insect
is the resul€ of the union of the male and female, the
agamic when that condition is absent.

The theories of non-sexual reproduction are very
complex. The facts, however, are simple. From
many oak galls which mature in the spring or early
summer females only emerge, and without assistance
of the male they lay eggs from which larve hatch.
This is known as parthenogenesis, a word given to the
phenomenon by Professor Sir Richard Owen. The
galls caused by these larve mature in early autumn, and
from them there issue both male and female imagines,
from the union of which eggs are deposited, and the
resultant larve produce galls like their agamic grand-
parent. The ability to reproduce parthenogenetic eggs

32 BRITISH OAK GALLS.

often secures the perpetuation of the species more
effectually than sexual reproduction. Individuals who
lay their eggs in winter are unhindered by the require-
ments of fertilisation, and the ability to reproduce
independently is an advantage to them during the
period of frosts and snow. It is not confined to
winter species. Cynips Kollavi and others possess no
male; all the imagines are perfect female forms.

CHAPTER V.
THE BRITISH OAK.

Tue British oak, known generally as the common
oak, is plentiful in the British Isles, and universally
distributed throughout Europe and Asia, except in the
extreme northern parts. It is the best known and the
most enduring of all forest trees.

Its botanical name is Quercus robur, fromthe Latin and
Greek respectively. The ancients were fully acquainted
with its durable and useful qualities, and thus it is not
surprising that the generic and specific names should
convey the meaning of hard or strong wood of oak.

The genus Quercus embraces about three hundred
species. Whether regarded as a commercial object, or
on account of a large number of the species being
useful in so many ways, the oak tree is of great
importance, and its utility is not surpassed by any
other genus of forest tree.

Q. robwr may be regarded as the type of the oaks
which have sinuated leaves. The tree attains dimensions
considerably in excess of those of other species of
Quercus, mainly as regards the size of the trunk and
the lower limbs. It is not very lofty, but its lower
limbs spread over a considerable area, Q. cerris fre-
quently surpassing it in height by forty to fifty feet,
but does not spread so far.

In summer and winter alike the British oak commands
attention: in early summer because of the delicate
emerald green of the unfolding leaves, which soon

expand into a wealth of rich green umbrageous verdure.
3

34 BRITISH OAK GALLS.

By the time autumn arrives other developments have
taken place, and mingled with the brown and sere
leaves there are countless leather- brown acorns.
Autumn winds and winter storms shake down the
acorns, tear off and scatter the foliage and leave the
tree in unclothed grandeur. Its huge trunk and
massive limbs, gnarled, scored, and weather-beaten by
tempests of hundreds of years, are then revealed to
perfection, while the characteristic twisted and elbowed
growth of the lesser branches and the twigs are clearly
silhouetted against the sky.

There is a considerable tendency to variation in the
growth of the tree, and on this account botanists do
not appear to be agreed with regard to Q. robux and
its varieties. Some are of opinion that there is but
one definite species, viz. Q. robur. Others consider
the trees which bear sessile acorns and stalked leaves
to be a distinct species, and trees with pedunculated
acorns and stalkless leaves another species, and have
named them Q. sessiliflora and Q. pedunculata respec-
tively. Other botanists recognise three forms: the
two just mentioned, but described classically as Q. robur
sessiliflora and Q. robur pedunculata, and an intermediate
form in which both acorns and leaves are pedunculated,
the leaves being somewhat pilose. To this form the
name of Q. robur intermedia has been given. Many
foresters distinguish two sub-species and_ several
varieties. Undoubtedly Q. robur exhibits two distinct
forms, one being represented by pedunculata, the other
by sessiliflora, with many unimportant intermediate
forms. That the extremes are sufficiently definite to
merit the terms of species seems to be the opinion of
most botanists and writers, theréfore throughout this
work they are used. Fruit and leaves of both are
shown on Plate III.

The growth of seedling oaks is very interesting,
much more so if the structure of the acorn be studied
before planting any. Acorns gathered in the autumn
will yield the greatest amount of instruction. Descrip-

THE BRITISH OAK. 35

tions in most botanical works will assist a beginner to
understand the various parts of the fruit.

Acorns intended for planting should be left out of
doors during the winter. If they have been kept
indoors they should be soaked for several days in
water. A large flower-pot nearly full of earth having
been prepared, six or eight acorns may be arranged on
the earth and a little loose earth sprinkled over them.
If this is done in March or April, healthy little plants
will be developed by July. The familiar acorn-glass
affords a pleasant way in which the growth of the root
and its fibres can be watched.

The two divisions of the inner part of an acorn
are the cotyledons, which contain reserve materials
for the maintenance of the young plant. When
they absorb water the pericarp (or outer skin)
bursts at the pointed end, and the radicle pushes
its way out, bends downwards, and penetrates verti-
cally into the ground, becomes the root, and sends
out on all sides root-fibres which pick up nourishment
from the soil. Meanwhile the plumule has appeared
from the same opening; rising slowly and pointing
upwards, it becomes the stem of the future tree. It
grows from the part known as the hypocotyl, and
elongates into a slender stem upon which at first scale-
leaves appear. When it has attained about three inches
delicate-lobed foliage-leaves unfold. For some time the
plumule and the radicle draw their nourishment from
the cotyledons, which rapidly dissolve in’ order to
supply the demand. When wholly exhausted the coty-
ledons disintegrate and fall away from the hypocotyl.

At the end of the first year the primary root will
have attained a length of about fifteen inches, and the
young stem be about six inches high.

If it is desired to keep the little trees, they should
be removed from the pot and each replanted in a
separate pot or put in open ground. A most interest-
ing study may be enjoyed if one or two acorns each of
Q. pedunculata, Q. sessiliflora, Q. cerris, and @. Ilex be

36 BRITISH OAK GALLS.

planted in a flower-pot and allowed to remain for
several years.

For experimental gall-growing acorn seedlings are
best at the third or fourth year.

The following observations made of the growth
from an acorn of a small tree may be of interest :

A large acorn of Q. pedunculata was planted in
open ground of a garden in the autumn of the year
1875, and the spot marked. The following summer
the seedling developed in the usual manner. It has
now (1908) grown to the following dimensions:
Height, 20 ft.; girth of trunk at emergence from
the ground, 35 in.; at 3 ft. from the ground, 28 in.;
area covered by lower limbs, 15 ft. in diameter.

The oak often throws out new wood during the
summer in the form of long, pale-green (red also some-
times) sappy shoots, which frequently bear many fully-
developed leaves. These shoots are known as Lammas
shoots, from the fact that they are seen early in
August. They grow from buds, which instead of
remaining dormant until the following spring thrust
out their latent growth on account of a wet season
following several hot,dry months. Some trees always
produce these shoots. A specimen shown to the author
several years ago was 7 inches long, with 12 leaves
on it. It was growing from a shoot of the year,
measuring 5 inches, with 9 leaves, all of which bore
a great number of Neuroterus lenticularis galls,
while the leaves of the Lammas shoot had no galls
on them.

The strength and durability of oak timber is such
as is found in no other European tree, and when
grown in perfection it is the most valuable wood pro-
duced in temperate climates. It is hard, little liable
to crack or split, and being close-grained is easy to
work. The heart-wood varies somewhat in colour; its
normal colour is a pale brown.

The technical properties of oak wood are very
varied. The chief feature is the annular rings, which

THE BRITISH OAK. 37

are well marked. In a transverse section (across-
grain or horizontally as the tree stands), they can be
easily counted and the age of the tree ascertained—
one ring for each year. In the centre is the pith, 1
to 4 mm. in diameter, formed of small, thick-walled
cells. The annular rings are slightly undulating,
bending outwards between the medullary rays, which
are of two kinds; one large, broad, and glossy, the
other very numerous and small (see Plate II). Itis
impossible to distinguish between the wood of the
two species.

“Oak wood makes excellent charcoal, especially
for metallurgic purposes; the Sussex iron, formerly
regarded as the best produced in Britain, was smelted
with oak charcoal from the great woods of the adjacent
weald”’ (‘ Encyclopedia Britannica,’ art. ‘“ Oak.’’)

The bark is the most valuable part of the tree, and
its value depends upon the amount of tannin it con-
tains. The trunk and large limbs yield an abundant
supply. In young trees the yield is about 8 per cent.
of tannic acid; in old trees it is much less. Trees of
thirty to forty years’ growth yield the largest per-
centage. (. sessiliflora yields a larger amount of
tannic acid than does Q. pedunculata.

The flowers are monecious (7. e. both sexes on the
same tree). The staminate or male flowers of each
species are arranged in clusters on long slender fila-
ments, and are known as catkins. The female or
pistilate flowers are sessile in one species (from which
it takes its specific name), and pedunculated in the
other, and either single or in groups of two, three,
or more.

The leaves of each species are broad and deeply
sinuated, the lobes being bluntly rounded. They are
arranged on the twig in an alternate manner. Nor-
mally they attain a length of 12 to 14 cm. and 7 to 9
cm. at greatest breadth of blades. There is, however,
considerable variation. A perfectly-formed mature
leaf off a large tree may not exceed 3 cm. in length,

38 BRITISH OAK GALLS.

while from a sapling of about two years’ growth the
author obtained in 1898 several leaves 36 cm. long
and 19 cm. wide. :

Many leaves also are long and very narrow, with
entire margins and a blunt extremity.

Although the general hue of the upper-surface of
the leaves towards the close of summer is dull brown,
this colour often changes either wholly or in patches
to a warm russet-brown, with blotches of yellow, light
orange, and red. Specimens that have had large
numbers of galls of the genus Newroterus upon them
show these colours to perfection, especially noticeable
in the case of galls caused by N. nunvismatis.

Leaves from which there is a total absence of chloro-
phyll do not bear galls.

On young trees and brushwood the withered leaves
often remain until the following spring, when the
growth of new wood and expanding buds causes them
to fall off.

Two other species of Quercus may also be briefly
described, since they are referred to in subsequent
pages:

(1) The Turkey oak, Q. cerris (Plate IV, div. A).

It is a tall, graceful tree with long, narrow, deeply-
notched, dark green leaves, which have a petiole of
medium length. The acorns are large, ovoid in shape,
about half of which is enclosed in the cupule. The
‘interior of the cupule is silvery-white; the exterior is
covered with scales which are very long (12 to 15
mm.), and very numerous (as many as 400), and
yellowish-green in colour.

This oak was introduced into England by Miller
about the year 1735. It is now somewhat commonly
distributed over Britain, and as it flourishes in nearly
all soils, and grows twice as fast as Q. robur it is a
good and useful species in parks, plantations, etc.
The wood is good, but it is not so heavy as that of
Q. robur.

In some seasons enormous numbers of acorns are

THE BRITISH OAK. 39

produced. They are exceedingly acrid; this may be
much reduced by baking.

The trees are raised best from acorns.

(2) The evergreen oak, Q. Ilex. (Plate IV, div. B).

The natural habitat of this tree is in the southern
parts of Europe.

It bears an abundance of leaves which are dark
bluish-green. on the upper-surface and covered with
greyish pubescence on the under-surface.

The tree is an evergreen. The shape of the leaf is
mostly ovate, terminating with a sharp point. The
margins may be entire, or serrated, and sometimes
prickly, when it has much the appearance of the
holly, a resemblance which has caused it to be named
Quercus Ilex, or the “holm qak.”

The young shoots are as remarkable for their light
hue as the full-grown tree is for the characteristic
sombreness of its foliage.

The acorns are on short peduncles, and oblong in
shape; sometimes sweet and bitter acorns are pro-
duced on the same tree, but it is usual for a tree to
bear either all sweet or all bitter.

In early life the tree grows very rapidly, but after a
few years much more slowly. In warmer climates
than England it attains a height of 80 or 90 feet, and
lives to a great age. It has a great partiality for sea-
air, and it thrives well along the sea coasts of England,
especially in the south. It can bear the rough south-
west gales without injury.

The colour of the wood is dark brown, very hard,
close grained, durable and flexible.

CHAPTER VI.

HINTS ON COLLECTING AND MOUNTING
OAK GALLS.

CoLuecrine oak galls is not at all difficult. Searching
for them is a delightful occupation. Good eyesight is
essential, because there are many, kinds small in size
and obscure in growth.

The equipment for collecting is simple. A vasculum
fitted with a broad shoulder-strap is no trouble to
carry; but if the collector’s object be to make an
extensive collection, or to photograph the various
forms and aberrations of galls, it is necessary to carry
a spacious receptacle for the specimens. Several small
tin boxes are likewise necessary. In them rare or
special specimens can be put without fear of damage
they might sustain amongst the other twigs.

One essential implement of the collector is a’pair of
nippers with sharp edges (Fig. 1). They far surpass
a knife in efficiency for severing twigs. To cut twigs
with some kinds of galls on them (e. g. Aphilothrix
albopunctata, A. Malpighti) with a knife is in most
instances to lose the gall, because the movement of
the twig will jar off the gall,and when it has fallen
amongst grass, leaves, etc., it is exceedingly difficult
to recover.

When using nippers to a twig which has upon it a
scarce gall, or a very fine example, a sheet of paper
spread beneath the twig will enable the gall to be
recovered if it should fall off.

A pruner or averancator, with cord attached, is
another requisite (Fig. 2). When on the end of a
stick, specimens can be secured which otherwise would

HINTS ON COLLECTING AND MOUNTING OAK GaLLs. 41

be out of reach. It is especially useful for cutting off
galled catkins, and Teras terminalis.

A walking stick is a useful, although not necessary,
part of the collector’s equipment; because with knife
or saw a sapling can be obtained which when ten or
fifteen feet high is of greater value than the ordinary
companion.

A small tenon saw will facilitate the acquisition of
specimens of Dichena quercina when on large oak
stems. A little tallow in a tin box will be wanted, to
smear on the saw and prevent binding when cutting
thick green wood.

Field glasses are useful in detecting small galls
high up in large trees. Galls of Andricus cirratus, A.
nudus, and A. pilosus are not easy to see at a distance
of eight or ten feet above one’s head. ‘An alternative
is to prune catkin-bearing twigs until galls are
obtained; but that method is destructive and not
recommended.

The collector should always have a strong knife.
There are many ways in which it is useful.

A small fern-trowel (Fig. 3) with narrow blade is
wanted when the root galls are sought; it is also
helpful when stripping off a piece of bark with
Spathegaster Taschenbergi or Trigonaspis crustalis
upon it. ,

A large sheet of newspaper or brown paper is of
great value. Without it galls are often lost. A few
30 em. lengths of brown string should not be for-
gotten.

A note-book and pencil are absolutely necessary.
Particular spots where galls have been, or are to be
found, should be entered, with dates when found, or
when the places should be re-visited to observe develop-
ments in growth, or to remove the specimens under
observation. Rough outlines of: the places, such as
will refresh the memory and act as guides without
loss of time, are also desirable.

The collector will frequently find galls that are not

42 BRITISH OAK GALLS.

sufficiently grown to be of advantage and therefore
it is well to allow them to remain in situ. In order to
find them again on the next visit to the spot the twig
should have a piece of string tied on it leaving the
long ends loose. Make a note of any feature that will
facilitate identification of tree or bush. Brown
coloured string will not be readily noticed by anyone
passing the spot, but the collector will soon find it
again. The author has watched the growth and after-
wards obtained many fine specimens in that way.

Great care has been taken in the selection and
arrangement of the specimens illustrated in the follow-
ing plates, and also in the descriptions of the species,
to assist the collector in discovering them. It is not,
therefore, here necessary to describe the usual part of
tree or bush most likely to yield specimens.

Leisure and patience are needful and a thorough exa-
mination of twigs, leaf-axils, and leaves should be-made.

When searching for oak galls the peculiarities of
the alternation of the generations should not be for-
gotten, and therefore districts should be sought, and
frequently visited, where the woods contain plenty of
oak saplings of from three to eight years’ growth, with
a number of large trees there as well, or near by.
Very damp woods do not usually yield many kinds.
The reason why is as yet unknown.

Diligent and careful search amongst oak scrub is
generally rewarded with many specimens. Not onl
should the outer twigs and leaves of a bush be
thoroughly scrutinised, but examination made of the
interior and the small shoots at the base.

The stunted growth on road-side banks, especially
the banks of old or little-used lanes, should always
receive attention, and hedges around fields amply
repay careful search.

A windy day is not recommended as a suitable
occasion on which to search. The continual move-
ment of the foliage makes detection very difficult and
wearies the eyes.

HINTS ON COLLECTING AND MOUNTING OAK GALLS. 43

Mounting galls and the imagines which emerge from
them may be accomplished in various ways. The par-
ticular method of arrangement in the cabinet or wall-
case may be left to the collector to adopt which ever
is most suitable to the conveniences at command. One
thing is most essential: the galls must be allowed to
dry thoroughly before placing them in their final
positions.

- The following suggestions may prove useful to
the collector who has not decided upon any plan of
arrangement :

A small label should be affixed to each specimen,
or cluster of specimens, bearing (7) the species of oak,
(b) the cause of gall, (c) locality where found, (d) date
of find, (e) a number corresponding with the same in
note-book or catalogue.

Imagines of average size may be fixed on a small
piece ot white card, or put in a small glass phial, which
has upon it a number corresponding with that on the
gall-label, and date of emergence. Parasites and
inquilines should be put in a separate phial, labelled

, accordingly, and placed by the side of that containing
the Cynips.

Very small imagines which require a lens or micro-
scope for their examination may be mounted in the
following manner. Cut a piece of card of about
double the thickness of a post-card, the same size as a

microscope slip, viz. 75 mm. by 25 mm. and with a
steel punch of 12 mm. diameter make a hole in the card.
Remove the slight blur caused by the punch with a
sharp knife, or rub it down with the thumb-nail.
This part of the card is then seccotined, and a micro-
scope cover-slip placed on and allowed to dry. When
dry, affix a name label on the card, fill in particulars
such as have already been suggested, and then place
the creatures in the cavity of the card. Seccotine the
margin of the cavity and close it in with another
glass slip. Put it aside to dry with a small weight on
it to keep it flat and firm.

44, BRITISH OAK GALLS.

Microscope slides may be obtained with cavities in
them of various depths. In such the insects can be
placed, and kept secure by a cover-slip ‘affixed and
‘ringed in the usual manner.

If the collector wishes to secure the numerous insects
that emerge from most galls, they should be put in
glass jam-jars and fine muslin tied over the opening.
A little experience will dictate the most suitable places
in which the jars should be kept. Some require a good
amount of warmth, some may be placed in sunshine,
others require shade. All should be attentively watched
and mould removed when it appears.

From some galls insects will emerge during the
second, and occasionally the third year, after the galls
matured ; therefore it is not advisable to remove them
too soon from the jars. But there are also others
which will not yield any insects unless natural sur-
roundings are very closely imitated, and for this
purpose ordinary flower-pots with earth, sand, dead
leaves, and such like in them are as satisfactory as can
be obtained.

To have a number of seedling oaks of two or three
years’ growth, and carry on experimental breeding of
the makers, and observe the growth of the galls they
produce, is a most fascinating study.

Collections of oak galls in museums are rare; very
few private collections exist; the collector and student
has, therefore, an opportunity of acquiring an interest-
ing and unusual amount of material in a little-known
subject, and of adding to scientific knowledge.

Preserving galls in their natural beauty is a very
difficult matter. There does not appear to be any
known or recognised method by which they can be
prevented from shrivelling and loss of colour. If
gathered when mature the hard and woody kinds do
not alter very greatly. The succulent kinds, however,
shrivel quickly and lose their colour. It does not
seem to be possible to preserve their colours or shape
in any way comparable with their pristine condition.

HINTS ON COLLECTING AND MOUNTING OAK GALLS. 45

A few experiments with fluids as preservatives show
that methylated spirit or even pure alcohol is of no
value as they extract all colours. Pure glycerine, or
a mixture of equal parts of glycerine and water, is of
little value. Solutions of corrosive sublimate, and also
of formalin, are not successful mediums, for in many
cases the leaf, the stem, or the gall itself loses more or
less of the natural colours, and then the true value of
the gall is deficient.

There is, perhaps, no better record of the natural
appearance of the galls than an accurately coloured
drawing, or a photograph as near to, or the actual size
of the specimens it represents.

Fig. 1.—A pair of nippers. Fie. 2.—A pruner. Fig, 3.—A fern-trowel.

46 BRITISH OAK GALLS.

TERMS EMPLOYED IN THE SYNOPTICAL TABLES.

The following terms employed in the synoptical tables
of each gall are intended to convey these meanings :

‘English name of gall’: The majority of the English
names occur in ‘Alternating Generations,’ and- are
very appropriate.

‘Position of gall’’: This indicates where the gall is
normally situated. Deviations are referred to else-
where.

‘‘Manner of growth’’: The general appearance of
the gall; its shape, etc., and whether concealed or
obvious.

‘“‘Colours’’?: The first mentioned indicates that the
gall is of that colour when in earliest stages of growth,
and that it assumes the shades and tints following
until it arrives at or passes maturity, when it is usually
of that colour named last.

‘‘ Average dimensions of a mature specimen’’: These
must not be regarded as hard and fast measurements,
but more as guides to the collector and student.

‘‘May be sought during the months of”: The
months mentioned are inclusive.

‘Growth is complete by the end of’: With refer-
ence to galls, such as the Neuwroterus, Biorhiza, and
other genera of similar growth, the month stated indi-
cates that the galls complete the stage of growth in the
situations in which they began growth, and not that
they have arrived at a condition in which the imagines
always emerge. It must be borne in mind that many
galls expand considerably with the return of spring.

TERMS EMPLOYED IN THE SYNOPTICAL TABLES. 47

Observations were made in the south of England;
an allowance of a week or two should therefore: be
made by the collector in northern localities.

‘*The typical condition of the gall is ’’:

‘*Unilocular and unilarval’’: The actual gall struc-
ture consists of one larval cell only, and contains one
larva only.

“Pleurilocular but unilarval’’: The gall structure is
made up of more than one larval cell (sometimes as
many as, or more than, fifty cells), but that each cell
contains one larva only. The expression does not
include galls usurped by parasites or tenanted by
inquilines. Parasites usually live in cells (e. g. in gall
of C. Kollavi), but inquilines merely cause cavities in
the tissues of the gall.

‘‘Bilocular but unilarval’’: That within the gall
structure are two cavities, one of which is occupied by
the larva; or that a single larval cell is surrounded by
an envelope of gall-substance which may be thin and
non-adherent to the larval cell as in Andricus curvator,
or thick and adherent, as in A. injflator.

‘‘Parasites, Nos.,” ‘‘Inquilines, Nos.”’: To minimise
space, and obviate the frequent repetition of names, a
complete alphabetically arranged list of the parasites
and inquilines having numbers corresponding with
those in the synoptical tables, will be found at the
end of the volume.

As regards the synonyms of the insects, it should be
noted that the lists are neither strictly comprehensive,
nor do the names profess to be placed in chronological
order, nor is reference made to the literature in which
they are to be found.

48 BRITISH OAK GALLS.

Except when otherwise specified, the galls may be
found on either Quercus pedwnculata and Q. sessilifiora.

The word “gall” is held to mean the actual growth
surrounding the cavity containing the larva, whether
it be thin, as that of Spathegaster albipes; or thick as
that of Dryophanta scutellaris; or the tissues which
surround two or more larval cells, such: as Teras
terminalis or Aphilothriz radicis. In three species,
Andricus curvator, A. inflator, and Aphilothria fecunda-
trix, it is necessary to remember that the actual larval
chamber is concealed within a non-adherent case, or
by leaf scales, which may be quite correctly also
termed the gall.

All the specimens illustrated by photographs (except
Plates II, XXXII, LX, div. B, and LXI), were
gathered by the author within a radius of ten miles of
Hastings.

Fre, 4.—mm., em., and inch scale.

CYNIPIDEUS GALL-PRODUCERS. 49

A TABLE OF BRITISH CYNIPIDAUS GALL-PRODUCERS
WITH THEIR ALTERNATE GENERATIONS (WHERE

KNOWN).
Sexual Generation. Agamous Generation.
Andricus estivalis.
3 amenti.
» circulans. ? Cynips Kollari. ——
* cirratus. Aphilothrix callidoma.
“3 clementine.
eee curvator. = collaris. «
us gemmatus. 5 corticis.
ass elandium.
9 glandulee.
sue inflator. elobuli. -
e: lucidus.
45 noduli. 3 radicis.
on nudus. és Malpighii.
rae pilosus. . fecundatrix. ——
wen ramuli. s autumnalis.
5 solitarius.
ae is testaceipes. is Sieboldi. «+
- albopunctata.
re marginalis. ——~
i quadrilineatus. —
3 seminationis. —~
—— Teras terminalis. Biorhiza aptera. +
» Trigonaspis crustalis. » Yrenum. <=
Dryophanta agama. —
4 disticha. —
Spathegaster verrucosus. ie divisa.
. a similis. ae longiventris. —
» ie Taschenbergi. ,, scutellaris. =<
—_— i tricolor, Neuroterusfumipennis. -
— 6 albipes. - leeviusculus. —
—<m 5 baccarum. bs lenticularis. —
— vesicatrix. be numismatis. —
om e Aprilinus. ? ,, ostreus. as
53 punctatus.

4,

50 BRITISH OAK GALLS.

Andricus estivalis, Giraud.
(Plate V, div. A.)

Andricus xstivalis, Mayr, Cameron, Mosley.

English name of gall.— The Cup Gall.”

Position of gall.—On staminate catkins of Q. cerris.

Manner of growth.—Sessile, glabrous, gregarious, conglomerate.

Colours.—Pale green, greenish-yellow, brown.

Average dimensions of a mature specimen.—Height,
10 mm.; breadth, 8 mm. ‘

May be sought during the months of May to July.

Growth is complete by the end of June.

The typical condition of the gall is bilocular, but unilarval.

The larva pupates in the gall. The imago emerges during
June and July.

Parasites, Nos. 14, 24, 180. Inquilines, Nos. 3,4. (These
figures correspond with those in the list at end of volume, where the
names of the insects and their authors’ names are given in full.)

This gall appears to have escaped the notice of
British collectors. I am not aware of any record of
it bemg found in Britain. It is so distinctive that no
collector could fail to identify it. Probably it may be
discovered, especially as A. glandium has been found
in acorns of the same oak (see p. 59).

Cameron captured a female insect at Loch Lomond,
which agreed with a type sent him by Professor Mayr
(‘ Brit. Phyto. Hymen.,’ vol. iv, p. 107). He does not
state, however, if he found any of the galls.

The galls occur in numbers of 20-40, conglomerated
on the catkin stalk, and while growing somewhat
resemble a mulberry. The size of the clusters varies
considerably. Some measure 35 mm. in length and
75 mm. in girth. They are more or less pressed into
one another at the point of attachment to the catkin
stalk by reason of their number, but they are quite
free from each other at their distal extremity. The
stalk becomes twisted and thickened.

A single gall is about 10 mm. high, 8 mm. in breadth,
pointed at the base, and opening out at the top into a
cup shape. It consists of two parts, an outer case and

ANDRICUS AMENTI. 51

the larval cell within it. The lower half contains one
or more cells; there may be as many as five.

The outer wall rises above this portion and forms an
empty cup-shaped space. The rim of this outer
growth, when mature, often becomes ragged, shrunk,
and twisted, it also curls inwardly, meeting at or near
the centre.

The colour of the gall is a very pale green, or a
greenish-yellow, and during the period of formation it
is soft and succulent, ultimately it hardens consider-
ably. The investing tissue is at first greenish-yellow,
often suffused with red, which, as growth proceeds,

turns reddish-brown, and when mature is hard and
woody.

Andricus amenti, Giraud.
(Plate V, div. B.)

Andricus amenti, Mayr, Fitch, Cameron, Mosley.

English name of gall. —‘‘ The Hairy Catkin Gall.”

Position of gall.—On staminate catkins of Q. sessiliflora.

Manner of growth.—Pilose, single, and in clusters.

Colours.—Pale green, greenish-yellow, brown.

Average dimensions of a mature specimen.— Length,
2mm.; breadth, 1 mm.; girth, 3 mm.

May be sought during the months of May and June.

Growth is complete by the end of June.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
June and July.

Parasites, Nos. 62, 83, 104.

This gall was first recorded for Britain by Professor
Trail, who found it at Braemar. It is also recorded
from Kew.

The galls are small and inconspicuous. They are
found attached to the staminate catkins of Quercus
sesstliflora, in groups of twos and threes, but some-
times as many as eight in one cluster.

The shape of the gallis oviform, somewhat elongate,
rounded and narrow at the base, tapering towards the

52 BRITISH OAK GALLS.

apex, which is bluntly pointed or sometimes mam-
milated. It is hard and woody, with very thin walls
which form a large larval cavity without an inner gall.
The exterior is covered with short, simple, yellowish
hairs, most of which fall away when the gall is past
maturity and the surface becomes rough.

“The gall is very similar to that of pilosus, but
generally the latter may be known by being somewhat
larger, not so globular, stouter, and not tapering so
much at the apex, as a rule, nearly as broad as at the
base; the hair is longer” (‘Brit. Phyto. Hymen..,’ vol.
iv, p. 94).

On account of their very small size these galls easily
escape observation, but their presence may often be
detected if catkins with bent and thickened stalks are
carefully examined with the aid of a pocket lens.

The imago is very small, about 1:7 mm. long; yellow,
and orange in colour; wings hyaline. It eats its way
out of the gall during the latter part of June or quite
early in July.

The galls do not fall, and often remain, together
with the stalk, on the tree throughout the summer.

Andricus circulans, Mayr.
(Plate V, div. C.)

Andricus circulans, Cameron, Fitch, Mosley.

English name of gall.—< The Turkey Oak Bud Gall.”

Position of gall.—In axillary buds of Q. cerris.

Manner of growth.—Glabrous, glossy, gregarious, con-
glomerated.

Colours.—Yellowish-brown, red, reddish-brown.

Average dimensions of a mature specimen.— Height,
4mm.; breadth, 15 mm.; girth, 45 mm.

May be sought during any month of the year.

Growth is complete by the end of August.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during May.

Parasite, No. 18.

Alternate agamous generation (according to Beyerinck),
Cynips Kollari, Hartig.

ANDRICUS CIRRATUS. 53

The late Miss E. A. Ormerod, LL.D., found some of
these galls on a tree of (Quercus cerris in Kew gardens
in the year 1878, which, although not exactly cor-
responding with the continental form of this species,
were, however, considered by Cameron to be sufficiently
hike those of A. circulans to warrant the inclusion of
this gall in the list as British.

