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THE ANNALS OF
APPLIED BIOLOGY

CAMBRIDGE UNIVERSITY PRESS
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OF ECONOMIC BIOLOGISTS

EDITED By
E. E. GREEN, Way’s End, Camberley (late Government Entomologist, Ceylon)
AND
Proressor B. T. P. BARKER, National Fruit and Cider Institute, Bristol
Dr S. E. CHANDLER, Imperial Institute, London
F. J. CHITTENDEN, Royal Horticultural Society’s Gardens, Wisley
J. C. F. FRYER, Board of Agriculture and Fisheries, London

Proressor F. W. GAMBLE, The University, Birmingham

Proressor PERCY GROOM, Imperial College of Science and Technology, London
Dr A. D. IMMS, The University, Manchester
Proressor R. NEWSTEAD, The University, Liverpool
Proressor J. H. PRIESTLEY, The University, Leeds

Volume IV_ 1917-18

CAMBRIDGE
AT THE UNIVERSITY PRESS
1918

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CONTENTS

Nos. 1 and 2 (September, 1917)

Frit Fly (Oscinus Frit) eo Winter Wheat. By F. R.
PETHERBRIDGE

Some Farm Insects observed in ihe Mipeeavaetl Nees,
1913-1916. By C. L. Watton, M.Sc.

A Note on Agricultural Oecology in Mid-Wales. By C. i
WALTON, M.Sc.

On a Disease of the Beech ced by Ragen vw Pol ymor a
Wett. By R. J. Tasor, B.Sc., and Kate Barratt, M.Sc.
(With Plate L.)

The Life History and Beano of ae Giese ‘Mites. By
NELLIE B. EALEs, B.Sc. (Lond.)

Investigation of Bulb Rot of Narcissus. Part I. The Native
of the Disease. By E. J. WELSFoRD, F.L.S. (With 5 Text-
figures. )

Note: ona Plague of Pepciass ina Ractory. iP R. i HARPER
GRAY, M.A., B.Sc. (Agric.), M.Sc.

A Bacterial Bion of Pear Blossoms oceurring in South
Africa. By ETHEL M. Dorpee, M.A., D.Sc., ELS. (With
7 Text-figures.) :

A Last of Coccidae ee various Genera of Bisnis By
K. ERNEST GREEN, F.E.S., F.Z.S.

Note on the Immunity of analog Parasites to Eidrocy: anic
Acid Gas. By E. ERNEST GREEN .

No. 3 (December, 1917)

On the Larval and Pupal Stages of Bibio Johannis L. By

HusBert M. Morris, M.Sc. (Manch.) (With Plate II and
12 Text-figures.)

Two Experiments in House F amisanen By H. Muscwieni:
LEFROY.

The Locust in ean us. By Wa p. DELANE SrmBBING, Fr. Gs:

Mussel Beds; their Productivity and Maintenance. By
FRANK 8S. WRIGHT

PAGE

36

47

75

90

91

115
AS)

12350

vi

bo

Contents

No. 4 (March, 1918)

Ustulina Zonata (Lev.) Sacc. on Hevea Brasiliensis. By
A. SHARPLES, A.R.C.S., D.LC., Mycologist. Department
of Agriculture, Kuala Lumpur, Federated Malay States.
(With Plates III—VIII and 1 Text-figure.) . : :

A Study of the Capsid Bugs found on Apple Trees. By

F. R. PETHERBRIDGE and M. A. Husain. (With Plates
IX—XI.)

Notes on the Strawberry ees Beetle (Cater Heels taal
Linn.) By H. C. Erruatoun, F.E.S., M.R.A.C. (With
3 Text-figures.)

. Observations on Pimpla pomorum Bate a Paesite a ae

Apple Blossom Weevil (including a ieee of the
Male by CLAUDE Mor Ey, F.Z.S.). By A. D. Imms, M.A.,
D.Sc. (With Plate XII and 5 Text-figures.) . :
A List of Coccidae affecting various Genera of Plants. By
EK. ERNEST GREEN, F.E.S., F.Z.S. (Continued from p. 89)

PAGE

153

179

206

VoLUME IV SEPTEMBER, 1917 Nos. 1 and 2

FRIT FLY (OSCINUS FRIT) ATTACKING
WINTER WHEAT.

By F. R. PETHERBRIDGE.
(School of Agriculture, Cambridge.)

From enquiries sent in during the past three years, there is little
doubt that in addition to the damage it does to late sown spring oats,
the “frit fly” must also be reckoned as a pest of winter wheat in this
country. Several observers have recorded this fly as attacking winter
wheat on the continent.

The first enquiry was received in March, 1914, from Mr C. J. Little-
wood, Whitwell Hall, Skeyton, near Norwich. Specimens of dead and
dying wheat plants were sent in and in these the larvae of the “frit fly”
were found. Unfortunately the wheat was ploughed in just after the
plants were sent, but this will serve to show that the damage done
must have been considerable. This wheat was sown about December Ist.

On March Ist, 1915, an enquiry was received from Mr H. V. Shering-
ham, Blue Stone Farm, South Creake, Norfolk. Here 54 acres of wheat
were sown on November 11th—15th, receiving a dressing of farmyard
manure, and following a crop of Rye Grass and Clover. Mr Sheringham
writes as follows: “The wheat was slow in coming up owing to
excessive rain.” Although about 20 °% of the plants were attacked by
the larvae of the “frit fly” the wheat tillered well in the spring and pro-
duced a fair crop (about 32 bushels per acre).

In 1916, an enquiry was received from Messrs Tayton, White Hall
Farm, Syderstone, Norfolk, concerning fields quite near to Mr Shering-
ham’s farm.

Three fields were badly attacked by the larvae of the “frit fly,”
their previous cropping being:

WIT = 1912 1913 1914 1915 1916
32 acres Oats Turnips Barley Italian Rye Grass Seeds mixture left Wheat
and = Suckling down
Clover j
AS 55 Wheat Turnips Barley Perennial Rye Grass Wheat
and Red Clover
ey Wheat Turnips Barley Italian Rye Grass Wheat
and and Suckling
Kale Clover

Ann. Biol. rv 1

2. Frit Fly (Oscinus Frit) attacking Winter Wheat

The wheat was sown on Oct. 14th—20th and received 10 loads of
farmyard manure per acre.

On all these fields about 25 % of the plants were attacked when
examined on February 9th. No attack of “frit fly” was noticed in
the spring corn of 1915.

Neighbouring fields of wheat were visited and “frit fly” larvae
were found in all cases.

A field of rye joining a field of badly attacked wheat was apparently
free from “frit fly.”

In December, 1912, and January, 1913, Edmunds! found “frit fly”
larvae in Rye Grass in a clover ley and also in Golden Oat Grass (Avena
flavescens) and in False Oat Grass (Arrhenatherum avenaceum).

Baranov has also recorded the spring generation of flies as laying eggs
on the following grasses: Phleum pratense, Alopecurus pratensis, Lolium
perenne, Triticum cristatum, Festuca pratensis, Avena flavescens and
Poa pratensis.

The writer also found “frit fly” larvae on Italian Rye Grass (Lolium
utalicum) on March 6th, 1916.

In this connection it is interesting to note that the above attacks
are all after crops of Rye Grass or Italian Rye Grass.

The 18 acre field was ploughed up on May Ist—#rd and sown with
Barley on May 4th which on threshing showed a yield of 36 bushels
per acre. The other two fields were left and yielded about 20 bushels
of wheat per acre. It will be seen from this that the “frit fly” is capable
of causing a considerable reduction in the yield of winter wheat.

On February 21st, 1913, a sample of Winter Oats and Vetches was
received from Wickham Market, Suffolk, and in the Oats larvae of the
“frit fly’ were found. This crop followed a crop of late-sown spring
oats and was sown on October 12th.

The above observations are interesting in connection with the life
history of the “frit fly.”

Mr Littlewood’s wheat was sown about December Ist and Mr
Sheringham’s wheat which was not sown until November 14th was slow
incoming up. If the “frit fly” has only three broods in a year we should
have expected the wheat to be safe from an attack under these con-
ditions. Is this attack of winter wheat caused by the third brood of
flies which hatch out from the pupae in the ears of oats or from
those in the shoots of cereals or grasses (usually in September), or is it
a fourth brood? In this connection the following may be of interest:

' Joint Report, Harper Adams College, 1912.

F. R. PETHERBRIDGE 3

In a sample of spring wheat from Chaul End, near Luton, sown the
third week in April, 1916, three larvae and two empty pupa-cases of
the “frit fly’ were found on October 3rd. (Other larvae very similar to
those of “frit fly” but not yet identified were also found.) This crop
was also badly attacked by the “Hessian Fly” Cedidomyia (Mayetiola)
destructor and a number of young tillers were present as is usual in
late-sown spring wheat.

Hitherto three broods of the “frit fly” have been recognised.

Brood | appears in April and May and lay their eggs on spring corn.

Brood 2 appears in July and lay their eggs on the ears of oats or
barley or on the shoots of cereals and grasses.

Brood 3 appears in August and September and lay their eggs on the
shoots of grasses or early-sown winter corn.

Without further knowledge of the life history it is difficult to
account for the above attacks on winter wheat.

Among the possibilities which would account for these late attacks
of winter wheat are the following:

(1) The third brood of flies may hatch out over a very long period
and the last ones lay their eggs on winter wheat.

(2) Some of the third brood of flies may be capable of living until
December before laying their eggs.

(5) The larvae of the third brood of flies may under certain con-
ditions give rise to a fourth-brood of flies which lay their eggs on winter
wheat.

(4) In a letter Fryer suggests that “The third brood of flies may
migrate from the plants on which they hatched to the wheat which is
sown after the former host plants are ploughed in.”

Cases 1, 2 and 3 seem rather improbable as it would necessitate the
emergence of the fly in cold weather of which at present there is no
record.

Case 4 seems more probable as several observers have found “frit
fly’ larvae in the shoots of grasses and it is quite possible that migration
takes place from these plants to the wheat. This would also account
for the absence of the adult fly in the winter months.

It will be seen from the above that more knowledge of the life history
of the “frit fly” is needed in order to find out the most efficient means
of reducing attacks on winter wheat. We know that early-sown spring
corn in a good seed bed usually escapes attack, but as the fly can lay
its eggs on grasses there is always the danger that our winter wheat will
be attacked even if we sow our spring corn early.

1—2

SOME FARM INSECTS OBSERVED IN THE
ABERYSTWYTH AREA, 1913-1916.

By C. L. WALTON, MSc.

(Departments of Agriculture and Zoology, University College
of Wales, Aberystwyth.)

The following insects were collected and observed during the pro-
gress of a Survey of Agricultural Zoology which I recently carried out
in the Aberystwyth Area.

The area examined comprised some 250 sq. miles, and included the
Plynlymon mountain mass; the wooded river valleys and foot hills;
the wide peat bog bordering the southern bank of the Dyfi Estuary ;
the cultivated region of hill and valley about the coast and lower
reaches of the rivers Rheidol and Ystwyth; and a region of high, bare,
ill-drained hills (largely coated with boulder clay) lying to the S.E. and
within the Teifi watershed. The predominant features of the whole
include slaty and grit rocks, overlaid to a very large extent by peat
and boulder clay; a moist climate; an Agriculture in which sheep
farming predominates, followed in order by cattle raising, dairying
and horse breeding. Corn and root growing are seldom more than
subsidiary in value; while fruit growing hardly exists; and market
gardening, to a limited extent, around Aberystwyth only.

During the progress of the Survey little attention was paid to any
gardens other than those of the farmers, and in the mountains few farms
can boast a garden worthy of the name. In many groups the lists
are by no means complete, the scope of the Survey was a wide one,
and special attention was given to the Liver Rot of sheep. The work
was carried out under a grant from the Board of Agriculture and
Fisheries.

CABBAGE BUTTERFLIES.

Karly in September, 1914, I left Aberystwyth and travelled down the
coast of Cardigan Bay (chiefly on foot) into Pembrokeshire and visited
several parts of that county. Up to the time of leaving the Survey

4

©. L. Watton 5

Area I had not received any complaints or noted any unusual abund-
ance of the larvae of the White Butterflies, and my attention was
first drawn to an attack upon Swedes and Rape in adjacent fields
upon a cliff farm near Fishguard. Subsequently I saw others, while
Cabbages were, in many places reduced to mere skeletons. I returned
to Aberystwyth by train and noted some damaged Swedes as soon as
the Survey Area was entered. I made about 40 enquiries, and dis-
covered that whilst not so severe as in 8.W. Wales, these pests were
sporadically abundant within the Area. Following these enquiries
I visited a number of the places whence damage was reported.

The larvae of Pieris brassicae and P. rapae damaged garden Crucifers,
and to a lesser extent Swedes from sea level to 1100 feet. The damage
to Broccoli and Sprouts, however, was not equally distributed; steep
banks lying in the sun; the upper parts of fields and similar hot, dry
situations suffered most, while gardens and fields in damp situations,
near rivers, etc., were least affected.

Two of the more severe cases were reported from mountain valleys ;
one from the upper portion of the Ystwyth (about 700 feet) following
a swarm of butterflies which were noted about the Swedes at the end
of August; the other from the steep slopes of the Rheidol valley.
This latter was visited when the Swedes were being harvested, and
there was little difference in size between the roots from the upper
half of the field which had been badly stripped, and the lower which was
but lightly attacked, the damage having being done too late to seriously
affect growth. Both in Pembrokeshire and in the Aberystwyth Area
farmers reported that broadcasting lime and soot had been without
effect. Within the Survey Area one farmer tried dusting with Basic
Slag after a shower (on Swedes) and another had no success with a
dressing of Baking Powder applied to cabbages !

Mr D. J. Morgan the Agricultural Organiser for Cardiganshire in-
formed me that he had observed Keating’s powder (Pyrethrum) used
upon Cabbage with excellent results. Commencing on September 28th
I experimented upon several rows of Cabbages in an Aberystwyth
garden; dusting with lime produced little results, and watering with
brine practically none, but a dusting of Pyrethrum was rapidly effective.

A large proportion of the larvae in Aberystwyth gardens were
parasitised, and quite half the larvae and pupae observed attached to
walls, ete., in early October showed the yellow cocoons of the Braconid,
Microgaster glomeratus.

During September and October, 1915, I noted slight damage to

6 Farm Insects observed in the Aberystwyth Area

Swedes in two instances, in each case the margins of the fields being
affected, but no serious outbreak followed the unusual abundance of 1914.

In 1916 a number of the larvae of P. brassicae were present upon
Swedes near Crosswood at the end of July, and upon Cabbage in gardens
during September, and the parasite above mentioned was again in
evidence, especially about Aberystwyth.

FLEA BEETLES.

I received fifty complaints of damage to root crops by Flea Beetles
and investigated a large number of these.

Two species are present, Haltica nemorum and H. oleracea. The
former is generally the more abundant and at times is locally predomi-
nant, but usually both are present, and often in about equal proportions.
These pests appear to be always present, and only await the advent
of the needful crop and weather conditions in order to multiply and
work havoc. Dry weather and sunshine are essential to these beetles
and heavy rain either ends, or very much limits their ravages.

Young root crops on dry slopes, hillsides and banks are usually
the worst damaged, but I have seen considerable harm done in low
fields as well.

Should adverse conditions delay growth the damage done is generally
ageravated, the continuance of conditions favouring the pests may
result in the first sowing of seeds failing entirely, while even a second
may be damaged.

It is notable that comparatively few complaints are heard from
farms where lime and basic slag are regularly used. On many farms
it is usual to give a dressing of quick lime prior to sowing the root crop.

During July, 1915, I noted a slight attack on mangolds. The
situation was high and sunny, and it was evident that the Swedes having
made a very vigorous growth, the beetles had migrated to the contiguous
rows of mangolds, of which, however, only the two nearest rows were
affected. In 1916, mangolds were severely attacked, and in a number
of instances the crop was considerably reduced. In one case roots
had not been grown upon the field within local memory, two crops of
oats having followed an old rough pasture, prior to the root crop.
Damage continued in this field up to mid July, and included succes-
sively mangolds, swedes and turnips. Polygonum persicaria was a
common weed in this field (and often abounds in mountain root fields)
and was also badly riddled by the beetles.

Soaking seed in paraffin has proved of benefit. One farmer broad-

C. L. Warton %

casted basic slag upon a badly infected patch without obvious benefit
and two others remembering the customs of their grandfathers dragged
branches of Elder (Ysgawn) over their fields, but, as one of them said,
‘only made ’em hop.”

AppLE WEEVIL, Anthonomus pomorum, Lin.

The Apple Weevil occurred in some abundance in May, 1914, upon
apple blossom in a farm garden three miles 8. of Aberystwyth. A
considerable number of apples had been planted about the house and
buildings and latterly somewhat neglected. The beetle was also
present upon crab apples in the same vicinity, but whether the pest
was introduced with the apples or was endemic upon the crabs it is not
possible to say; but probably the former. I have since found this
weevil in one or two other gardens, all far apart.

Crover WEEVIL, Apion apricans, Herbst.

The Clover Weevil was seen in some abundance in July, 1916, among
hay crops when being harvested, near Crosswood, and several were
obtained on pasture fields while gathering mushrooms in September
in the same locality.

WrrREWoRMS, Agriotes sps.

Thirty-two farmers and several gardeners complained of wireworm
attack in varying degrees of severity. Oats, wheat, swedes and potatoes
were the crops involved, but principally oats and swedes.

As mentioned under flea beetles, farmers who make a free use of
lime, basic slag, kainit, etc., seldom complain of these larvae. Almost
all the worst attacks were in the second successive crops of oats follow-
ing old, and often “foggy” pastures; the damage to the first crop
being either slight or not recognised, and there is no doubt that many
of these outbreaks could be avoided, by care and observation.

The majority of the affected fields are situated on sunny hill-sides,
where the soil is shallow and dry. Many of the complaints (and almost
all relating to swedes) came from the S.W. region of the Area surveyed,
—named by myself the “Coastal Uplands,’ and most of the cases of
young swedes being pulled up by rooks are due to the energetic search
for the larvae by these birds.

Notwithstanding the abundance of the larvae, I have found it
difficult to obtain more than odd specimens of the adult beetles and
hence cannot say anything about the relative distribution of the species.

8 Farm Insects observed in the Aberystwyth Area

Several farmers harrowed in a dressing of soot and subsequently rolled,
with excellent effect, while both kainit and lime have proved their
value.

On some farms about 15 ewt. per acre of ground lime mixed with the
surface soil during the preparation for roots, helps greatly to clear the
land of these pests.

Plain rolling, although doubtless of assistance, seldom effects a cure
on the light stony soils.

One farmer experimented with plots as follows:

1. Rolling every other day.

2. Applied soot and then rolled.

3. Applied salt and rolled.

4. Applied a dressing of nitrate of soda.

No. 2 proved most effective, followed in order.by 4. This man noted:
a daily advance of two yards by these larvae, he now controls any
patches that appear by the use of soot, harrow, and roller.

The value of basic slag in controlling Agriotes larvae was noted by
Umnoy in 1914. Part of a field manured with superphosphate was
injured, while a neighbouring part manured with basic slag was not
attacked?.

CHAFER Breties, Phyllopertha horticola, Lin., ete.

I have never seen a single specimen of the common Cockchafer
(Melolontha vulgaris) within the Area, except about the town of
Aberystwyth; and of Cetonia aurata, the Rose Chafer, one complaint
of damage to rambler roses reached me. From the appearance of
the foliage and the description given it is probable that that insect
was the cause.

P. horticola. The so-called Garden Chafer, however, is locally
exceedingly abundant at times. It is typically an inhabitant of the
“slope land,” and swarms about the dry sunny sides of the mountain
valleys. The adults were very abundant in June, 1915, especially in
the Northern valleys, and in August—September the larvae abounded
in the pasture lands of these slopes. Rooks and other birds assembled
upon these places in hundreds and in their search for the grubs literally
dug up acres of the already loosened herbage. Notwithstanding
their efforts a considerable number of larvae remained; but there is
no doubt that this Chafer is largely controlled by these birds. Further

1 A. Umnov. Report on the Work of the Entomological Bureau of Kaluga, 1913.
(Abstract from the Russian, in Review of Applied Entomology, April, 1914.)

©. L. Watton 9

examination in March and September, 1916, showed that these pastures
had largely recovered by the latter date. I have heard the term
Chwilen y rhedyn or fern beetle applied to this insect in the Llyfnant
Valley, where also I was informed that it had damaged garden apples.

APHIDES.

I am indebted to Prof. F. V. Theobald, M.A., of the South Eastern
Agricultural College, Wye, for the identification of all the species here
recorded with the exception of S. lanigera, R. ribis and M. cerasi. Apart
from these and 4. rumicis, none are of economic significance agricul-
turally.

With regard to the above species Rhopalosiphum ribis is seldom
common and little fruit is grown in the Area apart from private gardens.

Aphis rumicis sometimes occurs in numbers upon mangolds, and in
1915 I noted it abundantly upon Atriplex patula growing among man-
golds on July Ist. A watch was kept, but none were observed upon
the mangolds until July 7th when migration commenced. In 1916
this pest was scarce, and I only obtained a few from Docks in July and
August, and a very few on Broad Beans in early September. This
species was so abundant upon Broad Beans in 1915 that a large pro-
portion of the crop failed completely, the plants presenting a stunted
and scorched appearance. Beans are not grown as a field crop within
the Area, only a few rows being seen, here and there. Even in gardens
the practice of “topping” is practically unknown, and hence no check
is given to the pest. During 1916 this insect was also as infrequent
on beans as on mangolds.

Macrosiphum granarium was found upon black oats near Crosswood
during July, 1915, but not in sufficient abundance to make any differ-
ence to the health of the crop.

Schizoneura lanigera. This species is to be found practically wherever
apples are grown but generally in small amount. With certain ex-
ceptions, the farmers of the Area give but little attention to gardening,
especially those living at high elevations. Market gardening could, in
certain parts, be practised to a much greater degree.

The following is a list of recorded species, together with their host
plants:

Phylloxera quercus, Fons. Oaks in hedge, abundant at Crosswood,
Aug. 1916.

Schizoneura lanigera, Hausmann. Apple.