For many years I have most carefully examined
stubs and trees of Q. cerris but have failed to find the
galls.

During dry and hot weather the long linear scales,
which are a noticeable feature of Q. cerris, close
towards one another over the galls and hide them from
view to so great an extent that detection is difficult,
but when the atmosphere is damp the scales relax and
stand out in such a manner as to allow the galls to be
seen.

These galls are gregarious in their manner of growth,
occurring in clusters of three, four, or even eight, and
they are sometimes so closely packed together as to be
considerably flattened ; at times there may be one gall
in the centre with others arranged round it in a circle.
The normal shape is an elongate ovoid and very similar
to small ant pups. The walls of the gall are very
thin.

The resemblance of these galls to those of the closely-
allied species, A. burgundus, Gir., is very great. The
imagines, however, are quite different, and in addition
to this, the galls may be distinguished from each other
by the fact that those of A. burgundus do not appear
until about five weeks later than those of A. circulans.

Andricus cirratus, Adler.
(Plate XIV, inset.)

Andricus cirratus, Mayr, Cameron.

English name of gall.—‘‘ The Tufted Gall.”

Position of gall.—On staminate catkins of Q. sessiliflora.
Manner of growth.—Gregarious, pilose, concealed.

ot BRITISH OAK GALLS.

Colours.—Pale green, dark green, brown.
Average dimensions of a mature specimen. — Height,
2mm.; length, 1] mm.; girth, 3 mm.

May be sought during the months of April (late), May, and
-June.

Growth is complete by the end of May.
The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
June.

Alternate agamous generation: Aphilothrix callidoma,
Hartig.

This gall does not appear to be very widely
distributed throughout Britain, or it may be, that by
reason of the inconspicuous habitat, as well as its
small size, it has been overlooked, or confused with
that of A. ramuli.

The imagines of callidoma apparently prefer to
oviposit in catkin buds situated high up in the
tree, where, without the aid of a pruner, they are
unattainable. I have only once found them within ten
feet of the ground. Upon the same tree, with field-
glasses, numerous others could be seen twenty and
thirty feet higher up.

“he gall is placed on the stalk of the male catkin ;
at its base two shallow impressions may be recognised
which are derived from the sutures of the anthers
from which the gall sprang. The galls are often
placed so closely together that they appear to form
one woolly mass” (‘ Alternating Generations,’ p. 54).

The affected catkins are considerably shortened and
seldom project beyond the bud, while others growing
from the same stem attain normal dimensions.

The shape of the larval chamber is oval; the
diameter of its long axis is about 2mm. It is rounded
at the base and apex; from the former spring a few
long white hairs which are three or four times longer
than the gall. The gall grows quickly, reaches
maturity in about twenty days, and then falls to the
ground.

It may be distinguished from A. ramuli because it

ANDRICUS CLEMENTIN2. 55

tlevelops about a month earlier, and the imagines also
appear earlier.

Andricus clementine, Mayr.
(Plate V, div. D.)

Cynips clementine, Giraud; Andricus clementine, Cameron ;
Mosley ; Aphilothriz clementine, Giraud.

English name of gall.—‘ The Pointed Pea Bud Gall.”

Position of gall.—In axillary beds of Q. sessiliflora.

Manner of growth.—Pilose, solitary, rugose, ovoid, spheroidal.

Colours.—Pale yellow, dark yellow, brown.

Average dimensions of a mature specimen.— Height,
5 mm.; breadth, 3 mm.; girth, 9 mm.

May be sought during the months of October and November.

Growth is complete by the end of October.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
following autumn.

Parasite, No. 66. Inquilines, Nos. 132, 145.

This pretty little gall has been recorded as British
by Cameron, who found it “in Cadder Wilderness
near Glasgow” (‘Brit. Phyto. Hymen.,’ vol. iv, p.
105). There does not appear to be any other record
of its occurrence in Britain.

- Owing to its small size and rather close resemblance
to other axillary bud-galls it may have escaped detec-
tion by other gall collectors.

The normal shape of the gall is spheroidal, and it
would bear a close resemblance to Aphilothrix globuli
but for a small conical projection on its summit due to
an elongation of the outer surface. The base also is
elongated to a point, but that is not noticeable while
the gall is in situ. When both these features are
pronounced the shape is somewhat ovoid.

The surface has scattered over it a number of small
flattened conical projections, which are concealed
beneath a quantity of vitreous whitish hairs, some
being recurved in the direction of the point of attach-
ment, while others near the summit are straight and

very numerous.

56 BRITISH OAK GALLS.

The gall consists of two thin layers, and an mner
loose larval chamber.

The colour of the external layer is dark-yellow;
that of the internal layer reddish-brown, the larval
chamber more or less yellowish.

The imago which causes the gall appears to prefer
to oviposit among the highest branches of the tree.

A peculiarity about this gall has been observed, viz.
that they fall to the ground after the first frost,
retaining the bud-like scales attached to their base.
When A. globuii falls to the ground the scales have
either previously dropped off or they are left on the
twig. :

z globuli has never been observed so high up on the
tree as Andricus clementine grows.

Andricus curvator, Hartig.

~
(Plates VI, VII.)

Andricus curvator, Mayr, Miiller, Fitch, Adler; A. perfoliatus,
Schenck; A. dimidiatus, Schlechtdl.; Cynips curvator, Thomson ;
C. axillaris, Hartig.

English name of gall.—‘ The Curved Leaf Gall.”

Position of gall.—On blade, mid-rib, or petiole of leaf.

Manner of growth.—Glabrous, glossy, single, conglomerated,
anastomosing.

Colours.—Pale green, light brown.

Average dimensions of a mature specimen.— Length,
8mm.; breadth, 8 mm.; girth, 24 mm.

May be sought during any month of the year.

Growth is complete by the end of July.

The typical condition of the gall is bilocular, but unilarval.

The larva pupates in the gall. The imago emerges during
August.

Parasites and inquilines are given on p. 58.

Alternate agamous generation: Aphilothria collaris, Hartig.

This gall is widely distributed throughout Britain.
It appears in the form of a swelling of the young
leaves of both species of oak, as plentifully on young

ANDRICUS CURVATOR. oO”

stubs as on young andold trees. The leaf is consider-
ably distorted by the growth of the gall, and fre-
quently the material which would have formed a leaf
is almost absorbed in the formation of the gall, a small
portion only developing to form a ridge or frill upon
the surface. Under such conditions of growth the
gall-mass is usually more or less globular, but when
situated upon the blade of the leaf the shape is
very irregular, although the bulk may not be more
than normal.

A solitary mature globular specimen on the end of
a twig, having little or no leaf membrane attached,
has the appearance of a small gall of Cynips Kollavi.

Growth is rapid, and during the early part of the
time the gall is solid and firm, although somewhat
succulent, and it extends in equal, or nearly equal,
proportions on both surfaces of the leaf. As maturity
approaches a large cavity is formed, within which is
the inner gall; asmall, reddish-brown larval cell, ovoid
in shape, loosely adherent, with very thin walls, and
about 2 mm. in its long axis, occasionally with a minute
papilla at one end.

Two, three, and sometimes four galls will anastomose,
and upon cutting the mass open it will be seen that
the inner galls are in some cases separated by very
thin septa, or the cavity remains undivided.

When gall growth takes place at the base of a
petiole the whole of the petiole is involved and a con-
siderable swelling results. When situated at the:
extremity of a twig, and small portions of leaves
develop upon the gall structure, there is a close
resemblance to a gall of A. inflator.

It is extremely abundant on some trees, affecting
mostly the small twigs springing from the trunk, where
not infrequently almost every leaf is galled. It may
also be found in great plenty on bushes and very young
trees. Apparently it occurs but rarely on the higher
boughs of old trees.

Some of the imagines of Aphilothrix collaris emerge

58 BRITISH OAK GALLS.

from their galls so late in the spring that finding
the leaves too much developed they oviposit in the
buds of Lammas shoots, and in due course galls may
be seen upon the leaves of these shoots as well as on
leaves of the twigs from which the Lammas shoots
spring.

A few representative examples of galls on twigs and
leaf-petioles in autumn—winter condition will be found
on Plate VII, div. A, and a fine specimen of a re-
curved twig, in growing condition, is illustrated on the
same Plate, div. B.

Parasites and inquilines on this species are very
numerous.

Parasites, Nos. 19, 21, 26, 31, 34, 35, 37, 42, 44, 56,
59, 71, 75, 78, 80, 83, 87, 96, 98, 105, 108, 115, 116,
121, 146, 151, 154.

Inquilines, Nos. 69, 109, 127, 128, 180, 136, 139.

Andricus gemmatus, Adler.
(Plate V, div. E.)

Andricus gemmatus, Cameron, Mosley.

English name of gall.—‘‘ The Bud Gall.”

Position of gall.—In the leaf axils.

Manner of growth.—Glabrous, sessile, gregarious.

Colours.—Pale green, green, reddish-brown, brown.

AVERAgE dimensions of a mature specimen. — Height,
2mm.; breadth, 1 mm.; girth, 3 mm.

May be sought during the months of May and June.

Growth is complete by the end of June.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
July and August.

Alternate agamic generation: Aphilothria corticis, Linn.

This is a very small and obscure gall, and although
widely distributed it is not often observed. It is more
or less oval in shape, sometimes narrower at the apex
than at the base. The apex is frequently the only
portion visible, and very careful searching is necessary

ANDRICUS GLANDIUM. 59

to find the gall. The easiest way is by looking for a
minute hole in an axillary bud. Adler, who was the
first to discover this gall, says they are sometimes
found free on the shoots (‘ Alternating Generations,’
p. 39); and Cameron says they may be found on the
he - young leaves (‘ Brit. Phyto. Hymen.,’ vol. iv,
p- 89).

Andricus glandium, Giraud.
(Plates VIII, IX, div. A.)

oe glandium, Mayr, Cameron, Fitch, Mosley; A. rufescens,

ayr.

& ae names of gall.— The Acorn Gall,” “The Cotyledon
all.” =

Position of gall.—tIn the cotyledons (concealed by the pericarp).

Manner of growth.—Glabrous, glossy, gregarious, con-
glomerated.

Colours.— White, cream, pink, brown.

Average dimensions of a mature specimen.—Length,
4mm.; breadth, 3 mm.; girth, 9 mm.

May be sought during any month of the year.

Growth is complete by the end of September.

The typical condition of the gall is plurilocular, but unilarval.
Usual number of cells about eight.

The larva pupates in the gall. The imago emerges during the
spring. Caieron says, “they take from three to four years to
arrive at maturity.”

Inquiline, No. 145.

This gall is remarkable for the fact that although
there may be many larval cells in an acorn, there is
seldom any appreciable difference in the size of the
acorn as compared with others not containing galls;
consequently it is not until the pericarp is removed
that the collector can be certain of having obtained
them. The larval cells displace the same bulk of the
cotyledons as they occupy; they are not embedded in
them, and readily separate when the pericarp is

removed.
The shape of a mass of larval cells is sometimes

60 BRITISH OAK GALLS.

ellipsoidal, but mostly the outline is irregular. A
solitary larval cell, however, is ovoid in shape. It
measures 3 mm. long and 2 mm. broad. The walls
are thin. The interior is white or very pale-green or
yellow, and slightly glossy. The exterior is brown, or
reddish-brown.

This gall was discovered on Q. cerris in Kew gardens,
in the year 1877, by Miss EH. A. Ormerod, LL.D. I
believe I was the first in Britain to find the galls on
trees growing wild: In the first instance in acorns
that had fallen from a tree of Q. cerris, in Sir A. Lamb’s
park, at Beauport, near St. Leonards, in the spring of
1902, in considerable numbers; and then in a growing
condition on the same tree in the autumn. From that
tree, and others of the same species, in the same park,
I have obtained galls each year since. In the same
spring I also found the same galls in acorns on the
ground, and in other acorns still attached to the twigs
of a tree of Q. pedunculata in a wood at Hollington,
also at St. Leonards, but not in such numbers. The
two trees are, in a direct line, about three miles apart.

When acorns are kept under artificial conditions the
larvee delay their pupation for several years. I now
(May, 1908) have some that have been in the larval
state for six years. Parasites (species undetermined),
however, have appeared the summer following from
galls gathered from a tree in the previous autumn.

Andricus glandule, Mayr.
(Plate X.)

Cynips glandulx, Schenck; Aphilothriz glandulx, Mayr, Hartig,
“Fitch; Andricus glandula, Cameron.

English names of gall.—< The Thatched Gall,” “The Little
Acorn Gall.”

Position of gall.—In the axillary leaf bud.

Manner of growth.—Solitary, pedunculated, pubescent, glossy,
longitudinally grooved.

ANDRICUS GLANDULA. 61

Colours.—Pale green, green, pale brown.

Average dimensions of a mature specimen. —Height,
6 mm.; girth (at base), 12 mm.

May be sought during the months of July to September.

Growth is complete by the end of September.

The typical condition of the gall is bilocular, but unilarval.

The larva pupates in the gall. The imago emerges during the
following spring.

Inquiline, No. 1386.

This dainty little gall may be easily distinguished
from all other British oak galls by the profusion of
long white, silky, and glossy recurved hairs with
which it is almost covered, the exposed portion being
the papilla.

It develops from an axillary bud on young twigs;
very rarely on wood of more than two years’
growth.

As soon as it bursts from the bud it is distinctly
noticeable owing to the silky-whiteness of the long
hairs which are arranged like thatching (without the
rods and spars), on a circular hay-stack or wheat-
stack, the little papilla standing erect in the centre,
hence the English name of “thatched gall” which I
propose for it.

As growth proceeds the hairs remain adpressed to
the gall, the texture of which becomes woody.

The lower portion of the gall is expanded into a
turban-like base having occasionally a number of leaf-
scales adherent beneath it; these ultimately fall off and
expose a somewhat stout process or peduncle by which
the gall is held to the twig. In some examples this
basal portion is much more fully developed than in
others.

The shape of the gall when mature is that of a
truncated cone, bearing upon its summit a very small
mastoid growth, known as the papilla, which is subject
to much variation in size. Itisa pale greenish-yellow
colour and is destitute of hairs in all stages of its

development. .
During the winter the gall falls to the ground, or it

62 BRITISH OAK GALLS.

is pushed off by the growth of new wood in the follow-
ing spring.

When denuded of hairs the gall is seen to be longi-
tudinally furrowed, but this may sometimes be dis-
tinguished without the removal of the hairs, as in
inset specimen. (Plate X.)

When the gall is inhabited by an inquiline it does
not attain its usual proportions.

Internally the gall is divided into nearly equal parts
by a septum, the lower portion being hollow, or filled
with fibrous reticulations, the upper portion contains
the true gall, which is adherent to the inner walls.

Fic. 5.—Galls caused by Andricus glandulz. a. Young, showing leaf-
scales, and “thatched” appearance. B. Mature. c. Longitudinal
section. All x 2}, dele. ad nat. E.C.

The larval chamber has a whitish interior and is ovoid
in shape.

I am not aware as to the distribution of this gall in
Britain, whether it is plentiful or scarce; possibly it
extends over wide areas and would be more frequently
observed but for its brief period of growth, rapidity in
reaching maturity, and then falling to the ground.

It has occurred in all the districts in which I have
searched, but it appears to be extremely local, and
sometimes it will not be found on more than two or
three trees in the same wood, and those widely
separated from each other.

According to my own observations it occurs mostly
on oak bushes of eight to ten years’ growth, also on

ANDRICUS INFLATOR. 63

small trees, but more generally on the lower than the
upper branches; very rarely on scrub-oaks of less than
three years’ growth. |

Andricus inflator, Hartig.
(Plate XI.)

Andricus inflator, Adler, Miller, Mayr, Mosley, Fitch, Cameron ;
Cynips inflator, Thoms.

English name of gall.— The Twig Gall.’

Position of gall.—At the extremity of twig or shoot.

Manner of growth.—Single, glabrous, sessile, glossy.

Colours.—Green, dark green, brown, dark brown.

Average dimensions of a mature specimen. — Height,
15 mm.: breadth, 10 mm.; girth, 30 mm.

May be sought during any month of the year.

‘Growth is complete by the end of September.

The typical condition of the gall is bilocular, but unilarval.

The larva pupates in the gall. The imago emerges during
June to August.

Parasites, Nos. 21, 56, 83, 87, 154. Inquiline, No. 110.

Alternate agamic generation: Aphilothriz globult, Hartig.

The gall results from the gall-wasp laying its egg in
the axis of the terminal bud. When the bud develops
in the spring the apical portion remains whitish for a
long while.

In all stages of development the gall is easily
recognisable.

In some districts this gall is exceedingly abundant,
and many oak bushes have a very great number of the
galls on the twigs; but there 1s not always a pro-
portionate abundance of the alternate generation in
the succeeding autumn.

The egg is laid in the axis of a bud during September
or October by Aphilothrix globuli. No gall-growth
takes place until the following spring, when the larva
hatches. Rapid swelling of the tissues then begins,
resulting in an enormously thickened and stunted
shoot. During the summer leaves and occasionally
short twigs grow from the exterior of the gall. In

64 BRITISH OAK GALLS.

the mature state it is an attractive and interesting
object.

The exterior of the gall bears several ridges of
irregular outline which may, or may not, encircle the
growth. From these ridges, at different points, buds
develop in the autumn and remain until the following
spring, when most, if not all, become abortive and fall
off; if one remains a long slender twig may sprout
from it. I have seen several specimens in which the
termination of the twig bore a gall of the same
Species.

After the imago has emerged the outer gall continues
growing until the autumn—an unusual feature in
spring galls.

In the centre of the structure is a deep cylindrical
hole. It is about 3 mm. in diameter and 10-12 mm.
deep. At the bottom is the elongate-oval larval and
pupating chamber. An exceedingly thin septum,
slightly pilose on the interior, closes the mouth of the
hole.

“ Curvator, it may be noted, forms terminal swellings
like those of inflator ; but these are seldom so elongated,
and the internal cavity is larger and more particularly
wider” (‘ Brit. Phyto. Hymen.,’ vol. iv, p. 82).

Andricus lucidus, Mayr.
(Plate V, div. F.)

Cynips lucida, Hartig; Aphilothrie lucida, Mayr, Hartig;
Andricus lucidus, Cameron; A. lucida, Mosley.

English name of gall.—‘‘ The Bristly Gall.”

Position of gall.—In the axils of the leaves.

Manner of growth.—Sessile, hirsute, single, clustered, in-
deciduous.

Colours.—Pale brown, ultimately brown.

Average dimensions of a mature specimen.—Globular
form; girth, 30 mm.

May be sought during any month of the year.

Growth is complete by the end of September.

The typical condition of the gall is plurilocular, but unilarval.
Osual number of cells, about fifteen.

ANDRICUS NODULI. 65

The larvz pupate in the gall. The imagines emerge during
April and May.
Inquilines, Nos. 17, 182.

This gall is mostly globular in form, but it varies
in size, and also in shape from that of a cherry to
that of a walnut. It is found generally on bush and
scrub oaks.

“Its whole surface is covered with stiff, stalky, or
fibrous projections, which stand out radiately, and
terminate in a rusty-red papilla. In section it exhibits
a hard texture with numerous egg-shaped cavities; in
these live the larvee, without being separately enclosed
in an inner gall”? (Mayr).

Mosley recorded it in 1892 occurring in Whitley
Woods, Yorkshire.

Andricus noduli, Hartig.

(Plates XIT, IX, div. B.)

Andricus noduli, Mayr, Marshall, Adler, Miller, Walker, Mosley ;
A. trilineatus, Hartig, Cameron.

English name of gall.—‘‘ The Knot Gall.”

Position of gall.—Beneath the bark of twig and im leaf petiole.

Manner of growth.—Separate, gregarious, glabrous, concealed.

Colours.— White, very pale green, pale brown.

Average dimensions of a mature specimen.— Length,
2 mm.; breadth, 1 mm.

May be sought during the months of June to August.

Growth is complete by the end of July.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during

August and September.
Parasites, Nos. 56,108. Inquilines, Nos. 17, 110, 128, 145.

Alternate agamic generation: Aphilothrix radicis, Fabr.

Upon reference to Plate IX, div. B., it will be seen
that the autumn—winter condition of twigs and leaf
petioles containing many of these galls is very con-
spicuous on account of the swollen and nodulose

appearance. It is only when many galls close to each
5

66 BRITISH OAK GALLS.

other are developing, or have arrived at maturity, that
the twigs give evidence of their presence.

Solitary galls, or several scattered along an ordinary
slender twig, are difficult to locate. This may be
understood by referring to A, Plate XII.

The galls are much more abundant in twigs than in
leaf petioles.

This is a most obscure gall, and difficult for the
uninitiated gall collector to find. It may usually be
found by peeling off the bark of shoots near where
galls of Aphilothrix radicis have grown. It occurs
only in shoots of the year, or in‘a leaf petiole.

Its situation is beneath the bark, more or less
embedded in the xylem, and is therefore completely
hidden from view. Its presence in a shoot can only
be conjectured by a very slight swelling of the bark
immediately above where the gall is situated.

The gregarious habit does not furnish any additional -
indication. In a leaf petiole, however, considerable
thickening is produced, and the galls are usually more
numerous there than in a shoot. °

Mayr says: “On Quercus pubescens the swelling
occasioned by this gall is still less perceptible on
account of the tomentum on the surface, and sometimes
it (the swelling) is entirely absent.”

After the imago has emerged the swollen part of the
bark subsides, but the minute circular exit-hole betrays
the position of the empty gall.

I have found that this gall occurs more frequently
on stub-oaks, young trées, and bushes in hedges than
on large trees.

The gall is widely distributed throughout Britain,
and in places very plentiful, a fact accounted for by
the vast number of imagines from an average-sized
gall of A. radicis.

ANDRICUS PILOSUS. 67

Andricus nudus, Adler.
(Plate XIII, div. A.)

Andricus Malpighii, Cameron; A. nudus, Mosley.
English name of gall.—* The Bald Seed Gall.”
Position of gall.—On the flower-stalk of staminate catkin.
Manner of growth.—Sessile, glabrous, glossy, gregarious,
pointed.
Colours.—Pale green, yellowish-green, yellow, brown.
Average dimensions of a mature specimen.—Length,
15 mm. ; breadth, 1 mm.; girth, 3 mm.
May be sought during the months of May and June.
Growth is complete by the end of May.
The typical condition of the gall is unilocular and unilarval.
j The larva pupates in the gall. The imago emerges during
une.

Alternate agamic generation: Aphilothriz Malpighii, Adler.

This gall is found usually on the high branches of
large trees. It is very small and inconspicuous, and
but for its gregarious manner of growth would rarely
be noticed. It is ovoid in shape, with a minute nipple-
like process on the apex, upon which there may be a
very few small hairs ; otherwise it is perfectly glabrous.
Seven appears to be the usual number of galls in a
cluster, and seldom more than two clusters on the
same catkin stalk.

It was first discovered and described by Dr. Hermann
Adler during his investigations in 1876-8. I have
found it plentiful on Quercus sessiliflora at Hastings.

Andricus pilosus, Adler.
(Plate XIII, div. B.)

Andricus pilosus, Licht., Mayr, Cameron, Mosley.

English name of gall.— “ The Hairy Catkin Gall.”

Position of gall.—On the flower-stalk of staminate catkin.
Manner of growth.—Sessile, pilose, solitary (usually), ovoid,

pointed.
Colours.—Pale green, green, pale brown, dark brown.

68 BRITISH OAK GALLS.

Average dimensions of a mature specimen.— Length,
2mm.; breadth, 15 mm.; girth, 45 mm.

May be sought during the months of May and June.

Growth is complete by the end of May.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during June.

Alternate agamic generation: Aphilothrixfecundatriz, Adler.

This pretty little gall, although very similar in size and
shape to Andricus nudus, differs from it in being
thickly covered with whitish hairlets; it is also more
or less solitary in its manner of growth.

It is found mostly on Q. pedunculata; ‘the reason
for A. fecundatriz preferring” (to oviposit in the
catkins of) “‘ this species of oak is probably because it
flowers about fourteen days earlier than Q. sessiliflora ”
(Adler, ‘ Alternating Generations,’ p. 50).

Andricus ramuli, Linn.
(Plate XIV.)

Cynips quercus-ramuli, Linn; Teras amentorwm, Hartig; Andricus
ramuli, Schenck, Adler, Licht., Mayr, Miller, Fitch; Cynips ramuli,
Cameron, Marshall, Mosley.

Haplish names of gall.—‘‘The Woolly Gall,” “The Cotton
Gall.”

Position of gall.—On the staminate catkin.

Manner of growth. —Hirsute, gregarious, conglomerated, oval.

Colours.—Green, dark green, yellowish-brown.

Average dimensions of a mature specimen.— Length,
2mm.; breadth, 1 mm.; girth, 3 mm.

May be sought during the months of May and June.

Growth is complete by the end of June.

The typical condition of the gall is plurilocular, but unilarval.
Usual number of cells, about twelve. ;

The larva pupates in the gall. The imago emerges during
July and August.

Parasites, Nos. 21, 23, 45, 62, 64, 104, 154. Inquilines, Nos. °
17, 130, 136.

Alternate agamic generation: Aphilothriz autumnalis, Hartig.
This gall was observed in England by Dr. Sir

Thomas Browne, and mentioned by him in corres-
pondence with Dr. Merrett in 1668 (see Introduction).

ANDRICUS RAMULI. 69

It is undoubtedly one of the most distinctive and
delicate galls of the oak.

So far as my observations of this species have
extended, it appears that it may be found more
frequently on Q. sessiliflora than on Q. pedunculata.
On the continent, however, Q. pubescens seems to be
the favourite tree.

This interesting and most attractive growth is one
which commands more than a passing notice from all
persons who see it for the first time. It has the
appearance of a tuft of white cotton-wool, and among
the green leaves and yellowish catkins it looks
exceedingly pretty and dainty.

These galls attain maturity of form very rapidly,
and the period during. which they retain their pristine
beauty is also very brief; in sheltered positions it is
from five to seven days. Considerable care must be
exercised while gathering them. They are very
delicate, and any undue pressure will compress the
hairs and render it impossible to restore them to their
original form. Heavy rain will also disfigure them.
The hairs at first are more or less separate from each
other; about 15-20 mm. long, somewhat glutinous
and wool-like, and when in a mass are not resilient.

The entire structure, or compound gall, consists of
clusters of conglomerated larval chambers each of
which constitutes a true gall. The clusters vary in
number from two to ten, and contain about fifteen
larval chambers in each. It is from these clusters the
hairs grow, and being in close proximity to each other
unite to form an oval or globular-shaped mass of white
hairs, about the size of a walnut or a cherry respec-
tively.

In drying the mass diminishes to about half its
original size. This is due to the contraction of the
hairs, which become convoluted and interwoven. The
colour changes to a yellowish-brown soon after
maturity, and the imagines then make their exit. The
galls occasionally develop from a leat-bud.

70 BRITISH OAK GALLS.

Andricus solitarius, Mayr.

(Plate XV.)

Diplolepis solitarius, Fonsc.; Cynips ferruginea, Hartig, Schenck ;
Aphilothrix solitaria, Fonsc., Mayr, Fitch; Andricus solitarius,
Cameron, Mosley.

English names of gall.—The Hairy Spindle Gall,” “The
Red-haired Bud-gall.” ;

Position of gall.—Develops from a terminal or axillary bud.

Manner of growth.—Solitary, pubescent, spindle shape.

Colours.—Green, yellowish-brown, brown, reddish-brown.‘

Average dimensions of a mature specimen.— Height,
10 mm.; breadth, 4 mm.; girth, 12 mm.

May be sought during the months of June to September.

Growth is complete by the end of August.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
September.

‘Parasites, Nos. 38, 46, 66. Inquilines, Nos. 130, 136, 145.

Cameron appears to have been the first to describe
this gall for Britain. He found specimens in Cadder
Wood, near Glasgow. In the years 1873-5 it was
also found in Nottinghamshire by Mr. G. B. Rothera
and Dr. Ransom.

It is now distributed with moderate frequency all
over the country, growing more generally on bushes
in woods than on branches and twigs of trees. In
some localities it is abundant, in others seldom or
never seen.

The specimen in the inset of Plate XV is unusual in
having a small mamelon on its surface. The per-
sistent leaf-scales, characteristic of this species, at the
base of the gall are also easily noticeable.

This species is of remarkable appearance and vari-
able in form, situated indiscriminately in terminal
and axillary positions. Easily recognised by being
profusely covered with glossy and soft hairs of a
ferruginous colour, which are longer and denser at
the apex of the gall than elsewhere. When maturity is

ANDRICUS TESTACEIPES. 71

past most of the hairs fall off; they may also be easily
removed by leaves or twigs rubbing against them.

The gall is usually surrounded at its base by small
leaf-scales ; sometimes attached by a rather lone and
stout peduncle; almost always surmounted by a styli-
form prolongation, which may be two thirds the length
of the larval chamber, or even as long.

The style varies much in shape, sometimes quite
straight, sometimes considerably curved, ending bluntly
or bearing a small papilla; growing from the centre
of the apex of the larval chamber, or somewhat on one
side.

The larval chamber is large, the walls very thin.
Occasionally the exterior will be slightly constricted
near the base; sometimes longitudinally striated ;
almost always glossy when the hairs are removed,
and woody and hard in texture.

Seldom two galls on the same twig, very rarely
more than two. Some remain attached all through a
mild winter, others fall at the slightest touch.

Andricus testaceipes, Hartig.

(Plate XVI.) oo

Andricus Sieboldii, Mayr; A. testaceipes, Mayr, Adler, Licht.,
Kalt., Cameron, Mosley.

English name of gall.—‘ The Leaf-vein Gall.”

Position of gall.—On the petiole, under surface of mid-rib, and
its offshoots.

Manner of growth.—Glabrous, single, glossy, imbedded.

Colour.—Green..

Average dimensions of a mature specimen. — Length,
2mm.; breadth, 1 mm.

May be sought during the months of July to September.

Growth is complete by the end of August.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
August and September.

Parasite, No. 56.

‘Alternate agamic generation: Aphilothrix Sieboldi, Hartig.

72 BRITISH OAK GALLS.

Concerning Inquilines from this gall, Cameron says:
“ Synergus apicalis and Ceroptres arator are supposed
to be reared from the galls of testaceipes, but they
really may have been from those of noduli, the petiole
galls of which may have been mistaken for those of
testaceipes’ (‘ Brit. Phyto. Hymen.,’ vol. iv, p. 87).

Considerable doubt seems to exist in the minds of
some authors as to whether this species is, or is not,
the same as Andricus nodult. The habits of both
species are much alike; the galls of each are the same
in size and shape and develop in stem and petiole
alike, Andricus testaceipes alone, apparently, on the
veins of the leaf.

According to Adler the imagines cannot be distin-

Fie. 6.—Galls caused by Andricus testaceipes, on petiole and mid-rib of
leaf of Q. sessiliflora. dele. ad nat. E.C.

guished with certainty from each other, their time of
emergence is identical, and they oviposit in the same
manner. Mayr conjectured as to whether petiolar
galls containing a larva of Andricus nodult were
originally produced by A. testaceipes, and A. nodult
has only introduced its eggs, or whether the galls are
primarily produced by A. noduli alone. Although he
gathered hundreds of these galls in the months of
August and September he could not solve the
problem.

Adler’s experiments show that the imagines from
the galls in leaf-veins and petioles, known as those of
Andricus testaceipes, lay their eggs in shoots above
ground and produce Aphilothrix Sieboldi galls, which,
although gregarious, are unilocular ; and the imagines

APHILOTHRIX ALBOPUNCTATA. 73

known as those of Andricus noduli, from galls under
the bark of twigs, and petioles also, oviposit below
ground on roots and root-fibres and produce compound
plurilocular galls which are not only totally different
in shape, texture and colour, but are not gregarious,
viz. Aphilothrix radicis.

Aphilothrix albopunctata, Schlechtendal.
(Plate XVII.)

Cynips majalis, Giraud; C. albopunctata, Schlch.; Andricus
albopunctata, Mayr; Aphilothriz albopunctata, Adler, Licht., Mayr,
Fitch, Cameron, Mosley.

English name of gall.—‘ The Spotted Bud Gall.”

Position of gall.—In lateral and (occasionally) terminal buds.

Manner of growth.—‘Solitary, sessile, glabrous, glossy, longi-
tudinally grooved.

Colours.—Green, greenish-yellow, pale brown.

Average dimensions of a mature specimen.— Height,
8 mm.; breadth, 4mm.; girth, 12 mm.

May be sought during the months of May and June.

Growth is complete by the end of June.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
following spring.

Parasites, Nos. 39, 49, 56, 66,181. Inquilines, Nos. 130, 136.

I have found this gall, empty, but firmly attached
to a twig as late as September 10th (1907).

At C in Plate XVII is shown a young gall emerg-
ing from among the leaf scales. It is rather difficult
to obtain a specimen in that condition. It. will be
seen that the apex is depressed, the smooth-pointed
projection rising from the base of the concavity. The
depression quickly fills up and elevates the projection.

The sides of the young gall are longitudinally
furrowed; these also disappear as the gall grows,
but reappear when it has attaimed maturity.

This gall is subject to considerable variation in size,
shape, and manner of growth. Some illustrations are

74: BRITISH OAK GALLS.

here given. Care must be exercised when severing
the twig on which they are growing. They are easily
dislodged, and having fallen to the ground are seldom
recoverable. In the cabinet also care must be taken
in handling them. They are usually quite solitary,
i.e. not more than one on a twig. Occasionally two
may be found near each other, and one twig I found
had three within a distance of 33 mm., each growing
from lateral buds.

A large proportion of these galls will be found to
be quite empty. They are usually situated on the

smallest twigs, sometimes in company with Andricus
solitarius.

Its growth is rapid. When the gall bursts through
the bud scales it is usually green in colour, with very
few or no spots upon it. The exterior consists of a
somewhat thick soft rind which shrinks in thickness
a great deal as the gall nears maturity; beneath this
are the cell walls, which are thin. The larval chamber
is large and occupies the entire cavity. As growth
proceeds cream-coloured or pale-yellow spots appear
in the rind, elliptical in shape, and extending in a
longitudinal direction.

Numerous (15-20) furrows traversing the length of

APHILOTHRIX AUTUMNALIS. re)

the gall also appear. These are deeper, and also
broader in some specimens than in others.

The base is almost always surrounded by bud scales.
In some examples these are absent or indistinct. An
oceasional example will be attached to the twig by a
stout peduncle. Under a pocket lens a number of
very small purple, glossy papillae are seen in a few
specimens. The apex is generally surmounted with
a distinct projection, mostly simple, sometimes
recurved.

The gall develops as early as April, but normally in
May, from the buds of the previous year’s twigs. As
soon as maturity is past the gall falls off.

Of the many hundreds I have found of these galls
the largest measures 12 mm. high and 18 mm. at
greatest girth.

Cameron apparently considers this the same as
Aphilothrix quadrilineata, and all its characteristics
certainly favour the idea.

It appears to have been first recorded as British by
E. A. Fitch, from Essex in 1874.

It is common and widely distributed; more easily
obtainable on stub-oaks and small bushes than on
large trees.

Adler says: “ Aphilothriv albopunctata produces the
same gall as that from which it emerges.”

Aphilothrix autumnalis, Hartig.
(Plate XXIII, div. B.)

Cynips autumnalis, Hartig; Andricus autumnalis, Mayr ; Aphilo-
thriz autumnalis, Licht., Mayr, Fitch, Cameron, Adler.

English name of gall.—‘‘ The Autumn Gall.”

Position of gall.—In lateral, axillary, and terminal buds.

Manner of growth.—Sessile, glabrous, solitary, prolate.

Colours.—Green, brown. ;

Average dimensions of a mature specimen.— Height,
5 mm.; breadth, 4mm.; girth, 12 mm.

May be sought during the months of September and October.

Growth is complete by the middle of October.

76 BRITISH OAK GALLS.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago seldom emerges
until the spring of the second year.

Parasite, No. 56. Inquilines, Nos. 128, 133, 138, 144.

Alternate sexual generation: Andricus ramuli, Linn.

This is an obscure gall and not easy to find; more
than half of it, even when full grown, is covered with
bud-scales. The gall collector needs to be very
persevering when searching for it.

It is generally found in terminal leaf-buds, and
covered with a greenish succulent rind which ultimately
changes to a brownish colour and dries to a thin
layer, which remains on some specimens, but falls off
others and leaves indistinct longitudinal furrows on
the surface of the gall. The shape is that of a prolate
spheroid, the lower pole of which is unattached,
although imbedded in the xylem of the twig, the
upper pole produced into a mastoid form. It matures
rapidly and very soon afterwards usually falls to the
ground.

This gall bears a close resemblance to those of
Andricus collaris and A. globuli. There are, however,
a few distinguishing features. In comparing it with
the former species Cameron says “it 1s shorter and
more spherical than the gall of collaris . . . the
conical point is more distinct, and there is no
coloured band.” Mayr, referring to the same subject,
adds that there is much similarity between the’ galls
of Aphilothria autumnalis and Andricus globuli; both
are more than half covered with bud-scales, when
fresh of a green colour, thin fleshy reticulation beneath
the scarf-skin, and a small round wart at the summit;
but “it differs from the gall of A. globuli in its more
oval form, in the surface of the inner gall having no
reticular rings, but blunt longitudinal striations, which
also show on the surface of the brown gall.”

APHILOTHRIX CALLIDOMA, 77

Aphilothrix callidoma, Hartig.
(Plate XVIII.)

Cynips callidoma, Thomson ; Andricus callidoma, Mayr, Cameron ;
Aphilothriz callidoma, Licht., Mayr, Fitch, Adler, Mosley.

English name of gall.—“ The Stalked Spindle Gall.”

Position of gall.—Axillary buds.

Manner of growth.—Solitary, glabrous, glossy, spindle shape.

Colours.—Pale green, green, yellowish-green, brown.

Average dimensions of a mature specimen.— Length,
18 mm. ; girth, in centre, 9mm.

May be sought during the months of May to October.

Growth is complete by the end of August.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
following spring.

Parasite, No. 111. Inquilines, Nos. 138, 145.

Alternate sexual generation: Andricus cirratus, Adler.

The elegant shape and marked originality in the
form of this gall distinguishes it above all other
British oak galls.

It grows from an axillary bud, but more frequently
on the slenderest twigs of stub-oaks, and near the
ground, than in any other situation. Once only have
I found a specimen on a branch as high up as ten
feet from the ground. It is shown as an inset in
Plate XVIII.

The gail is cylindrical in outline, with each end
attenuated, producing a fusiform or spindle-shaped
growth. Each attenuation is solid, usually of great
length, the basal one generally the longest, sometimes
twice or three times longer than the central portion ;
the distal end may be short and recurved.

The larval chamber is situated in the centre. During
growth it is difficult to decide without dissection where
the gall is solid—the enlargement is so gradual. When
dry the attenuations shrink (in thickness only) almost
to a thread. As the larval chamber does not shrink
it can then be easily located. Its cell walls are very

78 BRITISH OAK GALLS.

thin, the interior is large, ellipsoidal in shape, about 5
mm. in its vertical axis, and 2 mm. in the horizontal.

The exterior has upon it longitudinal ridges, much
more distinct and sharp-edged in some specimens than
others, and entirely absent from some. Their colour is
frequently pink and purple, but it fades when the gall
is dry. They usually number from four to eight. I
have found a specimen with ten. Their symmetrical
arrangement can be seen best in a transverse section
of a gall.

Although the galls appear during several months
they grow quickly and mature rapidly, and fall to the
ground unless inhabited by inquilines. Those which
vary from the normal shape in having short peduncles
and are more obese, will remain attached to the twig
for a long while. ‘The length they attain is remark-
able. I have found dozens of varying sizes up to 22
mm., many 25 mm., and one 29 mm. long. They
usually project obliquely from the twig, and are
slightly curved, sometimes standing erect on a hori-
zontal branch and perfectly straight, sometimes at
right angles on an upright twig, very rarely pointing
downwards, and apparently never adpressed.

Mayr describes this gall, from specimens found on
Quercus pubescens, as “Scantily covered with mode-
rately short, white, deflected hairs.” Pubescence does
not appear when the galls are on other species of
Quercus.

These galls were first described by Malpighi in
1682; and Giraud was the first to breed and describe
the imago in 1859. EH. A. Fitch appears to have been
the first to discover it in England, at Rayleigh in
Essex, in 1874. I have found it local but plentiful in
woods and coppices in various parts of the Hastings
zoological district each season since 1899.

The majority of the galls are occupied by the
parasite or the inquilines.

The imago does not emerge from some galls until
the second spring after pupation.

APHILOTHRIX COLLARIS. 79

Aphilothrix collaris, Hartig.

Cynips collaris, Hartig, Schenck.; C. tegmentorum, Schtdl. ;
C. fasciata, Schtdl.; Aphilothrix collaris, Mayr, Adler, Licht.,
Fitch; Andricus collaris, Mayr, Cameron, Mosley.

English name of gall.—‘‘ The Collared Bud Gall.”

Position of gall.—In lateral and terminal leaf buds.

Manner of growth.—Solitary, glabrous, glossy, concealed.

Colours.—Green, greenish-yellow, brown.

Average dimensions of a mature specimen. — Height,
3 mm.; breadth, 2 mm.; girth, 6 mm.

May be sought during the months of August and September.

Growth is complete by the end of September.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
spring of the second year.

Parasites, Nos. 117, 50. Inquilines, Nos. 133, 135.

Alternate sexual generation: Andricus curvator, Hartig.

The quickest way to discover this deeply - hidden
gall is to longitudinally slice, with a sharp knife, every
bud on twigs of a likely bush until the typical appear-
ance of a galled bud is remembered; then by removing
a few leaf scales only of other buds undamaged speci-
mens can be secured.

A most obscure gall by reason of its diminutive size
and in being almost entirely concealed by: the leaf
scales until quite mature ; then only a small portion of
the apex is visible, which usually being brownish in
colour harmonises with the leaf scales and renders
detection very difficult.

“Tt is hard, woody, conical or oval, sometimes almost
round and smooth, the apex narrowed to a point, form-
ing a blunt cone surrounded by a zone differently
coloured from the rest of the gall” (‘ Brit. Phyto.
Hymen.,’ vol. iv, p. 90).

From the case of each gall is formed a slender
appendage which penetrates deeply into the axis of
the bud. When the gall is mature this appendage
contracts and the gall falls to the ground, but other
specimens which contain parasites or inquilines remain

80 BRITISH OAK GALLS.

in situ for some months firmly rooted in the twig,
affording “an instance in this of what is frequently
found to be the case, that when an inquiline lays its
ege in an immature gall the growth of the gall is
altered with the death of the original larva, and
becomes pathological” (‘ Alternating Generations,’
. 44).

Although the sexual generation is so plentiful,
collaris is somewhat uncommon and does not appear
to have been often found by the collector.

Fie. 8.—Galls caused by Aphilothrix collaris. a. In situ, nat. size.
sB. Enlarged x 4. c. Some leaf scales removed x 4. In part after
Mayr.

It is sometimes embedded in the leaf scales of A.
fecundatriz.

Aphilothrix corticis, Linn.
(Plates XIX, XXII, div. A.)

Cynips corticis, Hartig, Schenck., Kalt., Kirch., Thoms. ; Andricus
corticis, Mayr, Cameron, Mosley ; Aphilothrix corticis, Adler, Mayr,
Licht., Fitch, Ormerod.

English name of gall.—‘ The Bark Gall.”

Position of gall.—In the bark, in the rim of a callus, in axil of
a branch.

Manner of growth.—Glabrous, glossy, gregarious, conglome-
rated, embedded.

Colours.—Greenish-yellow, yellow suffused with pink, purple,
brown.

Average dimensions of a mature specimen. — Depth,
10 mm.; breadth, 4 mm.; girth, 12 mm.

May be sought during any month of the year.

Growth is complete by the end of May.

The typical condition of the gall is unilocular and unilarval.

APHILOTHRIX CORTICIS. 8L

‘i The larva pupates in the gall. The imago emerges during
une.

Parasite, No. 158. Inquiline, No. 131.

Alternate sexual generation: Andricus gemmatus, Adler.

This species of gall is often more or less concealed
by dead leaves, moss, or loose earth, but sometimes
situated prominently in a callus or other incrassation
of a stub.

The autumn—winter condition of these galls is shown
in Plate XXII, div. A.

Embedded deeply in the bark, and not easy to see,
because of their brownish colour, these galls are
constantly overlooked. It is only during the very
earliest period of exposure, and later on. after the
imagines have eaten their way out, that the galls
attract attention—in the former condition by reason
of their pale colour, in the latter, because of the
clusters of little holes.

They occur in aggregations, and vary in numbers
from three or four to forty or more, very rarely less
than three; mostly in a deep split in the bark;
frequently in a callus resulting from injury, or in the
new growth where a limb has been removed; some-
times in semi-exposed roots; and occasionally in the
axis of a bough growing out from the bole of the tree.

The shape of this gall is fairly constant, obconical
being the type. It varies, however, especially during
the period before maturity, when it may be oval with
the lower apex somewhat pointed; this ultimately
penetrates deeply into the tissue around it. When
conglomerated they are often greatly distorted,
flattened longitudinally, and irregular in size and
form.

The appearance of the gall when pushing through
the bark, is glossy, succulent, and fleshy, very pale
yellow, or greenish. The visible portion known as
the cap is more or less globose, and about 3 mm. in
diameter. The structure continues to rise until it is

6

82 BRITISH OAK GALLS.

about 3 mm. above its surroundings, by which time it
will have altered to a brownish colour, and the texture
hard and woody.

The cap is concave within, and soon. after the gall
reaches maturity it falls off, leaving the larval chamber
with a very thin but hard convex septum upon it, and
the upper margin of the thick cell walls exposed. The
imago ultimately eats its way through the septum.

The exposed margin is bordered by a thin rugged
rim, within which is enclosed a circle of about twenty
small punctures, with the hole of emergence in the
centre. These little punctures “belong to an earlier
period of growth; and through them. passed the
vascular bundles that nourished the upper sappy half
of the gall”’ (‘ Alternating Generations,’ p. 38).

Miss E. A. Ormerod appears to have been the first
to discover and record this gall in Britain, and also to
figure a type specimen in two conditions of growth
from a cluster found in 1877, in the neighbourhood of
Isleworth.

An oak stump in a coppice or a wood is one of the
surest situations in which to find these galls, more
especially if there be a number of small boughs
growing from the stump. A careful scrutiny should
also be made of trunks of old trees. When in clusters
and exposed, as shown in the centre of Plate XIX,
they are not difficult to find, but if a gall is solitary,
and in the folds of a callus, as seen near the top of the
same illustration, detection is less easy. After they
have turned brown, or if surrounded by moss, they
may very easily be overlooked, and on that account
their distribution may be much wider than is generally
known.

Aphilothrix fecundatrix, Hartig.
(Plates XX, XXI, XXII, div. B.)

Cynips gemmex, Linn., Sclnck.; C. fecundatriz, Hartig, Marshall,
Miller ; Aphilothri« gemmex, Mayr, Fitch; Aph. fecwndatriz, Adler,
Licht.; Andricus fecundatriz, Mayr, Cameron; .A. gemmzv, Mosley.

APHILOTHRIX FECUNDATRIX. 83

English names of gall.—‘ The Artichoke Gall,” “The Hop-
strobile Gall,” ‘The Hop Gall,” «The Larch-cone Gall.”

Position of gall.—In axillary and terminal buds.

Manner of growth, —Single, sessile, aciniform, concealed.

Colours.—Green, dark green, reddish-brown.

Average dimensions of a mature specimen. -— Height,
8mm.; breadth, 4 mm.; girth, 12 mm.

May be sought during the months of June to September.

Growth is complete by the end of August.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
following spring. Sometimes not until two or three years afterwards.

Parasites, Nos. 11, 30, 47, 56, 59, 66, 116, 118. Inquilines,
Nos. 128, 182, 145.

Alternate sexual generation: Andricus pilosus, Adler.

This gall was observed in England by Dr. Sir
Thomas Browne, and mentioned by him in correspon-
dence with Dr. Merrett in 1668 (see Introduction).

The branch shown on Plate XX has thirteen
strobiles growing on it, and it may be considered a
very fine and unusual example of so numerous an
ageregation.

This growth consists of two parts totally distinct
from each other in appearance, shape, size, structure,
manner of growth, and colour; the outer and easily
recognisable portion, composed of a large number
of imbricated leaf-scales; the inner and invisible
part, a small pip-like, glossy, more or less hard,
substance.

The leaf-scales are of two shapes. Those occupying
a central position are long, narrow, and thread-lke,
usually about ninety in number, and thickly covered
with long silky hairs. The external or enveloping
leaf-scales are not so numerous, oval or somewhat
triangular in outline, of varying shades of green,
mostly margined with a deeper shade of the same
colour, or with pink or purple, and these scales also
are thickly covered, but on the external surface only,
with long silky adpressed hairs, many more of which
spring from the margins and produce a delicate fringe.

84 BRITISH OAK GALLS.

The scales completely conceal, and effectually shelter,
the inner pip during its formation.

This pip, which is the true gall, constitutes the
nourishment for the larva, and within the tissues it eats
a cavity, forming the larval chamber. In shape it may
be pyriform, an elongated oval, or, like a grape-pip.
The smaller or lower end is truncated or flattened, and
placed in direct contact with, and affixed to, the axis
of the bud. The distal end is deeply depressed,
within which is situated a very small yellowish cone
having a glossy vertex. At first the colour is pale
green or greenish-yellow, which, however, soon
becomes dark green, and later reddish-brown. Early
in its formation it is soft and sappy, the cell walls thick,
and easily opened with a finger-nail, later it hardens
greatly. When nearing maturity numerous (40-50)
longitudinal striations, which extend from base to sum-
mit, may be seen on its surface. The average dimen-
sions are 8 mm. high and 12 mm. at greatest girth.
The interior is oval, whitish in colour, the larva occupy-
ing the entire space.

Until it attams its full growth the gall remains
firmly fixed, but about the second week in August the
axis of the bud contracts; the base of the scales thus
being brought close together press against the lower
part of the pip, causing it to separate from the axis
and finally to be pushed upwards until it falls out.
In Plate XX two strobiles can be seen where the galls
have reached a position in which a movement of the
branch will cause them to fall. They were in this
condition when found by the author.

During the early formation of the leaf-scales the
shape of the mass is more or less globular. Three
types of this form can be seen at d, e in Plate XXI.
It then emerges into the form of an ellipse or an oval,
r, a, the central scales soon afterwards pushing their
way through the distal apex and forming a cone or
strobile, when the appearance (b) is like that of a
miniature artichoke, hence one of its popular names.

APHILOTHRIX FECUNDATRIX. 85

When it reaches this condition it is an indication that
the gall is about to be pushed out, and this soon takes
place, g. The central scales continue to lengthen for
some time after the gall has gone (f), but their growth
is dependent upon the condition of the season, whether
it be early or late when the gall falls; if the latter,
no change takes place in the length of the scales.
These scales separate somewhat from one another, but
the whole cluster remains on the twig or branch
throughout the winter; the coldest and roughest
weather seemingly has no power to dislodge them.
The new growth in the spring usually pushes them off
(see Plate XXII, div. B).

They are mostly sessile and axillary in their situation ;
many, however, are elevated on a peduncle 20 mm. or
more long, and many others are in a terminal position.

Soon after the gall has fallen to the ground it
attains maturity. The exterior becomes hard and firm,
the colour deepens to a reddish-brown, and it is difficult
to find amongst dead leaves, grass, loose earth, etc.

It remains in that condition for a period which
may extend to two and a half years, before the imago
issues from it. Some galls, however, do not leave the
scales from various causes, the principal being the
presence of parasites or inquilines instead of the
rightful owner. Such examples are occasionally found
in the winter and spring.

These strobiliform growths are exceedingly common
all over England, and are found more plentifully on
bushes and young trees than on large trees during the
months of June and October, both inclusive, in a fresh
state, varying according to the locality, and in the old
condition for many months more.

Cameron and Fitch both state that the larve and
pupe of a Tortrix, Carpocapsa juliana, may be commonly
found among the leaf-scales and the imago easily
reared.

86 BRITISH OAK GALLS.

Aphilothrix globuli, Hartig.
(Plate XXIII, div. C.)

Cynips globuli, Hartig, Schenck., Kirch.; Aphilothriz globuli,
Mayr, Licht., Adler, Fitch; Andricus globuli, Mayr, Cameron,
Mosley.

English name of gall.—‘ The Globular Gall.”

Position of gall.—In lateral and terminal buds.

Manner of growth.—Sessile, solitary, glabrous, globular, oblate.

Colours.—Pale green, green, greenish-brown, bluish.

Average dimensions of a mature specimen. —Globular ;
girth, 12 mm.

May be sought during the months of September to November,
and occasionally in December.

Growth is complete by the end of October.

The typical condition of the gall is unilocular and unilarval:

The larva pupates in the gall. The imago emerges during
April of the second year.

Parasites, Nos. 14, 38, 44, 56, 113, 118. Inquilines, Nos. 1,
138, 138, 145.

Alternate sexual generation: Andricus injlator, Hartig. :

A favourite situation for these galls is on the long
and slender twigs which so often grow from the bole
of an old oak situated in a more or less open wood. I
have seen scores of such twigs with from one to eight
galls in terminal and axillary positions.

Small bushes near the bole of the tree, or more
generally those just beyond the limits of the lower
branches, will also frequently yield numerous speci-
mens, while the small twigs of the branches themselves
will often have galls.

This is one of the late autumn galls, specimens fre-
quently being seen in sitw during November and occa-
sionally in December. It is a pretty little gall, mostly
oblate in shape; this, however, is not apparent until
it is mature and divested of the outer rind. Many
specimens are quite spherical. It is formed in a bud
and bursts through the leaf-scales during October.
For a short time only a small portion of the growing
gall can be seen, but ultimately about two thirds of

APHILOTHRIX MALPIGHII. 87

its bulk is visible, the lower third being concealed by
the leaf-scales. These do not fall off.

The gall is composed of two layers, the outer form-
ing 4 soft, thick, sappy, green rind, which envelops
the larval chamber all the while it is on the twig, but
“‘when the gall falls out of the bud the sappy rind is
loosened, and the woody inner gall left bare” (Adler,
‘ Alternating Generations,’ p. 40). If, however, the
gall is gathered before maturity, this exterior dries
and shrinks, producing irregular reticulations which
unite at the apex in a point, caused by a small cone
beneath. The inner layer, which forms the larval
chamber, has thin walls enclosing a large cavity,
whitish inside. The outer surface of these walls is
marked with a network of very fine irregular lines,
only to be seen with the aid of a pocket lens. This
portion becomes hard and woody when the gall is fully
developed. At the point opposite the base grows the
small cone previously mentioned, reddish or yellowish
in colour. It is not visible while the rind is soft and
thick.

Aphilothrix Malpighii, Adler.
(Plate XXITI, div. A.)

Andricus Malpighii, Mayr, Cameron, Mosley.

English name of gall.—‘“ Malpighi’s Gall.”

Position of gall.—In axillary buds.

Manner of growth.—Solitary, sessile, slightly pilose, spindle
shape.

Coloukes—* Green, often with reddish stripes” (Cameron).

Average dimensions of a mature specimen. — Height,
4.mm.; breadth, 15 mm. ; girth, 45 mm.

May be sought during the months of September and October.

Growth is complete by the end of September. ;

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
spring of the second year.

Alternate sexual generation: Andricus nudus, Adler.

88 BRITISH OAK GALLS.

This gall stands more or less obliquely from the
twig, upon a hemispherical base formed of the aborted
bud out of which it has grown. It.may be sessile, or
attached by a short peduncle. It is in the form of
a narrow cylinder, the distal end of which bears a
small, glabrous, glossy, mastoid process.

Its growth occupies about three weeks, by which
time it reaches maturity and then falls to the ground.

A special feature characterising the growth of this
gall is the hemispherical reddish-brown base which is
firmly adherent to the twig in a leaf axil.

The gall appears to be rare. I have never found
more than the one specimen illustrated, although

a. After Cameron,
s,c. After Adler, each x 2. pv. The same specimen as in Plate
XXIII, div. A. x 4. dele. ad nat. H.C.

quantities of galls of Andricus nudus are found year
after year in the same wood. I found it in a wood at
Hastings during September 1901, and knowing for
certain that I should not be able to ‘visit the spot again
for several weeks, gathered it, but unfortunately failed
to rear the inhabitant. .

Cameron describes the gall as smooth. My speci-
men is clothed with numerous short, recurved,
adpressed hairlets, of a somewhat golden colour,
except at the apex, and devoid of ridges. Adler does
not refer to the presence or absence of hairlets.
Cameron’s illustration (‘ Brit. Phyto. Hymen.,’ vol. iv,
Plate VII, fig. 2) corresponds as regards position, base,
size, and partly in outline, with my specimen.

Adler, in ‘ Alternating Generations,’ Fig. 12, illus-
trates two galls on a twig. They are sessile, and

APHILOTHRIX MARGINALIS. 89

much more spindle-shaped than the previous speci-
mens, and also distinctly ridged—a feature neither
mentioned by him in his description of the gall,
referred to by Cameron, nor found in my specimen.

There may be, however, variations in mode of
growth such as would allow each of the above to be
representative.

They are illustrated in Fig. 9 for comparison, and
to assist the collector to identify any he may find.

Aphilothrix marginalis, Schlechtendal.
(Plate XXIV, div. A.)

Cynips marginalis, Mayr, Schltdl.; Andricus marginalis, Mayr,
Cameron; Aphilothriz marginalis, Mayr, Licht., Adler, Fitch,
Mosley.

English name of gall.—‘ The Marginal Gall.”

Position of gall.—On margin of leaf; sometimes on mid-rib.

Mannert of growth.—Sessile, solitary, glabrous, glossy.

Colours.—Green, striped with pink or red, yellowish, brown.

Average dimensions of a mature specimen. — Height,
4mm.; breadth, 3 mm.; girth, 9 mm.

May be sought during the months of May and June.

Growth is complete by the end of June. —

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
same or the following month.

Parasite, No. 66.

Cameron says: “Neither as regards the gall, or
insect, is this to be known from A. 4-//neatus. I have
no doubt that it is only A. quadvilineatus, the galls of
which occur on the leaves” (‘ Brit. Phyto. Hymen..,’
vol. iv, p. 96). Mayr remarks that they so greatly
resemble each other as to be indistinguishable.

In form this gall is irregular; it may be conical,
oval, or roundish, more or less deeply ribbed ‘longi-
tudinally, and when on leaves larger than when on

catkins.
The larval chamber is large with thin walls.

90 BRITISH OAK GALLS.

Aphilothrix quadrilineatus, Hartig.
(Plates XXV, XITI, div. C.)

Andricus quadrilineatus, Hartig, Schenck, Mayr, Fitch, Cameron,
Mosley; Aphilothriz quadrilineatus, Adler, Licht.; Cynips 4-lineatus,
Thoms; Andricus flavicornis; A. ambiguus; A. verrucosus; A.
peduncult; A. glabrusculus, Schenck.-

English name of gall.—‘“ The Furrowed Catkin Gall.”

Position of gall.—On the flower-stalk of staminate catkin.

Manner of growth.—Sessile, glabrous, glossy; gregarious,
longitudinally grooved. :

Colours.—Pale green, greenish-yellow, reddish-brown.

Average dimensions of a mature specimen.— Length,
4mm.; breadth, 3 mm.; girth, 9 mm.

May be sought during the months of May and June.

Growth is complete by the end of June.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
following spring.

Parasites, Nos. 8, 66,154. Inquiline, No. 180.

I have found as many as thirty-five of these galls
on a catkin stalk measuring 70 mm. in length.

The regularity with which the galls of this species
appear on the same tree is remarkable. I have
observed several trees, 80 to 150 years old, for the
past fifteen years on which they have occurred each
summer without intermission. Probably they were
there many years before my observations began, and
they will annually reappear until the trees are thrown,
or they decay.

This gall was first found in Britain by Professor
Trail, in the year 1873, at Aberdeen. In the following
summer EH. A. Fitch discovered it at Raleigh in Essex.
It is now well known, and widely distributed all over
the country.

It appear to be more frequently found on Quercus
pedunculata than on Q. sessiliflovu, and often itis on the
same catkin as Spathegaster baccarum and Aphilothriv
seminationts.

It is subject to great variations in size, shape, and

APHILOTHRIX RADICIS. 91

also in the number, length, and depth of the furrows.
Some examples are quite smooth, and but for the
absence of the sharp pointed apex peculiar to the
galls of Aid/ricus nudus, many small specimens might
pass as that species. Yet mature galls of A. quadri-
lineatus often show a papilla when dry; A. audus,
however, never attains the same dimensions.