10 Farm Insects observed in the Aberystwyth Area

Callipterus quercus, Kaltenbach. Crosswood, 1915. Collected on
Oats, but probably came from an Oak near by.

Aphis prum, Reaumur. Damsons.

A. rumicis, F. Beans, Mangolds, Docks and Atriplez.

A. cardui, Lim. Carduus arvensis. 1916.

A. urticaria, Kalt. Nettles. Crosswood.

A. loti, Kalt. Lotus sp. Crosswood.

A. gossypu, Glover. A Cucumber grown in the open was killed by
this insect. Crosswood, July, 1916.

A. hederae, Kalt. Aralia sieboldii. Aberystwyth.

Rhopalosiphum ribis, L. Garden Currants.

R. lactucae, Kalt. Sonchus oleraceus.

Macrosiphum rosae, L. Rambler Roses, also on Dog Rose in hedges.

M. jaceae (L.). Centaurea niger and Lychnis diurna.

M. lactucae, Kalt. Lettuce. Aberystwyth.

M. granarium, Kirby (M. cerelis, Kalt). Oats, July, 1915.

M. absinthi, L. Wormwood. Crosswood, July, 1916.

M. pseudorubiellum, Theobald. Brambles. Crosswood, July, 1916.
A species recently described.

Myzus cerasi, Fabricus. Cherry (on wall). Llanfarian.

M. circumflecus, Buckton. Cineraria. Pontrhydgroes.

Amphorophera rubi, Kalt. Brambles.

Also several others not yet correctly determined.

ScALE INSECTS.

Seale insects are not at all common within the Survey Area, with
the exception of Chionaspis salicis, L., which is common upon Ash,
Birch and various species of Sallow (Salzx) from sea level to the upward
hmit of the tree growth.

Lepidosaphes ulmi (Mylilaspis pomorum) is to be found in some
gardens, but very seldom in any abundance. It does not occur in
such a manner as to suggest that it is native in the Area, and would
appear to have been introduced with nursery stock. It was abundant
on apples in one garden in Aberystwyth and upon a pear trained against
a wall in another. Elsewhere it only occurred in very small numbers
and then usually upon young isolated trees.

Lecanium persicae (Geofirey) has been sent me. twice from private
gardens and L. capreae (L.) once from a similar situation.

Nine species were obtained from indoor and green-house plants

C. L. WALTON dik

chiefly about Aberystwyth and the experimental green-house of the
Botany Department of the University: these nine were as follows:

1. Aspidiotus hederae, Vallot. On a pot palm.

2. A. cyanophylli, Signoret. Leaves of Cycas revoluta.

3. Frorinia foriniae, Targioni-Tozzetti. Palm, with A. hederae.

4. Diaspis zamiae, Morgan. Upon & sporocarp (megaspore) of
Dioon edule.

5. Chionaspis aspidistrae (Signoret). Ferns.

6. Lecanium hesperidum (l.). Common upon pot ferns.

7. L. perforatum (Newstead). Palm.

8. L. hemisphericum (T. T.). On Macrozania spiralis.

9. Dactylopius longispinus (T. T.). Vines; beneath scales of Cycas
revoluta; and larvae beneath leaves of Dorstenia sp.

CECIDOMYIDAE.

Only two have been noted as harmful.

Perrisia crataegi (Winn), which affects the tips of young Hawthorn
shoots causing them to assume the appearance of a rosette. This
insect is common, and aflects a considerable proportion of the shoots
in the lowlands.

The second species is Rhabdophaga salicis (Schrank) which I have
obtained galling species of Salix on the banks of the Ystwyth, near
Aberystwyth, and elsewhere; it is not at all abundant.

CRANE Fuites, Tipulidae.

I have only recorded three species, although others undoubtedly
exist, one of which was very abundant on the Dyfi Flats in 1914; the
specimens then collected were, however, unfortunately lost. Tipula
oleracea, Lim., is at times very common, but only one complaint con-
cerning it reached me, specimens being sent in 1913 by Sir KE. Pryse,
Bart.; the larvae were exceedingly abundant in one of his fields at
Gogerddan. T. lateralis, Meig., was fairly common in 1916, and Pedicia
rivosa, L., was obtained on mountain pastures.

Onion Fry, Phorbia cepetorum, Bouché.

The Onion Fly was noted several times from leeks. In October,
1915, in a farm garden near Borth, a bed of leeks 40 « 15 feet in extent
was destroyed, only about a dozen plants remaining when I visited
the place on November 4th. From 3 to 7 larvae were obtained from
each of these leeks.

12) Farm Insects observed in the Aberystwyth Area

MAnGoup Fry, Pegomyia hyoscyami, Panz. (P. betae, Curt.).
The Mangold Fly. I have never seen young Mangolds attacked,
nor any appreciable damage done, but a few brown blisters are to be
seen now and again. I have failed to obtain the adult fly.

PIOPHILA CASEI.

I observed this fly in hundreds in one farm house, and obtained the
larvae from bacon and hams that were hanging from the ceiling of the
kitchen. These maggot-like larvae can “skip” freely, and do not seem
to harm the bacon to any great extent, since no foul or decayed place
could be found even where the larvae were feeding.

LIPURA AMBULANS, IL.

This minute Apterous insect was observed in November, 1915, in
large numbers upon leeks in a farm garden near Borth. The leeks had
been very severely attacked by the Onion Fly (P. cepetorum). Some
adjacent carrots were also attacked, but were not seriously injured.
The same pest was obtained damaging the seeds of French Beans
sown in an Aberystwyth, garden in the Spring of 1916. Sminthurus
luteus, Lubbock, was fairly common upon field mushrooms at Crosswood
in September, 1916. Several other related species were observed in
small numbers.

ANTS.

Time did not allow of a full study of many groups of subsidiary
interest, and I am chiefly indebted to Mr F. 8. Wright of the Zoology
Department, Aberystwyth, for the following identifications of Ants
collected during the course of the Survey.

The nomenclature is that of Donisthorpe, British Ants, 1915.

1. Monomorium pharaonis, 1. bie i ajuscas ali.

2. Myrmica laevinodis, Nyl. 6. F. rufibarbis, ¥.

3. M. ruginodis, Nyl. 1. F. picea, Nyl.

4. Formica rufa, L.

All the above records refer to workers.

F. fusca seems to be the most widely distributed, and has been taken
from sea level to 1000 feet.

M. pharaonis was only obtained from the town of Aberystwyth
where it Was causing annoyance in a bakery and also in a tobacconist’s

ac)

shop.
F. rufa is confined to woodlands containing an admixture of Coni-

ferae.

C. L. WALTON us

WASPS.

These insects are usually fairly abundant, but were peculiarly
scarce in 1916, although queens were plentiful during the spring and
I obtained specimens of Vespa vulgaris, V. germanica, and V. rufa;
the two formercommonly. Old nests of V. sylvestris have been observed
but I have not taken the insect.

Humeste Bees, Bombv.

I am indebted to Mr T. Alan Stephenson for the following notes
on the Bombi and Psithyri of the Aberystwyth Area.

At my suggestion he gave considerable attention to these groups
during 1915-16.

Twelve species of Bombus and five of Psithyrus have occurred,

namely :
1. Bombus lapidarius, Linn. 7. B. lapponicus, Fab.
2. JB. terrestris, Linn. 8. B. hortorum, L.
3. B. lucorum, Linn. 9. B. derhamellus, Kirby.
4. B. soréensis, Fab. 10. B. sylvarum, L.
5. B. pratorum, Linn. 11. B. agrorum, Fab.
6. B. gonellus, Kirby. 12. B. helferanus, Seedl.
1. Psithyrus rupestris, Fab. 4. P. campestris, Panzer.
P. distinctus, Perez. 5. P. quadricolor, Lepeletier.

2

3. P. barbutellus, Kirby.

Of these, B. agrorum is the most abundant and widely distributed
species, while lapidarius, lucorum, and hortorum, are almost equally
common.

B. sylvarum and helferanus are fairly frequent; while terrestris,
pratorum and soréensis are scarce. B. jonellus only occurred two or
three times; while of derhamellus, three queens have been taken,
and of lapponicus a single male only.

Of the Psithyri the most abundant is campestris, which preys upon
B. agrorum: P. barbutellus is fairly frequent, as one would expect from
the fact that it is parasitic on B. hortorum. P. rupestris is more fre-
quent than barbutellus, while of distinctus two queens have been obtained,
and of quadricolor one only.

Toe Honry Bru, Apis mellifica.

The Isle of Wight disease has caused serious loss around Aberystwyth
during the course of the Survey. Commencing apparently near the

14. Farm Insects observed in the Aberystwyth Area

town, it rapidly spread and involved several flourishing apiaries, and
has so far extended its ravages some 24 miles beyond the town. Thanks
probably to their isolation, the country bee keepers so far remain un-
affected, and it is greatly to be hoped that the disease has reached
its limits. Apart from this scourge, local bee keepers have little to
complain of and would do well. The usual bee pests, Wax Moth,
Braula caeca, etc., are present but not in excess. The Blue Tit is
responsible for taking a few bees.

NEMATUS RIBESIT Scop.

The Gooseberry Sawfly was fairly common in farm gardens in 1914,
and was noted as high as 800 feet at Pont Erwyd. In a garden near
Llanfarian the larvae appeared about April 25th and I noted a second
brood there by June 20th, when, also, Red Currants were attacked
adjoining the Gooseberries, although plenty of foliage still remained
upon the former.

Finally, the following Mites may be mentioned.

ERIOPHYES RIBIS Nalepa. H. AVELLANAE Amerl.

The first of these two bud mites occurs sporadically in gardens.
BE. avellanae is common in Hazels on hedgerows.

Tyroglyphus longior, the Hay Mite, was sent me from Pembroke-
shire where it was destroying an Oat rick; and another correspondent
sent specimens from feeding stuffs in N. Wales.

T. siro was found feeding upon the crystallised sugar on the top of
a jar of jam, Aberystwyth.

A NOTE ON AGRICULTURAL OECOLOGY
IN MID-WALES.

By €:.L.. WALTON, MSc:

(Departments of Agriculture and Zoology, University College
of Wales, Aberystwyth.)

During the progress of the Survey of Agricultural Zoology which
I recently carried out in the Aberystwyth Area, some interesting and
instructive inter-relations between wild and domesticated animals were
noted.

The more natural conditions prevailing over large portions of Mid-
Wales permit such interaction to be noted with greater readiness than
would be the case in closely cultivated areas, where conditions are more
controlled.

In the instances about to be given the main factors are:

(1) The distribution of the rabbit, which depends largely upon
the physical conditions, and human control (which affects thei relative
abundance).

(2) The Sheep Industry, which is profoundly under the influence
of the local custom of transhumance, involving the movement, twice
yearly, of great numbers of sheep between upland and lowland.

(3) The abundance of foxes (a condition again somewhat in-
fluenced by the War).

(4) The number of sheep dogs kept; often excessive and insuffi-
ciently controlled.

In addition to the above are:

(5) The Poultry Industry.

(6) Hunting.

(7) The Sheep disease “Gid,’ due to the cysts of the parasitic
Tape Worm Taenia coenurus, of which the hosts are the dog and the
sheep.

(8) The distribution of the polecat, which is closely linked with
that of the rabbit.

16 A Note on Agricultural Oecology in Mid-Wales

These two last are quite subsidiary and only included to show the
complexity of the local animal inter-relation. My attention was
drawn to these conditions through the complaints of farmers, shepherds,
and poultry keepers, regarding serious losses of lambs and poultry,
due to foxes.

The physical features of the area dealt with include the wide,
open, grassy and peaty uplands of the mountain complex of which
Plynlymon is the centre; the foot hills and river valleys often rough
and wooded; the cultivated and fertile lowland and coastal region,
and the large peaty tract bordering the Dyfi estuary and known as
Borth Bog, or the Dyfi Flats.

On the mountains the sheep receive relatively little attention, and
the amount of necessity depends very largely upon the size and nature
of the holding or “walk,” the number of sheep, and the persons respon-
sible for their care. Even if more or less tended by day, the sheep are
exposed to any danger that may threaten them during the night and
early morning. The condition of affairs here described may possibly
apply, with some modification, to other mountain areas.

During the progress of the survey I received 70 complaints of damage
to lambs and poultry by foxes, and it would have been easy to add
largely to that number if farm visiting had been continued on the same
scale in 1916 as in the previous years. The complaints, as indicated
above, fall under two heads:

(a) lambs, (b) poultry, and these must be considered separately.

Foxes are common in the area, and are hunted by the pack of hounds
kept by Sir Edward Pryse, Bart., at Gogerddan, near Aberystwyth,
about the centre of the area. This pack has not, of course, hunted to
the same extent since the outbreak of War, and foxes seem to have
increased both in numbers and boldness.

A second pack has quite recently been started on the southern side
of the area. Cubs were reared, and poultry raided even in the tewn of
Aberystwyth, and many foxes were perforce destroved by farmers
and others throughout the area in sheer self-protection. The chief
losses of poultry are, of course, practically confined to the lowlands
and valleys, few poultry being kept at higher elevations, and in addition
to the direct loss there must be added the discouragement of poultry
keepers. Part of the loss is due to bad management, and careless
housing of fowls due to slackness on the part of the poultry keepers,
and partly owing to lack of suitable places in which to house them.:
The loss of lambs occurs chiefly in the mountains, and in certain districts
is serious.

C. L. Watton 17

That much of the loss is due to foxes is certain, but I do not consider
that the whole of the damage attributed to them can be laid to their
account.

Dogs are responsible for a considerable share, and often I believe
the dogs of the farmers themselves, though many are unwilling to
admit it. Dogs are left loose in some instances with a view to pro-
tection from foxes. It is my opinion that too many dogs are kept on
many of the farms and sheep walks, and very frequently these are not
sufficiently well fed. Quite a number of outbreaks of lamb killing
have been traced to dogs (and some of these were destroyed) during
the progress of the Survey, but it is unlikely that I have heard of more
than a part of the total.

Again, these dogs, and others, are very seldom kept shut up at
night, and a considerable proportion roam the hills at will. When
stopping here and there in the hills during the course of the Survey
I have been disturbed during the nights by such prowling dogs. It
would no doubt be difficult to track many, but the practice is very
harmful in this and other connections. Nevertheless, although some
part of the total loss is attributable to dogs, the fact remains, that
a heavy and unnecessary toll is taken by foxes at the expense of sheep
farmers. Complaints of loss vary from four or five lost to 40 or 45,
and in the spring of 1913, one group of eight sheep walks together
claim to have lost 500 lambs. The most dangerous period in the
hills is usually May, when thousands of ewes and lambs are taken from
the lowlands to the mountain walks for summer grazing. A proportion
of ewes are lambed on the sheep walks, in some cases depending largely
on the elevation and the amount of improved land available.

If a map is constructed showing the distribution of these troubles
it will be noted that a very considerable proportion of the complaints
of loss come from the hill country lying W. of Plynlymon, and more
or less in the centre of the Survey Area, and further that it comprises
the hinterland of the region most hunted. Another point of great
importance shown by mapping is the distribution of rabbits within
the area. It will be observed that very few rabbits occur in this region
showing the greatest damage to lambs, in marked contrast to the state
of affairs in the southern part of the area. There is no doubt that
foxes everywhere depend very largely upon rabbits for their food, and
in these hills rabbits are either very locally distributed or quite absent.
Moreover it so happens that the maximum number of lambs are available
just when the vixens have to feed their cubs and teach them to hunt;

Ann. Biol. ty 2,

18 A Note on Agricultural Ocecology in Mid-Watles

and finally, it is contended by some that hunting in the lower lands
drives lowland vixens into the hills and so further accentuates the
coincidence of circumstances which cause trouble. I have myself
examined lambs found dead, and partially eaten, upon the sheep walks
in that region, and consider their deaths were due to fox attack.

A minor annoyance due to foxes is the manner in which they tear
and mutilate rabbits caught in traps and snares. Foxes are made
aware of the whereabouts of such rabbits by their cries when first
caught. A curious custom, the origin of which is obscure to me, is
that of putting raddle or red paint upon the back of lambs, to keep
off foxes. Another local idea is that foxes show a preference for white
fowls; and this may be explained perhaps by the greater prominence
of such birds at night, etc.

One farmer says that he has observed toxes catching moles, digging
them out as dogs sometimes do.

Rabbits are particularly abundant along the coast region between
Aberystwyth and Borth, and also in the valley of the Ystwyth; but
comparatively few complaints as to damage have been made to me.
This is possibly due to the amount of rough land and the wide range
they usually enjoy, for very seldom does a colony occupy narrow
limits surrounded by cultivated land. In certain cases, however,
I have seen considerable damage to young corn, and also to meadow
grass. Throughout the remainder of the lowlands and slope lands
rabbits are usually present in small numbers, but on the mountain
tops they are very scarce, or entirely absent, especially on peat. There
are several interesting exceptions; in one instance at an altitude of
1300 feet, a colony is established in a fir plantation, three miles from
any other colony of which [ am aware.

The other exceptions are due to the physical characters of the
Drosgol Grits, -which weather into rough screes formed of blocks of
stone that provide shelter for rabbits from whence it would be ex-
tremely difficult to dislodge them. I am aware of three such isolated
colonies, two at 800—1000 feet, and the other at 1200—1600 feet.
From what I can gather, certain changes have taken place in the
local distribution of recent years; in two districts a reduction in
nymbers is apparently due to persistent trapping, etc., but in another
to a severe outbreak of Coccidiosis (Himeria stiedae), which disease I
have several times observed. I have not been able to obtain any
rabbits suffering from Liver Rot, but several farmers informed me that
during recent outbreaks they observed flukes in the livers of rabbits

C. L. Watton 19

killed on their farms. A liver containing a very considerable number
of flukes was sent me from Mid-Pembrokeshire in 1913.

The distribution of the Polecat (Mustela putorius), which is by no
means uncommon in North Cardiganshire, seems to be largely governed
by that of the rabbit, upon which it largely preys. The polecat is
now and again responsible for some loss to poultry keepers. I conclude
therefore that foxes are over abundant in the area, and, as elsewhere,
are a needless source of loss to sheep farmers and poultry keepers.
In rough country it is always difficult for the hunt, however well in-
tentioned, to kill all troublesome foxes, and the more their numbers
increase the greater becomes the difficulty of the chase. The present
over abundance will doubtless, to some extent, be dealt with by the
sufferers. As regards the dog problem, although sheep farmers claim
that large numbers are needful in order to work their widely-ranging
flocks, I nevertheless consider that a diminution in their number,
coupled with a greater control and better feeding and attention in some
cases, would result in a reduction of trouble, and also in the number of
young sheep suffering from “Guid.” There will probably always remain
enough foxes to provide sport for the hunting people.

Rabbits again could with advantage be reduced in numbers in
certain districts, and land given up to them utilized to better purposes.
On the whole they can usually be readily controlled within the area
under consideration.

A general account of the Mammals of North Cardiganshire will be
found in a paper by Mr F.S. Wright, in the Zoologist for September, 1916.

2—2

ON A DISEASE OF THE BEECH CAUSED
BY BULGARIA POLYMORPHA WETT.

By R. J. TABOR, B.Sc., anp KATE BARRATT, M.Sc.

(From the Department of Botany of the Imperial College of Science and
Technology, London.)

(With Plate I.)

During the last few years, a number of the pollard beech trees at
Burnham Beeches have suffered from a disease which has apparently
caused the death of several specimens, and is seriously affecting some
others. The symptoms of the disease are very marked. At various
points on the surface of the bark a brown liquid exudes which rapidly
concentrates to a dark viscous gum}, collecting in gouts near the point
of exit and, if in quantity, trickling down to lower levels. ‘The material
is partially soluble in water, with the result that in wet weather it is
washed down and may be thus distributed over a considerable area
of the lower part of the trunk. The effect is very unsightly and the
trees attacked are readily detected (Fig. 1). Frequently the gum
provides a medium for the growth of various saprophytes, yeast, bacteria,
moulds, etc., and then becomes of a creamy consistency and buff or
pinkish in colour.

The effect on the tree is very serious. The bark from which the gum
proceeds is already dead, and since the affected areas are often rapidly
extended, the life of the tree may be seriously threatened.

These pollards are probably some of the oldest beeches in existence.
Their life has been prolonged far beyond what is generally regarded as
the normal limit of the species by the systematic pollarding, which—
as was usual in ancient forestry—was done at such a height as to pro-
tect the young shoots from browsing animals. The cessation of cutting,
however, permitted the growth of a few of the more favoured shoots
and the trees now bear several fine limbs rising from the crown.

1 This substance has been referred to throughout as gum, though its exact nature has
not yet been determined,

R. J. Taspor and Kare Bargrarr 21

It is obvious that pollards are particularly exposed to the attack
of parasites which can obtain an entrance and destroy the heart wood,
and these old beeches are in most cases nothing but hollow shells.
The outer wall of wood and bark has also suffered frequently from
accidental injury and disease, and is now a patchwork of dead and living
tissue. In fact it is astonishing to observe in some instances, how
restricted is the tract of living, conducting tissue, which connects a
well-developed limb above with the root system below. It must
operate as a limiting factor in the relations between the root system
and the leafy canopy dependent upon it above; and it is a fact that
the trees are extremely sensitive to anything which tends to disturb
these relations, e.g., dry seasons, clearing and felling in the immediate
neighbourhood. For the same reason they demand constant attention
in the matter of pruning, mulching, etc. It is obvious that any attack
on these vital tracts must rapidly prove fatal, and they are particularly
exposed to the ravages of facultative parasites which have established
themselves on the neighbouring areas of dead tissues. Moreover
diseases affecting the bark are much more rapidly fatal than those
attacking the wood, since the death of the inner bark and with it the
cambium, deprives the tree not only of the means for conveying its
elaborated food materials, but of its capacity for forming new tissues.
A number of fungi are found constantly growing on the pollards, and
amongst others Fomes fomentarius, Stereum hirsutum, S. purpureum,
Armillaria mucida, ete.

The Ranger, Mr M. C. Duchesne, observed that fruit bodies of
Bulgaria polymorpha, Wett., were often abundant on trees exhibiting
the gumming. The evidence of association however between the
fungus and the disease was not at all convincing.