Considerable indecision appears to have existed
amongst writers as to the identity of this gall when it
was first noticed on the continent. Its great varia-
bility doubtless accounts for. this, and it also affords an
explanation of its many synonyms, to which Schenck
unnecessarily contributed five.

Some years it appears in great profusion, clusters
‘of eight and ten galls being frequently found on a cat-
kin stalk. A very fine example I found in 1907 con-
sisted of fifteen galls upon one stalk within a length of
23 mm.

“ Notwithstanding that this gall is very abundant it
is by no means easy to rear the fly. From the
majority of the galls parasites are usually obtained ;
then the larva in a large number of instances does not
develop into the imago for two years” (‘ Alternating
Generations,’ p. 91).

Aphilothrix radicis, Fabricius.
(Plates XX VI, XXX, div. A.)

Cynips radicis, Fabr., Hartig, Schenck, Kalt., Marshall ; Aphilo-
thriz radicis, Mayr, Adler, Licht., Fitch, Walker, Miller ; Andricus
radicis, Mayr, Cameron, Mosley.

English name of gall.—‘ The Truffle Gall.”

Position of gall.—On exposed roots, base of trunk and branches
growing therefrom. ;

Manner of growth.—Glabrous, sessile; solitary, conglomerated.

Colours. --Cream, pink, orange, red, reddish-brown.

Average dimensions of a mature specimen. — Height,
45 mm.; length, 60 mm.; breadth, 40 mm.

May be sought during any month of the year.

Growth is complete by the end of the second autumn. —

The typical condition of the gall is plurilocular, but unilarval.
Usual number of cells, about sixty.

92. BRITISH OAK GALLS.

The larva pupates in the gall The imago emerges during the
second spring.

Parasites, Nos. 44, 108, 149, 152, 161, 175, 178. Inquiline,
No. 131.

Alternate sexual generation: Andricus noduli, Hartig.

This gall was observed in Britain by Sir T. Browne,
M.D., in 1668 (see Introduction).

In the year 1870 it was brought before the
notice of entomologists by A. Miller, who reared some
imagines.

It is so distinctive in situation, texture and colora-
tion that once having been seen there is no difficulty
in recognising it in any of its various forms, and of
distinguishing it from the other root gall, Biorhiza
aptera.

The typical situation for this gall is on the largest
roots of old oak trees where they branch off from the
base of the trunk, and partly, or entirely, concealed
by loose earth, leaves or moss. It is found also at
a depth of about six inches below the ground, and
it occurs on the trunk of the tree, rarely, however,
at a greater height than two feet from the ground level,
and still more'rarely on a smal] branch springing from
the base of the trunk, as shown in Plate XXX, div. A.
Of many dozens of specimens I have seen two only
have occurred in such an uncommon situation. The
most certain place, perhaps, to find this gall, is a hedge
bank where a stub-oak forms part of the hedge,
and its roots (here and there exposed) are old
and extensive. The alternate generation is sure to be
near by.

The form of the gall is exceedingly variable. It is
difficult to define a typical figure.

When formed below ground the shape depends
upon the density of the surrounding earth, and it may
be flat, ovoid, pyriform, globular, or as indicated above ;
and sessile or attached by a stout peduncle. Moreover
it does not appear to attain so great proportions as

APHILOTHRIX RADICIS. 93

when above ground. I have observed that when
situated on the trunk, or a branch, the majority of
single growths (i.e. like that in Plate XXX, div. A),
approach a reniform or an oval shape, and are sessile.
Such a specimen may be regarded as the result of the
oviposition of but one imago, whereas that in the lower
half of Plate XXVI, being due to several, perhaps four,
imagines.

The size, likewise, differs considerably, varying from
that of a marble to upwards of 30 cm. at greatest
girth.

The gall appears in September and continues grow-
ing for some weeks. About November it ceases to
grow until the spring, when formation is resumed, and
by the end of the summer it ismature ; the larvee then
pupate and remain in that condition through. the
winter, the imagines coming out about April. During
formation the gall is succulent, of the consistence of a
potato, more or less smooth externally and slightly
glossy; when nearing maturity it becomes firmer, and
finally hard and woody. Small and medium size
aérial specimens usually have about half their surface
deeply furrowed, producing elevations of irregular
shape, size, and height, and mostly pointed.

The larval chambers are exceedingly numerous.
They are normally globular in shape, about 3 mm. in
diameter, with thin, hard, and woody walls, firmly
affixed to each other in a somewhat concentric pattern,
and occupying the centre of the surrounding tissue.
After the gall has arrived at maturity this tissue
undergoes various changes. It loses much of its solid
nature, becomes soft and open in texture, thus offering
little resistance to the imagines in eating their way to
the exterior. Finally it decays away, leaving the
tenantless larval chambers in a conglomerated con-
dition, whitish in colour, and adherent for some time.

The colour is regulated according to situation.
Below ground it is white, or dirty white, sometimes
with a rose tinge; beneath leaves or moss it is suffused

94, BRITISH OAK GALLS.

with pink or red, lasting for some time, then deepening
to brown; upon the trunk it is mostly reddish-brown
throughout the whole of its growth, changing at last
to chocolate brown.

The largest specimen of this gall of which I have
any record was composed of five sections, forming an
oblong-obvate outline and ob-compressed, and attained a
girth of 82 cm. It grew on the short stump of a very
old oak tree in a wood near Hastings. I visited the
spot intermittingly during a period of twenty-five
months to note its growth, and then, as hundreds of
imagines had left it and there were signs of approach-
ing decay, I removed it for further examination.
Another interesting specimen I discovered at Hastings
was growing out of an ivy stem encircling a large oak
tree. The gall was in its first year of growth and
consequently immature. For several reasons I was
obliged then and there to remove it, and did so by
sawing away a length of the ivy stem, with the gall
remaining upon it. It was globulose in form, brownish
in colour, with a rough surface, and 25 mm. in
diameter. It is now in my collection of oak galls.

The popular designation of “truffle gall” is: singu-
larly appropriate, both its appearance and manner
of growth when beneath the ground coinciding with
that of the fungus. The black truffle (Tuber melano-
spermum) exists a few inches under ground, and
although partial to beech woods is found amongst oaks
also. Its external appearance is very much like that
of a radicis gall.

Aphilothrix seminationis, Giraud.
(Plate XXIV, div. B.)

Cynips seminationis, Giraud, Mayr; C. inflorescentix, Schltd. ;
Aphilothrix seminationis, Adler, Licht., Fitch, Mosley; Andricus
seminationis, Mayr, Cameron.

English name of gall.—“ The Barley-corn Gall.”

Position of gall.—On the stems of staminate catkins and on
leaf margin.

APHILOTHRIX SIEBOLDI. 95

Manner of growth.—Solitary, glabrous, glossy, spindle shape.

Colours.-—Cream, green, greenish-yellow, suffused with pink or
red, brown.

Average dimensions of a mature specimen. — Length,
6 mm.; breadth, 2°5 mm.; girth, 7-5 mm.

May be sought during the months of May and June.

Growth is complete by the end of June.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
following spring.

Parasite, No. 44. Inquilines, Nos. 127, 130.

This gall is slightly pubescent when young. Some
specimens are slightly pedunculated, and also marked
with longitudinal ribs more or less sharply defined.

Catkin stems bearing these gall are often abnormally
thickened, and remain on the twigs all the summer.
Leaves are peculiarly indented or deformed in shape.

The gall closely resembles that of A. callidoma, but
may be distinguished from that species by its point of
origin—it never grows from a bud.

Aphilothrix Sieboldi, Hartig.
(Plates XXVII, XXVIII, XXIX, XXX, div. B.)

Cynips Sieboldi, Hartig; C. corticalis, Schenck; Aphilothrix
Sieboldi, Mayr, Adler, Licht., Miller, Walker, Fitch; Andricus
Sieboldi, Mayr, Cameron, Mosley.

English name of gall.—‘‘ The Red-barnacle Gall.”

Position of gall.—On small branches and twigs near the ground.

Manner of growth.—Sessile, glabrous, glossy, gregarious.

Colours.—Cream, yellowish, pink, crimson, reddish-brown.

Average dimensions of a mature specimen.— Height,
6 mm.; breadth, 6 mm.; girth, 15 mm.

May be sought during any month of the year.

Growth is complete by the end of September.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
following spring.

Parasites, Nos. 44, 66,175. Inquiline, No. 131.

Alternate sexual generation: Andricus testaceipes, Hartig.

This gall was first recorded as British by A. Miller
in ‘The Gardener’s Chronicle,’ No. 40, p. 1312; fig.

96 BRITISH OAK GALLS.

239 illustrating a specimen (1870). It was also in-
dependently found by H. Moncrieff at Portsmouth in
January, 1873, the specimen being a good sized twig
with a large aggregation of galls around it.

The galls may now be found in almost any hedgerow
containing oak bushes.

When the habitat of this gall is understood there is
little difficulty in finding numerous specimens in
localities where they occur. It is almost certain to be
found quite low down near the roots in thick parts of
a hedge, sometimes hidden by dead leaves, moss, or
loose earth. Very seldom at a greater height than
three feet above the ground, and never on the higher
boughs, nor in a situation exposed to direct sunlight.
A favourite place is on a road-side bank which is well
covered with herbage, including small oak bushes
whose shoots are occasionally cut off by the hedge
trimmer. In such spots I have found some of the
best, and most remarkable specimens in my collection.
Diligent and careful search is however often necessary.
It appears to be restricted to certain areas, and not
found at all in some localities. It is one of the most
distinctive ‘of the oak galls, and unlike any- other
British species.

An egg is laid by Andricus testacerpes beneath the
bark of a shoot in late summer. The gall begins to
grow during September, and the bark soon rises in
consequence. At the close of the autumn, growth
ceases, but with the return of spring it is resumed.
About May the bark bursts, and the gall increases
rapidly. Before the end of July it has reached
maturity, and the larva pupated. During August and
September the imago develops within the puparium,
but it does not emerge from the gall until the following
spring.

The red colour of the gall varies in intensity. I
have found them where concealed from all light, of a
very pale yellow or cream colour, the apex only slightly
touched with pink. A cluster of this kind is depicted

APHILOTHRIX SIEBOLDI. 97

in the lower right hand corner of Plate XXVII. And
from that condition they advance through all shades
of pink and red to a deep purple. It is rarely, if ever,
green.

The shape is generally conical; some specimens are
oblate with the apex produced into a small papilla.
The lower portion is also conical descending deeply
into the zylem, and remaining there after the decay of
the superstructure. During growth many specimens
have the upper surface rounded, and when crowded
together they are considerably compressed, and there
does not appear to be any apex or papilla, but both of
these ultimately develop and can be seen.

The substance of the gall is composed of two layers.
The inner, yellowish in colour, thin, and woody, and
striated from the apex to the periphery. It encloses
a rather large larval chamber. The outer layer is
much thicker. It is composed of a soft and sappy
rind containing the red colouring matter, and from it
a slightly sweet _mucilaginous substance exudes. It
may frequently be covered with a bloom. Ants are
very fond of the sweet substance, and build a dome of
earth over clusters of the galls. I have found several
very fine examples of this. Whilst recognising the
fact that the protection thus afforded prevents para-
sites and inquilines from attacking the galls, I do
not agree with those who consider the sweet substance
as a means devised by the gall to entice ants to it and
induce them to protect it; nor that the exudation is
for the purpose of énsnaring unfriendly insects and
other small creatures. Repeated observations lead me
to the conclusion that ants are aware that by building
a dome, the galls are protected from premature
evaporation and drying, thereby securing a more
copious and lasting exudation for their exclusive enjoy-
ment. Galls not protected from the drying action of
midsummer heat in this way, or by dead leaves, moss,
or earth have less moisture in the rind than those which
are protected. :

98 BRITISH OAK GALLS.

When the gall is mature the rind dries, cracks, and
falls away, leaving the yellowish-brown inner layer.
If the gall is gathered before maturity, the rind will
dry and adhere as a thin skin, so closely as to show
the striz beneath it. ;

Small birds, principally tits, break open the galls
in winter time, and devour the inhabitants.

This gall seldom occurs singly, 7.¢. only one on a
shoot or twig; it is characterised by the large numbers
clustered together—seventy or more within a linear
distance of 7 cm.

When a great many are crowded on a shoot, they
penetrate the zylem so deeply that further growth of

Fie. 10.—Galls caused by Aphilothriz Sieboldi illustrating typical shapes
and situations. Nat. size, dele. ad nat. E.C.

the shoot is prevented. It does not, however, decay,
but will remain attached for some time, and, frequently
shoots may be found bearing new galls near to those
of one and two previous years.

This gall received its specific name after M. von
Siebold, who was one of the earliest to find the galls
at Dantzig and Frieburg.

Biorhiza aptera, Fabricius.
(Plates XXXI to. XXXTIT.)

Cynips quercus terminalis, Fabr.; Teras terminalis, Marshall ;
Biorhiza terminalis, Mayr; Cameron. Biorhiza aptera, Adler ;
Mayr; Miller; Marshall. Cynips aptera, Fabr.

English name of gall.— The Root Gall.”

Position of gall.—On roots and rootlets.

Manner of growth.—Glabrous, sessile, gregarious, coalescent.

Colours.—Pink, yellowish-brown, red, reddish-brown, chocolate
brown.

BIORHIZA APTERA. 99

Average dimensions of a mature specimen.—One larval
cell: Height, 8mm.; girth, 30 mm.

May be sought during any month of the year.

Growth is complete by the end of October.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
winter and the spring.

Parasites, Nos. 15, 175.

Alternate sexual generation: Teras terminalis, Fabr.

“The time given:by different authorities for the
appearance of the flies varies, some having found them
in November and some in March; according to my
own observations the latter date must be considered
exceptional, at least in this place (Schleswig). I have
for many years found the flies regularly in the end of
December and beginning of January” (Adler, ‘ Alter-
nating Generations,’ p. 71).

This gall appears to have been well known in the
south of England prior to the year 1874, But it had
only been observed. on the roots of oak trees that had
been blown down by gales, and not as the result of
entomological research. It occurs on the subterranean
roots only; on the largest and thickest, as well as on
the most slender, but with greatest frequency on those
varying in dimensions from that of a quill to that of a
lead pencil.

Tt is seldom solitary, but when so the size ranges
from 5 mm. to about 15 mm. in diameter, and the
shape is more or less globular.

The general condition of growth is gregarious, and
in conglomerated clusters of considerable numbers;
the overcrowding in some masses being so great that
distortion and fantastic shapes are the result. Some
clusters resemble the gall of Aphilothrix radicis, but
may be easily distinguished, from that species by (a)
the outline of the cluster showing each separate larval
chamber; (b) each larval chamber, although attached
to those next it, may be separated without injury; or
(c) by making a transverse section, when it will be

100 BRITISH OAK GALLS.

seen that the larval chamber of this species is very
much larger than that of A. radicis.

The galls of B. aptera may readily be obtained by
removing earth with a small trowel, or a piece of stick,
from the side of a bank on which an oak tree is grow-
ing. A position similar to that depicted on Plate
XXXII, will yield an abundance of specimens. They
are always covered with earth—sometimes sparingly—
and usually at a depth of about three inches.

In the year 1873 some of these galls were found on
the roots of Deodars at Wimbledon, and were exhibited
at a meeting of the Royal Horticultural Society by Dr.
Masters. It was considered to be the first instance in
which a Cynips had been known to attack any species
of Conifer. They have since been found on the roots
of Prunus, Fagus sylvatica, and Vitis vinifera.

The male imagines are always alate, the females are
mostly apterous; occasionally there are rudimentary
wings. Upon leaving the gall the female creeps up
the bole of the tree, along a limb, and after choosing a
terminal bud, bores a large number of holes with her
ovipositor ; the ova being afterwards pushed down the
holes until they form a mass at the base of the bud.
The operation of oviposition is sometimes very pro-
tracted. Dr Adler observed that one female occupied
eighty-seven hours in depositing 582 ova in two buds
(‘ Alternating Generations,’ p. 72).

The presence of so large a number of ova (about 290),
and a corresponding number of holes, in so small a
bud as that of the oak, must inevitably injure the
interior, and extensive destruction of the tissues of the
plant does actually take place ; so much so that occa-
sionally the whole bud axis is cut through, and no gall
formation takes place. When, however, gall formation
begins the apex of the real bud is severed from its
twig, and, remaining loosely attached to the swelling,
is lifted up and retained for some time. See Plate
LVII, div. A.

The beautiful photo-micrographs on Plate XXXII,

BIORHIZA RENUM. 101

by W. H. Hammonp, of a transverse section through
a bud with ova in situ, and of three ova alone, deserve
careful examination.

Biorhiza renum, Hartig.
(Plate XXXIV.)

Trigonaspis renum, Mayr; Trigonaspis megaptera, Cameron :
Biorhiza renum, Giraud, Adler, Miiller, Mayr, Fitch.

English name of gall.—‘‘ The Kidney Gall.”

Position of gall.—On the under-surface of leaf.

Manner of growth. — Glabrous, glossy, gregarious, con-
glomerated. :

Colours.—Yellowish-green, green, red, purple, dark brown.

Average dimensions of a mature specimen.—Reniform
type: Height, 1] mm.; length, 2mm.; breadth, 1 mm.

May be sought during the months of September and October ;
occasionally November.

Growth is complete by the end of October.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during

May and June.
Parasites, Nos. 2, 10, 59, 74,105. Inquilines, Nos. 134, 138,

1389, 140, 148, 145.
Alternate sexual generation: Trigonaspis crustalis, Hartig.

The ovoid and spherical forms, and solitary speci-
mens of this gall are apt to be confused with those of
Neuroterus ostreus by anybody beginning to collect oak
galls. Many examples are very much alike. Several
features, however, serve to distinguish the species. B.
renum is rarely spotted, and then not to the same
extent as N. ostreus, the latter though is sometimes
without spots. B. enum never has the little valve-
like membraneous pieces of leaf tissue at its base, nor
the minute papille on its surface as does N. ostreus,
while the latter never occurs in parallel rows.

The shape and mode of growth of this gall are both
distinctive and attractive. The shape is that indicated
by its specific appellation, viz. like a kidney. Occa-
sionally specimens develop into an ovoid and a spherical

102 BRITISH OAK GALLS.

form. The galls occur in groups and in large num-
bers on the under-surface of the leaf attached to the
mid-rib and the lateral offshoots, in parallel rows,
and numbering as many as sixty on a leaf. Hach
_gall is complete and distinct from those near it, and
is held in its position by an extremely short and
delicate peduncle, so slender that the gall is easily
detached. During the month of September they appear
as if by magic. The growth is rapid and the first
stage is completed very speedily. During October the
peduncle shrivels, and the galls fall to the ground. A
few will persist until early in November if climatic
conditions are favourable. I have found specimens as
late as the 12th of the month.

Rearing the imagines is a difficult matter. The
larvee are but partly grown when the galls fall, and
they do not pupate until the early autumn of the
following year. Some emerge during the months of
December and January, most of the remainder not
until May and June following; while a few delay their
appearance for six or even twelve months longer.

The best place to search for these galls 1s amongst
the leaves of stunted oak-bushes on hedge banks that
have a northern aspect; and in well wooded districts
they may be found in great profusion.

Cynips Kollari, Hartig.
(Plates XXXV to XXXIX.)

Cynips Kollavi, Mayr, Schenck., Newman, Fitch, Straton,
Walker ; C. lignicola, Marshall, Stainton, Parfitt; C. quercus petioli,
Quercus terminalis, Westwood ; C. tinctoria, Vollenhoven.

English names of gall.—‘‘ The Devonshire Gall,” “ The Oak
Marble,” “ The Oak Nut,” “The Marble Gall.”

Position of gall.—On twigs and on branches.

Manner of growth.—Single, solitary, gregarious, coalescent,
glabrous, spherical.

Colours.—Pale green, golden yellow, emerald green, dark green,
brownish-yellow, reddish-brown.

Average dimensions of a mature specimen.—65 mm.

CYNIPS KOLLARI. 103

May be sought during any month of the year.

Growth is complete by the end of August.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
September and October.

Parasites, Nos. 44, 51, 52, 54, 57, 61, 68, 108, 116, 179.
Inquilines, Nos. 17, 130, 182, 134, 137.

Alternate sexual generation: (According to Beyerinck),
Andricus circulans, Mayr.

“These galls are not acorns, as the oak would have
willed that they should be, but are the nearest approach
to acorns that the oak can produce under its affliction.
; The gall consists of two parts,—the larger is
spherical . . . and represents the carpel of the
acorn, or the acorn proper, and the saucer-shaped
cushion, on which it rests, represents the cupule
or cup, or calyx; the small pointed process
exactly opposite the point of attachment being the
persistent stigma of the acorn.” EH. Newman, ‘The
Entomologist,’ No. 135, p. 28+.

A very great amount of interest surrounds this gall.

The casual observer is attracted by its globular
form; warm brown colour; solid and hard texture.
Noticed by such, usually when hedgerows are leafless,
or perhaps in a collection of galls, or in a museum
case, little thought is given to its rightful place in gall
nomenclature; consequently it is more frequently
spoken of as the oak-apple, than by its correct name
of oak-marble.

The gallist, however, regards the brownish sphere
as replete with most interesting features.

At one time it was the subject of a great amount of
entomological literature, and correspondence; and
probably its remarkable qualities will continue to
furnish themes for many writers.

Cynips Kollavi made its appearance in England
about seventy-four years ago. In the year 1834 it was
observed in Devonshire by Mr. Jordan, but he did
not make the discovery known to entomologists, until

104 BRITISH OAK GALLS.

about twenty years later. In 1848 Mr. Parfitt
noticed many of the galls in the same county, as also
did Mr. Stainton a few years later. Its authentic
history, however, as British, commenced on November
6th, 1854, when Mr. Rich was present as a visitor at
the meeting of the Entomological Society of London,
and exhibited some sprays of oak thickly covered with
large galls. Mr. Rich reported at the meeting, that
the gall was very abundant in Somersetshire, and
Gloucestershire. (‘Proc. Ento. Soc.,’ 2nd series, vol.
ili, p. 38.)

At first the gall was observed only in the vicinity of
Exeter, where, in two large nursery gardens, young
oak trees were greatly distorted. For many years it
was known as the Devonshire gall. From those
south-western counties it gradually spread along the
north-western part of England and over Wales. In
the year 1858 Mr. F. Smith, of the British Museum,
obtained from Devonshire a very large number of the
galls, and distributed them in different localities around
London, for the purpose of observations. By so doing
the spreading of the species throughout the remainder
of England was accelerated. Now-the gall may be
found in almost every hedgerow, where there is oak,
throughout the whole of Britain, in some districts in
great abundance.

Soon after the galls had become ubiquitous im the
three counties previously mentioned, many persons
were apprehensive that the growth of oak trees, and
the timber, would be imperilled by the destruction of
the acorns, and the distortion of the twigs, if the
spreading of the gall remained unchecked. Several
writers advocated that the galls should be utilised in
the manufacture of ink, and, since they seldom formed
on any part of the tree at a greater height than a few
feet, children should be employed to gather them, and
by that means extermination would be soon accom-
plished. Analysis, however, showed that not more
than 17 percent. of tannin could be obtained from the

CYNIPS KOLLARI. 105

gall, whereas the true ink-gall yielded 40 per cent.
more.

At the time of its appearance in this country the
manufacture of cloth was a prominent industry in
Exeter, Tiverton, and several neighbouring towns;
and large quantities of Cynips tiuctoria were imported
for dyeing purposes. Whether C. Kollari was intro-
duced for experimental purposes with the hope of
superseding the Aleppo species, there is no confirma-
tory evidence. It will perhaps never be ascertained
how this species of Cynips origimated in this country.
_C. Kollart was known prior to that period for very
many years throughout the whole of middle HEuropean
countries.

As the gall spread over the country, and became
known among entomologists, it was occasionally
mistaken for three Continental forms of similar
appearance and habit. One is CO. lignicola, which is
rather larger than a pea, occurs singly, also in twos
and threes; it has a large oval larval cell, and is
generally of a spherical form, but it is distinguished
by having an outer covering similar in appearance to
leaf scales. Another form is (. conglomerata, which
sometimes occurs singly but mostly in dense semi-
racemous clusters of fifteen to twenty-five individuals,
also rather larger than a pea. Externally it resembles
a normal gall of C. Kollari in having a small style, and
in being hard and brown when mature; also internally,
in being composed of a spongy parenchyma. C. Kollart
has also been confused with C. tinctoria, the ink-gall
from the Levant, on account of its external features.
Although the normal form of C. Kollari is smooth and
spherical, an examination of Plate XXXV will reveal
a remarkable similarity as regards size, shape, papille,
and ridges. The larval cell in both is central and
ellipsoidal inform. The imagines also, of each species,
are much alike.

The oak-marble is found in great profusion in
hedges, along lanes, and scrub oaks in coppices. Low

106 BRITISH OAK GALLS.

bushes and young trees in woods are sometimes badly
attacked. Fully developed trees do not often bear
alls.

i Towards the end of September, or early in October,
the parent Cynips emerges from a gall of the year,
and at once seeks leaf buds in which to oviposit. She
appears to prefer buds on slender and delicate twigs,
but occasionally pierces those on the sides of larger
branches. As soon as the egg is deposited, growth
and development begin. A blastem forms around the
ege and the larva hatches. A small and inconspicuous
“swelling is then formed on the twig. Very slight
increase takes place until the following April or May.
The embryo gall then becomes more readily noticeable,
and by the end of June it will have attained the size
of an ordinary pea, bright green in colour if exposed
to the light, but golden yellow if im deep shade.
Many specimens are also tspotted, or streaked with
crimson. Until the gall attaims several millimetres in
diameter, the tissues are enclosed within an epidermis
which contains a reddish sap. Few or many one-cell
hairs are scattered over its surface.

During July larva and gall rapidly enlarge; the
epidermis, not keeping pace with the increase, splits
into numerous small scales which quickly fall off
leaving the surface a beautiful apple-green colour.
Early in August considerable internal changes take
place, the principal being that the primary nutritive
tissue disappears, and oil globules and several pro-
teids form the food of the occupant of the cell, the
walls of which harden considerably. Little change
is then noticeable except in coloration, until the
latter part of September. The structure has then
become firm and hard. It has attained maturity,
and assumed a_ brownish-yellow' or reddish-brown
hue. It is firmly attached to the seat of growth,
and will maintain its position for two, three, or
more, years, neither wind, rain, hail, nor frost, dis-
lodging it.

CYNIPS KOLLARI. 107

The gall may be sessile and axillary upon the side
of a stout branch or shoot, or it may be terminal
upon a thin stem a few millimetres only in length,
or securely affixed to a long slender twig. An
example of the latter character, found by the author
at Hastings in 1895, is of a globular specimen, 66 mm.
in girth, situated terminally on a twig 88 cm. long,
and not more than 3 mm. in diameter throughout
its entire length.

Normally the gall is globular. It is smooth all
over, except at the pole opposite to that of attachment
to the twig where it bears a small, sharp-pointed
style (which is occasionally bifid), chocolate brown in
colour. It consists of dead tissue, and is sometimes
described as the pseudo-stigma, and the pseudo-carpel.
It can be recognised during early development.
When normal development of the gall is arrested early
by parasites, or inquilines, the style is accentuated
(Plate XXXVI, figs. 7, 8).

Many oak-marbles gathered in winter and spring,
have numerous small dark brown. excrescences upon
them which have pushed their way through the
exterior of the gall. Hitherto these appear to have
been known as brown bodies. In January, 1908, the
author, believing them to be due to fungoid agency,
sent speciméns to the Royal Herbarium at Kew. They
were there identified as being attacked by the fungus
Phoma gallorum, Briard, a species for the first time
recorded as occurring in Britain. See Plate XXXIX,
div. A.

The surface of the gall frequently has one or
many small conical protuberances upon it (Plate
XXXV), which vary much in size and height.
There may be only one (figs. 17, 18), or as many as
twelve or fifteen (fig. 7), all separate (figs. 10, 11),
or coalescent in the form of a ridge (fig. 8), or
ridges (fig. 5). For these conical elevations I
propose the name of papille. They are quite distinct
in shape from the style. They arise gradually from

=

108 BRITISH OAK GALLS.

their surroundings and are of the same texture: and
colour.

In the year 1897 M. W. Beyerinek (“Ueber di
Sexuelle Generation von Cynips Kollari,” ‘ Marcellia,’
vol. i, p. 13) imprisoned a few imagines of C. Kollari
on a young tree of @. cerris, and observed that
they pierced the buds. Upon opening the buds,
he found that a number of ova had been deposited.
In October, 1901, the experiment was repeated,
and in the following February there were signs
of gall growth. By April galls of Andricus circulans
had fully matured, and early in the following month
imagines came out, which proved to be those of A.
circulans. Further experiments were made with a
like result—an enormous number of circulans galls on
every twig of the experimental tree.

He also found that out in the open, the galls of
C. Kollart showed first indications of growth at the
beginning of June, or about fourteen days later than
the emergence of A. circulans. This he regarded
as a further confirmation of the alliance, and alter-
nating, of the two species. He was not able to get
A. circulans to oviposit in Q. pedunciulata. He also
believes that A. burgundus is the sexual form of
C. tinetoria.

Dryophanta agama, Mayr.
- (Plate XL.)

Cynips agama, Hartig; Dryophanta agama, Hartig, Miiller,
Cameron, Fitch.

English name of gall.—“< The Yellow Pea Gall.”’

Position of gall.—On the under-surface of the mid-rib and its
offshoots.

Manner of growth.—Single, glabrous, glossy, nodulose (incon-

94

i , oblate. \
spicuous), oblate Q het bon

Colours.—Pale yellow, orange yellow, yellowish-brown.

Average dimensions of a mature specimen.—Height, 4mm.;
length, 5mm.; breadth, 4mm.

May be sought during the months of June to August.

Growth is complete by the end of August.

: DRYOPHANTA AGAMA, 109

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
the autumn.

Parasites, Nos. 39, 47, 88, 89, 119, 122, 159, 177, 180.
Inquilines, Nos. 127, 128, 134.

The specimens shown in the plate can hardly be
considered as typical of this species. They were not
found until past maturity, and the leaves were begin-
ning to wither; consequently the galls are slightly
above the average normal size, and fewer in number
than is usual.

In the Hastings district they are rare, and no other
specimens have been found that would serve the
purpose of an illustration.

This species is not mentioned in ‘ Alternating

Fie. 11.—Sections of galls caused by (a) Dryophanta agama, (B) D. disticha,
(c) D. divisa. All x 2. Dele. ad nat. E.C.

Generations, and very little is recorded about it in
any treatise on galls.

The galls are found mostly on oak bushes in woods,
and stunted growths along hedge banks. One year
they may be numerous, the next, scarce, and no reason
can be assigned.

Their normal position is on the offshoots of the mid-
rib; they are, however, occasionally attached to that
also. They vary in number on a leaf to as many as
ten, seldom more than twelve.

In shape they are oval, or ovoid, occasionally
globular, much flattened next the leaf. They are
attached by a very short, but stout, peduncle. The
position of attachment does not show on the upper
surface of the leaf.

110 BRITISH OAK GALLS.

The texture of the gall is hard, but the walls are
thin ; and the larval chamber very large. The exterior
is rarely suffused with pink or red. This forms one
external distinguishing feature from D. divisa, which is
pink during the greater part of its growth. Both
species are about the same size, but divisa is generally
shghtly larger. Both, also, frequently have flat,
reddish-brown, very small nodules scattered over the
exterior.

This gall was first observed in England about forty
years ago, the imagines having been reared by Albert
Miller and recorded in ‘ Proc. Ento. Soc. Lond.,’ 1870,
XXXIV.

Although an alternate generation does not appear to
be known, the fact that the imago does not normally
pass the winter in the gall, would indicate that a sexual,
or spring form, may exist.

Dryophanta disticha, Hartig.
(Plate XLI.)

Cynips disticha, Hartig, Schnk.: Aphilothrix disticha, Mayr ;
Andricus disticha, Mayr; Dryophanta disticha, Mayr, Cameron.

English name of gall.— ‘The Two-Cell Gall.”

Position of gall.—On the under-surface of the mid-rib and its
offshoots.

Manner of growth.—Single, glabrous, slightly glossy, unique
in form.

Colours.—Yellowish-white, pale yellow, light brown, reddish-
brown.

Average dimensions of a mature specimen. — Height,
4mm.; length, 6mm.; breadth, 4mm.

May be sought during the months of July to September.

Growth is complete by the end of August.

The typical condition of the gall is bilocular but unilarval.

The larva pupates in the gall. The imago emerges during
the autumn.

Parasites, Nos. 19, 44, 46, 47, 59, 64, 105, 112, 114, 117, 120,
150, 151, 154, 180, 183. Inquilines, Nos. 127, 134.

In some districts this gall is exceedingly rare.
Nowhere does it appear to be plentiful. Only very

DRYOPHANTA DISTICHA. 111

seldom will as many as fifteen or twenty galls be found
on one bush ; but when this does occur the contiguous
bushes may be searched in vain for more specimens.

This gall is very distinctive in appearance and
construction. It is firmly attached by a very small
pointed portion of its base. The point of attachment
does not show on the upper surface of the leaf. It
may be found more frequently on oak trees and bushes
in woods than on those along hedgerows ; occurring
rather sparingly, not many leaves on the same branch
being galled, and, seldom more than six or eight
specimens on one leaf.

The interior is bilocular ; a condition caused by the
convergence of the inner walls to form a thin hori-

Fie. 12.—Three aspects of the same gall caused by Dryophanta disticha.
a. Side. B. Top. c. End. All nat. size. Dele. ad nat. E.C.

zontal division devoid of any opening. The upper
cavity is tenantless. The lower cavity is the larval
chamber. The imago eats its way out through the
base of the structure.

Exteriorly the gall is glabrous, slightly glossy, and
unique in outline. The upper portion is distinctly
umbilicated, from the centre of which there arises, in
some specimens, a minute papilla. When viewed
under a lens, most of the galls are seen to be studded
with few, or many, raised brown spots. The shape of
the gall’ is sometimes circular, but normally it is
longer than broad, the height being about the same as
— the breadth.

This species is not mentioned in ‘ Alternating
Generations’; and it appears to have escaped the
notice of most British gall collectors.

112 BRITISH OAK GALLS.

The remark anent a sexual form of D. agama (p.
110), applies to this species also.

Occasionally examples will be found developing on
the upper surface of a leaf.

Dryophanta divisa, Adler.
(Plate XLII.)

Dryophanta divisa, Mayr, Fitch, Miller; Cynips divisa, Hartig ;
Spathegaster verrucosus, Schltdl., Adler, Licht., Mayr.

English name of gall.—‘‘ The Red Pea Gall.”

Position of gall.—On the under-surface of the mid-rib ‘and its
offshoots.

Manner of growth.—Single, glabrous, glossy, globulose,
oblate.

Colours.—Pale yellow, orange yellow, pink, red, light brown.

Average dimensions of a mature specimen. — Height,
5mm.; length, 6mm.; breadth, 5 mm.

May be sought during the months of June to October.

Growth is complete by the end of September.

The typical condition of the gall is unilocular and unilarval:

The larva pupates in the gall. The imago emerges during
October and November.

Parasites, Nos. 19, 39, 44, 47, 49, 88, 95, 105, 119, 125, 151, 177,
180. Inquilines, Nos. 127, 134, 142.

Alternate sexual generation: Spathegaster verrucosus,
Schltdl.

With the aid of a lens it can be seen that the
surface of these galls is frequently dotted with minute
papille, and occasionally there will be a well-defined
flat papilla a little darker than the | surrounding
colour, opposite the basal attachment.

The pink or red colour may be entirely absent, but
even when present its vividness fades with age, and it
is sometimes completely changed to a pale brown.

This gall is similar in appearance to that of D.
agama, but several features distinguish it from that
species ; e.g. (a) very glossy surface, (b) pink colour,
(ce) normally more numerous upon a leaf, and (d) more
widely distributed ; but the infallible characters are
(1) the thick walls, (2) small larval chamber, and (3)

DRYOPHANTA LONGIVENTRIS. 113

inability to flatten the gall with pressure between the
thumb and finger.

Many specimens are spherical. The normal con-
dition is slightly longer than broad, and distinctly
flattened at the top and bottom. It is attached by
a short, but stout, peduncle.

The usual number on a leaf is about 10 to 15, but
25 to 35 is not unusual. On one occasion I found
three leaves, all on one stem, bearing 32, 32, and 35
galls. In some seasons they are in such profusion
that their weight causes the leaves to hang down
considerably. They are often found in company with
either, or all, of the Newroterus species on the same
leaf.

The name “red pea gall” is indicative of the
beautiful colour with which nearly all specimens are
suffused during development; when mature the red
fades, leaving a pale, but pleasing shade of brown. In
common with all the globular oak-leaf galls, they
normally remain attached to the leaf all through the
winter, although that may have fallen after several
frosts.

Dryophanta longiventris, Hartig.
(Plate XLIIL.)

Cynips longiventris, Hartig; Dryophanta longiventris, Adler,
Cameron, Mayr, Fitch, Miller.

English name of gall.—‘ The Striped Gall.”

Position of gall.—On the under-surface of the mid-rib and its
offshoots. ;

Manner of growth. —- Single, glabrous, glossy, globulose,
papillated.

Colours.—Pale yellow, with pink or red bands, stripes, or spots.

Average dimensions of a mature specimen. — Height,
7mm.; length, 9mm.; breadth, 8mm.

May be sought during the months of July to October.

Growth is complete by the end of September.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
October. 3

114 BRITISH OAK GALLS.

Parasites, Nos. 12, 25, 28, 44, 119, 125, 151, 180. Inquilines,
Nos. 128, 134. ,

Alternate sexual generation: Spathegaster similis, Adler.

A very attractive and pretty gall, retaining its
singular outline and much of its delicate coloration,
as a dry specimen in the cabinet.

When inhabited by inquilines the structure seldom
attains the normal dimensions. If gathered before
maturity it shrivels, and the papille, whether solitary
or in ridges, stand out prominently.

No doubt need be entertained as to the identity of
this gall. It is unlike any other form, from its earliest
growth, to maturity. The most noticeable feature

Fie. 13.—Sectional aspects of gall caused by Dryophanta longiventris.
A. Cross section. 3B. Longitudinal section. c. Transverse section.
All x 2. Dele. ad nat. E.C.

is the number of pale-coloured papille scattered all
over its surface, which frequently coalesce and form
ridges extending from side to side, and also in concen-
tric and circular outlines. The depressed portions of
the gall are pink and red; colours which are
accentuated by the pale yellow of the papille, and
which do not entirely disappear even when the gall is -
past maturity.

The shape is globulose, but flattened at the base ;
the basal portion being transversely indented by the
rib of the leaf. It is firmly attached to the rib by
a small projection of its own growth. Development is
arrested when tenanted by parasites or inquilines and
the size remains small, but under normal conditions
it may be 8 mm. high, and 10 mm. in diameter.

If a number of the galls be gathered late in Sep-

DRYOPHANTA SCUTELLARIS. 115

tember, the imagines will continue to emerge during
the following month, and until the middle of
December.

Albert Miller appears to have been the first to
record this species occurring in Britain, having found
it about forty years ago in the neighbourhood of
Norwood.

It is moderately abundant in the Hastings district.
I have found it almost exclusively on oak bushes of
Q. pedunculata in woods where there are also large
oak trees; the earliest date being June 30th.

5 hae rarely more than eight galls develop on one
eaf.

Dryophanta scutellaris, Hartig.

(Plates I, XLIV, XLV.)

Cynips quercus folii, Linn. ; C. folii, Hartig, Schenck, Schltdl. ;
C. seutellaris, Schenck ; Dryophanta folii, Mayr, Miller, Marshall,
Cameron ; D. scutellaris, Mayr, Oliver, Fitch, Adler.

English name of gall.—“ The Cherry Gall.”

Position of gall.—On the under-surface of the mid-rib and its
offshoots. ;

Manner of growth. —Single, glabrous, glossy, globulose,
succulent.

Colours.—Pale yellow, yellowish-green, pale green, pink, rose-
madder.

Average dimensions of a mature specimen.—Globulose
form—diameter, 17 mm.

May be sought during the months of July to October, and on
fallen leaves until April or May of the following year.

Growth is complete by the end of August.

The typical condition of the gall is wnilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
autumn and winter. ‘“ According to some observers the flies appear
in October, and according to others not until March . . if kept
in aroom they appear in November, but not . . . if in the open
‘air. The fly begins in October to gnaw a passage from the central
chamber . . . towards the periphery, but does not quit the gall

. thisdependsentirely uponthe weather. . . . IThavere-

peatedly noticed that the warm days of January and February
entice the flies out . . but should frost continue many flies
do not appear until March” (Adler, ‘ Alternating Generations,’

p. 61).

116 BRITISH OAK GALLS.

Parasites, Nos. 6, 7, 9, 19, 48, 44, 46, 56, 67, 77, 88, 96, 125,
151, 166, 180. Inquilines, Nos. 60, 110, 184, 142, 145.

Alternate sexual generation: Spathegaster Taschenbergi.

This is the largest, most conspicuous, and brightest
coloured, of the leaf galls. Very few galls can vie
with it for beauty.

It grows on the under-surface of the leaf, firmly
attached to the rib by an exceedingly small projection
of its own growth. The basal portion is not flattened
as is the case with most of the leaf galls, but there is
often a long narrow indentation caused by the rib of
the leaf. Specimens are occasionally to be seen on the
upper surface of the leaf; they are usually rather
smaller than the normal size. Some turn dark red
and reddish-brown when only half developed, and are
more succulent than others not so coloured.

The composition of the gall, is a tough outer rind
enclosing a soft, loose, and spongy parenchyma, in the
centre of which is the larval cavity without any inner
gall. When old, and the moisture has dried, the
surface becomes greatly wrinkled.

It is somewhat variable in size, but not excessively
so. The largest I have found measured 23 mm. in
diameter. Upon examination it proved to be perfectly
free from parasites and inquilines.

The numbers on one leaf also fluctuate somewhat.
Three, four, and five are frequently seen; six, seven,
and eight occasionally. The largest number I have
found on one leaf is twelve. Highteen on two leaves
—although not English specimens—as shown on Plate
XLV, are worthy of recording, as also is the Frontis-

lece.
Some galls fall from the leaves at the approach of
autumn, others continue to adhere, although the leaf
itself has fallen.

The imagines are easy to rear; some emerging
during October and November, others in the following

spring.

NEUROTERUS FUMIPENNIS. 117

Neuroterus fumipennis, Hartig.

(Plates XLVI and LX, div. A.)

Neuroterus fumipennis, Tasch., Mayr, Thoms., Adler, Licht.,
Fitch, Miller, Cameron, Marshall; Spathegaster tricolor, Schenck,
Hartig, Mayr, Adler, Licht.; S. varius, Schenck.

English name of gall.—‘ The Cupped Spangle Gall.”

Position of gall.—On the under-surface of the leaf.

oe of growth.—Gregarious, numerous, cupulate, stellately
pilose.

Colours.—Green, greenish-yellow, covered by pink, rose-madder,
and red hairlets.

Average dimensions of a mature specimen. — Height,
1:5 mm.; diameter, 3mm. ;

May be sought during the months of July to September.

Growth is complete by the end of August.

The typical condition of the gall is unilocular and unilarval.
Pr larva pupates in the gall. The imago emerges during

ay. : :

Parasite, No. 182. Inquiline, No. 142.

Alternate sexual generation: Spathegaster tricolor, Hartig.

When this gall occurs in great profusion on a leat
the appearance is very beautiful. The prevailing
colour is rose-madder, varying from a pale shade to a
very deep tint. It is wholly due to numerous micro-
scopic stellate hairlets, which, under magnification give
off an aureate sheen. As the leaf and the galls dry
the colour diminishes in brilliancy.

Concerning the profusion of this gall: One leaf
measuring (without petiole) 153 mm. long and 68 mm.
from tip to tip of widest lobes, supported 489 galls,
and so crowded were they that 18 galls were within
one square cm. A part of the leaf is shown on Plate
LX, div. A. -

It is sometimes difficult to distinguish most immature
and some mature specimens of this gall from those of
N. lenticularis. They resemble each other very closely
by reason of a profusion of very small reddish glossy
hairlets scattered upon the upper and under-surfaces.

118 BRITISH OAK GALLS.

In its normal and typical condition there are several
distinctive features. (a) Itsaverage diameter (3 mm.)
is less, (b) the upward curve of its rim is more pro-
nounced, (c) the central papilla is not so distinct, (d)
the under-surface is rarely whitish or yellowish, (e) nor
is it usually so abundant as N. lenticularis.

The mode of attachment to the leaf is by means of
an extremely short and thin peduncle which retains
the gall with considerable tenacity until the autumn,
when it decays and the gall falls from the leaf. The
moisture of the earth allows development to continue
gradually until the gall is about double its former
thickness.

Cameron remarks: “The larva does not develop
until April, being later in its development than lenti-
cularis and numismatis, the imago not appearing until
May ” (‘ Brit. Phyto. Hymen.,’ vol. iv, p. 134). Adler
also says: “ Although these galls fall to the ground in
October it is only during the month of March [of the
following year| that larval development begins;
towards the end of April it becomes a pupa, and the
perfect insect appears in May” (‘ Alternating Genera-
tions,’ p. 28).

Some years this gall, in common with the other
Neuroterus species, occurs in extraordinary abundance,
not only as regards the number of oak leaves bearing
galls, but the profusion of the galls on the leaves.
The autumn of 1907 was such an occasion.

Neuroterus leviusculus, Schenck.

(Plate XLVIT.)

Neuroterus pezizeformis, Schltdl.; N. leviusculus, Mayr, Adler,
Fitch, Schenck, Licht., Cameron; Spathegaster albipes, Schenck,
Licht., Mayr, Adler.

English name of gall.—‘‘ The Smooth Spangle Gall.”

Position of gall.—-On the under-surface of the leaf.

Manner of growth.—Glabrous, glossy, separate, scattered,
cupulate.

NEUROTERUS LZVIUSCULUS. 119

Colours.—Pale yellow, yellowish-green, green, pink, red.

Average dimensions of a mature specimen. — Height,
1 mm.; length, 4 mm.; breadth, 3 mm.

May be sought during the months of July to September.

Growth is complete by the end of August.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during the
spring.

Parasites, Nos. 165,182. Inquiline, No. 142.

Alternate sexual generation: Spathegaster albipes, Schenck.

This gall appears to have been first noticed in
Britain by Miss EH. A. Ormerod, LL.D., who found
specimens on oak trees in Kew Gardens in 1870.

Fie. 14.—Galls caused by Neuroterus leviusculus. a. On upper sur-
face of leaf. 3B. 1-6, variations in outlines. co. 1-3, bowl shape, on
under-surface of leaf. bp. 1-4, diagrammatic sections. All x 2,
dele. ad nat. E.C.

In both shape and colour this gall is subject to
greater variations than those of its congeners.

The gall may resemble a beautiful miniature cream-
coloured waxen cup, with a tiny cone, standing up like
a spike, from the base of the concavity. It may bea
delicate shade of yellowish-green, and shaped like an
elegantly formed saucer, the centre having a minute
papilla. Yet another form, is that of a tiny plate,
rose-red or purple in colour, with hardly a trace of a
central elevation. Many cupulate examples are pale
in colour, except the rim which may show quite a con-
trast in a bright red, or a reddish-brown.

The outline of the gall is mostly rather longer than
broad, or even half as long again as broad. Many
specimens are circular.

The margin may be entire, or incised to nearly half

120 BRITISH OAK GALLS.

its breadth, and there may be two or three incisions
in the same gall.

The centre of the gall is usually occupied by a small
sharp-pointed cone, paler in colour than the surround-
ing tissues with sometimes a few whitish vitreous hair-
lets at its base. ;

This gall never occurs in such profusion on a leaf as
the other Newroterus species, but it more frequently
develops on the upper surface of the leaf. In common
with them, however, it is attached by ‘a delicate
peduncle, and it is also deciduous. It is always
glabrous, and sometimes highly glossy.

Neuroterus lenticularis, Olivier.

(Plate XLVIII.)

Cynips lenticularis, Olivier; C. quercus-baccarum, Linn. ; Neuro-
terus Malpighti, Hartig, Tasch., Thoms., Miller, Marshall; N.
lenticularis, Adler, Mayr, Schenck, Fitch ; N.laeviusculus, Schenck ;
N. pexizeformis, Schltdl.; N. fumipennis, Hartig; Spathegaster
interruptor, Hartig; 8. varius, Schenck.

English name of gall.— The Common Spangle Gall.”

Position of gall.—On the under-surface of the leaf.

Manner of growth. —Gregarious, pilose, separate, conglomerate,
numerous.

Colours.—Green, greenish-yellow, covered by orange-red, rose-
red, crimson, and reddish-brown hairlets.

Average dimensions of a mature specimen. — Height,
15 mm.; diameter, 5 mm.

May be sought during the months of July to October.

Growth is complete by the end of August. ;

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
March and April.

Parasites, Nos. 19, 29, 47, 56, 76, 83, 108, 116, 123, 154, 163,
165, 182. Inquiline, No. 142.

Alternate sexual generation: Spathegaster baccarum, Linn.
It he tae ceeds ea

This is the largest, and the most abundant of the
cupulate, lenticular galls. It occurs throughout Britain.
The first sign of gall growth, on the under-surtace

NEUROTERUS LENTICULARIS. 121

of the young and tender leaf, is a number of minute
pimples, which rapidly enlarge to small yellowish-green
discs closely adhering to the leaf, but attached only
by the delicate and small pedicle peculiar to the
lenticular galls. It soon attains its maximum propor-
tions. The gall structure retains its yellowish-green

ae _—s WE

A. B. Cc.

Fie. 15.—Diagrammatic sectional outlines of galls caused by: a.
Neuroterus lenticularis. 3B. N. fumipennis. c. N. leviuseutus.
All x 4, dele. ad nat. E.C.

colour, but it is concealed by a dense covering of
radiating stellate hairlets of an orange-red or reddish-
brown colour.

The periphery is circular, the rim slightly curved
upwards; in the centre is a small obtusely conical
elevation. The under-surface is almost flat, with a

SHIGA FERS EGERTON
PERCE CORG SU, § CE gro

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Fie. 16.—Section of leaf, and a mature gall caused by Neuroterus
lenticularis showing tissues and stomata in leaf; larval chamber
(in centre), and stellate hairlets on lower margin of the gall.
x 18. In part, after Beyerinck. dele. E.C.

few whitish spots near the margin, and but few hair-
lets. —

These galls are scattered all over the under-surface
of the leaf, but very rarely attached to the mid-rib, or
its offshoots. The upper surface exhibits minute pale
yellowish spots corresponding to the point of attach-
ment.

122 BRITISH OAK GALLS.

The usual number of galls on a leaf is 80-100. These

figures are, however, greatly exceeded in seasons when
such galls are prolific.

_ They fall to the ground late in September, and dur-
ing October, development continuing very gradually

through the winter, and until the imagines emerge in
March and April.

They are extensively eaten by game birds.

Neuroterus numismatis, Olivier.

ee _ eee

(Plate XLIX.)

Cynips numismatis, Olivier; C. quercus-tiare, Curtis ; Newroterus
Reaumuri, Hartig, Schenck, Marshall ; N. nuwmismatis, Mayr, Adler,
Licht., Miller, Cameron; Spathegaster vesicatriz, Schltdl., Mayr,
Adler, Licht.

English name of gall.—‘ The Silk-Button Spangle Gall.”

Position of gall.—On the under-surface of the leaf.

Manner of growth.—Glossy, smooth, hemispherical, gregarious,
umbilicate.

Colours.—Golden yellow, bright ochre, golden brown.

Average dimensions of a mature specimen. — Height,
15mm.; girth, 9 mm.

May be sought during the months of August to October.

Growth is complete by the end of September.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
March and April.

Parasites, Nos. 18, 89, 40, 41, 72, 76, 168. Inquiline,
No. 142.

Alternate sexual generation: Spathegaster vesicatrix, Schltdl.

Mayr considers this to be “the most beautiful of
all the lenticular galls.”

The entire gall is covered, and also coloured by
closely set, smooth, glossy, golden-brown adpressed
hairs, and these impart to it a very real appearance of
a diminutive silk-covered button.

The galls are deciduous, falling to the ground in
October and November, maturing during the next

NEUROTERUS OSTREUS. 123

three months. The imagines appear earlier than those
of any leaf gall.

This small, but strikingly beautiful, and unique
shaped gall, excites admiration on account of its
attractive appearance, and also because of the enor-
mous numbers so frequently to be seen on a leaf.
Probably there is no other gall so numerous within any
given area as this species.

In the summer and autumn of 1904 oak galls were
unusually abundant, and those of M. numismutis
appeared to exceed all other kinds. Mr. E. W. Swan-
ton, of the Educational Museum at Haslemere, kindly
communicated to me that he “ picked three leaves (of
Q. pedunculata), at random from an oak branch, the
leaves of which were plentifully sprinkled with the
silk-button gall, and carefully counted the galls upon
them. On the first were 502, the second 558, the
third 681; a total of 1741 galls—an average of 580 for
each leaf.’ I noticed the same phenomenon in several
parts of Sussex during the same autumn, and have in
my own collection leaves bearing similar numbers.

The gall is small and requires the aid of a lens to
discern the peculiarities of its structure. It appears
as a small flat disc attached by an extremely short
pedicle, grows rapidly, and varies much in size.
Ultimately it becomes circular in outline, flat next to
the leaf, and hemispherical in shape. A circular
depression at the top occupies rather more than one-
third of its total diameter.

All the lentiform galls appear to have been observed
in England by Dr. Sir Thomas Browne, and mentioned
by him in correspondence with Dr. Merrett in 1668.

Neuroterus ostreus, Hartig.

(Plate L.)

Neuroterus ostreus, Giraud, Mayr, Miller, Fitch, Adler; Andricus
ostreus, Mayr, Cameron.

124 BRITISH OAK GALLS.

English name of gall.—‘‘ The Oyster Gall.”

Position of gall.—On the under-surface of the mid-rib and its
offshoots.

Manner of growth.—Glabrous, glossy, ovoid, spherical.

Colours.—Pale yellow, yellowish-green, pink, pale brown.

Average dimensions of a mature specimen. —. Ovoid:
Height, 2mm.; length, 3mm.; breadth, 2mm.

May be sought during the months of August to October.

Growth is complete by the end of September.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
March. When kept under favourable conditions, imagines will
appear from galls, which have matured early, during November ;
but from others late in maturing the imagines do not emerge
until March.

Parasites, Nos. 5, 44, 79. Inquilines, Nos. 141, 142.

Alternate sexual generation: Spathegaster Aprilinus, Gir.

Leaves bearing from 12 to 30 galls are frequently
seen. I found during September, 1901, near Hastings,
a twig of @. pedunculata having eight leaves, all of
which were galled, the total number of galls upon
them being 207. The largest leaf measured 115 mm.
long, and had 42 galls upon it.

The only galls with which this species can be con-
fused are those of Dryophanta divisa, and Biorhiza
renum. It is however more frequently met with than
the former, and less frequently than the latter. When
mature it is smaller than D. divisa, and seldom
spherical. Other distinguishing features are given in
‘the description of B. renum.

Growth is rapid, and complete in about four weeks.

When the gall emerges from the mid-rib or its off-
shoots it is enveloped by a thin membrane of leaf-
tissue, which splits longitudinally and forms two flaps,
or valve-like parts, at the base of the gall; these in
time wither and fall away. It is in consequence of
these flaps bearing a fanciful resemblance to the valves
of an oyster shell, that the gall received its trivial
name.

During the earliest stage of development the gall is
uniformly coloured, but later, numbers of little spots

NEUROTERUS PUNCTATUS. 125

appear, at first pink, then red, crimson, and ultimately
dark brown. The spots have then become slightly
elevated, and soon afterwards the colour fades into
harmony with the remainder of the gall as it finally
assumes a yellowish-brown hue.

The gall structure is moderately hard, and contains
a relatively large larval cavity without an inner gall.
It is subject to considerable variation in shape and
size; features which are mainly due to the presence of
parasites. Depth of colour appears to depend upon
exposure to the sun.

A gall occasionally develops on the upper surface of
a leaf. See Plate L, s.

Neuroterus punctatus, Cameron.

The gall produced by this species is most obscurely
situated. I have no record of its occurrence, and I
regret inability to describe or illustrate it.

For the guidance of the gallist who might capture
the imago, or wish to search for the gall; and also for
the student who does not possess, nor have access to,
a copy of the work, the following is given in extenso
from ‘ Brit. Phyto. Hymen.,’ vol. iv, p. 183:

“ Spathegaster punctatus, Bignell, u.M.M., ii (2)
176. Black; legs flavous, upperside of hind coxe,
antenne except the first two or three joints, which
are lighter fuscous. Eyes not so large nor so promi-
nent as those of baccarwm. Thorax: the mesonotum

‘trilobate, with deep furrows continued to the scutellum,
where the punctures are very shallow, the sides closely
punctured. Wings hyaline.

“ Length 2°5 mm.

“ At first it has all the appearance of Spathegaster
baccarum, but when closely examined the sculpture of
the thorax separates it from that species, and the wings
are free from fuscous clouds.

“Tn baccarwm the mesosternum is separated from the
mesonotum by a raised rounded ridge, much more

126 BRITISH OAK GALLS.

prominent than that of the species now described, and
the furrows on the mesonotum are much shallower
and shorter (Bignell, l.c.).

“Bred by Mr. Bignell from oakbuds which apparently
were not expanded or distorted.

“ The inquiline is Saphylotus connatus. Plymouth.”

Spathegaster albipes, Schenck.
(Plate LI.)

Spathegaster albipes, Mayr, Fitch, Licht., Schltdl, Adler;
Neuroterus albipes, Cameron. :

English name of gall.— Schenck’s Gall.”

Position of gall.—On the margin of the leaf and on the
mid-rib.

anne of growth.—Single, solitary, sessile, oviform, slightly
pilose.

Colours.—Yellowish-white, greenish-yellow, pale brown.

Average dimensions of a mature specimen. — Length,
2mm.; breadth, 1mm.

May be sought during the months of April to June.

Growth is complete by the end of May.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
June.

Inquiline, No. 128.

Alternate agamic generation: Neuwroterus lxviusculus,
Schenck.

Several writers are of opinion that this gall is
indistinguishable from other galls of similar shape and
size.

In various features it coincides with those of
Andricus nudus, A. gemmatus, A. circulans; and a
continental species, Andricus burgundus. The imago,
also, does not possess any definite characters whereby
it can be separated.

Cameron appears to have been the first to record
this species as British. He found many specimens in
the neighbourhood of Glasgow.

It now appears to be generally distributed through-

out Britain.

SPATHEGASTER APRILINUS, 127

S. albipes is found in the latter part of April only
in very mild seasons, and when the foliage is well
advanced. The second week in May is the usual
time of development. Galls, from which the occupant
has emerged, may occasionally be found in situ as late
as the middle of September (one found September
10th, 1907).

The peculiar contraction, incision, or indentation, in
one half of the blade of the leaf, often draws attention
to the gall, when, otherwise it would be overlooked.
Its pale colour also harmonises with the under-surface
of the leaf rendering the gall less conspicuous.

It is moderately common, and widely distributed,
but somewhat local. Seldom more than one gall
appears on a leaf, and more rarely is it seen growing
from the petiole; but instances are known where
galls are situated on either side of the mid-rib, and
also of two galls side by side on the same margin.
The side of the gall opposite that next the leaf is
generally raised to form a slight ridge, or there may
be a few minute protuberances. During growth the
distal end of the gall terminates with a minute dark-
coloured style which disappears at maturity, as also
does much of the pilosity.

It is somewhat remarkable that so small a gall, and
the diminutive area it occupies, should arrest so large
an amount of leaf tissue as is often the case, causing
in some leaves an indentation more than fifty times
the area of the gall. It is due to the fact that gall
formation begins “on the rudimentary leaf while yet
in the bud” (‘Alternating Generations’ p. 19), and
when the leaf expands it cannot recover itself.

Spathegaster Aprilinus, Giraud.
(Plate LIT, div. A.)

Neuroterus Schlechtendali, Mayr, Schltdl., F. Loew ; N. Aprilinus, i
Cameron ; Spathegaster Aprilinus, Mayr, Licht., Beyer., Adler, Fitch.
English name of gall.—*“'The April Bud Gall.”

128 BRITISH OAK GALLS.

"Position of gall.-—Mostly in terminal, but also in axillary
buds.