At the time our attention was first called to the disease the fruit
bodies of the fungus were scarce. Trees showing the gumming often
exhibited no trace of Bulgaria, whilst on the other hand felled logs,
with the bark covered with the scars and remains of old fruit bodies,
usually showed no evidence of gumming. It was possible moreover
that the disease might have no connection with a parasite, but have
resulted from some functional disturbance. Our attention was therefore
directed not only towards the examination of the diseased bark for
evidence of the presence of any living organisms which might be con-
cerned with the disease, but also to determining whether the disease
could be transmitted to healthy trees.

22 Disease caused by Bulgaria Polymorpha

ASSOCIATION OF BULGARIA WITH THE DISEASE.

A number of specimens consisting of portions of wood and bark
from diseased trees were forwarded for examination. They all showed
a covering of gum on the surface of the bark which in most cases was
dead. Examination of the bark yielded no results of any value. In one
specimen only, a yellow mycelium was found between the bark and the
wood. This was probably the mycelium of Bulgaria, but attempts to
cultivate it failed. Subsequent examination of the trees from which the
specimens were cut, suggested that in some instances the gum on them
had trickled down from a diseased area higher up the trunk. Two
specimens were placed in a damp chamber and kept under observation
for about 18 months. No exudation of gum occurred from these speci-
mens. <A few saprophytic moulds appeared at first on the gum and later
Stereum hirsutum in abundance on both specimens. In the spring of
1916 the examination of the infected trees was resumed and was con-
fined to the careful investigation of one badly diseased tree in Victoria
Avenue, Burnham Beeches. One of the two main branches of this
tree had died and had been removed in the winter of 1914-15. The
log showed abundance of Bulgaria fructifications during 1915. The
remaining branch of this tree is still living and apparently healthy,
but a considerable area of the bark at the base is dead and although
no gumming has taken place in this region, yet infection experiments
(described below) show that the same disease is in question. It was
from the base of the main trunk that the specimen, referred to above
as showing yellow mycelium, had been obtained. Fresh portions of
bark from this region, which was gumming freely, were brought into the
laboratory and on one of them a yellow mycelium appeared. This
was transferred to an artificial medium and has been kept in continuous
cultivation. Of the various media tried, prune agar proved to be the
most satisfactory. Four weeks after the material had been collected
a fructification of Bulgaria appeared on the bark and could be clearly
traced in connection with the yellow mycelium.

Ascospores were collected on sterile cover glasses suspended over
the apothecium, and were transferred to various media. They ger-
minated readily and gave rise to a mycelium identical with that obtained
from the diseased bark. Other specimens of bark brought in later
also developed fruit bodies of the fungus, and portions of bark taken
from other diseased trees in every case yielded the yellow hyphae.
Pure cultures of the mycelium have been under observation for many

R. J. Taspor anpd Kate BaRRATT 433

months both on nutrient jelly and on sterilised bark and wood. The
characteristic apothecia of Bulgaria have appeared in a number of the
cultures, and thus complete confirmation has been obtained as to the
identity of the mycelium present in the diseased bark.

INFECTION EXPERIMENTS.

The first infection experiments were started in the autumn of 1915,
before the mycelium had been found in the bark, and were directed
towards determining whether the disease could be transmitted from
affected to healthy trees. For this purpose, portions of bark were re-
moved from the affected area at the base of the living branch of the
pollard in Victoria Avenue. The bark was cut out, with suitable pre-
cautions, with a circular punch and transferred to holes cut with the
same punch in the living bark of a healthy pollard. They were secured
with grafting wax. Of the grafts made in this way, one shrivelled
and cracked and fell out, and another gave no visible result, but the third
examined on May 7th, 1916, showed a trickle of gum from the lower
edge of the graft forcing its way through the grafting wax (Fig. 2).
This exudation continued during the whole of the year. Examination
of the bark around the graft showed that the gum was proceeding
from the stock, and thus established the fact that the disease was com-
municable and certainly of parasitic nature. The difference in the
behaviour of these three grafts is very probably due to the fact, that the
two which failed were cut from well within the dead region of the bark,
the other from the margin of the diseased area where the fungus was
presumably in active growth. It may be pointed out moreover, that
the absence of gumming from these unsuccessful infections resolves
any doubts as to the exudation of gum being merely a traumatic
response.

When later, the yellow mycelium described above had been isolated
and identified, a second series of infection experiments were initiated.
The same pollard on which the first experiments were made was now
infected in two places on July 11th with actively growing mycelium,
in one case from that obtained by germinating spores of Bulgaria.

The surface of the bark was cleaned and a deep cut, extending to
the cambium, made with a sterilised chisel. The bark was gently
levered up and a portion of agar, with the actively growing marginal
hyphae from a plate culture, was inserted and pushed down into contact
with the wood. The bark was then pressed back into position and the
wound covered with grafting wax. At the same time two young trees

24 Disease caused by Bulgaria Polymorpha

were similarly infected. Three weeks later, July 31st, one of the in-
fections on the pollard showed signs of gumming, and by the end of
August they were both gumming freely (Fig. 3). Mycelium of Bul-
garia has been isolated from the bark, though up to the present no
ascophores have appeared on the tree.

On the other hand, the infections on the young trees have yielded
no visible result. These same young trees were again infected with
active mycelium on Sept. 27th, but without success, and they are now
apparently quite free from disease.

The power of resistance to the attack of the fungus possessed by
the young bark on the living trees is further exemplified by the results
of experiments in the laboratory. On July 20th a series of cultures
in potato dishes were established on portions of wood and bark about
4’”” x 3” taken from a young healthy branch, severed for the purpose.
One half of these specimens were sterilised in the autoclave before
infecting, the remainder were infected straight away with actively
growing mycelium at the junction of bark and wood. The infections
were uniformly successful on those specimens which had been killed
and sterilised, but failed to establish themselves on the living bark,
although in several instances a second infection was attempted. The
results of these experiments were so significant that they were repeated
on Oct. 6th. Five specimens of living bark and wood 4” x 3” being
infected with mycelium together with five similar specimens killed in
the autoclave. Four days later the fungus was spreading rapidly
on the dead bark but had apparently made no progress on the living
specimens, the latter were then reinfected, but without result.

In no instance was it possible to establish Bulgaria on the untreated
bark, although in one or two cases it maintained itself for a short
time on the dead tissue at the point of infection. It is obvious that
the living tissues of these specimens cannot long retain their vitality,
and it would no doubt be possible to get Bulgaria to grow successfully
after a short time, if it were not for various saprophytic moulds, and
particularly a dense white mycelium, possibly of one of the Polyporaceae,
which appeared on all the specimens and against which Bulgaria could
make no headway. ‘The results obtained from the foregoing experi-
ments and those on the living trees indicate that whilst the fungus
can establish itself readily on dead bark and on the bark of old trees,
it fails completely when the bark is young and actively living.

When the fact is borne in mind that infections on young, healthy
trees failed completely, though made with actively growimg mycelium

R. J. Taspor ano Kate BARRATT 25

of the fungus, it may be concluded that there is little danger of the
fungus establishing itself by chance infection of spores on young, vigor-
ous maiden trees. The success of the inoculations on the pollard can
probably be ascribed to the impaired vitality of these trees, and the
consequent lowering of the power of the living tissues to resist attack.
The fungus established on a dead area of bark can thus invade the
neighbouring living tissues, it develops rapidly in the inner bark and
attacks the cambium and the superficial layers of the wood. It may
be as well to emphasise the fact that on these beeches at any rate
Bulgaria does very little injury to the wood, but is responsible for the
death and destruction of the bark.

DISSEMINATION OF THE DISEASE.

The familiar black apothecia of the fungus appear in early autumn
(Fig. 5). They eject their spores in such abundance that the surround-
ing bark is covered by a black sooty deposit. The investigations of
Tulasne(1) and Brefeld) have shown that the spores germinate readily,
giving rise to secondary conidia or to mycelia directly according to the
conditions of germination. The ascospores thus serve as a ready
means for the dissemination of the fungus but by no means the only one.
If they establish the mycelium on an exposed wound it is able in the
enfeebled trees to extend itself to the living tissues. The principal
development of the fungus takes place in the spring and early summer,
as is evidenced by the active gumming that goes on at that time.
When the bark has been completely permeated by the fungus the
latter collects between the outer bark and the thin covering layer of
cork, and forms shallow stromata on which are later formed the apo-
thecia. Before these appear however, other fructifications are developed
on the stroma in the form of numerous pycnidia. These are borne
in irregular fructifications which form close beneath the lenticels and
usually split the cork at those points. These prominences show in
surface view the numerous irregular openings of the pycnidia, from
which emerge rounded masses, or fine tendrils of black paste, which
make their appearance on the surface of the bark, hardening on exposure
to the air but readily dispersing when moistened with water (Figs. 4
and 5).

This paste consists entirely of the pycnoconidia (stylospores)
described by Tulasned). ‘They bear, both in size and form, a strong
resemblance to the ascospores and behave in a precisely similar way on
germination. In all the material examined at the right season these

26 Disease caused by Bulgaria Polymorpha

pyenidial fructifications were abundant. Their regular occurrence and
relative importance appear to have been generally overlooked by later
writers although Tulasne refers to them as occurring not infrequently.
Fuckel(3) described them and identified them erroneously with T'e-
mella foliacea, Pers. (Ulocolla, Brefeld), with which they have no con-
nection. Fuckel had apparently never found them in conjunction with
the apothecia and says “Die Combination beider mag immerhin als
gewagt erscheinen; die entfernte Aehnlichkeit aber der Conidien mit
den Schlauchsporen und die Analogie mit Coryne-Arten, verliehen
derselben doch grosse Wahrscheinlichkeit.”

The pyenoconidia are produced during the summer months, the
apothecia in the early autumn and they can frequently be found together
on the same stroma (Fig. 5). Biffen(6) observed the formation of the
pyenidia in his cultures of Bulgaria on oak wood and they have appeared
in all our cultures both on the bark and on plum agar.

OrHER Recorps oF PARASITISM OF BULGARIA.

The suggestion that Bulgaria should be classed as a facultative
parasite was first put forward by Ludwig(4) who described in 1887 a
fatal attack on a fine specimen of Quercus rubra. A similar instance
is recorded by Hennings(5) on the same species of Quercus, and this
author is inclined to regard the fungus as a dangerous parasite.

Biffen(6), who studied the effect of the hyphae on oak wood, found
that the action was too slight to warrant the supposition that the
fungus is capable of causing a really serious tree-disease such as Ludwig (4)
assumed. A reference to the latter’s account however, shows that he
attributes the death of the oak to the destruction of the bark by
Bulgaria, and not to its effect on the wood. The results of the present
investigation clearly indicate that in the beech also, the fungus is
primarily a bark-parasite.

So far as the authors are aware, no account has hitherto been published
of an attack on the beech, apart from a statement by Massee(7) that
he has seen it on living beech, and no infection experiments have been
recorded. It is noteworthy that at Burnham Beeches the pollard oaks
have so far been quite free from attack.

The investigation has been confined to the pollard trees at Burnham
Beeches, but the Ranger, who has examined beech plantations in various
parts of the country, has found the disease on mature maiden trees in
several areas in Buckinghamshire, at Tring in Hertfordshire, Walton-
on-Hill in Surrey, and in the Goring district of Oxfordshire. It is

THE ANNALS OF APPLIED BIOLOGY. VOL. IV, NOS. 1 and 2 PEATEs!

Fig. 1. Diseased pollard beech

Fig. 2, Graft made in September 1915. Fig. 3. Bark of pollard infected with

Photographed in July 1916 to show living mycelium, July 1916. Photo-
the gum exuding from the lower edge eraphed eight weeks later when
of the graft at A. xt. actively gumming. x4,

Fig. 4. Masses of pycnospores exuded through Fig. 5. Stroma exposed by the removal of the
cracks in the bark from the pyenidia on the superficial cork showing masses of pyenospores
stroma beneath. x 3. at A, young apothecium £6, and mature

apothecium with hymenium exposed C. x j.

R. J. Tapor anp Kare Barratt a7

obvious therefore, that the peculiar circumstance of the pollard trees
is not alone responsible for their susceptibility, and it must be con-
cluded that Bulgaria may prove a dangerous parasite to old beeches,
more especially when from various causes their vitality may become
impaired.

Up to the present the actual source and nature of the “ gum” has
not been determined. Preventive and remedial measures are under
consideration.

SUMMARY.

A gummuing disease of pollard beeches is described which is associated
with the presence of Bulgaria polymorpha, Wett. on the trees.

A mycelium isolated from the diseased bark has been cultivated
and has produced the fructifications of Bulgaria.

A pollard has been infected with the disease by grafting in a piece
of diseased bark, and also by introducing the mycelium of Bulgaria.

Repeated infections of young, vigorous trees with the mycelium
failed to produce the disease.

It is concluded that Bulgaria is a dangerous facultative parasite on
old beeches, but that young healthy trees are able to resist infection.

We take this opportunity to record our thanks to M. C. Duchesne,
Esq., the Ranger of Burnham Beeches, for the facilities he has readily
afforded us and for the information he has placed at our disposal.

BIBLIOGRAPHY.

1, Tunasne, L. R. Nouvelles Recherches sur ? Appareil Reproducteur des Cham-
pignons. Annales des Sciences Naturelles, 1. Ser. t. 20, p. 160, 1853.
BREFELD, O. Untersuchungen aus dem Gesammtgebiete der Mykologie, x, p.
301, 1891.
3. FucKxer, L. Symbolae mycologicae. Beitrage zur Kenntniss der rheinischen
Pilze. Jahrbiicher des Nassawischen Vereins fiir Naturkunde, xx1u—xxtv,
p. 286, 1869.
4. Lupwie, F. Ist Bulgaria inquinans ein Wund Parasit? Centralblatt fiir Bak-
teriologie und Parasitenkunde, Bd. u, p. 521, 1887.
5. Henntnas, P. Ueber das Vorkommen von Bulgaria polymorpha (Oeder) an
lebenden Eichen. Zeitschrift fiir Pflanzenkrankheiten, tv, 266, 1894.
6. Brrren, R. H. On the Biology of Bulgaria polymorpha, Wett. Annals of
Botany, xv, p. 119, 1901.
7. Masser, G. A. A Textbook of Plant diseases, p. 162, 1899.

bo

THE LIFE HISTORY AND ECONOMY OF
THE CHEESE MITES.

By NELLIE B. EALES, B.Sc. (Lond.).
(Zoology Department, University College, Reading.)

The work on Cheese Mites, of which this paper gives a preliminary
report, was undertaken in the Zoology Department of University
College, Reading, at the suggestion of Dr R. Stenhouse Williams, of
the Dairy Research Institute, and in collaboration with Mr A. Todd,
Manager of the British Dairy Institute, University College, Reading.

The losses due to the depredations of cheese mites are very severe.
According to statistics obtained by Dr Williams, about 100,000 Stiltons
(the cheeses most affected) are made annually in this country. These
cheeses weigh on the average when ripe about 14 lbs., and before the
war sold at the rate of ls. per lb. Estimating the average loss due to
cheese mites at 23 % of the whole cheese (a not very excessive estimate)
and the labour involved in attending to the cheeses at 4d. per week for
each 100 cheeses for a period of 26 weeks, we obtain the following
figures :

Value of 100,000 cheeses each weighing 14 Ibs. at 1s. per lb. £70,000

Loss due to cheese mites 24 °% £1,750
Labour 4d. per week for each 100 cheeses for 26 weeks (approx.) £433

Total loss £2,183

With a view to minimising and if possible preventing this loss the
following work was done, aided by a research grant from the Board of
Agriculture and Fisheries.

SYSTEMATIC PosITION.

The nearest relatives of the Mites are the Spiders and Ticks. In
these forms the body is incompletely divided into two, the fused head
and thorax and the abdomen. There are four pairs of legs in the adult
and two pairs of mouth parts, which are adapted for biting, piercing
or sucking.

NELLIE B. EALES 29

Many mites are parasitic, for example, the Itch mites. Others,
like the cheese mites, feed on food substances, while a few are carnivorous
and beneficial. As a group the Mites are much simpler in organisation
than the spiders and though not very numerous in species, they cause
an immense amount of damage, owing to their short life cycle, their
rapid propagation, their powers of resistance and their means of distri-
bution.

SPECIES.

Four species attack cheese. All of these are to be found on old
Cheddars and three species on Stiltons and Wensleydales. It must
be remembered, however, that although unpressed, ungreased cheeses
suffer most damage, old cheeses of any kind are lable to attack.
Further, these so-called cheese mites do not confine their depredations
to cheese, but will thrive equally well on flour, stored grain, dried fruits
and drugs, hay, etc., provided these are allowed to get damp. The
four species of Cheese Mite, which all belong to the same family of
Mites, are:

(1) Carpoglyphus anonymus' The Cheddar Mite.

(2) Tyroglyphus siro Stilton and Cheddar Mites.
(3) Tyroglyphus longior 2 be és
(4) Aleurobius farinae a = x

Carpoglyphus is readily distinguished from the other three species
by its greater opacity. It is of a deep cream colour when found on
cheese. Tyroglyphus siro is a somewhat sluggish species with heavy
body, short legs and long hairs. Tyroglyphus longior closely resembles
Tyroglyphus siro, but it is less heavily built and is exceedingly active.
Its hairs are very long and its legs pinkish. Alewrobius farinae, the
Flour Mite, has deep reddish brown legs and short hairs. The first
pair of legs in the male are very stout and spurred at the base.

Lire History.

The life history, which is similar in all the species, consists of four
stages, the egg, larva, nymph and adult male or female. From egg to
adult stage occupies about four or five weeks. In working out the
life history the method suggested by Michael was used?. Glass cells

1 The name Carpoglyphus means the fruit-cutter, because this species frequently
attacks dried fruits. T'yroglyphus means cheese-cutter, Aleurobius farinae the living
organism found in flour.

2 British Tyroglyphidae, i. p. 135,

30) Life History and Economy of the Cheese Mites

were made by fixing a glass ring about one-eighth of an inch in height
to a slide. The adult male and female were then placed in the cell
along with a small piece of cheese, the base of the cell having been
previously covered with a piece of blotting paper, which was kept
moist. The upper rim of the glass circle was smeared with vaseline
and a small strip of glass placed on the top as a lid to prevent the
mites escaping. The cells were examined every day under the micro-
scope and records of the duration of the various stages were kept.
When about three eggs had been laid the male and female were removed
but the eggs left. The exact date when the egg was laid was therefore
known and the young stages became used to living in the cell. It
was much more difficult to keep the mites alive, if the cells were
started with the larva or the nymph stage.

The eggs are white oval bodies, so small as to be only just visible
to the naked eye. They hatch in about 10—12 days after being laid.
On hatching, the young mite is known as a larva. It is colourless
and of a glassy appearance, and has three pairs of legs only. The
larva feeds actively for about a week, then becomes quiescent and
casts its skin, emerging as the first nymph. The first nymph has four
pairs of legs and is somewhat larger than the larva. It moults again
and becomes the second nymph, larger and more highly chitinised than
the first nymph. After its third moult, the mite emerges as an adult
male or female, the sexual organs not being functional until the final
stage is reached.

In Tyroglyphus longior, however, there is an additional stage after
the first nymph stage, which is specially adapted for distributing the
species. This stage is known as the Hypopus stage and occurs under
favourable conditions, that is, when the mites are allowed to breed
unchecked. The Hypopus is like a minute tortoise. It is extremely
small, pinkish in colour, and has a hard, shelly back of chitin. The
legs are short, the mouth parts rudimentary, and there is no evidence
that it feeds. On its ventral side it has a sucker plate by means of
which it attaches itself to other mites, to flies and moths which alight
on the cheeses, or even to the skin and clothes of human beings. It
is thus carried about until it finds a suitable place, when it drops off,
moults to become a second nymph, and commences feeding.

PractricaAL CONSIDERATIONS.

The following questions present themselves for solution.
(1) How do new dairies become infected with mites ?

NELLIE B. EALES Sil

(2) How do new cheeses become infected in a cheese room pre-
viously attacked ?

The second question may be more conveniently dealt with first
and its solution involves to a large extent the answer to the first question.
Stiltons are usually made from April to September, and are then
cleared out of the dairies by December. From December till the end
of April, that is to say, till the next Stilton season, the Stilton room
is usually empty or is used for other cheeses which are not attacked by
mites unless very old. From such a cheese room, which had been
used since Christmas only for cheeses that are not usually attacked,
scrapings from corners, window ledges and shelves were taken in June.
In each case, amongst a mass of dust and dead bodies of mites, a few
live mites were found. The new Stiltons were placed on the shelves
at the end of June and in a fortnight’s time showed numbers of mites
on the coat. The mites that attacked the new Stiltons, therefore, were
already present in the cheese room. The ordinary cleansing methods
had failed to kill them, yet the greatest care is taken in this dairy to
keep the place thoroughly clean. Eggs were never seen in the scrapings ;
all the individuals were adults, and it appears probable that the interval
between the Stilton periods is tided over by adults. Now if these
few adults are the source of mite attack on the new Stiltons, how do
they spread from cheese to cheese and from shelf to shelf? It is obvious
that on emerging from their retreats they will crawl to the nearest
cheeses, but this does not entirely explain how they pass from one
shelf to another. ‘Two experiments were carried out in order to ascer-
tain this. In both these experiments the crawling of the mites to the
cheese was prevented by a band of grease in the one case and by a water
bath in the other.

Experiment 1. A trestle stool, which had never been used in the
cheese room, was thoroughly scrubbed and placed in the centre of the
Stilton room. The legs were thickly smeared with vaseline about six
inches from the floor. Any mites, therefore, that attempted to crawl
up from the floor would be caught by the grease band. A sheet of
plate glass was placed on the trestle and on it four new Stiltons. These
cheeses were turned each day by the same student, who did not touch
any of the mite attacked cheeses, so that it was improbable that she
could carry mites to these four cheeses. Since the mites could not
crawl on to the cheeses, and these were nevertheless attacked about two
weeks later than the other Stiltons in the room, there were three
possibilities :

32. Life History and Economy of the Cheese Mites

(1) That the mites could be carried by flies, which were observed
crawling over the cheeses.

(2) That the mites, being so small, could be blown by a draught
across the small space between shelves and trestle.

(3) That the person who turned the cheeses, in spite of the care
taken, may have carried the mites.

A fly paper was hung up in the room and the flies caught on it were
examined under the microscope. Mites in small numbers were found
attached to their legs, so that there seems to be no doubt that mites
can be carried in this way. In fact, the Hypopus stage (see life history
above) is specially adapted for conveyance by this means. If the mites
can be carried short distances by flies, there is every possibility that
new cheese rooms become infested by mites carried by flies, moths
and other insects which have previously visited places where these small
creatures abound.

Experiment 2. The trestle in this case was not grease banded, but
on it was placed a large bath containing water to a depth of about
two inches. It had been previously ascertained that mites could not
traverse a piece of water, so that any mites that crawled up the legs
of the trestle and over the edge of the bath would fail to reach the
cheeses, which were placed on boards elevated above the water.
These cheeses were attacked by mites at about the same time as those
in Experiment 1, that is to say, about two weeks later than those
that were put on the shelves, and presumably from the same causes,
for moths and flies were seen on these cheeses also.

Of the three possibilities mentioned above, therefore, the first
becomes a fact, viz., that flies and moths can carry the mites. No
experiment has yet been made to show whether the mites can be blown
through the air, though it is highly probable that this is the case, at
any rate for short distances. The possibility of the person who turned
the cheeses conveying mites must not be overlooked, though every
care was taken to prevent it. Anyone who has turned mite-eaten
cheeses, however, will realise that human beings can carry mites from
one place to another, and will have experienced the tingling and itching
sensation due to the presence of the mites on the skin. Although
mites have no eyes!, they can distinguish between light and darkness,
and of the two they prefer darkness. If the breeding cells mentioned
above were kept in the light, the mites hid under the blotting paper

‘

1 Carpoglyphus has
if this mite can see,

‘eye-like organs,” but these have no pigment and it is doubtful

NELLIE B. EALES 33

and it was often very difficult to find them. By keeping the cells
in the dark, however, the mites appeared to thrive better and were
more easily found when the cells were examined from day to day.
It follows from this that mite attack is worse in a dark cheese room
than in a light one, and the practice of having cheese rooms partly
or entirely under-ground is favourable to the mites, although necessary
in order to maintain an even temperature.

Their fondness for darkness, however, is excelled by their love of
cracks, crevices and corners. They creep into cracks in the cheese
boards and shelves, and soap and boiling water will not kill them.
It is, in fact, extremely difficult to kill the adult mite and almost im-
possible to kill the egg. These mites have no breathing organs, but
breathe through the thin cuticle, so that it is far more difficult to kill
them by suffocation or fumigation than it would be if they possessed
breathing tubes like those of insects. The methods employed in the
dairies for keeping them in check are therefore often only waste of good
material. Some cheese makers, for example, dip the cheese in formalin,
believing that the formalin will kill the mites. Mites have been kept
immersed in 5 % formalin for over a week and at the end of that time,
though some had died, many were still active! The formalin washes
off the surface mites, but kills none of them. A very large number of
substances were experimented with, but only two were found which
killed the mites within a short time. These were Carbolic acid and
Carbon bi-sulphide. Carbolic acid, being poisonous, cannot be used
on the cheeses themselves, but it might be used for scrubbing the shelves,
and especially the corners. A 5% solution killed the mites in two
minutes; increasing the strength did not cause their death any sooner
than this. Four 10 1b. Stiltons were removed to an unused room,
freed from mites and kept free by the use of Carbon bi-sulphide. This
substance is a heavy, yellow and evil-smelling liquid which vaporises
very readily and which leaves behind neither smell nor taste. It is
used on flour, grain and many other food stuffs and destroys all forms
of animal life. It is not harmful when breathed in small quantities
by human beings, but is highly inflammable and should not be brought
near a light. The vapour of the bi-sulphide kills the mites almost in-
stantaneously, but although it is a heavy gas, the vapour does not work
underneath the cheeses, neither does it kill the eggs. The bi-sulphide
was used in several ways until the most satisfactory was found.
(1) The cheese was covered with a bell jar and a shallow vessel con-
taining the bi-sulphide was stood on an inverted gas jar placed inside

Ann, Biol. 1v 3

34 Life History and Economy of the Cheese Mites

the bell jar. The bi-sulphide was then left to evaporate. The reason
for elevating the fumigant is that the vapour is heavy and therefore
sinks. The majority of the mites were killed, but some still survived
at the base of the cheese. (2) The cheese was sprayed with the bi-
sulphide by means of an ordinary garden spray. It was then inverted
and the base treated. This method is, however, wasteful. (3) The
cheese was painted all over the surface with the bi-sulphide by means
of a large paint brush. This method was found to be the most effective,
though it would be difficult of application on a large scale and the cost
might be prohibitive?.

It was necessary to treat the cheeses three times, once to kill the
adults, a second, at an interval long enough to allow for the hatching
of the eggs, to kill the larvae, and a third after a similar interval to
make sure that all were killed. Thus the four cheeses received their
first treatment on September 11th, 1916, the second twelve days later,
and the third after the same interval. No mites were afterwards
observed, the cheeses ripened satisfactorily and were kept free from
mites from October, 1916, to February, 1917, when they were returned
to the dairy and sold.

Further experiments with Carbon bi-sulphide will be carried out on a
larger scale during the present year. I do not think, however, that it
would be easy to free large numbers of Stiltons from mites by any fumigant
when once they have been attacked. The mites are so small and breed
so rapidly that it is extremely difficult to exterminate them. The
hope seems to lie rather in preventive methods, that is, in a thorough
cleansing of the dairy in the interval between the clearing out of the
ripe Stiltons and the making of the new ones, and an attempt to do this
will be made in the cheese room at University College, Reading.

The following recommendations arise naturally from what has been
said above:

(1) All the windows should be netted to prevent the entrance of
flies and moths, which carry mites. If doors are left open, they should
have a netted inner door for the same purpose. ‘This precaution
would also eliminate ‘“‘skippers’ from the cheeses, by preventing the
ingress of cheese flies.

' The price of Carbon bi-sulphide is at present 11d. per lb. About 5—8 ozs. were
used for the four cheeses in question at each fumigation and there were three such fumi-
gations, so that the total cost was about ls. 6d. for the four cheeses. The cheeses were
subsequently turned but not brushed as there was no dust on them, The cost of brushing

was therefore saved.

NELLIE B. EALES 35

(2) There should be a very thorough cleansing of the dairy between
one Stilton season and the next in order to kill those mites that persist
and are waiting to attack the next set of Stiltons. Corners, window
ledges and crevices of any kind are their favourite hiding places, and the
whole of the ceiling, walls, floors, shelves and their supports should
be thoroughly cleansed, and all woodwork treated with 5 °% Carbolic
solution. If the walls are not tiled or made of glazed brick, they
should be lime-washed every vear. Limewash does not kill mites, but
the movements of the brush would dislodge them or perhaps crush
them.

(3) It is advisable to have movable shelves of short lengths.
Ideally the shelves would be made of glass, as then only could one be
sure that there were no mites on them. The supports are better made
of iron than of wood, because, with scrubbing, the cracks in the wood
increase in number and depth and so harbour the mites. For the same
reason, floors should be made of concrete, with gutters for drainage.
Tf the Stilton room is not in use between the Stilton seasons, the
shelves should be removed, treated with Carbolic and then kept in
daylight and allowed to dry.

(4) When Stiltons are attacked by mites, the damage is lessened
very considerably by brushing the cheeses daily and removing the mite
dust.

36

INVESTIGATION OF BULB ROT OF NARCISSUS}?.
PART I. THE NATURE OF THE DISEASE.

By KE. J. WELSFORD, F.L:S.

(From the Department of Plant Physiology and Pathology, Imperial
College of Science and Technology, London.)

(With Five Text-figures.)

INTRODUCTION.

The date of the first appearance of the disease in this country 1s
somewhat doubtful. Mr J. W. Barr, of Messrs Barr and Sons, states
that he first observed it about twelve years ago in some bulbs of
Narcissus Horsfieldii wmported from Holland.

Massee(9) found Fusarium bulbigenum (Cooke and Massee) in Nar-
cissus plants suffering from bulb rot and ascribed the disease to this
cause. As, however, no infection experiments were carried out, and
as there seems some evidence that Fusarium bulbigenum may exist in
healthy bulbs, it is clear that the nature of the disease was not settled
by Massee’s observations. The absence of definite knowledge as to
its cause and the increasing ravages of the disease obviously made an
investigation very desirable.

Diseased bulbs were obtained in April, 1915, and a_ preliminary
examination showed them to be infested with various animal pests,
chief among which were Rhizoglyphus echinopus, Eumerus strigatus,
Merodon equestris, and Tylenchus devastatrix; certain scales were also
found to contain Fusarium bulbigenum and bacteria. It was necessary,
therefore, to determine which, if any, of the above was the primary
cause of the bulb rot.

1 This investigation was undertaken jointly by the Imperial College of Science and
Technology and the Royal Horticultural Society.

E. J. WELSFORD a7

INFECTION EXPERIMENTS.

A series of experiments was begun in September, 1915, on bulbs
grown in cold frames at the Imperial College of Science and Technology,
and in prepared beds at Chelsea Physic Gardens. It was found, however,
that more trustworthy results would be obtained if the bulbs could
be grown under better conditions, such as those obtaining in the larger
nurseries. For this purpose, Messrs Barr and Sons were good enough
to provide facilities, and since March, 1916, experiments and observa-
tions have been carried out in their fields and drying sheds at Taplow.

Infection with Bacteria.

Infection experiments were carried out with seven strains of bacteria
which had been isolated from diseased bulbs and grown on either
Narcissus or potato-mush agar. Healthy bulbs were planted in
September, 1915, and were infected with pure cultures of the several
strains in the following month. A piece of the bulb was cut out with
a sharp sterilised scalpel and a portion of agar with the bacteria was
placed at the bottom of the pit, after which the piece of bulb was re-
placed. Healthy cut and uncut bulbs were planted as controls. When
the plants were examined in the following spring and autumn, they were
all found to be quite healthy.

The experiments were repeated during May and June, 1916, but
again with negative results.

It was, therefore, concluded that the bacteria which had been isolated
from the scales of diseased bulbs were not the cause of the disease.

Infection with Fusarium bulbigenum.
fo}

This fungus was isolated from diseased bulbs and grown on sterilised
potato-mush agar, it grew vigorously and produced conidia of the
Monosporium and Diplocladium types. A series of experiments was
then made; sixty bulbs of the varieties Narcissus Leedsu, Narcissus
bicolor Barri conspicua, Narcissus incomparabilis Cynosure, were cut
and infected with portions of agar bearing Fusarium. The Fusarium
was used in three stages: (1) rapidly growing non-fruiting mycelium
from the edge of a culture; (2) mycelium bearing conidia of the Mono-
sporium type, and (3) mycelium with conidia of the Diplocladium type.

In every case the bulbs remained perfectly healthy, though the fungus
was often found growing between the dead outer scales of the bulb.
There was no indication that the fungus had any action on healthy
bulbs. The examination of a large number of bulbs leads to the

38 Investigation of Bulb Rot of Narcissus

conclusion that Fusarium bulbigenum is very often present on the surface
of the dead and dying outer scales of healthy bulbs. It is especially
abundant in bulbs which have been injured, but even on rotting scales
it seldom penetrates far into the tissues. It is evident, therefore, that
the presence of Fusarium bulbigenum is not sufficient to account for
Narcissus rot.

Infection with Black mycelium.

A very dark coloured, almost black mycelium was isolated from
diseased bulbs ‘and a series of infection experiments was carried out.
The infected bulbs remained perfectly healthy. It was, therefore, obvious
that this mycelium did not cause bulb rot, and no attempt was made
to obtain conidia or to determine the fungus.

Kumerus strigatus and Merodon equestris.

It has been shown by f#ryer(4) that the larvae of these two insects
do much harm to Narcissus plants, causing a weak, distorted growth,
and the loss of a large number of plants. The damage caused by them
is, however, quite distinct from the symptoms known as bulb rot.
Infection with Rhizoglyphus echinopus.

These bulb mites are very common on unhealthy bulbs, and are
consequently easily obtained for experimental work. The mites were
lifted off the diseased bulb with a sable brush and were gently trans-
ferred to a healthy bulb, some being put between two injured scales
and some between two perfect scales. The bulbs were not planted
until the mites were seen to move and were therefore presumably
uninjured by the manipulation. These insects undoubtedly do a
great deal of harm; they puncture the scales, and gradually cause
their destruction, thus weakening the bulb; but in no case was bulb
rot obtained by the use of Rhizoglyphus echinopus, and it seems, there-
fore, improbable that the mite causes the disease either by eating the
bulb or by carrying bacteria into its tissues.

Infection with Tylenchus devastatrix Kuhn.

During the course of this investigation more than one hundred
diseased bulbs have been dissected and in all of them eelworms or their
eggs have been found. Small portions of tissue containing live worms
were consequently easily obtained and were placed on the ‘cut surface
of the scales of healthy bulbs. Fifty bulbs infected in this way were
planted in a box of sterilised soil in October and were kept in a cold
frame till the following spring. By the middle of February they all

EK. J. WrLSForD 39

showed the characteristic symptoms of the disease under investigation,
namely, precocious growth, an abnormally well-developed root system,
blotches on the leaves and, above all, discoloured and rotting bulb
scales. No Fusarium was observed. Another set of bulbs treated in
a similar way, but planted in unsterilised soil, also developed bulb rot.
Healthy bulbs, some of which were cut and the rest uninjured, were
planted in both sterilised and unsterilised soil as a control; all these
bulbs remained healthy and showed no symptoms of disease.

When these results are considered in relation to the invariable
presence of eelworm in naturally diseased bulbs and to the fact that
organisms, such as Fusarium and bacteria, which may be found associ-
ated with these nematodes, are unable to cause bulb rot, it becomes clear
that the eelworm, T'ylenchus devastatrix, is the sole cause of the disease.

CourRSsE OF DISEASE.

Healthy bulbs may become infected at any time of the year pro-
vided the ground is sufficiently warm for the eelworm to be active.
When the tissue in which eelworms are living becomes decayed they
forsake it and pass into the ground. In a short
time they infect another bulb, entering it either by
the bases of the old leaves, which, as is the case
with Monocotyledons, are unprotected by a callus,
or by young leaves which have been injured and
are just pushing up through the soil (Fig. 1). The
first noticeable sign of disease in the young leaves
is the appearance of pale green areas; these areas
become yellow, and, then spreading downwards,
produce discoloured “stripes” on the bulb scales.
If such an affected portion of leaf is examined,
eelworms will be found in the tissue; they lie
parallel to the course of the vascular bundles and
pass downwards between the cells (Fig. 2). In a
few weeks after infection the tissue will contain

W310)
a large number of eelworms and probably also
numerous eggs. It is sometimes difficult to be Fig. 1. Infection at
certain of the presence or absence of eelworms crown on bases of
and especially of their eggs, but both can be eld Jeaves,;and> on
demonstrated easily by the following method. The ee

material to be examined is fixed in 25 % acetic-alcohol and hand-
sections are stained in Ziehl’s carbol fuchsin for about an hour, the stain

40 Investigation of Bulb Rot of Narcissus

is washed out in alcohol till the plant tissue is almost colourless. By
this method the eggs and worms are stained a bright red and are seen
as easily in thick as in thin sections.

The infected leaf slowly dies from the tip downwards, and the eel-
worms, both mature animals and larvae, migrate into the lower portion
of the leaf within the bulb. The dead upper portion of the leaf falls
on to the ground and if the weather is sufficiently warm the eggs hatch
and young larvae are soon liberated in the soil through which they can
pass to a healthy bulb. Cold weather makes the eelworms sluggish,
or dormant, or even kills them, and consequently checks infection.

Having once entered the bulb, either through the old leaf bases
or the young foliage, the eelworms pass slowly downwards to the “plate”
leaving the scales discoloured as a whole or in part. If such a diseased

SSS Se Se ie Sa
Comte aoe
OAT TTT

CTO Oo TTT

Fig. 2. Eelworms in tissue of bulb scale. x 300.

bulb is cut across transversely the discoloured scale is seen as a brown
ring or part of a ring (Fig. 3). If cut longitudinally the diseased scales
appear as clearly marked brown stripes (Fig. 4). It is generally the
case that bulbs which have a discoloured scale have also an unusually
luxuriant root system.

When the eelworms reach the plate they leave the scale down which
they have travelled and enter another scale up which they make their
way. Thus they are able to reach the green blades again. Blades
infected in this way look quite healthy till they suddenly fall over and
die. Such a stage is reached in about the month of June when whole
masses of leaves may fall within a week. It is obvious that this falling
of the foliage is not due to any new outbreak but merely marks a stage
in a disease which has been present in the bulbs for many weeks.

As the season advances the diseased bulbs contain an increasing
number of eelworms, eggs, and larvae. When such bulbs are removed

EK. J. WELSFORD 41

to the drying sheds many of the mature worms forsake the scales, no
doubt owing to the gradually increasing dryness, and they may be
found in bunches among the roots. In this position they are subjected
to rapid desiccation and they soon become dormant and fall off, often
on to healthy bulbs. If such worms become moistened they revive
in a very short time and speedily infect the material around them.
Again, if the sheds are warm, the eggs, which have been deposited in
the scales, hatch and the larvae attack the tissue in which they are

Fig. 3. Diseased bulb showing
ring of brown tissue.

Fig. 4. Diagrammatic drawing of bulb which has been
cut in half longitudinally. Second year of attack.
Infection spreading up from plate. a=crinkly leaves
growing at right angles to bulb.

lying. Dry, cool conditions check the spreading of the disease and
prevent the occurrence of fresh infection; unfortunately such condi-
tions are difficult to obtain in practice.

When diseased bulbs are planted in the autumn a certain proportion
of them die and liberate eelworms which infect their neighbours. Those
which survive start growing earlier than healthy bulbs (Fig. 5), and in
the spring often produce one or more curved leaves showing crinkled

42 Investigation of Bulb Rot of Narcissus

areas (Fig. 4). Owing to the large number of eelworms in such bulbs
it usually happens that the disease spreads quickly, thus separating
the scales from the plate; such plates bearing only roots are often
found in beds in which the bulbs are very badly attacked. It seems
probable that in these cases the disease has started in the previous
year.

Ss
pee
_—
VAs

Fig. 5. Early growth of diseased bulb. August.

GENERAL CONSIDERATIONS.

Eelworm is well known in Kurope because of the destruction it
causes to various cultivated crops, especially to rye, hyacinth and
onion.

Kuhn (5,6) in 1867 and 1868 described a disease in rye and showed
that it was due to the action of an eelworm, Anguillula devastatriz.

In 1881 Prillieux (0) investigated the “ring” disease of hyacinths
and attributed it to an eelworm, Tylenchus hyacinth. Two years
later the onion disease was shown by Beyerinck (1) to be due to T'ylenchus
Alli.

E. J. WrLSFORD 43

Owing to the terrible destruction of hyacinths in Holland the
“ring disease,” as it is called, has been thoroughly studied in that
country, more especially by de Mann(7) and by Ritzema Bos(2,3). The
latter believes that the slight differences which exist between the
eelworms parasitic on rye, hyacinth, onion and numerous other plants
are not of specific value but are due to environment. He considers
that the eelworm present in these plants should be called Tylenchus
devastatrix, Kuhn, and he publishes a diagnosis of the species with a
detailed description and numerous figures (10. pp. 185, 220). As the
characteristics of the eelworm found in Narcissus bulbs in England
agree exactly with the diagnosis of Tylenchus devastatrix as given by
Ritzema Bos, there seems no doubt of the correctness of the identification
here put forward.

According to Ritzema Bos (in. pp. 232-254), Tylenchus devastatrix
attacks a variety of cultivated and wild plants, and though it is capable
of passing from one to the other it does not do so easily. He con-
cludes that there are physiological varieties of the species and says:
“Tl paraitrait done qu'on peut admettre comme régle, que le Tylenchus
devastatriz se fixe dans les plantes dans lesquelles les ancétres ont vécu
depuis plusieurs générations, de préférence a d’autres espéces de plantes ;
et que, toutes choses égales d’ailleurs, il prefére ordinairement la plante
ayant une parenté étroite avec celle dans laquelle vivaient les généra-
tions précédentes, a celle qui en est plus éloignée dans le systéme.

“Jestime qu’on pourra trouver dans ce qui précéde la clef de bien
des choses, inexpliquées jusquwici relativement & Vapparition et a la
disparition des maladies vermiculaires dans nos cultures.

“Tl résulte d’ailleurs de ce qui a été traité jusqu ici dans ce chapitre,
que, si au point de vue morphologique il faut considérer comme une espéce
unique les Tylenchus des jacinthes, ceux de Voignon, ceux du seigle,
du sarrasin, du tréfle, ete., et ceux de la mousse Hypnum cupressiforme,
il existe néanmoins des différences physiologiques entre les différentes
Tylenchus, selon que leurs ancétres ont vécu durant un grand nombre
de genérations, dans telle ou telle plante.”

The differences between the eelworms of hyacinths and of onions
indicated by Ritzema Bos suggest a comparison with the “biologic
forms” described for various parasitic hosts. It is to be noted, however,
that Ritzema Bos ascribes to the eelworms merely preferences for their
original host while the biologic forms are normally confined by physio-
logical differences to their particular host or set of hosts. The physio-
logical differences between the onion and hyacinth “forms” of eelworm,

44 Investigation of Bulb Rot of Narcissus

if they exist, are obviously less definite than those which differentiate
the biologic forms of the Uredineae and of the Erysiphaceae.

If the eelworm of Narcissus follows the behaviour described by
Ritzema Bos for that of the hyacinth and of the onion it is clear that
while the bulbs are in the ground there is very little fear that it will
migrate to neighbouring weeds. However, directly the bulbs are lifted
any eelworms remaining in the ground are likely to migrate to suitable
weeds! which thus would become valuable traps. It is desirable,
therefore, that before replanting the ground all weeds should be removed
and burnt; weeds should never be allowed to wilt on the soil nor should
they be dug in.