Manner of growth.—Single, solitary, glabrous, vesiculate,
ovoid.

Colours.—Pale green, greenish-yellow, pale pink, light brown.

Average dimensions of a mature specimen. — Height,
8mm.; girth, 15 mm.

May be sought during the months of April and May.

Growth is complete by the end of May.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
May.
Inquilines, Nos. 17, 72.

Alternate agamic generation: ? Neuwroterus ostreus, Hartig.

The dimensions of the largest gall of this species, of
which I have a record, is—height 15 mm., girth
21 mm.

The proportion of axillary buds containing galls,
as compared with terminal buds, is one in four.

“There seems to be some doubt as to the agamic
form of this species.” Beyerinck bred Neuroterus
Aprilinus from galls of Andricus solitarius. Von
Schlechtendal and F. Léew consider N. Schlechtendalt
the agamic form. Mayr considers, “ that ostreus,
being an Andricus, can hardly be the agamic of a
Neuroterus” (‘ Brit. Phyto. Hymen.,’ vol. iv, p. 140).
Adler is strongly of opinion that it is NV. ostreus, and
his experience and experiments entitle him to be
regarded as correct.

Probably no other British oak gall equals this.
species in the rapidity with which it develops, and
reaches maturity. It is also one of the most obscure
as regards its situation. The enfolding leaf-bud
scales, and the very few days required for it to become
mature and shrivel, combine to render its discovery a
difficult matter, overcome mainly by experience..
Four or five days only, are necessary, from the time
the gall expands sufficiently to increase the size of the
bud, until growth ceases, and the imago escapes.

SPATHEGASTER BACCARUM. 129

A few of the large outer leaf scales of the bud
surround the base of the gall and assist in retaining
it in position. The greater part of the upper portion
of the gall is bare except for a few of the small inner
leaf scales which adhere to it. The gall does not fall
to the ground. The structure is of a vesiculate nature,
with thin, soft, and sappy walls. The interior forms
a large larval chamber. There may be two or three
larvee, each occupying a separate cell, but a larger
number of cells generally denotes the presence of
inquilines. The cells are oviform in shape, and
arranged perpendicularly on their own longitudinal
axis. They are large in comparison with the size of
the larva. The arrangement is sometimes indicated
on the exterior of the gall.

The gall occupies about two-thirds of the bulk of
the bud. In shape it is an elongate ovoid, flattened
on the inner side for about four-fifths of its entire
length. It is found more plentifully on stub-oaks of
about five to seven years’ growth, than on full grown
trees.

Spathegaster baccarum, Linn.
(Plate LITT.)

Cynips Quercus baccarum, Linn.; Spathegaster interruptor,
Hartig; S. baccarwm, Mayr, Fitch, Miller, Adler, Marshall ;
Neuroterus baccarum, Mayr; N. lenticularis, Cameron. S

English name of gall.—< The Currant Gall.”

Position of gall.—On the staminate catkins, and on the leaves.

Manner of growth.—Glabrous, glossy, gregarious, succulent,
globular.

Colours.—Pale green, greenish-yellow, pink, red, purple.

Average dimensions of a mature specimen.—On catkin :
Girth, 7mm. On leaf: Girth, 10 mm.

May be sought during the months of May and June.

Growth is complete by the end of June. ;

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during

June. oy Moy , F

130 BRITISH OAK GALLS.

Parasites, Nos. 37, 44, 94, 147,151, 154, 166,180. Inquilines
Nos. 127, 128, 130, 186, 138.

Alternate agamic generation: Newroterus lenticularis,
Oliver.

The galls which develop on catkins are generally
suffused with pink, or spotted or striped with red;
those on leaves are mostly a rich translucent green.

They are very soft and contain an abundance of a
whitish, tasteless fluid.

No name more appropriate than that of “ currant,”
could have been bestowed upon this gall when growing
on a catkin peduncle. When on the under-surface of a
leaf, a portion of the gall becomes contexturate with
the leaf tissues, the attached portion being marked
by a pronounced convexity on the upper surface of the
leaf, where it is mostly of a red colour.

The size of those on leaves, is generally about one-
fourth more than that of those on catkins.

Rapid development of the imagines is necessitated
by the soft, succulent, and perishable nature of the
galls, the entire metamorphosis occupying less than
fourteen days.

This gall is extraordinarily abundant in some years
on both catkins and leaves; twigs and small boughs
are frequently weighed down with them. Quercus
sessiliflora often yields finer specimens, both as regards
size, and numerical abundance, than the other species
of oak.

It is the commonest of the globular galls, and, but
for the restraining action of numerous parasites, and
indirectly of inquilines, many oak trees would have no
acorns.

The gall consists of a very sappy and soft cellular
tissue. The larva occupies -the centre, eating a large
spherical cavity.

As soon as the imago has escaped, the structure
shrivels and decays ; when, however, parasites or inqui-
lines are in possession it retains the globular form,

SPATHEGASTER SIMILIS. 131

turns a brown colour, and may be found in that condi-
tion as late as the month of September.

This gall was observed in England by Dr. Sir Thomas
Browne, and mentioned by him in correspondence with
Dr. Merrett in 1668 (see Introduction).

Spathegaster similis, Adler.
(Plate LIT, div. B.)

Spathegaster similis, Licht., Mayr, Cameron.

English name of gall.—‘ The Green Velvet-Bud Gall.”

Position of gall.—In dormant adventitious buds of the bark
and small twigs.

Manner of growth.—Solitary, sessile, pubescent, ovoid, pointed
at apex.

Colours.—Pale green, green, pale brown.

Average dimensions of a mature specimen. — Height,
2mm.; girth, 5mm.

May be sought during the months of April and May.

Growth is complete by the end of May.

The typical condition of the gall is unilocular and unilarval.
ao larva pupates in the gall. The imago emerges during

ay.

Alternate agamic generation: Dryophanta longiventris,
Hartig.

This gall was discovered by Dr. Adler in the course
of his experimental breeding with D. longiventris.
His remarks are as follows: “ The gall is like Spathe-
gaster Taschenbergt but more slender and pointed ; of
greenish-grey colour and with a velvety rind. The
colour is caused by a greenish pigment, but this tint
is rendered dull by a covering of long white hairs,
imparting to it a grey tone. It is especially the
stronger and longer pubescence which is the important
distinction between this and the 8. Taschenbergi gall”
(‘ Alternating Generations,’ p. 66).

It is scarce in many localities, rare in others, and
not found at all in most districts.

I have found but one specimen, which unfortunately
was not in a good conditions

132 BRITISH OAK GALLS.

Spathegaster Taschenbergi, Schlechtendal.
(Plate LIT, div. C.)

Dryophanta Taschenbergi, Mayr; Spathegaster Taschenbdergi,
Mayr, Fitch, Adler; §. floseuli, Giraud; S. Giraudi, Tschek. .

English name of gall.—-“ The Purple Velvet-Bud Gall.”

Position of gall.—In dormant adventitious buds of the bark
and small twigs.

Manner of growth.—Solitary, sessile, pubescent, ovoid, rounded
at apex.

Colours.—Violet, dark violet, purple.

Average dimensions of a mature specimen. — Height,
3mm.; girth, 6mm.

May be sought during the months of April and May.

Growth is complete by the end of May.

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
May and June.

Alternate agamic generation: Dryophanta scutellaris, Hartig.

The beautiful colour of this dainty little gall is
“caused by a peripheral layer of pigment cells,
studded over with short white hairs which give
the velvety appearance to the surface. The imner
kernel of the gall is soft and consists of cells con-
taining starch granules; these are completely eaten
by. the larva, so that ultimately nothing is left but a
thin rind” (‘ Alternating Generations,’ p. 63).

A most beautiful little gall, and worth any amount
of trouble to obtain. It is very distinctive in appear-
ancé, but somewhat obscure in its habitat.

The galls should be looked for amongst the clusters
of adventitious buds and little twigs on the trunks of
old trees in woods. Three is the usual number in a
cluster, but solitary specimens are not infrequent.

It is advisable to search for them on sunny days ;
the intensity of light enables the collector to see them
more readily.

Considering the abundance of the agamic form, the
comparative scarcity of tis gall is remarkable.

SPATHEGASTER TRICOLOR, 1383

Spathegaster tricolor, Hartig.

(Plate LIV.)

Newroterus tricolor, Mayr, Cameron; Spathegaster tricolor,
Schenck, Mayr, Adler, Licht., Fitch, Marshall, Miller; S. varius,
Schenck.

English name of gall.—- The Hairy Pea Gall.”

Position of gall.—On the under-surface of the leaf.

Manner of growth.—Pilose, sessile, globular, succulent, con-
glomerated, glistening.

Colours. — White, very pale green, pale yellow.

Average dimensions of a mature specimen.—Girth, 18mm.

May be sought during the months of May to August.

Growth is complete by the end of June.

The typical condition of the gall is unilocular and unilarval.
The larva pupates in the gall. The imago emerges during
July. :

Parasite, No. 44. Inquilines, Nos. 127, 130, 139.

Alternate agamic generation: Neuroterus fumipennis, Hartig.

This gall is very distinctive and easily recognised.
It occurs more frequently on scrub-oak bushes, and
stunted, and hedge-trimmed growth along road-side
banks, than in any other situation. In some districts
it is exceedingly abundant.

It occurs in clusters of as many as 15-20 on one
leaf, and many will coalesce.

Aggregations of this species are sometimes so large
that a leaf, or several leaves on the same twig, will be
entirely transformed into gall masses, as shown in the

late.

‘ When solitary the gall is situated on the mid-rib or
its offshoots. When first noticeable it is like a tiny
hairy elevation of the leaf; as growth proceeds the
hairs separate and elongate, some attaining a length
of 5-7 mm. They are slender, vitreous and iridescent ;
at first pink, then crimson, ultimately turning brown,
losing all colour, or falling off.

The gall has an acid flavour.

134, . BRITISH OAK GALLS.

Spathegaster verrucosus, Schlechtendal.

Spathegaster verrucosa, Schltdl., Mayr, Fitch ; Dryophanta verru-
cosa, Mayr; D. divisa, Cameron; Spathegaster verrucosus, Adler.
English name of gall.—‘<The Red Wart Gall.”
‘ Acca of gall.—On the leaf, and in axillary and terminal
uds.
Manner of growth.—Single, solitary, glabrous, glossy.
Colours.—Greenish-yellow, pink, orange, red, reddish-brown.
Average dimensions of a mature specimen.— Height,
4mm.; girth, 6mm.
May be sought during the months of April to June.
Growth is complete by the end of May.
The typical condition of the gall is unilocular and unilarval.
The larva pupates in the gall. The imago emerges during
May.

Alternate agamic generation: Dryophanta divisa, Adler.

On the surface of the gall, and generally near the
apex, is a very small raised disc, or mamelon. Some
galls have more than one. Under magnification it is
seen to be a circular, or oval, elevation about 1 mm.
in diameter, with.a depressed centre through which
the imago eats its way out. This mamelon is some-
what variable in colour, but when the gall is mature it
assumes the reddish-brown hue of its surroundings.

This gall develops upon three different situations.
On the leaf from the end of the mid-rib, or the margin
of the blade; at the termination of a twig, and, the
axillary bud. This is explained by Adler as being due
to the fact that D. divisa usually lays her eggs “in
the rudimentary leaves.” <A slight deviation from the
normal situation of the egg “ makes all the difference
as to the positions of the gall. If the egg lies on the
point of a leaf, the gall develops on that spot, and the
full grown leaf bears a gall on its point; but if the
egg lies deeper in the base of the leaf, the whole leaf
surface is absorbed, and the gall rests directly on the
shortened petiole. . . . the gall is merely substi-
tuted for the leaf. When the egg is sunk still deeper
into the axis of the bud the whole bud is absorbed in

SPATHEGASTER VESICATRIX. 185

the gall formation” (‘ Alternating Generations,’ p. 70).
The bud may be axillary on a twig, or of adventitious
growth on the bole of a large tree.

The bud galls are inconspicuous, bursting through
the large outer leaf scales only when nearly mature ;
a feature in which they resemble S. aprilinus and
Aphilothrix albopunctata.

Those on the leaf, although small, are not difficult
to find. They are sessile.

The shape of the gall varies. Some are fusiform,
others oval, but the prevailing form is cylindrical, the
distal end terminating in curved blunt conical pro-
jection.

The walls of the gall are very thin. The interior

Fie. 17.—Galls caused by Spathegaster verrucosus. All nat. size.
In part after Cameron and Adler. dele. E.C.

constitutes a large larval cavity, without an inner gall.
The exterior consists of a peculiar granular glossy
rind, clothed with many minute soft pustules filled
with a clear liquid. Adler conjectures this is a means
of protection against parasites (l.c., p. 69).

Spathegaster vesicatrix, Schlechtendal.
ee ee a ade rear a
(Plate LV.)

Spathegaster vesicatriz, Mayr, Fitch, Ormerod (Miss) ; Newroterus
vesicatriz, Mayr; N. numismatis, Cameron.

English name of gall.—“ The Blister Gall.”

Position of gall.—In the blade of the leaf.

Manner of growth.—Single, solitary, glabrous, glossy, radiate.

Colours.—Pale green, grey, pale brown.

186 BRITISH OAK GALLS.

. Average dimensions of a mature specimen. — Height,
‘5mm.; diameter, 3mm.

May be sought during the months of May to October.

Growth is complete by the end of May.

The typical condition of the gall is unilocular and unilarval.
Many galls, although externally in every way normal, and without
any trace of opening, are quite empty.

The larva pupates in the gall. The imago emerges during
June.

Alternate agamic generation: Newroterus nuwmismatis,
Oliver. ;

Dr. Trail appears to have been the first in Britain
to find, and to record the occurrence, of this species.
On July 5th, 1873, he “observed specimens on leaves
of the common oak at Banchory,” where he had “ seen
a few about a month before in their earlier stages,
without recognising them as galls.” On the 27th of
the same month and year, Miss E. A. Ormerod, LL.D.,
observed the gall on leaves of Q. pedunculata, “ and
noted it as affecting both sides of the leat.”

During the earlier stages of growth the gall is
somewhat difficult to detect, but as development
(which is rapid) proceeds, both upper and under-
surfaces of the galled portion of the leaf project
convexedly, and from green, the colour soon passes to
grey or whitish. By then, a small papilla will have
manifested itself on the summit of the supra con-
vexity, and from it to the circumference, a number of
narrow ridges radiate. The radii are not always
continuous from the margin to the centre. Although
the opposite surface is typically less distinctly marked,
many specimens exhibit both papilla and radii with
equal clearness, while others are quite smooth.

The larva occupies the whole of the cavity, there is
no inner gall. When mature the imago eats its way
out through either surface, and the gall will continue
to grow after the tenant has vacated it. An inquiline
(a Synergus), and a parasitic. Torymus, are known to
inhabit the gall.

The periphery of the gall is circular, or oval, and,

TERAS TERMINALIS. 137

‘as indicated in its trivial name, it is blister-like in its
mode of expansion. Seldom more that two appear on
a leaf. They may be on either side of the mid-rib, or
coalescent; occasionally absorbing part of a small
vein, but rarely, if ever, on the mid-rib. When on
a lobe of the leaf distortion is sometimes produced
similar to that caused by S. albipes.

During many years of research I have on several
occasions noticed galls on leaves of stub-oaks, very
similar to S. vesicatriv. Small blisters, about 3 mm.
in diameter; irregular periphery; when in nerve axils,
triangular; without radii, grooves, or papille. Pale
green, and greenish-yellow, broadly margined with
red. The interior fully occupied with a pure white
apodous larva, cecidomyian in shape, about 2 mm.
long and ‘5 mm. at widest part. It eats its way out
and falls to earth to pupate. Afterwards the supra
convexity becomes concave. I have neither been able
to have the larva identified, nor rear the imago.

Teras terminalis, Fabricius.
(Plates LVI, LVII.)

Cynips quercus-terminalis, Fabri. ; Andricus terminalis, Fabri.,
Mayr, Walker, Fitch; Teras terminalis, Miller, Marshall, Adler ;
Biorhiza terminalis, Cameron.

English names of gall.—‘ The Oak Apple,” “King Charles’
Apple,” “The Apple Gall.” :

Position of gall.— Axillary and terminal on twigs.

Manner of growth. —Single, glabrous, glossy, globular,
spongy. ; ; }

Colours.—Yellowish-white, suffused with pink and red, pale
brownish yellow. . :

Average dimensions of a mature specimen.— Diameter,
25 mm.

May be sought during any month of the year.

Growth is complete by the end of June. —

The typical condition of the gall is plurilocular but unilarval.
Usual number of cells about thirty. :

The larve pupate in the gall. The imagines emerge during

June and July.

188 BRITISH OAK GALLS.

Parasites, Nos. 19, 20, 22, 32, 33, 36, 39, 44, 55, 56, 58, 63, 65,
80, 81, 82, 84, 85, 86, 90, 91, 92, 98, 97, 98, 99, 100, 101, 102, 106,
107, 116, 118, 148, 151, 158, 154, 155, 156, 157, 160, 164, 167, 168,
169, 170, 171, 172, 178, 174, 176, 180, 184 (see pp. 150-152).
Inquilines, Nos. 71, 73. “

Alternate agamic generation: Biorhiza aptera, Fabr.

Hyper-parasites and other insects and creatures
that have been found upon, within, and reared from
galls of 7’. terminalis are very numerous. The student
desirous of following the subject will find them
enumerated in ‘ The Entomologist,’ No. 152, February,
1876, pp. 29-42; also in ‘ Brit. Phyto. Hymen.,’
vol. iv, p. 120, and in ‘ Alternating Generations,’
pp. 77-79.

This gall received its specific name because of its
propensity in developing, usually, from a terminal
bud. It, however, develops from axillary buds with
equal frequency and vigour.

It is an exceedingly familiar object to persons living
in rural districts, and also to those who notice oak
trees while passing along country roads, or through
woods during the months of May and June, and also
July, if the season is late.

The autumn-winter condition of the gall is not so
well known. When partly decayed, and most of the
inhabitants have escaped from the tissues, the remnant
is so unlike its summer condition that few persons

-regard it as connected with the soft and delicately
tinted oak-apple of May and June.

When Biorhiza aptera deposits her numerous ova
she almost severs the bud from the twig with the
continuous puncturings of her ovipositor. Immedi-
ately, therefore, gall growth begins, the few remaining
connecting cells are ruptured, and the whole of the
bud (with, perhaps, the exception of a few basal
outer leaf scales), is lifted from its base, and remains
adherent to the surface of the gall. The bud may
thus be retained in an upright position, or in a jaunty
attitude, and unless removed by wind, or other causes,

TRIGONASPIS CRUSTALIS. 1389

it will remain in a lightly attached manner for several
days. Expansion of the surface of the gall ultimately
causes it to fall.

The growth of the gall is rapid, and does not cease
until it has attained, in some specimens, a girth of
134 mm. (= 54 inches), and even larger. Although
generally solitary in mode of growth, as many as five
are sometimes crowded together. When mature,
suffused with pink or madder, and surrounded by
several leaves this gall is among the most charming
of those on the British oaks.

This gall was observed in England by Sir Thomas
Browne, and mentioned by him in correspondence
with Dr. Merrett in 1668 (see Introduction).

Trigonaspis crustalis, Hartig.
(Plates LVIII, LIX.)

Cynips megaptera, Panzer; C. crustalis, Thoms.; Trigonaspis
crustalis, Licht., Adler; TI. megaptera, Mayr, Walker, Marshall,
Miller, Cameron; 7. renum, Mayr.

English name of gall.—‘<The Pink Wax Gall.”

Position of gall.—Low down on bark of trunk, and small twigs
growing therefrom.

Manner of growth.—Single, glossy, glabrous, gregarious,
globular, succulent.

Colours.— White, cream, greenish-yellow, pink, red, reddish-
brown.

Average dimensions of a mature specimen.—Girth, 30 mm.

May be sought during the months of April to June.

Growth is complete by the end of May. ;

The typical condition of the gall is unilocular and unilarval.

The larva pupates in the gall. The imago emerges during
May and June.

Parasites, Nos. 124, 162, 151, 16, 53. Inquilines, Nos. 129,
130, 134, 189.

Alternate agamic generation: Biorhiza renum, Hartig.

This gall was well known in England many years
prior to 1874.

It is unusually succulent. The tissues are very
fully charged with an acerb, cloudy fluid of which as

140 BRITISH OAK. GALLS.

much as 10-12 mins. can be obtained, by pressure,
from a large gall. The disagreeable bitterness of the
fluid makes the gall exceedingly unpleasant to the
human palate.

This gall is exceedingly pretty and attractive. The
English name of “ pink wax” is eminently suitable.
It bears some resemblance to Spathegaster baccarwm,
but while that species is almost tasteless, this species
is very astringent.

In size, even although mature, it varies greatly ;
some species being not more than 12 mm. in girth,
others attaining 45-50 mm. in girth.

In shape also there is considerable variation, some
being oval, ovoid, and spherical. The prevailing form
is globular, slightly depressed where attached, and
occasionally at the opposite pole also. The walls are
very thick; the larval cavity very small.

The mode of growth is such that the gall appears
to be sessile, a deception increased when it is sur-
rounded with moss, lichen, ivy, or very small twigs.
Its origin is from a bud, not from the bark. It is
always attached by a peduncle, which although small,
delicate, and easily severed, retains the gall until
mature, or the tenant has emerged, and even when it
has shrivelled, and become inconspicuous.

At intervals of several years they are particularly
abundant, many hundreds appearing on the trunks of
old trees. They are found most frequently low down
the bole of the tree; they also affect small twigs in the
same lowly position, especially when lightly covered
with loose earth and leaves; they may also be sought
on twigs along the bottom of a hedge; but, the best
place of all is the stump of an old pollard oak in a
wood or lane.

CYNIPS TINOTORIA. 141

GALLS CAUSED BY
CYNIPS TINCTORIA

on twigs of Q. pubescens.
CYNIPS CALICIS

on cupules of Q. pedunculata.
(?— undetermined)

on cupules of Q. Ilex.

Cynips tinctoria, Mayr.
(Plate LX, div. B.)

English names of gall.—<The Aleppo Gall,” “The Ink
Marble.”
Position of gall.—On twigs of Q. pubescens.

The gall caused by this species is so little known and
so seldom seen that a brief notice of it may be useful
to the student.

It will be seen upon reference to Plate XXXV,
figs. 1, 2, 3,; and Plate LX, div. B, that C. tinctoria
bears a very close resemblance to C. Kollari, and many
specimens of the latter might be easily mistaken for
the Aleppo gall.

But tinctoria, when mature, is very much harder in
texture than Kollari in the same condition, and the
cell-walls are quite stone-like. Itis surprising that the
imago is able to eat a way out through so hard a
texture.

C. tinctoria is about the same size as Kollari and
grows in the same positions.

It is found in various parts of Turkey, principally

142 BRITISH OAK GALLS.

along the Mediterranean Sea, in the part known as
the Levant, the chief market for it being at Aleppo,
a town about twenty-five miles inland, in a district of
the same name; and from this circumstance it is called
the Aleppo gall. It is the most useful and valu-
able of all galls. Ink is manufactured from them,
the process being as follows: The galls are coarsely
powdered and thoroughly mixed with chopped straw
to maintain porosity. of the mixture, put into a deep
narrow oak vat having a perforated false bottom,
with a tap. Lukewarm water is then poured in,
and this percolating, extracts and carries the tannin
of the galls with it; this is drawn off and repeatedly
run through. <A sufficient quantity of water is
used, in proportion to the galls, to produce as nearly
as possible about 50 per cent. of tannin. After fer-
mentation has taken place the solution is exposed to
the air, the tannin splitting up into gallic acid and
sugar. Salt of iron (green vitriol), and gum senegal
are added. The tannin of the oak gall is different
from the tannin of the oak bark.

Another gall, found in certain parts of China, is
also used in the manufacture of writing ink. It is
hollow, brittle, irregular in shape, covered externally
with a grey pubescence. It is caused by an Aphis,
and contains a rather higher percentage of tannin than
does the Aleppo gall. Both kinds are of more com-
mercial value if collected before the insect emerges.

A gall found in Japan is used for the same purpose.
It is rich in tannin, but does not:contain so much as
the former kinds.

Almost all plants contain tannin, but very few yield
the kind suitable for ink-making ; the particular kind
contained in galls is known as gallo-tannic acid.

Tannin can be dissolved out of plants with a mix-
ture of spirits of wine and ether. The extract when
allowed to stand separates into two layers, the lower
being a strong solution of the tannin.

CYNIPS CALICIS. 148

Cynips calicis, Burgsdorff.
(Plate LXI, div. A.)
English name of gall.—‘“ The Knopper Gall.”

- Position of gall.—On the cupules of Q. pedunculata.
From Jersey, the Channel Isles.

This gall is plentiful on the Continent where it is
known as the “ Knopper Gall” (the gall-nut).

It occurs principally on Quercus pedunculata, but
also on Q. sessiliflora, and makes its appearance in
May and June.

It consists of two parts, a thick outer cone-shaped
structure, and a small larva cell. The outer structure
develops from between the acorn and the cupule,
sometimes interfering with the growth of both those
parts to so great an extent that they are abortive. It
assumes the shape of a truncated cone strongly ribbed
radiately, the edges of the ribs being uneven, indented,
or drawn out to a point especially around the base.
At the apical part is a small hole. The interior is
hollow, approximately the same shape as the exterior,
usually about 12 mm. diameter, and 4mm. at the hole.
In some specimens a thin transverse partition divides
the interior into two parts. Attached to the base of
this hollow is the larva cell, which is ovoid in shape,
5 mm. long and 3 mm. broad.

The imago eats its way out through the base of the
radiate structure, or, through the partition and escapes
through the hole, during February or March of
the following year.

The structure remains attached by the peduncle to
the tree throughout the winter.

I am not aware of any record of its occurrence in
England. The specimens illustrated were forwarded
to me from Jersey in 1902. I think, however, it is
not improbable that it may make its appearance in
the southern counties, and therefore include it in the
present series. ba

A free or loose inner gall, like that of C. calicis, is
also found in galls produced by C. cerricola on twigs
and bark of Q. cerris, on the continent.

144 BRITISH OAK. GALLS.

Undetermined gall on Q. Ilex.

Position of gall.—On the cupules of Q. Ilex.
? From the Isle of Wight.

The specimens on Plate LXI, div. B, were among
a number of galls sent to me for identification from
Chadwick Museum, Bolton, in 1902,-and were kindly
presented to me by the Curator, W. W. Midgley, Esq.

A label attached to them stated that they were from
the Isle of Wight, but the collector’s name was not on
it, nor the locality in which they were found. There
is therefore some doubt whether they are indigenous. If
they did grow there, probably more specimens might
be found in the island now, and perhaps on the con-
tiguous mainland also.

They appear to have been gathered before they were
mature.

The cupule is almost normal in bulk, and it is covered
with scales in the usual manner, but it is much plicated.
The interior is thickly lined with short whitish glossy
hairlets. At the base of this cavity is a diminutive
undeveloped acorn, which appears to afford protection
and food for the larva, and to constitute the true gall.
This acorn is reddish-brown in colour, it is firmly
attached to the cupule, clothed with microscopic hair-
lets, and, it consists of three superimposed parts. The
lower third is like a circular cushion, about 4 mm. in
diameter and 1°5 mm. high, and this portion appears to
be the larval chamber; upon it rests another cushion-
like part which is about 2 mm. high and the same in
diameter, projecting from the top of which are several
tiny black curved stigma-like filaments 1 mm. high.

The acorn bears a very close resemblance to galls
produced by Cynips galeata (Giraud), on twigs of Q.
pubescens, on the Continent. That species, however,
is about three times as large, and devoid of covering.

CUPULES OF Q. ILEX. 145

(). Ilex on the Continent is also galled by:

(1) Contarinia Ilicis (Licht.), causing small conical
growths, on under-surface of leaf.

(2) Dryocosmus Australis (Mayr), causing unilocular,
globular, green swelling of edge of leaf.

(8) Plagiotrochus Ilicis (Licht.), causing irregular,
sub-globose, multilocular swelling of leaf.

(4) Cecidomyia Lichtensteinit (Low), causing ovoid
pustules on under-surface of leaf.

(5) Diplosis sp., causing nail-like growths on under-
surface of leaf.

10

146 BRITISH OAK GALLS.

OTHER GALLS ON THE BRITISH OAKS NOT
PRODUCED BY CYNIPIDA.

Gall-pits caused by females of Asterolecanium variolosum,
Ratzeburg.

(Plate LXIT.)

Asterolecanium quercicola, Sig.; Planchonia fimbriata, Fons.;
Coceus variolosum, Ratz.; C. quercicola, Planchonia quercicola,
Bouch., Maskell, Froggatt; Asterodiaspis variolosus, Boas;
“A. quercicola, Bouch, Newstead.

English name of gall.—‘ The Pit-making Oak Coccid.”

Position of gall.—On small twigs of Quercus pedunculata and
Q. sessiliflora.

Manner of growth.—Single, gregarious, coalescent.

Colour.—Slightly paler than the surrounding part of the twig.

Average external dimensions of a mature gall-=pit.—
Height, 1mm.; length, 3mm.; breadth, 2mm.

May be sought during the months of May to October.

These peculiar circular, but mostly ovoid, swellings
on oak-twigs result from external influence.

They are due to the presence of female Coccide.
These msects pass their life in a fixed spot on the
twig, and as the result of their method of feeding, and
other causes, irritation is set up in the plant tissues
which produces elevated margins of bark around each
insect.

The pits thus formed are relatively very deep, the
margins rising sufficiently high to conceal the ventral
rim of the insect’s test.

These gall-pits may be found in many districts in
great numbers. Usually on tender and growing twigs
of small scrub-oak bushes among the low and straggling
herbage of a roadside bank ; but they not infrequently
appear also on terminal twigs of young trees in woods.

Tits are extremely fond of the insects, and search
most diligently for them. When a twig dies, either
naturally, or from being severed, the margins of the
gall-pits diminish considerably.

DIPLOSIS DRYOBIA. 147

Diplosis dryobia, Léw.
(Plate LXIII.)

Diplosis Liebeli, Kieffer.

Position of gall.—The margins of the lobes of the leaf.

Manner of growth.—Glabrous, glossy, crescent-shape.

Colours.—Pale green, green, light brown, dark brown, chocolate.

Average dimensions of a mature specimen. — Length,
15mm.; breadth, 2mm.