A list of the more common British weeds and cultivated plants
which have been described as affording shelter to Tylenchus devastatrix
is given here. It is compiled from papers of Ritzema Bos(2,3); it has
no claim to completeness.

Medicago sativa Hyacinthus romanus
Trifolium pratense ss orientalis
Polygonum fagopyrum - precox

ms convolvulus Tulipa gesneriana

bs persicaria Lilium candidum

z lapathifolium Fritillaria imperialis
Bellis perennis Galtonia candicans
Ranunculus acris Scilla sibirica

Geranium molle
Sonchus oleraceus

» campanulata
» cernua
Myosotis stricta Narcissus Tazetta
Plantago lanceolata .. Pseudo-narcissus
Poa annua Muscaria botryoides
Holcus lanatus

. comosum
Brassica rapa Humulus lupulus
Anthoxanthum odoratum Phlox
Centaurea jacea . Chelone glabra
ZA cyanus Solanum tuberosum

Spergula arvensis Wheat
Allium cepa Rye

,, proliferum Oats

5 vineale Vicia Faba

a5 schoenoprasum

' The question of the occurrence of migration and its extent would be well worth
investigation. .

EK. J. WELSFORD 45

Ritzema Bos found eelworms in some plants of Narcissus Tazetta
which he had planted in soil infested with the eelworm of barley, but
he states that bulb growers in Holland find that Narcissus bulbs do
not suffer from bulb rot. He says (11. p. 230) “J’appris aussi par des
cultivateurs de bulbes 4 fleurs de Haarlem, que les tulipes, les lis, la
couronne impériale et les narcisses ne sont jamais atteints de la maladie
causée par les anguillules (maladie annulaire).”’

Thus in 1887 it is clear that the eelworm disease of Narcissus was
little known in Holland though it was then very prevalent among
Hyacinths.

The occurrence of eelworm disease in Narcissus is mentioned by
Marcinoswski(8) in 1910 but no account is given of it and it seems
reasonable to conclude that though it was recognised in Holland in
1910 it was comparatively rare.

Hewitt (4A), working in Ireland, seems to be the only other investi-
gator who has described the occurrence of Tylenchus devastatrix in
Narcissus bulbs. His paper is short and deals mainly with the action
on the bulb and organism of various “‘steeps.” In the light of our
present knowledge it is clear that he was dealing with “bulb rot” ;
but his description of the diseased condition is so brief that apart from
the nature of the infecting organism the nature of the disease he
describes would remain uncertain.

The account given here of the cause and progress of the bulb rot
of Narcissus shows that certain precautionary measures will check to
some extent the ravages of the eelworm. Such measures may briefly
be summarised as follows:

(1) Narcissus should not be planted in ground previously infected
with Tylenchus devastatrix; the danger is especially great if the eelworms
have been liberated from a previous crop of Narcissus.

(2) Care should be taken to plant healthy bulbs only ; one diseased
bulb will soon infect many others.

(3) When a bulb does not produce foliage at the proper time it
should be dug up and burnt before it rots and liberates eelworms in
the soil.

(4) Bulbs with “crinkly” or very curved leaves should be burnt.

(5) Dying leaves should be gathered and burnt before they can
fall on the soil and so possibly infect it.

(6) Weeds growing in infected soil should be pulled up, put directly
into baskets, and burnt.

46 Investigation of Bulb Rot of Narcissus

SUMMARY.

The bulb rot disease, or ring disease, of Narcissus is due to the
attack of an eelworm, Tylenchus devastatriz. These eelworms are of
constant occurrence in the diseased bulbs, and the disease can be pro-
duced by infecting healthy plants with the eelworm.

A description is given of the symptoms and course of the disease
as 1t appears in nature, and certain precautionary measures are suggested.

I have great pleasure in expressing my thanks to Mr J. W. Barr
(Messrs Barr and Sons), Mr Hales (Chelsea Physic Gardens), Mr Leake
(The Floral Farms, Wisbech), Mr Pearson (Messrs J. R. Pearson and
Sons), and Mr J. Walker (Walker Bros.) without whose cordial co-
operation and generous help the work could not have been carried
out. I am also indebted to Mr J. C. Fryer for help and suggestions
with regard to treatment.

I should also like to take this opportunity of thanking both
Professor V. H. Blackman and Professor J. B. Farmer for their stimu-
lating and helpful criticism.

LIST OF PAPERS QUOTED.

1. Bryertnck, M. W. ‘De oorzaak van der kroefziekt van jonge ajuinplanten.”
Maandblad der Holl. Maatschappij van Landbouw, No. 9, 1883.

2. Bos, Rivzema. ‘‘Untersuchungen iiber T'ylenchus devastatrix.” Biol. Central-
blatt, 1887-8. Bd. vu, p. 232.

3. —— “L’Anguillule de la Tige (Tylenchus devastatrix) et les Maladies des Plantes
dues 4 ce Nématode.” Haarlem. Musée Teyler Archives, Sér. 2, 1887-1892,
p- 161.

4. Fryer, J. C. Narcissus Flies. Board of Agriculture and Fisheries Leaflet,
No. 286, 1914.

4a. Hewitt, T. R. Eelworms in Narcissus Bulbs. Jour. Dept. Agric. and Tech.
Instit., Ireland, xtv, 1914, pp. 345-353.

5. Kunn, J. Zeit. d. Landwirthschaftlichen Centralvereins der Provenz Sachsen,
L867, p. 99.
6. Ueber die Wurmkrankheit des Roggens und iiber die Uebereinstimmung.

7. pvE Mann, J. G. Die freie in der reinen Erde und im Siissenwasser lebenden
Nematoden der niederlandeschen Fauna, 1884, p. 142.

8. Marctnoswsk1, K. “‘Parasitiseche und semi-parasitische an Pflanzen lebende
Nematoden.” Arbeiten aus der Kaiserlichen Biologischen Anstalt f. Land- und
Forstwirtschaft. Bd. vit, 1910.

9. Massnun, G. “A disease of Narcissus bulbs.” Kew Bulletin, 1913, p. 307.

10. Prititreux, EK. “La Maladie vermiculaire des Jacinthes,’ J. de la Soc. Nat,
V horticulture, 3™°, sér, 1, 1881, p. 253.

47

NOTES ON A PLAGUE OF PSOCIDS
ING Av BACTORY ;

By R. A. HARPER GRAY, M.A., B.Sc. (Agric.), M.Sc.

(Lecturer and Adviser in Agricultural Zoology, Armstrong College,
. Newcastle-upon-Tyne.)

The small insects belonging to the family Psocidae cannot as a
whole be regarded as injurious either to growing plants, or to plant
products in their manufactured state. Their food is said to consist
for the most part of minute fungi, such as moulds, and of animal or
vegetable refuse, and they, therefore, are seldom attracted to any
material of value.

From time to time, however, Psocids are recorded as being destruc-
tive to such objects as corks, books, insects in collections, etc., and in
most cases it seems likely that the objects attacked had been kept in
damp surroundings and were, therefore, affected with moulds or other
fungi. An instance is mentioned by Theobald, for example, in which the
Psocid Atropos divinatoria was referred to him with the complaint that
it was appearing in large numbers from an old mattress, and “causing
some consternation”. ”

The genera most often associated with this type of damage are
Atropos, sometimes known as “Book Lice” (owing, doubtless, to the
fact that they are frequently found in the neighbourhood of old books
or papers which have not been disturbed for some time), and Caecilius,
but it seldom seems to have been recorded that either has been respon-
sible for serious loss from the financial point of view.

It may, therefore, be of interest to describe a case in which a stoppage
of work in an important factory where straw mattresses are made was
actually brought about by insects of the genus Caecilius (C. pedicularius®).
These psocids had established themselves to such an extent that when

1 Cambridge Natural History, vol. v, p. 393.

2 Report on Economic Zoology for the year ending September, 1910, in The Journal
of the South-Eastern Agricultural College, Wye, No. x1x.

% Specimens were submitted to Dr Gahan of the British Museum of Natural History,
who kindly identified them as belonging to this species,

48 Notes on a Plague of Psocids in a Factory

the large double doors of part of the building, referred to below as the
“loft, were opened in the morning, they could be seen flying out in
thick clouds. When, further, complaints began to be made by customers
about large numbers of insects appearing in bedrooms where newly
purchased mattresses were being used, the manager of the factory
recognised the seriousness of the outbreak, and wrote a letter to the
writer, requesting advice as to how to get rid of the pest.

In order to ascertain the nature of the buildings and the manner
in which the straw for making the mattresses was being stored, a visit
was paid to the factory, when it was found that three buildings were
involved, viz.

(a) the loft, in which the straw was stored,

(b) the making-room, in which the mattresses were made,

(c) the store-room, where the finished mattresses were stored.

The insects were most numerous in the loft, which measured 184 feet
high, by 28 feet long, by 15 feet wide, the other rooms being slightly
less. No fresh straw had been brought in after the old had been used
up, so that the nature of the flooring could be easily examined. It was
of concrete, and there were a few fairly wide cracks running across the
whole width. In these cracks immature forms of Psocidae were
observed.

The measures successfully adopted to get rid of the pest may be
put briefly as follows:

(1) The ventilators in the loft were closed, and all crevices (round
the doors, etc.) were covered over with paper carefully pasted on—the
door through which the fumigant was admitted being dealt with 1m-
mediately after being closed.

Ten pounds of rock sulphur (previously broken up in a sack by means
of a mallet) were placed in an iron pot, and some hot cinders thrown
ontop. The pot was placed in the middle of the room, and instructions
were given not to open the doors until twenty-four hours had elapsed.
The other rooms received similar treatment.

(2) The loft having been thoroughly ventilated after fumigation,
the walls were then carefully whitewashed (the whitewash containing
some carbolic acid) and the floors of all the rooms were washed out
with water and carbolic soap.

(3) It seemed probable that a few Psocids might appear in a week
or two, seeing that the eggs might not be affected by the treatment, and,
indeed, six days after the fumigation, a report was received stating that
the insects were beginning to reappear. The writer accordingly visited

R. A. Harper Gray 49

the factory and found a few Psocids mostly near the windows—in quite
a sufficient number to start another plague of them. It was, therefore,
decided to repeat the treatment, but to use fifteen pounds of sulphur
instead of ten pounds for the second fumigation. After twenty-four
hours’ fumigation, the floors were again washed out with carbolic soap,
and creosote was carefully poured down, along the cracks in the floor
of the loft. The manager was recommended to close up these cracks
with cement, after this second fumigation.

Six weeks afterwards a letter was received from the manager in
which he said: “I am pleased to be able to tell you that there has not
been a recurrence of the plague of flies,” and a recent examination of
the buildings showed that the treatment had been successful. The
cracks had been closed up with cement as recommended.

With regard to the probable source of the outbreak it should be
mentioned that straw coming in from one of the farms supplying the
factory was dirty and in bad condition. The supply of straw from the
particular farm was stopped when it was pointed out that this was most
probably the source of the trouble, and the writer recommended that
care: should be taken to secure good clean straw in future. It seems,
therefore, likely that the continued freedom from the pest now for
nearly six months, is due to this precaution following upon the measures
taken against the insects that had succeeded in establishing themselves
in the factory.

Although the Psocids do not attack man, it is interesting to record
that in the case of the above outbreak, an eruption appearing on the
skin of a child sleeping in a bedroom containing a newly purchased
mattress from which the insects were emerging, was not unnaturally
attributed by the mother to the presence of the Psocidae.

Ann. Biol. tv 4

50

A BACTERIAL BLIGHT OF PEAR BLOSSOMS
OCCURRING IN SOUTH AFRICA.

By ETHEL M. DOIDGH, M.A., D.8Sc., F.L.S.
(Mycologist, Union Department of Agriculture.)

(With 7 Text-figures.)

During the seasons 1914—15 it was observed by fruit growers in
the Stellenbosch district that a large percentage of the pear blossoms
blackened and then died, and that in some varieties only a very small
number of mature fruits were produced. The blackening was at first
attributed to Fusicladium, but winter spraying seemed to have no
effect on the prevalence of the trouble and specimens were therefore
sent to this Laboratory for examination. The discoloured tissues were
found to. be swarming with innumerable bacteria; from these a pure
culture was readily obtained of an organism which caused blackening
in pear blossoms, artificially inoculated within a few days. ‘The organ-
ism was re-isolated, and studied with a view to comparing it with the
two organisms which are known to cause blight in fruit blossoms and
which will be referred to in detail presently; one of these is the well
known ‘Fire Blight” organism, Bacillus amylovorus, which occurs
commonly in America, and the other a Bacteriwm recently described by
Barker and Grove, as causing a blight of fruit blossoms in England.
The South African organism proved to be distinct from either of these.

It is interesting to note that during some experiments carried out
at the Elsenberg Agricultural College, in an orchard which has since
been found to be heavily infected with the blossom blight, it was found
that if the flowers were covered with paper bags before they opened
almost 100° set, as many as 32 to one truss in some cases; whereas
when the flowers were not covered a large percentage fell. This was
attributed to the fact that the blossoms were sheltered by the bags
from high winds and sudden changes of temperature, but it seems
more probable that it was due to the flowers being protected from the

Erne, M. Dorar

51

visits of bees and other insects which have been shown both in this
case and in the case of other diseases of a similar nature to be the
principal carriers of infection.

Dimensions
Flagella
Capsule
Optimum Temp.
iy ID 12s
Pigment

Agar colonies

Nutrient Broth

Gelatine Stab
Milk

( Potato

Vegetable } Carrot

Cylinders | Turnip
_ Beet

Uschinsky’s solution

Indol

Diastatic activity
Group numbers

Comparative Schedule.

Bacillus amylovorus
‘9—3 uw x-7—lpe
Several peritrichous
None

25—30° C.

43-7° C.

None

White, circular, ele-
vated, wet, shining,
margins irregular

Clouding not heavy,
pellicle and rim
slight, moderate
amount of grey de-
posit

Slow crateriform li-
quefaction

Coagulated in 3—4
days, later digested
to pasty condition

Good growth on all,
best on beet, weak-
est on turnip, liquid
heavily clouded

Growth copious, not
viscid

Considerable quantity
produced

Barker and
Grove’s Organism

2—4 wp x -5— 8 uw
Polar 3—6
None

15—18° C.

Some fluorescence in
old cultures

Whitish, circular,
smooth margins

Wellclouded, appre-
ciable deposit and
slight rim and pel-
licle

Liquefaction rapid,
first crateriform
then stratiform

Slowly peptonised

Fair on potato,
feeble on carrot,
none on turnip

No growth

Reaction only ob-
tained after warm-
ing

Feeble

PALER Be yale

Bacterium
nectarophilum
-5—3 uw x -45—7 w

Polar 1—5
Always present
25—30° C.

40° C.
Fluorescent

Spreading, _ irre-
gular margins

Very turbid, de-
posit heavy, rim

and pellicle pre-
sent

No liquefaction

Slowly peptonised

Fair growth on all

but heavy on
none
Heavy, viscid
growth

None produced

Feeble
222,2332123

During September, 1916, I was able to visit the pear-growing
district, and to study the disease in the orchard; it was too early for
the late-flowering varieties, some of which are the most susceptible,
but considerable infection was found in the Keiffers and other varieties
which were then in flower. Information as to the susceptibility of the

different varieties was also gleaned from various growers, all of whom
mentioned the same varieties as the most lable to the disease.

Pear trees flowering in the Wellington District and in the Pretoria
District show no signs of the blackening: a trouble of a somewhat
similar nature has been reported from Potchefstroom, but it has not

4—2

52 Bacterial Blight of Pear Blossoms in South Africa

yet been ascertained whether this is identical with the blight at the
Cape or not. With the exception of a case of infection reported from
Wynberg, therefore, the disease is only known to occur up to the present
in the Stellenbosch District and at Elsenberg. It is particularly in-
teresting to find that there are three organisms showing a parasitism,
in many respects similar, in different parts of the world; it is therefore
my intention to describe the South African disease, and to compare it
with the blossom blight occurring in England and with that caused
by the fire bight bacillus in America.

Through the courtesy of Professor Barker and Mr Grove who supplied
me with a culture of their organism I have been able to make a detailed
comparison of the South African and English bacteria. My knowledge of
the American blight is less complete, being gathered from the literature
to which I have access, and which is by no means exhaustive; sufficient
information has been gathered by this means, however, to establish
the main points of difference between Bacillus amylovorus and the
other organisms causing blossom blight in pears.

I, Fire Buieat.

Bacillus amylovorus (Burr) de Toni.

The information summarised in the succeeding paragraphs has been
derived from the publications listed in the “ Literature cited ” (numbers
4—11).

“Hire blight’ was one of the first bacterial diseases of plants to be
recognised as such, and consequently has been studied in considerable
detail. It is very widely distributed in the United States and in Canada,
and has recently been recorded(8) from several places in Italy. It
causes very serious losses, amounting in California in the last fifteen
years to one-third of all the full-grown orchards, and to a money loss
estimated at $10,000,000 for the five years preceding the efforts for its
restriction begun in 1905 by the United States Department of Agri-
culture (8).

In 1912 a variety of pear in Switzerland was severely injured by «
bacterial invasion(7). It is thought that the disease may be similar
to the pear blight in America caused by Bacillus amylovorus, but com-
plete identification of the organism has not yet been found possible.

Although most common and most disastrous on the pear (Pyrus
communis) Bacillus amylovorus is also found as a parasite on the apple
(Pyrus malus), Quince (Cydonia vulgaris), a number of species of Prunus

3

or

Eruet M. Dorper

including the plum and apricot, and on numerous plants indigenous to
America. Of the varieties of Pear which was attacked, the Bartlett
is said to be very susceptible; other varieties are bracketed with the
Bartlett as susceptible, but there seems to be considerable divergence
of opinion on this point. The Keiffer, Duchess and Winter Nelis, and
the oriental group in general are more resistant.

Symptoms.

Although infection most frequently takes place through the flowers,
the blossom blight is not by any means the most serious phase of this
disease. When the blossoms are attacked the receptacle becomes
blackened first, infection taking place through the nectaries, but the
infection rapidly spreads into the ovary and the flower stalk and invades
the twigs. The blossoms and leaves of affected twigs become dis-
coloured, turning light or dark brown, or sometimes red, and finally
shrivel up and die. The spread of infection is frequently so rapid as
to result in the complete blackening and death of all branches and
spurs upon which flower clusters have been borne. The blight may
continue to extend down the branch or twig, the branch being entirely
killed as it progresses, and in course of time it may extend into the
larger limbs. The bark of infected twigs and branches becomes blistered,
and on the blistered areas there is often found a gummy exudate
which is crowded with the rods of the causal organism; this exudate
attracts the insects which are responsible for the further spread of the
disease. Immature fruit is frequently attacked; it becomes light
brown and finally black, the flesh soft and pulpy, and the skin somewhat
wrinkled. Ripe fruit seldom becomes infected.

The Characters of Bacillus amylovorus (Burr) de Toni.

Morphology.

Bacillus amylovorus is a short rod with rounded ends, -9—1-5y
< -7—1 in dimensions, longer (nearly up to 3) and slightly narrower
in old cultures.

It is motile by means of several (4—8) peritrichous flagella; no
capsules or spores have been observed. The rods are usually single or
in pairs, but in young cultures short chains made up of 3—4 individuals
have been noted.

The organism is Gram-positive.

54 Bacterial Blight of Pear Blossoms in South Africa

Cultural Characters.

Nutrient agar colonies are evident on the second and attain a diameter
of 2—3 mm. by the fourth or fifth day. They are white and granular,
or cloudy with a sharply defined white centre; the margins are entire
or slightly wavy. Submerged colonies are opaque, yellowish-white,
lenticular.

Nutrient agar stab. Growth takes place along the entire length.

Nutrient agar streak. In 24 hours there is a moderate opalescent
growth which spreads slowly. It is finally white, wet-shining, thin
along the middle, heavier along the sides, margins wavy, eventually
spreading over the surface of the slant. More rapid growth is induced
by the addition of the agar of 2 °% saccharose, dextrose or maltose or
5% glycerine. The water of condensation becomes turbid, but the
growth is not viscid.

Nutrient gelatine colonies are very slow growing, only appearing
after 3—5 days. The surface colonies are round, slightly raised, entire,
buried colonies spherical, granular. The medium is liquefied very
slowly.

Nutrient gelatine stab. Growth is at first filiform, and is slow and
feeble; surface growth spreading with irregular margin; slow crateri-
form liquefaction takes place, later becoming stratiform.

Nutrient bowillon is clouded after 24 hours and this is accompanied
by a slight acidity; after 48 hours there is greater cloudiness with more
or less persistent flocculi, the medium becoming alkaline, and in time
showing a tendency to clear. In sugar-free bouillon the liquid remains
clear for 24 hours except for a slight sediment. It is neutral at first,
becoming cloudy and alkaline after some days. The clouding is never
very heavy as compared with other organisms.

Milk is coagulated in 3—4 days; coagulation is followed by digestion
to a pasty or sub-gelatinous condition, with separation of supernatant
whey; this is at first acid, later becoming slightly alkaline. Litmus
milk is unchanged.

Blood serum. On this medium the growth is similar to that on
nutrient agar; there is no liquefaction.

Potato, carrot, turnip, beet. There is good growth on all these media ;
it is best on beet, weakest on turnip. In all alike a wet-shining white
streak forms along the line of inoculation; the liquid is heavily clouded,
white and nearly opaque. The tissues are not softened and there is
no odour, gas or pigment.

Eruet M. Dorpcr 55

Cohn’s solution. No growth.

Dunham's solution. The organism grows rapidly in this solution,
but the clouding is not dense; there is no pellicle or rim and the deposit
is slight.

Uschinsky’s solution. Growth copious but not viscid.

Biochemical and Physical Relations.

Enzyme production: Amylase. Amylolytic activity is indicated by
the fact that the organism liquefies starch jelly.

Gas. No gas is produced in fermentation tubes with glucose,
saccharose, lactose, glycerine, maltose or mannite.

Pigment. None, organism is white or greyish white on all media.

Indol. A considerable amount of indol is produced.

Acid and alkali production. Ordinary nutrient broth shows a slight
decrease of alkalinity, then a return to the original reaction. Broth
containing 2 °%, saccharose or glucose, gradually became acid; lactose
broth showed little or no change in two weeks.

Nitrates are not reduced to nitrites.

Colour reduction. Litmus milk and rosolic acid peptone water
showed progressive bleaching during the first week, but the colour
finally returned.

Toleration of sodium chloride. 3% did not inhibit growth.

Temperature relations. The optimum temperature is 25—30°C. ;
there is no growth at 5°C.; growth is very slow at 3°C. Thermal
death point (wet) is 43-7° C., 10 minutes exposure.

Desiccation. When organism was dried on cover glasses at about
20° C., 5 days had no effect, 76 days was fatal.

Insolations. 10 minutes exposure of freshly poured plates retarded
development; 30 minutes was fatal.

II. Buiossom BiicHt IN ENGLAND CAUSED BY BARKER
AND GROVE’S ORGANISM.

This disease is very widespread in England, probably occurring at
least throughout the midland and southern counties. The most sus-
ceptible varieties are the Beurre d’Amanlis and the Catillac.

The method of infection varies; sometimes the sepals turn grey
and blacken, the discoloration finally involving the whole of the calyx
and flower stalk, and the flower blackens and shrivels up. It may
then fall or it may remain attached to the shoot. The whole truss

56 Bacterial Blight of Pear Blossoms in South Africa

of blossom eventually dies and the spur may also die back to its point
of attachment to the branch carrying it. In other cases infection takes
place through the receptacle, which becomes blackened, the discoloration
spreading to the ovary.

The disease is carried from flower to flower by bees. An organism
has been isolated and the disease reproduced repeatedly by Barker and
Grove in the course of their study of the disease; and I was successful
in producing black spots on the receptacle with the culture which they
sent to me; these latter developed rather slowly as the room tempera-
ture was far above the optimum for the organism.

In a recent report (2) it is stated that an organism has been isolated
from diseased gooseberry bushes which is in all probability identical
with the organism causing the pear blossom blight.

The Organism.

A parallel series of cultures of this and the South. African organism
have been carried out; the characters of Barker and Grove’s organism
are described in some detail in their paper (1) but a few additional points
of interest have been observed in making the comparative study, which
may be added to their description.

Morphology.

The organism is a rod 2—4 x -5 the cells are mostly single
or in pairs, seldom in long chains. It is highly motile in young cultures
by 2—5, lophotrichic flagella (Fig. 1) which are four to five times as

my
Se

ian

Fig. 1. Barker and Grove’s organism 24 hrs. at 20°C. Ellis’ flagella stain. Zeiss
obj. 7s, No. 12 compensating ocular. Drawn with the aid of the camera lucida.

ETHEL M. Dorpar 57

long as the rods. No capsules have been observed. Involution forms
are produced in 24 hours in nutrient broth at 30°C. and in old cultures ;
these take the form of long threads up to 100y long and irregularly
swollen.

It stains well with all the usual stains, especially with Gentian violet
and is Gram-positive.

Cultural Characters.

Nutrient agar colonies. At 18°—20° C. the colonies are visible to
the naked eye in 48 hours; in three days the surface colonies are -5 to
3mm. in diameter, round-irregular, glistening and translucent; in four
days they are up to 5 mm. in diameter, of a light coppery tint by trans-
mitted light, creamy white by reflected light. Some of the colonies
are inclined to spread and become lobulate, but the majority are more
or less circular, with a smooth margin.

The submerged colonies are at first punctiform, afterwards lenticular.
There are a few crystals in old cultures.

Nutrient agar streak. Cultures form a flat, whitish glistening growth,
spreading out at the base of the slant; very old streaks are slightly
fluorescent. :

Nutrient agar stab. The best growth is at the top.

Nutrient gelatine colonies. Visible in 48 hours; the submerged
colonies are minute white points; those on the surface slightly larger,
with an undulate margin around which there is a slight indication of
liquefaction. After four days the surface colonies are sunk in small
craters of liquefied gelatine, they are moist and glistening semi-trans-
parent, often with a small white nucleus in the centre, surrounded by
several concentric rings of whitish, granular matter. Liquefaction of
the gelatine is complete in 8—10 days.

Nutrient gelatine stab. In three days at 18—20° C. there is a small
crater of liquefaction 4—8 mm. broad and 8—10 mm. deep, and the
surface growth has sunk to the bottom of the crater; in seven days
the liquefaction involves the whole thickness of the tube and becomes
stratiform.

Potato. On this medium there is a raised, creamy-white growth with
smooth edges along the needle track.

Turnip. No growth. :

Carrot. The growth on carrot is very scanty, thin, and spreading.

Parsnip. A very much raised, shining streak develops, standing

58 Bacterial Blight of Pear Blossoms in South Africa

about 2mm. high, the surface being almost semi-cylindrical; on one
cylinder the edges only were raised and the centre depressed.

Beet. On beet the organism grows fairly well, producing a raised,
gelatinous-looking growth along the needle track; the growth on the
surface of the liquid takes up the colour from the medium to some
extent and becomes fairly pink.

Blood serum. The organism does not liquefy blood serum, and the
streak is similar to that on nutrient agar, but the growth less copious.

Nutrient bouillon becomes slightly clouded in 24 hours, and in two to
three days is fairly heavily clouded. There is a considerable amount of
sediment and a very thin pellicle. In very old cultures a slight fluores-
cence may sometimes be observed.

Milk is not curdled, but is very slowly peptonised. In nine days
two-thirds to four-fifths of the liquid is clear; after one month the milk
is completely peptonised, the colour is reduced in litmus milk, and the
medium is distinctly alkaline to litmus.

Dunham's solution is slightly clouded.

Uschinsky’s solution. No growth.

Cohn’s solution. No growth.

Nutrient bouillon over chloroform. Growth was unrestrained in the
presence of chloroform.

Egg albumen. A medium composed of 1 gram powdered egg albu-
men and 50 ¢.c. of -05 °% potassium phosphate was well clouded in five
days.

Physical and Biochemical Relations.

Proteolytic actiwity. The organism is a fairly active proteolytic
agent; 1t slowly peptonises milk and there is a distinct smell of ammonia
from liquefied gelatine.

Cultures in nutrient bouillon were tested for ammonia by distillation
after five to 10 days at 20°C. In each case 50 ¢.c. of medium were
found to contain approximately -02 gramme of ammonia nitrogen.

In the egg albumen medium described above there was a positive
reaction for peptone after five days. A quantitative test by Sorensen’s
method showed that 50c.c. of the medium after five days contained
‘0035 nitrogen, in the form of amino acids and ammonia, ?.e. approxi-
mately 2-3 % of the total nitrogen had been broken down. A distil-
lation test for ammonia showed that the whole of this was in the form
of ammonia; and cultures tested after 10 days gave an almost identical

reading; the amount of ammonia had not increased.

ErHet M. DormwcE 59

Milk cultures tested in the same way gave a strong reaction for
peptone and for tyrosin after 10 days; and there was -011—-O17 grains
ammonia nitrogen in 50 c.c. of the medium.

Amylolytic action. Starch is very slowly destroyed; nutrient
bouillon containing -01 gram of soluble starch gave the red-brown
reaction of amylodextrin with Lugol’s iodine solution after about 10
days, and in three weeks the starch had completely disappeared.

Fermentation reaction. No acid or gas was produced in fermentation
tubes containing peptone water, tinted with litmus, and containing
2 % of any one of the following substances :—starch, laevulose, mannite,
glycerine, galactose, saccharose, dextrose, lactose.

Indol. No reaction for indol was obtained at room temperature
in 10 days old cultures in peptone water and nutrient broth, but after
warming a slight, but quite definite coloration appeared after the
addition of sulphuric acid and a nitrite.

Nitrates are not reduced to nitrites.

Gas production. It has been mentioned that no gas is produced
in fermentation tubes containing sugar solutions. In iron and lead
peptone solution and bouillon the precipitate was decidedly blackened,
showing that sulphuretted hydrogen had been liberated.

Atmospheric conditions. The organism is a facultative anaerobe ;
it grows slowly on glucose formate agar in an atmosphere devoid of
nitrogen.

Temperature. The optimum temperature lies between 15 and 20° C. ;
the thermal death point has not yet been determined.

Ill. THe Sourn Arrican DISEASE.

It has already been pointed out that so far as is known at present
the pear blossom blight only occurs in the Stellenbosch District and at
Elsenberg, that is to say in the region where the winter and early spring
is the rainy season and in that part of it where pears are extensively
grown. Several cases of blackening in blossoms and pearlets grown
in other parts of the country have been brought to our notice, but as
these occurred in hot dry weather after some six or seven months’
drought, it is more probable that the failure of the blossoms was due
in these cases to drought than to the bacterial blight, which only
spreads rapidly when the atmosphere is moist. Further investigation,
however, will be necessary before any definite statement as to the
geographical distribution of the disease can be made.

60 Bacterial Blight of Pear Blossoms in South Africa

Varieties affected.

Some of the late flowering varieties are the most susceptible.
Winter Nelis and Beurre Superfine are very badly affected, also the
Kastanje Bergamot; a number of other varieties including the Keiffer,
Beurre Diel and Bon Chrétien are also affected but not to the same
extent as those above mentioned. The Duchesse d’Angouléme appears
to be practically immune, as no sign of the disease could be found on
trees standing in an adjacent row to a number of Keiffers which were
badly affected.

Symptoms and spread of infection.

So far as can be ascertained up to the present the disease is confined
to the flowers, peduncles and very young fruits. No infections have as
yet been found on leaves or twigs, and I have failed to produce artificial
infections on these parts.

Infection almost invariably takes place through the receptacles ;
it usually takes place at more than one spot, a number of minute dark
spots appear on the receptacle, these rapidly increase in size, becoming
black and spreading until the whole receptacle is involved. Less
frequently the tissues of the receptacle are very completely invaded
before any blackening occurs, the whole assuming a greenish brown,
water-soaked appearance and later turning black.

When the receptacle is invaded the infection and blackening fre-
quently spreads to the styles and the ovary, and less frequently to the
flower stalk. Infected flowers fall, and in the case of susceptible
varieties in such numbers as to seriously affect the crop.

The rapidity with which the disease spreads from flower to flower
suggested that the infection is carried through the agency of bees.
With the assistance of Mr Neethling, the lecturer in Botany at the
Klsenberg Agricultural College, this point was satisfactorily settled.
He kindly co-operated with me in this matter by capturing a number of
bees which were working in the neighbourhood of the infected trees;
some of these were allowed to walk over some nutrient agar and then
released ; from others the mouth parts were excised, and dropped into
tubes of melted agar which were then set on the slant. The tubes
thus infected were then posted to me at Pretoria for examination.

Cultures of the causal organism were readily obtained from all five
of the tubes containing the bee traces; of the others the organism was
found in one into which the head and prothorax of the bee had been

ETHEL M. Dorper 61

dropped, but not in any of the tubes planted with the proboscis or
mandibles alone.

Artificial infections were readily produced with the culture isolated
from the bee traces.

It seems possible that ants may also be partly responsible for carry-
ing infections, as quite a number of them were noticed working in the
infected flowers at one farm in the Stellenbosch District.

Etiology.

When the organism causing the bacterial blight in pear blossoms
was first isolated in October 1915, the blossoming season in Pretoria
was almost at an end, but a preliminary infection experiment was carried
out with the few flowers which were still to be found on the trees. The
blossoms sent from Stellenbosch were shrivelled and quite black, but
bacteria were very plentiful in the tissues and no difficulty was ex-
perienced in obtaining a pure culture.

The weather was exceedingly hot and dry so that it was useless to
attempt any inoculations in the orchard. A number of twigs bearing
apple and pear blossoms were therefore carefully cut under water, and
conveyed to the laboratory where they were covered over with bell
jars; some of these were atomised with a suspension of a culture in
sterile distilled water, others kept as controls. The latter remained
fresh and showed no signs of drooping or discoloration during the
experiment. ‘The inoculated blossoms, however, showed water-soaked
spots on the petals, calyx, and peduncle after 24 hours; in 48 hours
these had become very numerous and began to turn brown, and in a few
days the whole flower had turned black and fallen.

The organism was readily re-isolated and inoculated into some young
pears by atomising as before; a few infections were thus obtained in
pearlets which had just set, but not on the fruit of the size of a walnut
or larger; that is to say, the organism seemed unable to attack the
young fruit after it had begun to harden.

After visiting the affected orchards in September, 1916, fresh
cultures were obtained from material collected, and a number of inocu-
lations were carried out with the organism thus freshly isolated, the
strain isolated the previous year and with Barker and Grove’s organism.
Inoculations were carried out in one of three ways; the flower was in-
fected by touching the receptacle with a platinum needle, which had been
charged with a small quantity of agar culture; a drop of a suspension
of an agar culture was placed on the receptacle with a fine pipette;

62 Bacterial Blight of Pear Blossoms in South Africa

or the whole inflorescence was atomised with a suspension of an agar
culture in distilled water.

When either of the first two methods was employed a number of
minute water-soaked spots appeared on the receptacle in 24—48 hours,
or, in the case of a heavy infection the whole receptacle became water-
soaked in appearance.

The infected areas soon began to turn brown and spread until the
whole receptacle was involved. The receptacle was finally quite black,
the blackening not infrequently spreading into the styles, ovaries and
peduncle; and the slightest movement was sufficient to cause the
infected flowers to fall.

When the inflorescence was atomised, infection was equally prompt,
discoloured areas appearing on the sepals, petals, ovary and peduncles.
In no case have I been able to infect the leaves or fruit spurs, and I have
not observed any such infections in the orchards.

All inoculations were carried out in the Laboratory under conditions
similar to those employed during the preliminary experiment carried
out in 1915; a schedule of the inoculations is appended.

It will be noticed that positive results were obtained in each case
when pear and apple blossoms were inoculated, but that attempts to
infect cherry, peach and nectarine were all unsuccessful. Up to the
present no natural infections on the apple have been found.

In each experiment an equal number of flowering branches were
kept as controls; and in no case did the disease appear in these.

No. Kind of Blossom Method Source of Culture * Results
1 Pear Atomiser Blossoms from Banhoek, Positive
Stellenbosch
2 Apple 55 5 » 99
3 Pear (young fruits) Ms Re-isolated from (1) =
a Pear Platinum needle Blossoms from Elsenberg a
5 - Pipette =e > ”
6 * Atomiser 2 es a
ul Cherry Pipette 3 or Negative
8 Pear s As (1) but after 12 months Positive
in cultivation
9 39 ss Blossoms from Ida’s Valley, A
Stellenbosch
10 eS a Re-isolated from (4) A
11 cr Atomiser Same as (4) op
12 Peach Pipette is 3 Negative
13 Nectarine ne Fe 55 af
14 Pear 55 2 x. Positive

15 ‘a Ae Bee traces a

Erne. M. Dorman 63

Pathological Histology.

Infection usually takes place through the nectaries, but the organism
sometimes finds its way into the green tissues of the flower and flower
stalks through the stomata.

The rods multiply very rapidly in the intercellular spaces, and it is
very noticeable that wherever the intercellular spaces are invaded, the
contents of the adjacent cells become plasmolysed and stain very deeply
with carbol fuchsin. In sections stained with carbol fuchsin and light
green these showed up in startling contrast to the normal cells which
stained light green and in some of which the nucleus could be plainly
seen (Fig. 2).

Fig. 2. Section through diseased receptacle, natural infection, drawn with
Edinger’s projection apparatus. An early stage of infection.

After the cells are plasmolysed and killed they disintegrate very
rapidly and collapse, the original cell outline completely disappears
and the diseased area consists of a disorganised mass staining intensely
with carbol fuchsin.

When the receptacle is infected the flowers soon fall, but in some
cases not until the infection has spread into the more deep-seated
tissues of the ovary, all of which become blackened and disorganised
(Fig. 3).

64 Bacterial Blight of Pear Blossoms in South Africa

Fig. 3. Section through diseased receptacle, natural infection, drawn with Edinger’s
projection apparatus, the scale is indicated. A more advanced infection showing the

collapsed tissues.

Morphology.

The organism is a short rod of very variable size and shape. A
pure culture may be readily obtained from infected tissues, but the
milky white masses of bacteria which diffuse out from such tissues
consist of rods which exhibit astonishing variations in size and form
(Fig. 6). The majority are short thick rods with rounded ends, measur-
ing for the most part -6—1-5 « -5—-7, but all the variations found on
various culture media may be seen. In addition to these there are
undivided rods up to 12 long, which are sometimes irregular in shape
but which stain intensely with carbol fuchsin; it would seem probable
that these are involution forms of some sort, although nothing resembling
them has been found in artificial culture media. The same remark
applies to fairly numerous rods of various lengths which stain faintly
and are only about -2j2in diameter. All the rods are distinctly capsuled,
and many of them are not stained evenly, showing 1—2 or, in the larger
individuals, as many as 5—6 colourless vacuoles.

Erne, M. DomGEr 65

Young cultures on agar (24 hours at 25°C.) show very similar
characters to those described above (Fig. 4) with the exception of the
two abnormal forms just mentioned. The size of the rods is very variable,
some are almost spherical, the limits of size being -5—3p x -45—7p;

82, 2b “a
Mn Se r)

on 2
IN \
Sh 10p
1
Fig. 6. Fig. 7.

Figures 4-7. Bacterium nectarophilum; magnification same as Fig. 1. Fig. 4. 24 hrs.

~

at 25°C. on nutrient agar. Fig. 5. Uschinsky’s solution, 7 days at 25° C.
Fig. 6. Direct from host plant. Fig. 7. 24 hrs. at 25° C., Ellis’s flagella stain.

the majority are 1—1-5 x -6—-65y. They are usually single or in
pairs but chains of 5—10 are fairly frequent, and these are peculiar in
that the rods are not as a rule placed uniformly end to end, but are

Ann. Biol. tv 5

66 Bacterial Blight of Pear Blossoms in South Africa

quite as frequently obliquely, or are attached almost laterally (Fig. 4).
One or two vacuoles, the contents of which do not stain with carbol
fuchsin, can be seen in many individuals; that these non-staining
areas are not due to plasmolysis is proved by the fact that they can be
clearly seen in the living condition with the dark ground illumination,
by which means also the capsule is plainly visible. The capsule stains
readily with carbol fuchsin or gentian violet, and is very obvious around
rods from the condensation water in tubes containing nutrient agar
cultures about four days old. The growth in the condensation water
is very viscid, in consistency almost like eg¢ albumen; short rods and
almost coccus-like forms predominate. These stain intensively with
carbol fuchsin, are surrounded by a colourless capsule and are em-
bedded in a slimy matrix which stains faintly.

After four weeks at 25° C. on nutrient agar only a small percentage
of the rods stain intensely, the staining of the majority being very faint
and uneven.

In broth cultures the prevailing forms are slightly longer than those
on agar, rods 2—2-5y long being frequent; the vacuolation is distinct.

Very characteristic rods are found in Uschinsky’s solution (Fig. 5).
Capsuled bacteria form a pellicle on the surface of the fluid; this sinks
when disturbed and forms a sediment. The capsule is very con-
spicuously developed, and the growth is viscid in character like that
described in the condensation water at the base of agar streaks; each
rod has one, two or more distinct vacuoles.

The organism is actively motile’in young cultures (less so as it
diffuses out from the tissues of the host) by means of 1—5 polar flagella ;
these are two to three times the length of the rod, and are occasionally
bi-polar but most frequently they are only at one pole. ‘The flagella
stain quite readily by Elhs’s modification of Loffler’s method (Fig. 7).

Staining reactions.

Carbol fuchsin is undoubtedly the best stain for this organism,
although it stains well with all the usual stains. It does not stain by
Gram’s method, and is not acid fast.

Cultural characters.

Nutrient agar (+15). Colonies are visible after 24 hours at 25° C. as
thin milky-white growths 1—3 mm. in diameter and rather irregular in
shape; after 48 hours, surface colonies are 1—2 cm. diameter, in thinly
sown plates, spreading, sub-circular to irregular in shape, the edges

ETHEL M. Dorper 67

being auriculate-lacerate; they are coppery by transmitted light,
creamy white to light dull, green yellow! by reflected light. In crowded
plates the colonies are small and somewhat raised; submerged colonies
are very small and are lenticular in outline. A greenish fluorescence
may always be observed from agar media on which this organism has
been grown; frequently this is very marked, and in thickly sown
plates can be detected after 24 hours’ growth. This characteristic
appears to vary with the composition of the medium, and the conditions
under which the organism is grown; it is more marked when the
organism has been in cultivation for some time than when it is newly
isolated, and also appears to be more conspicuous in cultures which
have been exposed to the light; slight variations in the composition
of the medium are also probably responsible in some degree for variations
of this kind. No crystals have been seen in old cultures. Under the
microscope the texture of the surface colonies is homogeneous and
very finely granular.

Nutrient agar (+ 15). Streak cultures on nutrient agar are wet-
shining, yellowish white, flat smooth, undulate at the edges, and inclined
to spread over the wetter parts of the medium. No crystals are formed.
There is always more or less fluorescence from the agar, but, as observed
in connection with the plate cultures, it is variable. Sometimes there
is a distinct greenish fluorescence from the agar and the bacterial
growth at the end of 24 hours; sometimes it is not marked until the
culture is five or six days old; it is more noticeable when the tubes
have been exposed to the light. The growth in the condensation
water is very viscid.

Nutrient agar. Stab. The best growth takes place at the top.

Dextrose agar. Streaks were also made on nutrient agar to which
2 % dextrose had been added. On this medium the growth was slightly
heavier than on ordinary nutrient agar; it was opaque, creamy white,
and the medium was rendered opaque, in contrast to ordinary nutrient
agar which remains translucent and exhibits a greenish fluorescence.

Hiss glucose medium produced a very similar growth to that on
dextrose agar, but it was more noticeably viscid, drawing out into
fine threads on the platinum needle.

Nutrient agar + 2% dextrose and litmus. The streak is similar
in character to that described on nutrient agar with dextrose, but
striking colour changes may be observed in the medium. On the

1 Colours are named according to Ridgway’s Colour Standards and Nomenclature
and have been carefully compared with colour charts in that publication.