May be sought during the months of June to September.

Growth is complete by the end of July.

The typical condition of the gall is unilocular but multilarval.
Usual number of larve, 4.

The larvz pupate in the ground. The imagines emerge
during the spring.

The margins of the lobes are curved upwards and
folded down upon the upper surface of the blade, form-
ing a thickened roll within which the larve live. The
edge of the recurved portion presses very closely upon
the surface of the leaf, preventing the intrusion of other
small creatures, such as mites, etc., and retaining the
larve until fully grown when it either gapes to allow
them to fall to the ground, or they push their way out.
The affected area is not easily noticeable from the other
surface of the leaf.

A species of Hriophyide, Hpitrimerus cristatus,
Nalepa, a mite which occurs in Central Europe,
causes the leaf-margins of Q. pubescens to curl in a
similar manner; the folded portions, however, affect
the under-surface of the leaf as well as continuing to
the extremity of each indentation of the leaf. There
is no change of colour in the rolled portions.

It is probable that this species may be discovered in
Britain.

The dimensions of the mites are: male, 0°12 mm.
long, 0°046 mm. broad ; the female, 0:17 mm. long,
0°057 mm. broad.

Plate LXIV is introduced from ‘ Zur Kenntniss der
Gattung Trimerus,’ by the kind permission of Dr.
Naepa, Vienna.

148 BRITISH OAK GALLS.

Galls caused by the Fungus Dicheena quercina, Fries.
(Plates LXV, LXVLI.)

Position of gall.—On twigs, branches and stems of Quercus
pedunculata, and Q. sessilifiora.
Synonym of fungus.—Opegraph quercina, Pers.

This remarkable fungus gall-formation is frequently
seen on stub-oaks by the road-side. Hedges, that are
periodically trimmed, are the best to search for
specimens. The fungus also affects young trees in
woods, where it forms masses of considerable size; but
trees of more than about fifty years old appear to be
less frequently attacked. In some districts it is very
abundant.

Not much is known about the habits of the fungus.
Spores settle in a crack or wound in the bark, and
when germination takes place the mycelium works
its way into the cambium layer and the pith, sets up
irritation, and consequent multiplication of cell tissue.

The earliest indication of attack is seen in a slight
rounded swelling of the bark, smooth and glossy. This
continues for a long time. It affects the smallest twigs,
also thick branches, and the stems.

The swelling of the affected part is very slow, and
it is some years before the epidermis yields to the
pressure of abnormal growth beneath it and splits,
mostly in a transverse direction to that of the twig.
The coraceous appearance of the excrescences is
peculiar to this fungus ; they are solid and hard.

The parallel and concentric ridges of projection,
correspond with the number of annular rings in the
branch.

The fungus probably lives for a great number of
years. Except when very abundant on a bush or
tree it does no serious injury.

P DICHAINA QUERCINA. 149

Gall caused by ? Dicheena quercina, Fries.
(Plates LXVII, LXVIILI.)

Position of gall.—On the trunk of Quercus pedunculata, in
Broomham Park, Guestling, Hastings.

This enormous swelling affords an excellent illustra-
tion of many such growths on oak, elm and other trees,
in parks, groves, gardens, and woods in many
localities.

It is remarkable that these growths do not cause
any noticeable diminution in the height, vigour in
expansion, or scarcity of foliage of trees thus affected.
Apparently the galls are not detrimental to the well-
being of the trees. This, of course, is not unusual,
because very few oak galls (excepting such as monopo-
lise buds and catkins) interfere with the development of
the surrounding tissues; a character more noticeable
in the galls on, and in, leaves, than in any others.

As far as can be ascertained, without cutting
into this gall, it is composed of the same materials as
the other portion of the trunk. It is without holes of
any considerable depth, and appears to be perfectly
solid.

The bark, or cortex, is scabrous. Although very
similar in appearance to'the bark of the trunk, it will
not peel off in the same manner.

The scale shown in each plate is 30 cm. (= almost
12 in.) The dimensions are :

Girth of trunk immediately beneath swelling 7 ft. 10 in.
Distance from ground to top of swelling. . 6ft. 3in.
Peripheral circumference of swelling . ‘ . 10ft. 3in.

Girth of trunk and swelling at equatorial line 11 ft. 10 in.

The fruiting stage of all the species of the genus
Dichena is rarely seen. Of some species it is not
known. Some species are common. All are true

parasites.

150 BRITISH OAK GALLS.

A LIST (ALPHABETICALLY ARRANGED), OF PARA-
SITES AND INQUILINES MENTIONED IN THIS
VOLUME, WITH NUMBERS CORRESPONDING WITH
THOSE ON PREVIOUS PAGES.

Abbreviations of authors’ names :—Bou. Bouché. Bri. Brischke.
Bur. Burmeister. Cam. Cameron. Dal. Dalman. Fab. Fabricius.
Fit. Fitch. For. Forster. Fon. Fonscolombe. Gir. Giraud. Har.
Hartig. Kal. Kaltenbach. Lat. Latreille. Lin. Linneus. May.
Mayr. Nee. Nees. Oli. Olivier. Par. Parfitt. Rtz. Ratzeburg.
Wal. Walker. Wes. Westwood.

AMERISTUS, ENTEDON,
1. parasiticus, 27. cecidomycarnus, Bri.
ANTHOMYIA, 28. cyniphidium, Bri.

2. gallarum, Htg.
AULAX,

3. pinnatus, Gir.

4. pumilus,

5. syncrepidus, Htg.

Bracon,
6. aterrimus, Rtz.
CALLIMONE,

7. antennatus, Wal.

8. auratus,

9. elegans, Wal.
10. fuscicrus, Gir.
11. inconstans,

12. longiventris, Bri.

18. mutabilis, Wal.

14. regius, May.

15. Roboris, Wal.

16. rubriceps, Lat.
CEROPTRES,

17. arator, May.

18. Cerri, May.
DeEcatroma,

19: biguttata, Bou.

20. immaculata, Wal.

21. Neesi, For.

22. signata, Rtz.
DicTYorTERyYXx,

23. Leeflingiana, Lin.
ELACHESTUS,

24. gallicolus, Gir.

25. cyniphidium, Rtz.

26. petrolatus, Nee.

29. flavomaculata, Rtz.

30. leptoneurus,

31. scianeurus, Rtz.
EvLopruvs,

32. agathyllus, Wal.

33. gallarum, Lin.

34, levissimus, Rtz.

35. metallicus, Nee.

86. ramicornis, Bri.
EvPrELMts,

37. annulatus, Gir.

38. azureus,

39. urozonus, For.
Euryroma,

40. wthiops, Wal.

41. curta, Wal.

42. gracilis,

43. nodularis, Wal.

44. rose, Nee.

45. semirufa, Gir.

46. setigera, May.

47, signata, Kal.

48. sqamea,

49. squamea, Wal.

50. verticillata, Nee.
Homauots,

51. auratus, Lin.

52. coeruleus, Fab.
LIMNERA,

53. exareolata, Bri.
MacroceEntrvs,

54, marginator, Nee.

PARASTIES AND INQUILINES MENTIONED IN THIS VOLUMK.

MeEcastiemus,
55. Bohemanni, Rtz.
56. dorsalis, Fab.

57. stigmaticans, Wal.
58. xanthopyzus, Foe.

MESOPOLOBUS,

59. fasciiventris, Wes.
NeEvROTERUS,

60. parasiticus. Har.
ODYNERUS,

61. trifascatus, Oli.
Ournx,
62. debilis, Gir.

63. Euedoreschus, Wal.

64. gallarum, Bou.

65. scianeurus, Rtz.

66. trilineata, May.
ORTHOSTIGMA,

67. gallarum, Rtz.
OryMRus,

68. punctiger,
PERICLISYUs,

69. Brandti, Cam.
PEzoMACHUS,

70. gallarum, Gir.
PLATYMESOPUS,

71. Erichsoni, Rtz.

72. tibialis, Bou.

73. Westwoodi, Rtz.
PLEUROTROPIS,

74. cyniphidium, Bri.

75. metallicus,

76. sosarmus, Fit.
Porizon,

7”. claviventris, Gir.
Poscts,

78. bipunctatus,
PrEROMALTS,

79. bisignatus, Gir.

80. cordairii, Rtz.

81. decidens, Wal.

82. delectus, Wal.

83. dissectus, Wal.

84. domesticus, Wal.

85. dubius, Wal.

86. Dufourii, Rtz.

87. Erichsoni, Rtz.

88. fasciculatus, Foe.

89. fuscipalpis, Fée.

PrrromaLus (contd.),
90. fuscipennis, Wal.
91. fusciventris, Wal.
92. gallicus, Rtz.

93. hilaris, Wal.
94. immaculatus, Gir.
95. incrassatus, Bur.
96. jucundus, Wal.
97. lecopezus, Ritz.
98. meconotus, Bri.
99. naubolus, Wal.
100. ovatus, Wal.
101. planus, Wal.
102. platynotus, Wal.
103. quercinus, Gir.
104, Ratzenburgi, Gir.
105. Saxesenii, Bur.
106. semifasciatus, Wal.
107. stenonotus, Rtz.
108. tibialis, Wal.

SAPHOLYTUS,

109. commatus, Htg.
110. connatus, May.
SIPHONURA,
111. brevicauda, Nee.
112. brevicaudis, Rtz.
113. chalybea, Rtz.
114. Schmidti, Rtz.
115. viridisnea, Rtz.

SYNTOMASPIS,

116. caudata, Wal.
117. caudatus, Bri.
118. crinicaudis, Rtz.
119. cyanea, Foe.
120. cyaneus, May.
121. dubius, Nee.
122. eurynotus, Fée.
123. fastuosus, Bou.
124. fastuosa, Wal.
125. lazulina, May.
126. regius, May.

SYNERGUS,

127. albipes, Bri.

128. apicalis, Bri.

129. erythrocerus, Htg.
130. facialis, Rtz.

131. incrassatus, Htg.
132. melanopus, May.
133. nervosus, Htg.

152 BRITISH OAK GALLS.

SyneReus (contd.), Torymus (contd.),
134, pallicornis, Bri. 158. corticis, Gur.
135. palliceps, 159. cultriventus, Rtz.
136. radiatus, May. 160. cyniphidum, Rtz.
137. Reinhardi, May. 161. erucarum, Gir.
138. ruficornis, Bri. 162. flavipes, Wal.
189. Thaumacera, Dal. 163. fuscicrux, Gir.
140. tibialis, Htg. 164, gallarum, Rtz.
141. tristis, May. 165. hibernans, May,
142. Tscheki, May. 166. incertus, Foe.
148. varius, Htg. 167. inconstans, Wal.
144. variolosus, Htg. 168. leptocerus, Wal.
145. vulgaris, May. 169. leucopterus, Wal.

TELENOMUS, 170. longicaudis, Rtz.
146. phalenarum, Bri. 171. minutus, Wal.

TETRASTICHUS, 172. muscarum, Nee.
147. atroceruleus, Gir. 178. mutabilis, Wal.
148. Diaphantes, Wal. 174. nanus, Foe.

149. quercus, Wal. 175. nobilis, Gir.
Torymvus, 176. propinquus, Foe.
150. abbreviatus, Boh. 177. pubescens, Foe.

151. abdominalis, May. 178. radicis, Gir.

152. amecenus, Lat. 179. regius (Devoniensis), Par.
153. appropinquans, Ritz. 180. regius, May.

154. auratus, Fon. 181. rubricipes,

155. autumnalis, Wal. 182. sodalis, Cam.

156. cingulatus, Nee. 188. variolosus, Bou.

157. confinis, Wal. 184. viridissimus, Bou.

The twenty-six continental forms of Oak galls of
which, according to Beyerinck, the sexual generations
are unknown, are: “ambigua, amblycera, argentea,
aries, caliciformis, caput-medusxe, conglomerata, coni-
fica, coriaria, coronaria, corruptrix, galeata, glutinosa,
Hartigi, hungarica, Kiefferi, lignicola, Mayri, mediter-
ranea, mitrata, Pantelli, polycera, Stefani, tinctoria,
tormentosa, truncicola”’ (‘ Marcellia,’ vol. i, p. 19).

153

A TABLE OF MONTHS IN WHICH THE BRITISH
GALLS ILLUSTRATED IN THIS VOLUME MAY BE
FOUND.

It indicates the months in which the gall-structures themselves
may be found, but does not necessarily imply that they will be in a
living condition, nor that the larve or pupe will always be within
them.

Name of maker of gall.

February.

March.

aoe:

fal

<_<

—

—

—_-

CYNIPIDE:
NDRICU s—

estivalis .
amenti
circulans .
cirratus
clementinze
ecurvator .
gemmatus
glandium .
glandule .
inflator -
lucidus
noduli
nudus
pilosus
ramuli
solitarius .
testaceipes

APHILOTHRIX—

albopunctata
autumnalis
callidoma. .
collaris
corticis
fecundatrix
globuli
Malpighii.

woe marginalis .
quadrilineatus

radicis
seminationis
Sieboldi .

BrorHiza—

aptera
renum

Cyrnips—

Kollari

[i libel «tld atl

| June.

| | #e ee ee] Heel HEH

ee xxx| | «*| *| *

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2/,\2)8
Bo) 8) ee cd
9/2/58 |8
2}o
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—|* |] * |]—
* | * | * | *
* | * |e | #
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F aan eee (eee (Hessen
a ee ee ee
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w | * | ® | €
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154

BRITISH OAK

GALLS.

Name of maker of gall.

January.

February.

April.

May.

June.

July.

CYNIPIDZ (contd.) :
' DryvorpHanta—

mom agama,

|... disticha

——~ divisa

— longiventris -

w= scutellaris

NEvROTERUS—
fumipennis
—~—— leviusculus
«eae lenticularis
—<. numismatis
—. ostreus
punctatus

xl SPATHEGASTER—
[~~palbipes .

— Aprilinus . ;

— baccarum .
similis .
Taschenbergi

wwe tricolor
verrucosus ‘

~we vesicatrix

TERas—
=e terminalis ‘

TRIGONASPIS—
crustalis
OTHER ORDERS:
ASTEROLECANIUM—
variolosum

CrcIpDoMYIA—
pustularis

bpraae one
dryobia

Dichana—
Sw quercina

eRe KK KK

* * KK

| | | #4" *

| August.

* * # * OK

| September,

xe * * |

* * * eK OK

|

| October.

ex «| |

| #* *|

| November,

| December.

155

A LIST OF MID-EUROPEAN OAK GALLS, WITH BRIEF
CHARACTERISTICS, AND POSITION THE GALL

OCCUPIES

ON THE TREE.

It is not improbable that some of these species may occur in

Britain.

Or AutHors’ NamgEs:

Fon. Fonscolombe.

Hartig. Kie. Kieffer.
Low. F. Low. May. Mayr. Nal. Nalepa. Rtz. Ratzeburg.

tendal. Tro. Trotter.

ABBREVIATIONS—

Bur. Burmeister, Can. Canestrini.

Tsc. Tschek. Wac. Watchl.

Foe. Fockeu.

Fre. Freymouth. Gir. Giraud. Hey. Heyden. Htg.
Kol. Kollari. Lic. Lichtenstein. Lin. Linneus.

Sch. Schlech-

Or CHaRacrERistics: Glab. glabrous. Greg. gregarious. Pedun. pedun-

culated. Pub. pubesc@mt. Pluri. plurilocular.

Uni. unilocular.

OF Position or GALL: up. s. upper-surface. un.s. under-surface. 1. leaf.
ax. axillary. t. terminal. un. g. underground.

The different species of Quercus are indicated by these figures :

1. pedunculata.

2. sessiliflora.

Sera. 'T. pseudo-suber.

3. pubescens. 4. cerris. 5. Ilex. 6, cocei-

Name Saad Be pee 8 Characteristics of gall, ee ph ed
CYNIPIDA:
ANDRICUS—
Adleri May. | Ovoid; 2mm. long; greg.; pub.;| Leat 4
uni.; red
ambiguus . Sch. | See flavicornis Catkin 1
Beyerincki Tro. | Conical; 2mm. high; pub.; uni.; 33 4
orange
burgundus Gir. | Elongate-oviform; 5 mm. long;|Ax.buds| 4
gree. ; reddish-brown
crispator . Tse. Globular; about 3 mm. diam.; Leaf 4
glab.; greg. ; yellow
Cydoniz Gir. | Lemon-shape; 12 mm. long; soli-| Ax.and| 4
tary ; sessile ; pluri. t. buds
fecundator — |?synonym of Aphilothriz fecunda- —= 1
tria
These species, and also A. ambi-
flavicornis Sch. guus and A. peduncult, possess Catkin 1
glabriusculus . all the features of Aph. quad- 35 1
rilineatus :
grossularize Gir. | Pyriform; 6-8 mm. long; greg.; és 4
glab.; green
hystrix Tro. | Globular; 2 mm. diam.; solitary;| Twig 1,4
uni.
Kirchsbergi Wat. | Globular; 3-5 mm. diam.; papil-| Bud 1,2
lated ; reddish-brown
lucidus Tro. | Globular; 10-15 mm. diam.; soli-| L. axil. | 1, 2
var. erinaceus tary ; fibrous projections ; pluri.
multiplicatus Gir. ‘| Ovoid; covered with distorted| Twigs |. 4
leaflets ; yellowish-brown /

156

BRITISH OAK GALLS.

Name a of Aubhor's Characteristics of gall. poole ope
CYNIPID& (cont).
ANDRICcUS (cont.)—
nitidus .| Gir. | Ovoid; 3 mm. diam.; solitary; | Un.s.1. 4
pilose ; uni.
occultus Tse. | Globular; 3 mm. diam.; greg.;; Catkin 3
uni.; brown
_Pantelli Tro Somewhat like Cynips coriaria ; ss 1
var. fructuum pluri. ‘
pedunceuli . Sch. | See flavicornis 53 1,2
petioli Htg. | Cylindrical; glab.; uni.; green Petiole | 1,2
Trotteri Kie. | Globular; 2 mm. diam.; greg.;/ Twig 3
glab.; pedun.; uni.
urneformis Fon. | Ovoid; striated; greg.; pedun.;| Up. s.1. 3
reddish-brown
superfetationis | Gir. | Ovoid; 5 mm. long; greg.; pub.;| Cupule |1,2,3
uni.
APHILOTHRIX—
lucida Htg. | Spherical; 12 mm. diam.; greg.;| Twig |1,2,3
pub.; pluri.; yellow 5
serotina May. | Ovoid; solitary; long hairlets; /Trunk,nr.| 1, 2
yellowish-brown ground
singularis . 4 Ovoid; 5 mm. long; pub.; uni.;/Ax.buds'| 4
green :
rhizomatis iss Conical; greg.; uni.; like A. Sieboldi| Near or | 1, 2
. un.
ground
BriorHiza — <
sinaspis Htg. | Globular; 5 mm. diam.; solitary; | Un.s.1.| 1,2
pedun.; uni.
Cyrnirps—
ambigua Tro. | A var. of C. conifica Branch 1
amblycera. Gir. | Very small; short conical projec-| L. axil | 1, 2
tions ; pub.; uni.
argentea . May. | Spherical; 17-30 mm. diam.; coro- 5 3
nated ; solitary ; uni.
aries . Gir. | Elongated; 5mm.at base; sessile;} L. bud | 1,2
; glab.; uni.
caliciformis 93 Globular; 5 mm. diam.; pub.; uni.;{ L.axil | 2,3
brown
calicis .| Bur. | See Plate LXI and p. 142 Cupule | 1,2
caput-meduse .| Htg. | Covered with numerous red, thread-| Fl. bud | 2,3
: like projections ; uni.
cerricola May. | Spherical; 25 mm. diam.; solitary | Twig 4
and greg.; uni.
conglomerata - Spherical; 7 mm. diam.; greg.; uni. ‘3 1,2,3
conifica 55 Irregular; furrowed; solitary;| Branch | 1,3
pub. ; uni.
conifica var. Tro. | Conical; 8-12 mm. high; sessile; ae 3
longispina furrowed ; solitary; uni.
coriaria .| Htg. | Irregular; covered with horn-like| Twig 1; 2
projections; solitary; pluri.
corruptrix Tro. | Globular; 6 mm. diam.; sessile; 5 1
var. ambigua solitary ; uni.

7

LIST OF MID-EUROPEAN OAK GALLS. 157
Suints ee of eee ‘ Characteristics of gall. ae pe pea
CYNIPIDE (cont.)
Cyrnips (cont.)—
exclusa Rtz. | Ovoid; 6mm. long.; glossy; glab.; Bud 1
uni.
, galeata Gir. | Bud-like; consists of two globular | Twig 1,3
portions, one containing larva
gemmea ie Globular; 4 mm. diam.; covered 2 1
: with papille; uni.
glutinosa . Pe Irregular; size variable; gluti- a 1,2,3
nous; greg.; reddish-yellow
glutinosa - Like the type; larger; glossy 55 1
var. mitrata
Hartigi May. | Spherical; 5 mm. diam.; covered| Bud 2
with conical projections
hungarica . ¥ Spherical ; 20-35 mm. diam.; soli- | Ax. bud 1
tary ; uni.
lignicola tes Globular ; 7 mm. diam.; solitary ;| Twig 1, 2
glab.; uni.
polycera Gir. | Campanulate; uni.; green L. axil | 2,3
polycera var. os Conical; 5-10 mm. high; sessile; | Small 3
subterranea greg.; pluri. roots
ramicola Sch. | Like A. Sieboldi Twig 3
tinctoria May. | See Plate LX and p. 141 L. axil | 2,3
truncicola i Spherical; 5 mm. diam. ; furrowed; Bud 3
uni.; brown
Dryrocosmus—
australis May. | Globular; 5-10 mm. diam.; glab.; | Edge of 5
uni.; green leaf
cerriphilus x Pyriform; 3 mm. long; greg.;| Twig 4
pedun.
DRYoPHANTA—
cornifex Htg. | Horn-shape; 4-6mm.long; greg.;| Un.s.1.| 3
uni.; green
folii . Lin Globular; 7 mm. diam.; solitary; Me 3
glab.; uni.
macroptera May. | Elongate-oval; variable size and| Twig 4
form ; solitary ; pluri.
NEvUROTERUS—
Januginosus Gir. | Spherical ; 5 mm. diam.; pub.;| Un.s.1. 4
greg.; uni.
minutulus os Spherical; 2 mm. diam.; greg. ; 5 4,7
glab.; uni.; reddish-brown
saliens Kol. | Ovoid; 3mm. long; greg.; glab. ; 5 4, '7
green
saltans. .| Gir. | “The jumping gall” —_ 1,2,3
Schlechtendali .| May. | Very small; pedun.; glab.; uni.;| Catkin |1,2,3
Ws : : ~green ~ ~~
PLagioTRocHUsS—|
cocciferea . Lic. | Sub-globose; 4-8 mm. diam.;| Un.s.l.| 6
woody ; pluri.; brown
ilicis . bs Sub-globose; irregular size; pluri.| Leaf 5

158

BRITISH OAK GALLS.

|Author’s

Name a of anaes Characteristics of gall. eee Rpeese
CYNIPID A (cont.)
SPATHEGASTER— 3
Giraudi Tse, | Ovoid; 3mm. long; solitary; pub.;| Ax. bud| 3
uni.
glandiformis Gir. |Globular; 7 mm. diam.; pub.;| Catkin | 4
pluri.; red
nervosa 3 Globular; 7 mm. diam.; solitary;| Leaf 4
pub.; uni.; green
SYNOPHRUS —
politus Htg. | Globular; 15 mm. diam.; uni.;| Ax. and 4
yellow, with white spots t. buds
DIPTERA :
ARNOLDIA— ee
Szepligetti Kie. | Small lenticular pustules Leaf 7
Crcrpomr1a—
cerris Kol. | Conical; 2mm. high; greg.; pub.;| Un.s.1.| 4
uni.
circinnans Gir. | Like Cee. cerris; about three times se 4
larger
Lichtensteini Léw. | Ovoid pustules; greg. 3 5
ConTARINIA—
ilicis . Lic. | Conical; 5 mm. high; sessile;| Un.s.1. 5
glab.; uni.
Dirrosis—
sp.?. — |Conical; 3-5 mm. high; “nail- ey 1
like”; glab.; uni.
Drromy1a—
circinnans Gir. |} 5 : 4
Lichtenstein Law. | ? Synonyms of Czcipomy1a — 5
HEMIPTERA : :
PHYLLOXERA—
coccinea Hey. | Rolled lobes of leaf, and swelling | Leaf 1
of mid-rib and nerves
LEPIDOPTERA : -
HELI0zELA—
stanneella. Fre. | Small; half only of twig affected; } Twig 3.
reddish-brown
ERIOPHYIDA:
EPiItRIMERUS—
cristratus . Nal. | Lobe-margins turned under, rolled | Leaf 3
and thickened
massalongoianus| Nal. | Small pale-coloured scabrous spots i 3

on leaf

BRITISH OAK GALLS. 159

The following galls are also mentioned by various Continental authors,
but without descriptions :

ANDRIcUs— Cyrnies (cont.)— ARNOLDIA—
Cecconit. mitrata. cerris.
pseudo-inflator. Stefanii. homocera.
rufescens. tinctoria-nostras.
suffator. tormentosa. Czcipomy1a—

Tozex. subulifen.

Crnips— F NrEvroTrerus— galeate.
coronaria. glandiformis. quercus, —
Kiefferi. pustularius.
Mayri. TRIGONASPIS—
mediterranea. synaspis. etc., etc.

Galls caused by Crnips Kouuari, Hartig.
Exhibiting ridges, papille, and styles.

PLATE XXXvV.

1, 2, 3. Galls caused by Cynips TINcTORIA with ridges and papille, intro-
duced to show how closely they resemble those of C. Kollari (of.
Plate LX, div. B).

The remainder are English specimens.

4, 5, 8,16. With well-defined ridges and papille like those on 1, 2, 3.

6 to 15. Well-defined papille only.

17, 18. A single style only on each.

19, 20, 21. A style and papille on each.

22. Large papille and ridge.

23 to 27. Very large single papille.

28. A specimen similar to 27, with papilla pointing towards observer.

29 to 33. Coalescent papille.

The point of attachment of each gall to the twig on which it grew, is
immediately above the figures, except in 29 to 33, where it is on the right-
hand side.

The specimens have been selected from amongst several thousands.
Unfortunately they do not look so remarkable as they really are, partly
because they are only two-thirds natural size, and much detail is lost in the

photograph.

160 BRITISH OAK GALLS.

Aberrant examples of galls of Crnips Kotuart, Hartig.

PLATE XXXVI.
SINGLE GALLS:
1. A very large globular specimen, 27 mm. in diameter.

2A typical normal globular specimen, 21 mm. in diameter, with three
beneath it dwarfed by parasites.

3. A cluster of five in various stages of development.

4, 5, 6. Pyriform in shape.

7, 8. Fully-grown but tenanted by parasites. Note distinct sharp style on
each gall.

9. Developing in a forked twig. 10. Developing in a recurved twig.
11. A similar specimen. The twig continues as in No. 10.

12, 18, 14. Distorted by same cause. Appearance as though pinched between
finger and thumb.

15. A normal specimen with rough brownish exterior.

16. A normal specimen with smooth buff exterior.

17. Completion of development entirely prevented by fungus.

18, 19, 20. Completion of development partly prevented by fungus.
21. Three galls on one twig greatly deformed.

22. One gall splitting into three parts.

CoaLEscent Forms:
23 to 37. Twin growths, unequal in size.
38, 39, 40. Each of these contain two larval cells.

41, 42. Co-equal in size, attached to twig where joined to each other (42 isa
very fine example).

43, 44, Co-equal in size, one only attached to twig ; 31, 32, the same also.
45, 46, 47. Each contain three larval cells.
48, 49. Each contain four larval cells.

31, 32, 43, 44, are interesting from the fact that only one gall is attached
to the twig; such forms are not common.

In the case of specimens without twigs, the point of attachment of the
gall is immediately above the figures, except 45, 46, 47, where it is on the
right-hand side, and 49 on the left-hand.

BRITISH OAK GALLS 161

The extraordinary manner in which some galls of Cynips Kollari grow in
geometrical, and in peculiarly-arranged groups, is exemplified in

PLATE XXXVII.
GROUP:
1, 2. Three’s. 3to8. Four’s. 9,10,11. Five’s.
12. Two two’s coalescent, one single.
13. Two coalescent, three single.
14. Two coalescent, four single.

Fourteen groups comprising sixty-one galls.

The conglomerate clusters they form are also remarkable ; a few are shown on

PLATE XXXVIII.

CLUSTER :
. Two galls coalescent and seventeen single.
. Two two’s coalescent, three coalescent, and seven single.
. Three two’s coalescent and four single.
Three two’s coalescent and eleven single. :
. Twelve single.
. Nine single.
. Three coalescent and eleven single.

DARA RON

. Eleven single.
Eight clusters comprising one hundred and six galls.
A few galls are obscured by those nearest to the observer.

11

INDEX

Words in italics are names of genera or species; figures in
italics refer to synonyms; figures in thick type indicate that the
reference relates to systematic position.