5—2

68 Bacterial Blight of Pear Blossoms in South Africa

sixth day the agar, which was a neutral litmus tint when planted with
the organism, is Killarney green, when viewed by transmitted light
facing the streak; viewed by transmitted light facing the side of the
slant the colour is deep red, nearest Nopal red. By reflected light the
upper part of the agar is still green, but from the deeper layers there
is a distinctly purplish light reflected. There was no further change
in colour during the six weeks the tubes were kept under observation.

Loffler’s blood serum is not liquefied, a streak culture on this medium
is similar to that on nutrient agar.

Cabbage agar. On this medium the organism forms a ribbon-like
streak, honey yellow, 3—4 mm. broad, and with a wrinkled shagreen
surface.

Nutrient gelatine (+ 15). Colonies at 20°C. attain a diameter of
about 4mm. in three days; they are thin, spreading, with a shghtly
irregular margin, in the centre of each colony there is a small, glisten-
ing, raised point; the remainder of the growth has a dull, ground glass
appearance. Submerged colonies are small, yellowish opaque.

There is no liquefaction, and colonies do not change further, except
to increase in size in thinly sown plates. There is no fluorescence in
this medium.

Nutrient gelatine stab. There is a growth similar to the gelatine
colonies, covering the surface of the medium and a filamentous growth
along the upper part of the medium; but no liquefaction during two
months and no development in the depths of the medium.

Nutrient gelatine streak is flat, about 4mm. broad with undulate
or crenate margin; here also the growth is dull and thin, and has the
appearance of ground glass when held up to the light.

Nutrient bowllon (+ 15) is heavily clouded in 24 hours at 20° C.,
and afterwards becomes very turbid. There is a tendency to pellicle
formation, but when disturbed the pellicle breaks up into flocculi and
sinks. A greenish fluorescence may be observed, and is usually very
noticeable especially from the surface of the medium. A considerable
amount of rather viscid sediment collects at the bottom of the tube or
flask.

Nutrient bowillon + 2% dextrose. The growth in this medium is
heavier than in nutrient broth to which no sugar had been added, but
the broth does not become fluorescent.

Nitrate bowillon becomes heavily clouded, and there is a thick
pellicle, but the fluorescence is not marked.

Dunham's solution is not a very favourable medium and does not

ErHet M. DormcGE 69

become very densely clouded; a slightly heavier growth was observed
in peptone water to which potassium nitrate had been added.

Nutrient bouillon over chloroform; growth was unrestrained in the
presence of chloroform; the tubes were clouded in 24 hours, turbid in
48 hours.

Litmus milk is slowly peptonised. After 24 hours at 25° C., the
fluid is clear to a depth of about 2 mm. from the surface, the remainder
of the milk being unchanged. After 5—6 days the upper third of the
medium is clear and translucent, the middle third is partially pep-
tonised, and the remainder still opaque and unchanged; the medium
thus exhibits three strata of approximately equal depth. In 8—10
days the whole of the milk has been peptonised, the colour is at first
unchanged by reflected light and reddish by transmitted light, but it
finally becomes slowly reduced from the top downwards leaving a
yellowish translucent fluid. There is a small amount of sediment.

Egg albumen. A medium composed of 1 grm. powdered egg albumen
in 50c.c. of -05 % potassium phosphate was used to determine the
proteolytic activity of the organism. The medium after sterilisation
is a colourless liquid in which the insoluble part of the egg albumen
has been separated out in white flakes; when planted with the organism
the liquid became clouded and then became deep sea foam green in
colour. The solid albumen was acted upon and became slimy and soft

in consistency.

Uschinsky’s solution is clouded in 24 hours at 25° C., after six days
it is very turbid, first the upper part of the broth, and gradually the
whole of it becoming light, dull, green yellow to clear, dull, green
yellow, the colour being much more noticeable by reflected than by
transmitted light. There is a fair amount of sediment and the rods
are normal and active. There is a ring above the medium, and a pellicle
which sinks if the tube is shaken.

At the end of 20 days the pellicle still continues to form, and to
sink when disturbed. A very heavy deposit is thus formed which
is very viscid and almost like egg albumen in consistency. After
some weeks the liquid becomes clear but yellowish; there is some
yellowish growth clinging to the sides of the tube and a deposit 1—2 cm.
deep in the bottom.

The organism also grows, but less vigorously, in a solution from
which the asparagin and ammonium lactate have been omitted and
replaced by ammonium sulphate. The organism is therefore able to
obtain its nitrogen from a simple salt.

70 Bacterial Blight of Pear Blossoms in South Africa

Cohn’s solution. No growth.

Potato. A creamy-white, wet-shining streak about 6—8 mm.
broad appears along the needle track; the edges are undulate.

Turnip. On turnip there is a thin, wet-looking, whitish growth,
almost covering the slant surface.

Beet. On beet the growth is heavier than on turnip and carrot
but it is not so spreading; it is yellowish and slightly raised.

Carrot. There is a very thin, whitish, wet-looking growth, in some
tubes almost completely covering the slant surface; in others where
the cylinder was drier only producing a streak a few millimetres wide
along the needle track.

Parsnip. On parsnip there is a good growth along the needle
track, 5—10 mm. wide, and slightly raised, shining.

Physical and Biochemical Relations.

Proteolytic actwwity. It has been pointed out in the section dealing
with the cultural characters of the organism that milk is slowly pep-
tonised. Ifa ten days old culture of the organism is killed by exposing
it to a temperature of about 55° C. for half an hour and then 3
of the culture run into each of a number of tubes of sterile litmus milk,
it is found that the milk is slowly cleared in precisely the same way as
if the organism were growing in the medium.

A series of flask cultivations was carried out with a view to testing
for the products of proteolysis. The media used were ordinary nutrient
broth, egg albumen (1 gm. in 50c.c. of -05 % potassium phosphate)
and milk; in each case 50 c.c. of the medium being sterilised in an

5 ¢.c.

Krlenmeyer flask of about 150 ¢.c. capacity. In this way the organism
received abundant aeration and growth was fairly rapid.

Cultures in nutrient broth were tested for ammonia by distillation
after five days at 25°C. The Nessler test could not be used owing to
the presence of an appreciable amount of ammonia in the control
flask.

A quantitative test showed that the amount of ammonia in the
culture had not increased from the fifth to the tenth day, the difference
in each case between the amount of ammonia in the culture flask and
the control being -016 grm. of ammonia nitrogen.

Kgg albumen after five days at 25°C. gave a definite reaction for
peptone and for tryptophane. The culture was tested by Sorensen’s
method for amino-acids and ammonia together at the end of the fifth
and the tenth day. After five days the result was -0148 grm. nitrogen

Eruet M. DorpcGEr ia

in the form of amino-acids and ammonia: if egg albumen contains
-150 grm. (approximately) total nitrogen, then 28% of the total
nitrogen had been broken down; after 10 days the figures were -007 grm.
or approximately 4-6 °% of the total nitrogen.

Milk cultures after ten days tested by the Sorensen method con-
tained -019—-022 grms. nitrogen in the form of amino-acid and ammonia.
When tested by distillation for ammonia alone, practically the same
figures were obtained; it was evident therefore that the amino-acids
had been reduced to ammonia.

Tested qualitatively the milk culture gave a very decided reaction
for peptone and for tyrosin.

The results recorded above are sufficient evidence that the organism
is a fairly active proteolytic agent.

Amylolytic action. Potato cylinders on which the organism has been
growing for any length of time give the red-brown reaction for amylo-
dextrin when treated with Lugol’s iodine solution rather than the
deep blue starch reaction.

Tubes containing 10 ¢.c. nutrient bouillon and -01 grm. soluble
starch were planted with a vigorous culture and incubated at 25° C.
It was between two and three weeks before the starch totally dis-
appeared. The action of the organism on starch therefore is com-
paratively slow.

Invertase and lactase are not produced by this organism. This is
shown by the fact that although the organism produces acid in solutions
containing dextrose and galactose it is unable to do so in those con-
taining lactose and saccharose. Were it capable of reducing these
sugars, acid would be formed in solutions containing them.

Fermentation reactions. No gas was produced in fermentation
tubes containing peptone water tinted with litmus and 2 % of various
carbohydrates. The amount of growth and presence or absence of
acid production may be scheduled as follows:

Carbohydrate Acid production Nature of growth
Dextrose Distinctly acid after 3 days Moderate
Dextrin None Very heavy
Galactose Distinctly acid after 3 days Moderate
Glycerine None Light clouding
Laevulose Ss ‘, .
Lactose i zy “3
Maltose aa ” ”
Mannite 39 35 os
Saccharose a3 es ae

QY
Starch rr) oe) 23

72) Bacterial Blight of Pear Blossoms in South Africa

A quantitative test for acid production was carried out with some
of the sugars mentioned above. Cultivations were prepared in bulk
in flasks containing 50 ¢.c. nutrient broth and 2 °% of the substances
to be tested. They were incubated for 10 days at 20°C. and were as
follows (expressed in degrees of Fuller’s scale).

Sugar Culture Control
Dextrose +35:5 +15-6
Glycerine +10 +15
Lactose 0 +15
Laevulose +10 +15
Saccharose 0 +15

It will be observed that except in the case of dextrose the culture
was slightly less acid than the control.

No reaction for alcohol or aldehyde was obtained in the distillate
from a culture in dextrose bouillon.

Indol. There was no indol in cultures in Dunham’s solution or
in nutrient bouillon after 10—12 days at 20°C. ‘Tests for phenol
were also negative.

Pigment production. It has already been pointed out in the section
on the cultural characters of the organism that it produces on certain
media a distinct greenish or greenish yellow fluorescence.

Colour destruction. Methylene blue was almost completely reduced
in 24 hours; neutral red and rosolic acid were not reduced. Litmus
was partially reduced in milk cultures but not in nutrient broth.

Nitrate reduction. Nitrates were not reduced to nitrites during
ten days growth in nitrate broth and in nitrate peptone water at 25°C.

Gas production. It has been stated that no gas is produced in
fermentation tubes containing various sugar solutions.

Cultivations were prepared in iron and lead peptone solution; the
precipitate began to blacken after some days, that in the tubes to which
iron tartrate had been added becoming decidedly black, thus showing
that some sulphuretted hydrogen had been liberated.

Growth under anaerobic conditions. The organism grows very slowly
in glucose formate agar in Bulloch’s apparatus from which the oxygen
has been absorbed. Control tubes under ordinary atmospheric con-
ditions made a very vigorous growth.

Temperature. The optimum temperature for growth lies between
25 and 30°C. The organism grows much more slowly at 20 than at
25° C. and at 35 than at 30° C.

The thermal death point is 49° C., ten minutes exposure in thin
walled test tubes containing 10 c.c. nutrient broth.

Erue, M. DorpGE 3

Reaction of medium. The bacterium is not specially sensitive to
the reaction of the medium in which it is grown. The optimum reaction
lies between + 10 and + 20 Fuller, + 15 taken as approximately the
optimum for cultural purposes.

The following table will serve to indicate the extreme reactions at
which growth will take place and the amount of various substances
necessary to inhibit growth.

Amount to restrain Amount to
Acid or alkali growth inhibit growth
Acetic acid +20 + 25
Citric acid +45 +50
Hydrochloric acid +18 +20
Malic acid +68 +70
Oxalic acid +35 +40
Tartaric acid +30 +35
Sodium hydrate +30 +55

Toleration of sodium chloride. Cultivations were made in nutrient
bouillon to which varying amounts of NaCl had been added. Growth
was unrestrained in tubes containing up to 4% NaCl, meagre in those
with 5 to 6 °% and inhibited in those with 7 %.

Desiccation. The organism is not particularly sensitive to desicca-
tion; cultures are readily obtained from cover slips on which the
organism has been dried for six weeks; more prolonged tests have yet
to be made.

Insolation. The bacterium is fairly sensitive to the action of direct
sunlight. Five minutes exposure is sufficient to destroy a large per-
centage of the rods and ten minutes to kill them all. The exposures
were made on a block of ice, to the mid-day summer sun, the plates
being further protected by being covered with glass basins containing
about 2 cm. of a 4 % solution of potash alum.

The growth of the organism is not restrained in the diffuse light of
the laboratory.

Nomenclature.

The organism appears to be one which has not previously been
described. I therefore propose for it the name Bacterium nectarophilum
n.sp., its chief characters are as follows:

Bacterium nectarophilum n.sp., parasitic in pear blossoms, causing
blackening of the receptacle and ovary, and less frequently of the sepals
and flower stalks; a short rod -5—3y x -45—7, majority are 1—1:5y
x -6—-65; rods single or in pairs, short chains are fairly frequent,

74. Bacterial Blight of Pear Blossoms in South Africa

capsule always present, motile by means of 1—5 polar flagella. Gram-
negative.

Forms spreading yellowish-white colonies in nutrient agar, fluores-
cent; fluorescence absent in media containing dextrose; gelatine is
not liquefied; nutrient bouillon heavily clouded; milk slowly pepton-
ised, no change in reaction. Uschinsky’s solution clouded, fluorescent,
growth viscid; potato growth moderate.

Fairly active proteolytic agent; starch slowly destroyed; acid
from dextrose and galactose, no gas or acid from any of the other
carbohydrates tested; no indol; nitrates not reduced.

Facultative anaerobe; optimum temperature 25—30°C.; v.p.P.
49° C.
LITERATURE CITED.

1. Barker, B. T. P. and Grove, Orro. <A bacterial disease of fruit blossom.
Annals of Applied Biology, vol. 1, pp. 85-97, 1914-15.

2, —— A bacterial disease of the Gooseberry. Annual Report of the Agricultural
and Horticultural Research Station, Long Ashton, Bristol, 1915, p. 97.

3. Dorper, E.M. A bacterial disease of pear blossom South African Fruit-Grower,
vol. 1, No. 7, January 1915, p. 125.

4. Duaaar, B. M. Fungous diseases of plants, 1911, pp. 121-129.

5. Jones, D. H. Bacterial blight of apple, pear and quince trees, Ontario Agri-
; cultural College. Bull. 176, pp. 1-63, 1909.
6. Jones, L. R. Studies upon plum blight. Centralblat. f. Bakt. 11 Abt. Band

Ix, pp. 834-841; 1902.

7. OstrerwaLpER, A. The bacterial bloom and twig blight of fruit trees. Landw.
Jahrb. Schweiz., Xx1x (1915), No. 1, pp. 29-30. Abstract in U.S.A. Depart-
ment of Agriculture, Experiment Station, Records, vol. xxxiv, No. 41, March,
1910.

8. Smiru, Erwin F. A. Conspectus of Bacterial diseases of plants. Annals of
the Missouri Botanical Garden, vol. , pp. 377-401, February—April, 1915.

9. —— Bacteria in relation to plant diseases, Washington, vol. 1, 1905, pp. 65, 71,
92, 113, 158, 215; vol. m, 1911, pp. 40, 65, 190.

10. Warre, Merron Bb. Results from recent investigations in pear blight. Proc.
Am. Ass. Ado. Sci. 40th meeting, Salem, 1892.

11. WuerzeLr, H. H. The blight canker of apple trees, New York (Cornell).
Agricultural Experimental Station, Bull. 236, pp. 104-138, 1906.

BoranicaL LABoratortiEes, PRETORIA.
January, 1917.

A LIST OF COCCIDAE AFFECTING VARIOUS
GENERA OF PLANTS.

By E. ERNrEsT GREEN, F.E.S., F.Z.S.

For several years I have been collecting records of the Coccidae
that infest different genera of plants, extracted—partly from my own
collections and observations, and partly from existing publications and
periodical literature. Mrs Fernald’s Catalogue of the Coccidae of the
World has, naturally, provided the foundation for such an undertaking,
and Lindinger’s Die Schildlause has afforded many additional records,
as have also the supplementary catalogues issued by the U.S. Bureau of
Entomology. Other papers that have been laid under contribution are
too numerous to mention.

The names are entered just as they are published. The compiler
does not hold himself responsible for the accuracy of the determinations.

I have found this list so useful, and such a time-saving device in my
own work, that [ propose to publish it, in parts, in the hope that it may
prove equally useful to others engaged in similar work. When a Coccid
is sent in for determination, a reference to my list immediately shows
what species of that particular genus have been recorded from the plant
in question. It is surprising how often this has provided a clue to the
identity of the species under consideration. The list, it must be acknow-
ledged, is far from complete and—from its nature—must remain so.
Fresh records will be constantly occurring, necessitating further additions.
But, with this as a foundation, it should not be difficult for individual
students to keep the list up to date for themselves.

I have not attempted to keep records for individual species of
plants. Nor do I consider that such an amplification of detail would
repay the labour entailed. As a matter of fact, it will be found that
few species of Coccidae are restricted to a single species of plant, though
many of them have a distinct preference for particular genera. A list
of the Coccidae found in the nests of, or associated with ants, is
included.

76 List of Coccidae affecting various Genera of Plants

With regard to nomenclature, | have—in the main—followed Mrs
Fernald’s Catalogue; but I have found it convenient to retain—in

their broader application—such genera as Lecaniwm, Aspidiotus, Chion-

aspis, Diaspis, ete.

ABIES (Coniferae).

PHENACOCCUS piceae.

PHYSOKERMES coloradensis, concolor,
piceae, sericeus.

LECANIUM sericeum.

CHIONASPIS pinifoliae.

POLIASPIS pini.

Levcaspis kelloggi.

ASPIDIOTUS perniciosus, ehrhorni,
meyeri, abietis, ostreaeformis,
tsugae, littleri.

LEPIDOSAPHES abietis, ulmi-japonica.

ABUTILON (Malvaceae).

CEROPLASTES novaesi.

Lecantum hesperidum, minimum,
oleae-mirandum, nigrum, oleae,
hesperidum-alienum.

ASPIDIOTUS Yossi.

ACACIA (Leguminosae).

LopHococcus vuilleti.

LLAVEIA mexicanorum.

MonopuHLEBUS herculus.

ASPIDOPROCTUS armatus, mirabilis,
tricornis.

IceryA koebelei, natalensis, purchasi,
longisetosa.

CALLIPAPPUS immanis.

ASTEROLECANIUM hakeae, ventruo-
sum, variolosum.

LECANIODIASPIS acaciae, africana,
anomala.

Rurzococcus grandis, grandis-spino-
sior, viridis, lobulatus, bicolor,
lidgetti.

Ertococcus multispinosus-laevigatus,

KERMES acaciae.

SPHAEROCOCCUS acaciae, obscuratus.

Eprcoccus acaciae.

PHENACOCCUS nivalis, farnesianae.

LacHNoptus hirtus.

PsEupococcus longispinus, acaciae,
albizziae, farnesianae, lanigerus,
robiniae, texensis, coccineus, per-
niciosus, iceryoides, filamentosus,

solitarius, quaesitus, nitidus, glo-
bosus, swezeyi, candidus, hilli.

TACHARDIA acaciae, nigra, aurantiaca,
argentina, lacca.

PULVINARIA paradelpha, tecta.

CEROPLASTES africanus, egbarum,
africanus-senegalensis.

CEROPLASTODES acaciae.

Incuisia fossilis, vitrea.

CTENOCHITON serratus, transparens.

Lecantum longulum, robiniarum,
oleae, cadaverosum, leve, scrobi-
culatum, mirificum.

CryPreEs baccatus.

PROTODIASPIS anomala.

Draspts_ boisduvallii.

CHIONASPIS capensis.

HEMICHIONASPIS aspidistrae.

CRYPTHEMICHIONASPIS nigra.

FIORINIA acaciae, rubra, rubra-pro-
pinqua.

ASPIDIOTUS caldesii, ceratus, fodiens,
hederae, niveus, perniciosus, ca-
melliae, rossi, unilobis, dentilobis,
acaciae, gidgei, subfervens, serra-
tus, africanus, junctiloba, tas-
maniae, conspiciendus, aurantii,
dictyospermi, lataniae, quadri-
areolata, bipartitus, phenox.

Aonipia glandulosa.

GYMNASPIS acaciae.

LEPIDOSAPHES acaciae, acaciae-al-
bida, convexa, grisea, spinifera,
corticoides, wilgae, multipora,
chitinosa, recurvata, intermedia,
somalensis.

ACALY PHA (Euphorbiaceae).

PsEUDOCOCCUS virgatus.
PunvinartiA floccifera.
PSEUDOPARLATORIA ostreata.

ACER (Aceraceae) ‘Sycamore,’ ‘Maple,’

etc.
PaLagococcus fuscipennis.
ERIOCOCCUS aceris.

EK. E.

ACER (Aceraceae)—cont.

PHENACOCCUS acericola, aceris.

PsEubDococctus comstocki.

PULVINARIA acericola, horii, hunteri,
innumerabilis.

LECANIUM aceris, canadense, cerasi-
fex, crawi, nigrofasciatum, rugo-
sum, tiliae, | websteri-mirabile,
corni.

CHIONASPIS platani, salicis.

HEMICHIONASPIS aspidistrae.

LEUCASPIS japonica.

AspIpiotus abietis, ancylus, com-
stocki, fernaldi-albiventer, forbesi,
hederae, juglans-regiae, ostreae-
formis, perniciosus, camelliae,
tenebricosus.

PARLATORIA pergandei, theae.

ADENOSTOMA (Rosaceae).
LECANIODIASPIS rufescens.
Ertococcus adenostomae.
LECANIUM adenostomae.

ADIANTUM _ (Filices)

Fern.’

PsEuDococcus longispinus.

Ripersia glandulifera.

Lecantum hesperidum, hemisphaeri-
cum, oleae.

PutvinartA floccifera.

CHIONASPIS dubia.

AESCULUS (Hippocastanaceae) * Horse-

chestnut.’

CrRrococcus parrotti.

PHENACOCCUS aceriola, hystrix, ace-
ris.

Punvinarta horii, innumerabilis.

LEcANIUM aesculi, coryli.

Asprptotus aesculi, ostreaeformis,
ohioensis, perniciosus.

LEPIDOSAPHES ulmi.

Dtaspis pentagona.

AGAVE (Amaryllidaceae).
GYMNOCOCCUS agavium.
PsEupococcus ephedrae. °
CEROPLASTES ceriferus.