Acorns, planting of, 35
Activity of cambium layer, 2
Adler, Dr. Hermann, on: gall-forma-
tion, 3; Cynipide ovipositing, 29;
inquiline laying egg in immature
gall, 80; rearing imago of Aphi.
quadri., 91. Appearance of ima-
gines: of Bior. aptera, 99; of Dryo.
scutellaris, 115; ovipositing of
Bio. aptera, 20, 100. Colour of
Spathe. similis, 131; of 8. Taschen-
bergi, 1382
Agamous generations, 49
Aleppo gall, The, 141
Alternating generations, xviii
Andricus zstivalis, 50
albopunctata, 73
ambiguus, 90
amenti, 51
autumnalis, 75
burgundus, 108
callidoma, 77
circulans, 52, 108, 108;
[ galls of, resembling those
of burgundus, 53
cirratus, 53, 77; distin-
guished from A. ramuli,54
clementine, 55; compared
with Aphi. globuli, 56
collaris, 79

Andricus corticis, 80
» curvator, 56,79; extremely
abundant, 57; ovipositing
in Lammas shoots, 58;
peculiarities of, 5; rapid
growth of, 57
P dimidiatus, 56
» disticha, 110
» fecundatriz, 82
» flavicornis, 90
by gemmx, 82
» gemmatus, 58, 81
» glabrusculus, 90
» glandulz, 60; distinetiveap-
pearance of, 61; gallsof,62
» glandium, 59; remarkable
feature in, 59
» globuli, 86
» ‘imflator, 63; exceptions to
rule in, 4
» lucidus, 64
> lucida, 64
ee marginalis, 89
» Malpighii, 87, 67
a noduli, 65,92; on Q. pubes-
cens, 66
» nudus, 67, 87
ostreus, 123
» pedunculi, 90
» perfoliatus, 56

12

164

Andricus pilosus, 67, 88
Be quadrilineatus, 90
ee radicis, 91
» vramuli, 68,76; hairs of, 69 ;
rapid maturity of, 69
» vrufescens, 59
» WSteboldii, 71, 94, 95
» solitarius, 70
» terminalis, 137
» testaceipes, 71, 95; galls of,
72; doubtful identity of,
72; Adler’s experiments
with, 72
» trilineatus, 65
» verrucosus, 90
Anthoxanthin, 8
Aphilothriz albopunctata, 73, 73;
galls of, 74; rapid
growth of, 74
es autumnalis, 75, 68
- callidoma, 54, 77; ele-
gant shape of, 77:
length of, 78; ridges
upon, 78
3 clementinz, 55
‘ collaris, 79; quickest
way to discover, 79;
galls of, 80
“a corticis, 58, 80; aggre-
gations of, 81; situa-
tions of, 82
“ disticha, 110
3 Secundatrix, 82, 68 ; pe-
culiarities of, 5; per-
sisting of, 85; shape
of leaf-scales, 83; the
pip, 84; variations in

form, 84
5 gemmex, 82
“A glandulx, 60
‘3 globuli, 63, 86; favour-

ite situations of, 86;
composition of, 87

lucida, 64
~ Malpighii, 67, 87; galls
of, 88; apparently

rare, 88

INDEX.

Aphilothriz marginalis, 89
Cameron on, 89
33 quadrilineatus, 90; great
variation in, 90; re-
gularity of appear-
ance of, 90
a radicis,65,91; numerous
larval chambers, 93;
typical situation of,
92; variable size of, 93
seminationis, 94
Sieboldi,71, 95; attacked
by tits, 98; first British
record of, 95; fondness
of ants for, 97; galls
of, 98: habitat of, 96;
red colour of, 96; shape
of, 97; substance of,
97
Pe solitaria, 70
Asterodiaspis quercicola, 146
66 variolosus, 146
Asterolecanium variolosum, 146
Aulax hypocheridis, gall of, 2
Autumn galls, weight of, 23

Beyerinck, W. W., on Cynips Kollari,

108
Biorhiza aptera, 98,188; condition
of growth of, 99; distin-
guished from A. radicis,
99; number of ova of, 21,
100 ; on roots; of Deodars,
100; of Fagus, 100; of
Prunus, 100; of Vitis vini-
fera, 100
a, renum, 101, 1389; distin-
guishing features of, 101;
imagines difficult to rear,
102; number on leaf, 22
terminalis, 98, 137
Black truffle, The, 94
Bloomfield, The Rev. E. N., M.A.,
explanatory notes of, xvi
Browne, Sir Thomas, M.D., quotation
from letters of, xv, xvii

INDEX.

British Oak, The, 33; growth of
seedlings of, 34; variation of
growth, 34

British Oak Galls, History of, xv

British Phytophagous Hymenoptera,
Monograph of, xviii; quotation
from vol. iv, 125

Cambium layer, The, nature of, 1 ;
activity of, 2

Cameron, Peter, on: Biorhiza aptera
ovipositing, 27; gall formation, 3;
gall of Andricus amenti, 52; Aphi-
lothria collaris,79; A. marginalis,
89; Neuroterus punctatus, 125;
inquilines in gall of Andricus tes-
taceipes, 72

Carpocapsa juliana, 85

Cecidomyia Lichtenstinii, 145

Charcoal from oak wood, 37

Coccus quercicola, 146

» variolosum, 146

Collecting oak galls, 42

Colours of galls, 7

Complex structure of galls, 6

Component parts of galls, 5

Contarinia Ilicis, 145

Cotyledons absorbing water, 35

Cynipide, The, as gall producers, 26 ;
as gall-wasps, xiv; as parasites,
26; accurate deposition of ova, 23;
affecting the oak, 26; alternate
generations of, 49; a. g. not con-
fined to, 30; cling with tenacity,
27; beautiful metallic colours of,
28 ; bi-sexual reproduction of, 31;
difficult to rear, 27; larve of, 30;
lethargic habits of, 27; method of
oviposition, 29; non-sexual repro-
duction of, 31 ; number of ova of,
29; ovum of, 29; pupa of, 30;
terebra of, 28

Cynips agama, 108

albopunctata, 73

aptera, 98

autumnalis, 75

axillaris, 56

or

”

22

2

165

Cynips calicis, 143

callidoma, 77

cerricola, 143

clementineg, 55

collaris, 79

conglomerata, 105

corticalis, 95

corticis, 80

crustalis, 139

curvator, 56

disticha, 110

divisa, 112

fasciata, 79

fecundatrin, 82

Serruginea, 70

folit, 115

4-lineatus, 90

galeata, 144

gemme, 82

glandulz, 60

globuli, 86

inflator, 68

inflorescentiz, 94

Kollari, 52, 102; Beyerinck
on alternate generation
of, 108; first appearance
in England of, 103; fun-
gus on, 107; growth of,
106 ; most durable British
gall, 6; ovaries of, 21;
possesses no male, 32 ; pro-
tuberances on, 107; sessile
and axillary, 107; simila-
rity to three continental
forms, 105; structure of,
6; tannin in, 104.

lenticularis, 120

lignicola, 102, 105,

longiventris, 113

lucida, 64

majalis, 73

marginalis, 89

megaptera, 139

numismatis, 122

quercus baccarum, 120, 129
» folu, 115
» petioli, 102

166

Cynips quercus-ramuli, 68
-terminalis, 98, 137
4s » -tiare, 122

» vradicis, 91

» ramuli, 68

» scutellaris, 115

» seminationis, 94

» Sieboldi, 95

» tegmentorum, 79

» tinctoria, 102, 105, 108, 141

2» we

Dichena quercina, 148

Diplolepsis solitarius, 70

Diplosis dryobia, 147

» Ltebeli, 147
» Sp. 145
Dryocosmus Australis, 145
Dryophanta agama, 108; gall of, 109;
shape of, 109; texture
of, 110
o disticha, 110; gall of,
109; apparently rare,
110; not mentioned by
Adler, 111; three as-
pects of gall of, 111
33 divisa, 112, 134, 134;
gall of, 109; distin-
guished from agama,
112; number on leaf,
22; profusion of, 113
folii, 115
longiventris, 113, 1381;
delicate coloration of,
114; peculiar shape
of, 114; three aspects
of gall of, 114.

% scutellaris, 115,132; Ad-
ler on flies of, 115;
beauty of, 116; com-
position of, 116

33 Taschenbergi, 1382

a verrucosa, 134

English name of gall, The—
Acorn, 59
Apple, 137
April bud, 127

INDEX.

English name of gall (contd.), The—
Artichoke, 83
Autamn, 75
Bark, 80
Bald seed, 67
Barley-corn, 94
Blister, 135
Bristley, 64
Bud, 58
Cherry, 115
Collared bud, 79
Common spangle, 120
Cotton, 68
Cotyledon, 59
Cup, 50
Cupped spangle, 117
Current, 129
Curved leaf, 56
Devonshire, 102
Furrowed catkin, 90
Globular, 86
Green velvet-bud, 131
Hairy catkin, 51, 67
Hairy pea, 133

» spindle, 70
Hop, 83

» Strobile, 83
Kidney, 101
King Charles’ apple, 137
Knot, 65
Larch cone, 83
Leaf-vein, 71
Little acorn, 60
Malpighi’s, 87
Marble, 102
Marginal, 89
Oak apple, xvi, 137

, marble, 102

» nut, 102
Oyster, 124
Pink wax, 139
Pointed pea-bud, 55
Purple velvet-bud, 132
Red barnacle, 95

» pea, 112

» wart, 1384
Root, xvi, 98

INDEX.

English name of gall (contd.), The—
Schenck’s, 126
Silk button spangle, xvi, 122
Smooth spangle, 118
Spotted bud, 73
Stalked spindle, 77
Striped, 113
Thatched, 60
Truffle, 91
Tufted, 53
Turkey-oak bud, 52
Twig, 63
Two-cell, 110
Woolly, xvi, 68
Yellow pea, 108
‘ Entomologist,’ The, for 1874 to 1878,
xvii
Epitrimerus cristratus, 147; dimen-
sions of, 147
Equipment for gall collecting, 40
Eurytoma rose in fourteen galls, xiv
Evergreen oak, The, 39

Fitch, E. A., Notes by, in ‘ The
Entomologist,’ xvii

Gall, definition of word, 48

Gall-flies, xiii
» -gnats, xiii

-midges, xiii

-wasps, xiv; diminutive size of,
20

Ground birds feeding on spangle
galls, 19 :

a

2

Hints on collecting and mounting
oak galls, 40

Ink, from a Chinese gall, 142
from a Japanese gall, 142
» how manufactured, 142
» marble, 141
Inquilines in oak galls, 150-152

»

Knopper gall, 143

Lammas shoots, 36

167

Mayr, Dr. G. L., translation from,
xvii; opinion on Neuroterus numis-
matis, 122

Megastigmus dorsalis in eleven galls,
xiv

Modifications in development due to
environment, 17; external in-
fluences, 16; inquilines, 17; in-
ternal influences, 17; overcrowd-
ing, 16

Mounting oak galls,suggestions for,43

Neuroterus albipes, 126
Aprilinus, 127
‘ss baccarum, 129
a fumipennis, 117, 120, 133 ;
gall of, 121; profusion
of, 117; typical condi-
tion of, 118; weight of,
23
leviusculus, 118, 120, 126;
gall of, 119, 121; out-
line of gall of, 119
“ lenticularis, 120, 129,130;
gall of, 121; ovipositing
of, 21; weight of, 23
#8 Malpighii, 120
numismatis, 122, 135,136;
Mayr’s opinion of, 122;
number on leaf, 22;
Swanton’s observations
on, 123
ostreus, 123, 128; rapid
growth of, 124 ; number
on leaf, 22
pezizeformis, 118, 120
punctatus, 125
Reaumuri, 122
Schlechtendali, 127
tricolor, 133
é vesicatria, 185
Numerousness of Autumn galls, 22
Newbigin, Dr. Marion, on colours, 7
Newman, E., on Cynips Kollari, 103
Oak bark, 37
galls, aberrations of, 13; begin-
ning of growth, 4; conditions

22

a7

168

of growth, 2; colours of, xiii;

dissimilarity of shapes of, 12;
duration of growth, 10; early
development, 3; modifications
in, 16; numerical aspect of,
20; positions occupied by, 11;
preservation of, 44; rapid
growth of, 10; resemblance to
Continental forms, 12; simi-
larity of growth of, 11; slow
growth of, 10; smell of, 18;
taste of, 18; variations—in
colour, 15; in shape, xiii; in
size, 14; in texture, 15
Oak leaves, colours of, 38
» tree, flowers of, 37; leaves of,
87; primary root of, 35
» wood, annular rings of, 37;
properties of, 36
Opegraph quercina, 148

Parasites, 150-152
Phloém, The, 1
Phoma gallorwm, 107
Pit-making oak coccid, 146
Plagiotrochus Llicis, 145
Planchonia fimbriata, 146
- quercicola, 146
Principles of oak gall formation,
The, 1

Quereus cerris, 88; bitterness of
acorns of, 39; scales on
cupule of, 38

5 Ilex, 39, 144; colour of
wood of, 39; rapid growth
of, 89

pedunculata, 84; observa-
tions on growth of, 36

*3 pubescens, 144

3 robur, 33; the type of oaks,
33

intermedia, 34

pedunculata, 34

55 » sessiliflora, 34

5 sessiliflora, 34

55 terminalis, 102

oe 2

2 ”

INDEX.

Saphylotus connatus, 126
Sexual generations, 49
Simplest forms of galls, 5
Some features of oak gall growth, 9
Spathegaster albipes, 118, 119, 126;
coinciding with some
Andricus species, 126
‘Aprilinus, 124, 127;
unequal rapidity of
growth of, 128
ee baccarum, 120, 129;
appropriateness of
name of, 180; extra-
ordinary abundance
of, 180
rr floseuli, 132
3 Giraudi, 132
Pr interruptor, 120, 129

5 punctatus, 125

3 similis, 114,131; Adler
on, 131; rarity of,
131

5 Taschenbergi, 116, 132;
beauty of, 132

5 tricolor, 117, 133; acid
flavour of, 133

55 various, 117, 120, 133

i verrucosa, 134

- verrucosus, 112, 134;
Adler on, 134; galls
of, 185

35 vesicatria, 122,122,135;

gall similar to, 137;
radii on surface of,
136
Southwell, Thomas, F.Z.S., xv
Steenstrup, J. J. S., on alternate
generations, 31
Straton, C. R., M.D., translation by,
xviii
Swanton, E. W., observations on red-
currant gall, 24; of Neuroterus
numismatis, 128; on abundance
of galls, 24
Synergus facialis in ten galls, xiv
» vulgaris in nine galls, xiv

INDEX.

Tannin in plants, 142
Tephritis bardane, xiii
Teras amentorum, 68
» terminalis, 98,99,137; autumn-—
winter condition of, 1388;
numerous creatures in gall
of, 18; first reference to, xv
Terms employed in the synoptical
tables, 46
Thistle stems, xiii
Trail, Dr., first to discover Spathe-
gaster vesicatrix, 136
Trigonaspis crustalis, 101, 139; bit-
terness of, 140; mode
of growth of, 140; un-
usually succulent, 139

169

Trigonaspis megaptera, 101, 139
55 renum, 101, 139
Tuber melanospermum, 94
Turkey oak, The, 38
Twenty-six Continental oak galls,
152

Urophora solstitialis, xiii

Walker, Francis, notes in ‘ The Ento-
mologist,’ xvii

Weight of autumn galls, 23

Winter, W. P., on pink’ cotyledons,
25

Xylem, The, 1

ADLARD AND SON, IMPR., LONDON AND DORKING.

PLATE II.

iE
!

Oak wood, showing the difference in appearance of the various sections.
Nat. size.
A. Transverse section (a cross grain, 3B. Vertical radial section (quar-
horizontally as the tree stands). tered, showing silver grain).
c. Vertical tangential section pv. Vertical section in a direction
(plankwise). between Band c.
Photo-micrographs by A. DEANE.
Adlard § Son, Impr.

PLATE III.

The fruit and leaves of

A. Quercus pedunculata. B. Q. sessiliflora,

Adlard J: Son, Impr-

PLATE IV.

The fruit and leaves of
A. Quercus cerris. B. Q. Ilex (fruit immature).

Adlard g- Son Impr.

PLATE V.

Galls caused by
A. ANDRICUS mstivaLis. After Mayr. 1. Lumature. 2. Vertical section.
Nat. size.

B. 35 AMENTI. After Cameron. Twice nat. size.

c. 3 cincuLans. After Mayr. Nat. size.

D. es CLEMENTINE. After Mayr. Nat. size. 1. Vertical section.
E. 33 GEMMAtTus. After Mosley. Nat. size.

FP. ; Lucipus. After Mayr. 1. Transverse section.

Adlard 4° Son, Impr.

PLATE VI.

Galls caused by ANDRICcUS cURVATOR on leaves of Q. pedunculata.
Four-fifths nat. size.

Adlurd §- Son, Impr.

PLATE VII.

A. Autumn-winter condition of galls caused by ANDRICcUS CURVATOR.
1, 2, 3, 6, 7, on twigs; 2, 4, 5, on leaf petioles.
s. A fine specimen of the same species.

Adlard &- Son, Impr.

PLATE VIII.

Galls caused by ANDRICUS GLANDIUM in acorns of Q. cerris.
Four-fifths nat. size.

Adlard §- Son, Impr.

PLATE IX.

A. Galls caused by ANDRIcUS GLANDIUM in acorns of Q. pedunculata.
s. Autwnn-winter condition of twigs containing galls (old) caused by
ANDRICUS NODULI.

Nearly nat. size.

Adlard §- Son, Impr.

PLATE X.

Galls caused by ANDRICUS GLANDUL# in leaf-buds of Q. pedunculata.
The specimen in inset is x 23.

Nearly nat. size.

Adlard § Son, Impr.

PLATE XI.

1.4)

Galls caused by ANpricus Inruator: a. Early spring condition. B. Late
spring condition. c. Summer condition. 1 and 2. Longitudinal sections
showing cylindrical cavity, arrow indicating the larval cell.

A and B nearly nat. size. c half nat. size.

Adlard 4: Son, Impr.

PLATE XII.

Galls caused by ANDRICUS NoDULI in twigs of Q. pedunculata.

A. Normal condition of twig. 8. Bark peeled off to expose galls. c. Por-
tion of twig B between transverse lines x 29.
a and B nearly nat. size.

Adlard § Son, Impr.

PLATE XIII. :

Galls caused by: a. AnpDRIcUS NUDUS; B. A. PILOSUS; C. APHILO-
THRIX QUADRILINEATUS; on staminate catkins of Q. sessilijlora.
A, nearly nat. size. B,c, x 2h.

Adlard § Son, Impr.

PLATE XIV.

Galls caused by ANDRICUS RAMULI on staminate catkins of Q. sessiliflora.
The inset is a gall caused by ANDRICUS CIRRATUS on staminate catkins
of Q. sessiliflora.

Both nearly nat. size.

Adlard 4 Son, Impr.

PLATE XV.

Galls caused by AnpRicus sonrrarius in leaf-buds of Q. pedunculata.
The inset is a typical specimen x 2}.

Three-fourths nat. size.

Adlard g- Son, Impr.

PLATE XVI.

Galls caused by ANDRIcUS TESTACEIPES in mid-rib on under surface of
leaves of Q. pedunculata.

Arrows indicate positions of galls.
Nearly nat. size.

Adlard § Son, Impr.

PLATE XVII.

Lid nn eC Bm.

|

Galls caused by APHILOTHRIX ALBOPUNCTATA in leaf-buds of
Q. pedunculata,
a, All nearly nat. size. 3B. The specimen marked *

x 23. c. A young
gall pushing through leaf-scales, x 5.

Adlard 4° Son, Impr.

PLATE XVIII.

Galls caused by APHILOTHRIX CALLIDOMA on twigs of Q. pedunculata.
The inset is of a specimen which grew ten feet above ground level.
Nearly nat. size.

aAldlard §- Son, Impr.

PLATE XIX.

is

Gall caused by APHILOTHRIX CORTICIS on moss-covered bole of
Q. pedunculata,
A. One young gall. B. Eight mature galls. c. After the imagines have
left the galls.
Nearly nat. size.

Adlard § Son, Impr,

PLATE XX.

Galls caused by APHILOTHRIX FECUNDATRIX in leaf-buds of Q. pedunculata.

Arrows indicate two galls emerging from among the leaf-scales.
Three-fourths nat. size.

Adlard g Son, Impr.

PLATE XXII.

Galls caused by APHILOTHRIX FECUNDATRIX in leaf-buds of Q. pedunculata.
The arrow indicates a gall emerging from among the leaf-scales.
The letters are referred to on pp. 84 and 85.
Four-fifths nat. size.

Adlard g- Son, Impr.

PLATE XXII.

A. Autumn-winter condition of galls caused by APHILOTHRIX CORTICIS.

gs. Winter-spring condition of galls caused by APHILOTHRIX
FECUNDATRIX.
Nearly nat. size.

Adlard §& Son, Impr.

PLATE XXIII.

Galls caused by: a. APHILOTHRIX MaLpuicir; B. A. AUTUMNALIS ;

c. A, GLOBULI; in leaf-buds of Q. pedunculata.
c, Spring-summer condition.

Nearly nat. size.

aAdlard & Son, Impr.

PLATE XXIV.

Galls caused by :
A. APHILOTHRIX MARGINALIS on leaves. (Past maturity.)
B. APHILOTHRIX SEMINATIONIS on staminate catkins of Q. pedunculata.
Both nearly nat. size.

Adlard g¢ Son, Impr.

PLATE XXV.

Galls caused by APWILOTHRIX QUADRILINEATUS on staminate catkins of
Q. pedunculata. Nearly nat. size.
The inset is of two galls x 4.

Adland §: Son, Inpr.

PLATE XXVI.

Galls caused by APHILOTHRIX RADICIS.
A. Section of mature gall, showing larva cells. B. Quadripartite specimen
in growing condition.
Nearly nat. size.

Adlard § Son, Impr.

PLATE XXVII.

Galls caused by APHILOTHRIX SimBoLp1 on twigs of Q. pedunculata.
Summer-autumn condition.
Nearly nat. size.

Adlard 4 Son, Impr.

PLATE XXVIII.

A bifureated shoot of Q. pedunculata, bearing numerous galls caused by
APHILOTHRIX SIEBOLDI, most of which are partly or wholly concealed
beneath a thin layer of earth formed by ants. A quantity of earth
also fell away when the shoot was cut.

Nearly nat. size.

Adiard & Son, Impr.

PLATE XXIX.

The same specimen as shown on Plate XXVIII, with the earth removed.

Adlard JS’ Son, Impr.

PLATH XXX,

A. B.

A. Gall caused by APHILOTHRIX RADICIS in an uncommon situation.
B. Galls caused by APHILOTHRIX SrEBoLDII in growing condition,
Nearly nat. size.

Adlard § Son, Impr.

PLATE XXXI.

Gall caused by Brorwiza apreRa on roots of Q. pedunculata,
Nearly nat. size.

Adlard §& Son, Impr.

PLATE XXXII.

A. Apical bud of Q. pedunculata containing ova of BloRHIZA APTERA, x 23.
Bb. Three ova removed from the bud, x 280.
c. Transverse section through the bud to show ova in situ, x 60.

sand c. Photo-micrographs by W. H. Hammond.

Adlard Ss Son, Impr.

PLATE XXXII.

Exposed roots of Q. pedunculata in Park Road, St. Leonards-on-Sea, wpon
which were found enormous numbers of galls caused by Brorwiza
APTERA. The scale (marked *) is 30 em.; the fern trowel indicates
where specimens in Plate XXXI were growing.

Adlard §* Son, Impr.

PLATE XXXIV.

Galls caused by BiorH1zA RENUM on under-surface of leaf of Q. pedunculata,
Nearly nat. size.

Adlard §- Son, Impr.

PLATE XXXV.

25. 26,
HU TTHTAENCTCHN EAN A
aM 10 20

32°

33.

Galls caused by Crnips KOLLARI, exhibiting ridges, papille, and styles.
Two-thirds nat. size.
For explanations see p. 159.

Adlard § Son, Impr.

PLATE XXXVI.

Galls caused by Cyrnips KOLLARI (aberrant examples).
y

Half nat. size.
For explanations see p. 163.

Adlard § Son, Impr.

PLATE XXXVII.

Galls caused by Cynips KOLLARI (geometrically-grown groups).
Two-thirds nat. size.
For explanations see p. 161.

sldlard §- Son, Impr.

PLATE XXXVIII.

ae “)

Galls caused by Cynirs Koxiarr (conglomerate clusters).

Half nat. size.
For explanations see p. 161.

Adlard §- Son, Impr.

PLATE XXXIX.

Galls caused by Cynips Koxtiari. a. Attacked by the fungus Puoma
GALLORUM. B. A specimen from which thirty-two inquilines have
emerged and one Cynips Kotiari; their holes are indicated by pins and
a match stick respectively. c. Specimens tenanted by parasites and
growth arrested thereby. d. A normal specimen for comparison.
e. Sections showing larva cells.

Specimen a x 2}. Band c nearly nat. size.

Adlard §- Son, Impr.

PLATE AL.

Galls caused by DryopHaNnTA AGAMA on under-surface of leaves of
Q. pedunculata.
The inset is of specimen x 2}.

Nearly nat. size.

Adlard g- Son, Impr.

PLATE XLII.

Galls caused by DryopHANTA DISTICHA on under-surface of leaves of
Q. pedunculata. The inset is of specimens x 2}.

Two-thirds nat. size.

Adlard § Son, Impr,

PLATE XLII.

Galls caused by DRYOPHANTA DIvISA on under-surface of leaves of
Q. pedunculata.

The inset is of specimens x 2}.
Two-thirds nat. size.

Adlard g- Son, Impr.

PLATE XLIII.

Galls caused by DRYOPHANTA LONGIVENTRIS on under-surface of leaves
of Q. pedunculata.

The inset is of a specimen x 2}.

Four-fifths nat. size.

Adlard 4 Son, Impr.

PLATE XLIV.

Galls caused by DryoPHANTA SCUTELLAEIS on under-surface of leaves of
Q. pedunculata,

The inset is of a specimen on upper-surface of leaf.
Nearly nat. size.

Adlard §- Son, Impr.

PLATE XLV.

Galls caused by DryopHANTA SCUTELLARIS on under-surface of leaves of
Q. pedunculata.
Nearly nat. size.

From. St. Goar’s, Haussen, o/n Germany.

Adlard § Son, Impr.

PLATE XLVI.

Galls caused by NEUROTERUS FUMIPENNIS on under-surface of leaf
of Q. pedunculata.

Nearly nat. size.

Adlard §& Son, Impr,

PLATE XLVII.

Galls caused by NEuROTERUS L#VIUSCULUS on under-surface of leaves of
Q. pedunculata,

The inset is of galls on leaf marked *
Four-fifths nat. size.

Adlard §- Son, Impr.

cpa: aL,

Galls caused by NEUROTERUS LENTICULARIS on under-surface of leaf of
. Q. pedunculata.

Four-fifths nat. size.
The inset is of a very pilose specimen, x 8. Photo. by A. W. BawTREE.

Adlard § Son, Impr.

PLATE XLIX.

Galls caused by NeurorERUS NUMISMATIS on under-surface of leaf of
Q. pedunculata,
Four-fifths nat. size.

The insets are of specimens x 12. Photos. by A. W. BAWTREE.

Adlard g- Son, Impr.

PLATE L.

Galls caused by NevRorERuS osTREUS on leaves of Q. pedunculata.
a. On under-surface. B. On upper surface.
The inset is of a specimen x 23.

Four-fifths nat. size.

Adlard §- Son, Impr.

PLATE LI.

Galls caused by SpATHEGASTER ALBIPES on leaves of Q. pedunculata.
Arrows indicate the positions of six galls.
The inset is of a specimen x 2}.
Four-fifths nat. size.

Adlard 4: Son, Impr.

PLATE LII.

Galls caused by :
A. SPATHEGASTER APRILINUS, in buds of Q. pedunculata; x indicates a
galled bud, * longitudinal section.
B. S. stmiuis, hairless and dry.

c. 8. TascHENBERGI on adventitious buds of Q. pedunculata. The inset
is of those specimens immediately above it, x 2}.

Nearly nat. size.

Adlard § Son, Impr.

PLATE LIII.

Galls caused by SparHEGASTER BACCARUM.
A. On leaves. B. On staminate catkins of Q. pedunculata.

Adlard §- Son, Impr.

PLATE LIV.

Galls caused by SPATHEGASTER TRICOLOR on under-surface of leaves
of Q. pedunculata.

Nearly nat. size.

Adlard & Son, Impr.

PLATE LV.

Galls caused by SPATHEGASTER VESICATRIX on leaves of Q. pedunculata.
Arrows indicate the positions of eight galls.

The inset is a specimen x 2},
Nearly nat. size.

«ldlard § Son, Impr.

PLATE LVI.

| Galls caused by TeRAaS TERMINALIS ontwigs of Q. pedunculata.
| Early summer condition.

Two-thirds nat. size.

| Adlard 4 Son, Impr.

PLATE LVII.

Galls caused by TERAS TERMINALIS.
A. Spring condition. Arrows indicate bud apices.
Bs. Autumn-winter condition on twigs of Q. pedunculata.

Adlard §- Son, Impyr.

PLATE LVIII.

Galls caused by TRIGONASPIS CRUSTALIS on adventitious buds on bole of
Q. pedunculata.

Three-fourths nat. size.

Adlard 4 Son, Impr.

PLATE LIX.

Galls caused by TrigoNaspPiIs CRUSTALIS on twigs of Q. pedunculata.
Five-sixths nat. size.

Adlard §- Son, Impr.

PLATE LX.

TC TLLAN ARMA PALL
iMm 110 2|0

Galls caused by
A, NEUROTERUS FUMIPENNIS x 2} (see p. 117). B. CYNIPS TINCTORIA.
Nearly nat. size.

Adlard § Son, Impr.

PLATE LXI.

Galls caused by CYNIPS CALICIS:
A. On capsules of Q. pedunculata. 1. Acorn. 2. Larva cell in centre of cavity.
From Jersey.
B. —? —?oncupules of Q. Ilea.
Both nearly nat. size.

Adlard § Son, Impr.

PLATE LXII.

Gall-pits caused by ASTEROLECANUM VARIOLOSUM on twigs of Q. pedunculata.
The inset is the portion of the twig between transverse lines, x 2).
Nearly nat. size.

aldlard & Son, Impr.

PLATE LXIII.

Galls caused by DipLosis DRYOBIA on upper surface of leaves of Q. pedunculata.
A. Under-surface of an attacked leaf.
Five-sixths nat. size.

Adlard § Son, Impr.

PLATE LXIV.

Epirrimerus cristatus, Nalepa.

A. Ventral view
B. Dorsal view
c. Under-surface of leaf of Q. pubescens.

From drawings by Dr. ALrrep Navera, Vienna.

} very highly magnified.

Adlard § Son, Impr,

PLATE LXV.

Galls caused by Dich#NA QuERcINA on branches of Q. pedunculata.
A. A. Branch divided longitudinally.
B. Tangential section of a growth similar to that above it.
c. Transverse section of a growth similar to that of B on Plate LXVI.
Two-thirds nat. size.

Adlard 4 Son, Impr.

PLATE LXVI.

Galls caused by Dico#NA QUERCINA on branches of Q. peduneulata,
A. An early stage of growth.
B. Longitudinal section of a similar specimen to a,
Both three-fourths nat. size.

Adlard & Son, Tape.

PLATE LXVII.

Sole of oak tree in Broomham Park, Guestling, Sussex

The seale is 807em.

Adlard & Son, Impr.

PLATE LXVIII.

Another view of tree of previous Plate.
The scale is 30 em.

Adlard § Son, Impr.

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