LECANIUM oleae, nigrum.

HEMICHIONASPIS minor.

Aspipiotus hederae, agavis, aurantii,
bowreyi, dictyospermi, ficus, la-
taniae.

*“Maidenhair

(GREEN Ta

LEPIDOSAPHES nigra, philococcus.
OPUNTIASPIS javanensis.

AGLAIA (Meliaceae).
PSEUDOPARLATORIA argentata.
ASPIDIOTUS gracilis.

AONIDIA viridis.
LEPIDOSAPHES travancoriensis.

AGONIS (Myrtaceae).

ERLOcOCcCUS agonis.
SPHAEROCOCCUS rugosus.
CHIONASPIS agonis.

AGROPYRON (Gramineae).
PsEubDococcus pulverarius.
TRIONYMUS perrisii, violascens.
PaRAFAIRMATRIA bipartita.
ACLERDA subterranea.

ERIOPELTIS festucae.
ANTONINA purpurea.

AGROSTIS (Gramineae).

Ertococcus insignis.
PsEubDococcus walkeri, pulverarius.
RIPERSIA corynephori.

ERIOPELTIS festucae.

AILANTHUS (Simarabaceae).
DIASPIS rosae, pentagona.
LEPIDOSAPHES ulmi.

ALBIZZIAE (Leguminosae).
PsgEubDococcus albizziae, perniciosus,

capensis, filamentosus, longispi-
nus.
LecaNntuM longulum, elongatum.
CEROPLASTES subsphaericus.
TACHARDIA albizziae, lacca.
HEMICHIONASPIS minor.
Aspip1otTus hederae.

ALLAMANDA (Apocynaceae).
Creroputo barberi.

LECANIUM mangiferae.

ALNUS (Betulaceae) ‘Alder.’
GOSSYPARIA spurius.

PHENACOCCUS farinosus, aceris.

PULVINARIA betulae-alni, ehrhorni,
innumerabilis, goethei, occidenta-
lis, innumerabilis-betheli, vitis.

LECANIUM alni, corni, coryli.

CHIONASPIS lintneri, salicis, wista-
riae.
ASPIDIOTUS ostreaeformis, pernicio-

sus, alni.
LEPIDOSAPHES ulmi.

78 List of Coecidae affecting various Genera of Plants

ALOCASIA (Araceae).

PsEuDOcOcCcUS longipes.

PINNASPIS buxi.

HEMICHTONASPIS aspidistrae.

Aspiprotus destructor.

ALOE (Liliaceae).

CHIONASPIS exalbida.

Aspipiotus hederae, cladii, dictyo-
spermi, mammillaris.

ALSTONIA (Apocynaceae).

LECANIUM viride, oleae.

VINSONIA stellifera.

LEPIDOSAPHES alstoniae.

AMELANCHIER, (Rosaceae).
PHENAcoccUS cockerelli, betheli.
LECANIUM kansasense.

Cutonaspts lintneri, salicis-nigrae.

AspiproTus fernaldi-albiventer, per-
niciosus.

LEPIDOSAPHES ulmi.

AMMOPHILA (Gramineae).
Psgubococcus hibernicus.
ASPIDIOTUS provincialis.

AMPELOPSIS (Vitaceae).

LECANIUM magnoliarum, nigrum.

_ AspIDIOTUS perniciosus, tasmaniae.

AMYGDALUS (Rosaceae) ‘Peach,’ ‘ Al-

mond,’ ete.

ASTEROLECANIUM pustulans.

PHENACOCCUS aceris.

PULVINARIA amyegdali.

LECANIUM armeniacum, canadense,
cerasifex, cockerelli, persicae, pru-
inosum, prunastri, rugosum, hemi-
sphaericum, nigrofasciatum.

Eprpraspis piricola.

Curonaspis furfura.

Drasprts leperii, pentagona.

AspriproTus ancylus, forbesi, juglans-
regiae, ostreaeformis, perniciosus,
camelliae, africanus, eyanophylli.

PSEUDOPARLATORIA pariatorioides.

PARLATORIA calianthina, proteus.

ANACARDIUM (Anacardiaceae).
CEROPLASTES floridensis.
ASPIDIOTUS personatus, sylvaticus,

replicatus.

ANANASSA (Bromeliaceae) ‘ Pine-apple.’
Psrupococcus bromeliae, ananassae,

citri.

Draspts bromeliae, boisduvallii.
AsprIpioTus bromeliae.
PSEUDISCHNASPIS bromeliae.
ANDROMEDA (Ericaceae).
CEROPLASTES floridensis.
CHIONASPIS salicis.
ANDROPOGON (Gramineae).
Errococcus kemptoni.
ACLERDA californica, obscura.
LECANIUM tenuivalvatum.
CHIONASPIS graminis.
ASPIDIOTUS marlatti.
ANGRAECUM (Orchidaceae).
CONCHASPIS angraeci.
ASTEROLECANIUM aureum, epidendri.
ANONA (Anonaceae) ‘Custard-apple,’
Sour-sop,’ ete.
Icerya albolutea.
ASTEROLECANIUM pustulans.
TACHARDIA lacca, decorella.
PsEUDOCOCCUS citri, capensis.
Strerococcus dimorphus, diversi-
seta.
CEROPLASTES denudatus, floridensis,
quadrilineatus, ugandae, rusci.
Ineutsta conchiformis.
LICHTENSIA crescentiae.
LAGOSINIA strachani.
Lecantum longulum, marsupiale, he-
misphaericum, nigrum, viride.
Howarpta biclavis.
DIASPIS miranda.
Asprp1otus cyanophylli, destructor,
translucens, gowdeyi.
ANTHURIUM (Araceae).
ASTEROLECANIUM aureum.
CEROPLASTES floridensis.
LECANIUM angustatum, anthurii, ni-
grum, hesperidum.
ANTIDESMA (Euphorbiaceae).
KUWANIA zeylanica.
LECANIUM antidesmae,
num.
GHIONASPIS flava, acuminata.
DINASPIS permutans.
ASPIDIOTUS rossi.
ANTIGONON (Polygonaceae).
CEROPLASTES ceriferus.
PULVINARIA antigoni.
Lecantum hemisphaericum.

oleae, pla-

By OE,

ANTS’ NESTS.

SrrGMAcoccus asper, ferox.

IceryA formicarum.

ORTHEZIA lasiorum, occidentalis, ca-
taphracta, floccosa, olivacea.

ORTHEZIOLA vejdovskyi.

ANOMALOCOCCUS cremastogastti.

Ruizococcus texanus.

Errococcus apiomorphae.

CEROPUTO lasiorum.

NATALENSIA fulleri.

TyLococcus madagascariensis.

Micrococcus silvestrii, oviformis.

PHENACOCCUS americanae, glacialis,
ripersioides, hirsutus, formicarum.

Psrupococcus claviger, cockerelli,
formiceticola, hirsutus, neomexica-
nus-indecisus, sorghiellus, myrme-
carius, sorghiellus-kingi, wheeleri,
eycliger, flagrans.

RIPERSIA arizonensis, aurantia, blan-
chardi, cockerellae, confusella,
europaea, fimbriatula, flaveola,
formicicola, kingi, lasii, minima,
montana, subterranea, tomlini,
trivittata, tumida, globata, viri-
dula, wasmanni, donisthorpei, for-
micarii, inquilina, sardiniae, tri-
chura.

RIPERSIELLA leucosoma.

TrerRMrirococcus aster, brevicornis.

Srrorococcus formicarii.

EXAERETOPUS formiceticola.

LEecaNtum formicarii, urichi, discre-
pans.

Lecanopsts formicarum,
myrmecophila.

Hovarpia troglodytes.

APOLLONIAS (Lauraceae).

LeEcantum hesperidum.

lineolata,

CRYPTASPIDIOTUS aonidioides, bar-
busano.

AsprIproTus lauretorum, dictyospermi,
camelliae.

Aontpta lauri.
Frorrnta_ pellucida.
‘APPLE’
Psgubococcus bakeri.
PubvrnartA amygdali, innumerabi-
lis.

GREEN 79

Lecantum hoferi, bituberculatum,

cerasifex, pyri, variegatum, oleae,
glandi.

Curonasprs furfura.

DIASPIS pyri.

EPprpraspis pyricola.

ASPIDIOTUS ancylus, forbesi, juglans-
regiae, ostreaeformis, perniciosus,
pyri, camelliae, aurantii, africa-
nus, tenebricosus, lataniae.

PARLATORIA Calianthina, proteus, de
structor, chinensis, pyri.

LEUCASPIS japonica.

LEPIDOSAPHES ulmi.

‘APRICOT.’

LECANIUM armeniacum, oleae.

D1aspis pentagona.

Aspipiotus forbesi, juglans-regiae,
perniciosus, africanus.

ARAULIA (Araliaceae).

PULVINARIA innumerabilis, floccifera,
psidii.

LECANIUM persicae, _hesperidum,
oleae, nigrum, persicae-crudum.

DraspiIs pentagona.

ASPIDIOTUS ficus, dictyospermi.

ARAUCARIA (Coniferae).

Errococcts araucariae, angulatus.

Psrupococcus aurilanatus,
adonidum.

CTENOCHITON araucariae.

ASPIDIOTUS rossi.

PARLATORIA pergandei.

ARBUTUS (Ericaceae).

LEcANIUM coryli, corni.

Asprptotus hederae,
dictyospermi.

ARCTOSTAPHYLUS (Ericaceae).

ERIOCOCCcUS uvae-ursi.

PULVINARIA ericae.

DIAsPpIs manzanitae.

ASPIDIOTUS dearnessi,
phyli.

CHIONASPIS salicis.

LEPIDOSAPHES ulmi.

ARDISIA (Myrsinaceae).

NIPPONORTHEZIA ardisiae.

LEcANIUM hemisphaericum, tessella-
tum.

CHIONASPIS acuminata,

ryani,

vitis-arbutus,

arctosta-

80 List of Coccidae affecting various Genera of Plants

ARECA (Palmae).
PSEUDOCOCCUS arecae.

LecaNIuM minimum, hemisphaeri-
cum, acutissimum.
HEMICHIONASPIS aspidistrae, dra-

caenae.
Draspts boisduvallii.
PINNASPIS buxi.
Aspiptotus lataniae, dictyospermi,
personatus.
FIORINIA fioriniae.
ARISTOLOCHIA (Aristolochiaceae).
IcERYA aegyptiaca.
Psrupococcus longispinus.
AsprpioTus lataniae.
ARMERIA (Plumbagineae).
PsEupococcus hibernicus.
Ripersté halophila.
ARTEMISIA (Compositae).
ORTHEZIA artemisiae, urticae.
Errococcus artemisiae, catalinae.
PHENACOCCUS artemisiae.
PsgEubDococcus artemisiae.
Ertum lichtensioides.
PULVINARIA artemisiae.
CEROPLASTES rusci.
ASPIDIOTUS Tossi.
ARTOCARPUS (Urticaceae).
MonoPHLEBUS octocaudata.
IcERYA aegyptiaca.
PsEUDOCOCCUS corymbatus.
LEecANTUM mangiferae, psidii.
CHIONASPIS subcorticalis.
ASPIDIOTUS artocarpi,
hederae, lataniae, trilobitiformis.
FIORINIA fioriniae.
ARUNDINARIA (Gramineae).
ASTEROLECANIUM lanceolatum, sole-
nophoroides.
ANTONINA socialis.
ACLERDA distorta, japonica.
Lerecantum arundinariae.
CHIONASPIS arundinariae, elongata.
ODONASPIS secreta.
ARUNDO (Gramineae).
ACLERDA berlesii.
CHIONASPIS berlesii.
ASPARAGUS (Liliaceae).
PsgEupococcus — longispinus,
tus.

longispinus,

virga-

Lecantum anthurii, hemisphaericum,
nigrum, oleae.
Fintppia ephedrae.
CHIONASPIS berlesii.
Aspipiotus hederae,
melliae.
ASPIDISTRA (Liliaceae).
HEMICHIONASPIS aspidistrae.
ASPIDIOTUS ficus.
ASPLENIUM (Filices).
Lecantum hesperidum, mori, oleae.
HEMICHIONASPIS aspidistrae.
CHIONASPIS dubia.
ASTELIA (Liliaceae).
PHENACOCCUS asteliae.
PsEUDOCOCCUS montanus.
LEUCASPIS gigas, stricta.
LEPIDOSAPHES cordylinidis, epiphy-
tidis, pryiformis.
ASTER (Compositae).
ORTHEZIA urticae.
Ertococcus eucalypti.
TACHARDIA australis.
LECANIUM oleae.
ATALANTIA (Rutaceae).
ASPIDIOTUS ficus.
PARLATORIA atalantiae.
FIoRINIA atalantiae.
ATHEROSPERMA (Atherosperma-
ceae).
LECANIODIASPIS atherospermae.
ERIOCHITON spinosus.
CTENOCHITON viridis.
CHIONASPIS eugeniae.
LEUCASPIS gigas.
Aspipiotus atherospermae.
LEPIDOSAPHES pyriformis.
ATRIPLEX (Chenopodiaceae).
ORTHEZIA annae, varipes.
Crrococcus coloradensis.
Arrreuicia gallicola.
Errococcus neglectus, tinsleyi, par-
cispinosus.
PHENACOCCUS simplex.
PsEupococcus solani-atriplicis.
PULVINARIA maskelli.
CEROPLASTES irregularis, breviseta.
LvuzuLAsPIs spinulosa.
LEPIDOSAPHES concolor, concolor-
viridissima, alba, alba-concolor.

cydoniae, ca-

EK. E.

ATYLOSIA (Leguminosae).
CEROPLASTODES cajani.
ASpPIDIOTUS orientalis.

AUCUBA (Cornaceae).
CHIONASPIS aucubae.
Aspripiotus hederae, dictyospermi,

aurantii-citrinus.

AVERRHOA (Oxalidaceae).
Lecantum longulum.
Ineutsta conchiformis.

AZALEA (Ericaceae).
Ertococcus azaleae.
PsEubDococcus azaleae.
PHENACOCCUS azaleae.
Aspripiotus duplex, paeoniae.

BACCHARIS (Compositae).
Crrococcus baccharidis, tuberculus,
badius.
Errococcus armatus, brasiliensis.
CEROPLASTES albolineatus, grandis,
iheringi, lucidus, novaesi.
ALICHTENSIA attenuata.
PULVINARIA pulchella.
Lercantum baccharidis, dura, resina-
tum.
Draspts_ baccharidis.
LEPIDOSAPHES perlonga.
BACTRIS (Palmae).
ASTEROLECANIUM urichi.
Drasprs boisduvallii.
BAHIA (Compositae).
PaLAkococcus townsendi.
ORTHEZIA californica.
CrROPUTO bahiae.
Ertococcus bahiae.
BAMBUSA (Gramineae).
ASTEROLECANIUM bambusae, delica-
tum, miliaris, miliaris-longum,
miliaris-robusta, solenophoroides,
coronatum, lanceolatum, ceri-
ferum, ceriferum-prominens, exi-
guum, flavociliatum, pudibun-
dum, rubrocomatum, tenuissi-
mum, tumidum, udagamae, bam-
busicola, masuii.
Ertococcus graminis, onukii.
PsEupococcus takae, monticola, pul-
verarius-bambusae.

Ann. Biol. Iv

(GREEN 81

ANTONINA bambusae, crawi, socialis,
zonata.

PSEUDANTONINA bambusae.

ACLERDA japonica, distorta.

Lecantum longulum, depressa, ni-
grum, arundinariae.

Draspis bambusae.

CHIONASPIS arundinariae, bambusae,
colemanni, howardi, elongata, li-
nearis, gudelura, annandalei.

Prynaspis bambusae.

FIORINIA bambusae, signata, tenuis.

LEvcASPIS bambusae.

OponaspPis bambusarum, canalicu-
lata, inusitata, secreta, simplex,
penicillata, schizostachys.

LEPIDOSAPHES bambusicola, bambu-
sae.

Iscunaspts filiformis.

ASPIDIOTUS ficus.

PARLATORIA zeylanica.

BANKSIA (Proteaceae).

CaLLipaPppus bufo.

ASTEROLECANIUM variolosum.

Ertococcus eucalypti.

CERONEMA banksiae.

Lecantum frenchi, fuciforme.

Asprptotus subrubescens, rossi.

Aontpt1a_ banksiae.

LEPIDOSAPHES — banksiae,
fulleri, grandilobis.

BAUHINIA (Leguminosae).
ASTEROLECANIUM pustulans.
Lecantum hesperidum.

BEAUMONTIA (Apocynaceae).
Lecantum beaumontiae.
Asprprotus trilobitiformis.

BEGONIA (Begoniaceae).

LEcANTUM begoniae, nigrum, hesperi-
dum, signiferum.

ASPIDIOTUS ficus.

BENZOIN (Lauraceae).

LECANIUM nigrofasciatum.

CHIONASPITS lintneri.

BERBERIS (Berberidaceae).

FoNSCOLOMBIA braggi.

LECANIUM magnoliarum, corni, per-
sicae.

Eprpraspis leperei.

LEPIDOSAPHES ulmi.

citricola,

82 List of Coccidae affecting various Genera of Plants

BETULA (Betulaceae) ‘ Birch.’
Xyxnococcus betulae.

STEINGELIA gorodetskia.

PHENACOCCUS aceris.

PULVINARIA vitis, betulae, occiden-
talis-subalpina.

Lecanrum douglasi, nigrofasciatum,
websteri, coryli, ciliatum, zebri-
num, transvittatum.

Cutonaspts lintneri-betulae, salicis.

AspIDIOTUS ostreaeformis, pernicio-
sus, camelliae.

LEPIDOSAPHES ulmi.

BEYERIA.

APIOMORPHA beyeriae.

TACHARDIA australis.

LEPIDOSAPHES beyeriae.

BIGELOWIA (Orchidaceae).
PouLvinaRiA bigeloviae.

Asprprotus bigeloviae, yuccarum.

BIGNONIA (Bignoniaceae).
PULVINARIA cupaniae, psidii.
CEROPLASTES cistudiformis.
LECANIUM viride.

BIOTA (Coniferae).

LECANIUM arion.

DIASPIS visci.

BOSSIAEA (Leguminosae).
PULVINARIA contexta.

AspIDIOTUS bossieae.

BOUGAINVILLEA (Nyctagineae).
ORTHEZIA insignis.
ASTEROLECANIUM § pustulans-seychel-

larum.

BRACHYGLOTTIS (Compositae).
‘TENOCHITON flavus.

FIORINIA minima.

BROUSSONETIA (Urticaceae) * Paper-

Mulberry.’ ,

LECANIUM corni.

Dtaspis pentagona.

Asprpiotus oreodoxae, longispinus,
hederae.

BURSARIA (Pittosporaceae).
CEROcCOCCUS auranticus.
Errococous eucalypti, tepperi, bur-

sariae, villosa.

BURSERA (Burseraceae).

IcERYA purchasi.

CEROPLASTES cCassiae, dugesil.

BUXUS (Euphorbiaceae) ‘Box.’
Eriococcus buxi.
PHENACOCCUS aceris.
Lecantum hesperidum, corni.
PINNASPIS buxi.
Asprp1otus hederae, aurantii, dictyo-
spermi, britannicus, rossi.

CACTUS (Cactaceae).

LLAVEIA cacti.

DactryLopius cacti, confusus, new-
steadi, tomentosus, indicus, argen-
tinus.

ERtococcus coccineus,
sus.

Psrupococcus mamillariae, virgatus.

PULVINARIA floccifera.

Draspts echinocacti.

ASPIDIOTUS cydoniae.

CAESALPINIA (Leguminosae).

TACHARDIA lacca.

PsEUDOCOCCUS virgatus.

CERONEMA africana.

ASPIDIoTUS subsimilis.

CAJANUS (Leguminosae) ‘ Pigeon-pea.’

TACHARDIA lacca.

PHENACOCCUS insolitus.

Stretococcus dimorphus, diversiseta.

Lecantum elongatum, oleae, cajani.

CERONEMA africana.

ERrocHITON theae.

CEROPLASTES africanus, ugandae.

CEROPLASTODES cajani, chiton.

CALADIUM (Araceae).
Psgupococcus longispinus.
PULYINARIA darwiniensis.

CALAMAGROSTIS (Gramineae).
TRIONYMUS perrisii.
ERIOPELTIS lichtensteini.

CALAMUS (Palmaceae).
ASPIDIOTUS calami.
LEPIDOSAPHES mexicana.

CALATHEA (Marantaceae).

ASTEROLECANIUM aureum.

PSEUDOCOCCUS citri.

HeMICHIONASPIS aspidistrae.

CALLICARPA (Verbenaceae).

MaLLococcus sinensis.

Howarpta biclavis.

Diaspis pentagona.

multispino-

BK. E.

CALLISTEMON (Myrtaceae).

PSEUDOCOCCUS citri.
CHIONASPIS candida.
AsPIDIOTUS dictyospermi, rossi.

Aontp1a pulchra.

CALLITRIS (Coniferae).
PULVINARIA maskelli-spinosior.
DIASPIS visci.
CRYPTASPIDIOTUS mediterraneus.
POLIASPIS exocarpl.
CHIONASPIS striata.

CALLUNA (Ericaceae) ‘ Ling,’ ‘Heather,’

ete.

ORTHEZIA cataphracta.
ERIOCOCCUS ericae.
PsEubococcus calluneti.
Lecantum pulchrum, franconicum.
Asprptotus bavaricus.
LEPrIpOSAPHES ulmi.

CALOPHYLLUM (Guttiferae).
ASTEROLECANIUM gutta, ceylonicum.
ErtorpEs cuneiformis.

LECANIUM bicruciatum, frontalis, ca-
lophylli, tessellatum, tripartitum.

CEROPLASTES rubens.

Asprprorus dictyospermi, calophylli.

CALOTROPIS (Asclepiadaceae).
LECANIUM oleae.

ASPIDIOTUS orientalis.

CALYCOTOME (Leguminosae).
LECANIUM persicae.

Aspripiotus hederae.

CAMELLIA (Ternstromiaceae).

Lecantum hesperidum, depressum-
simulans, hemisphaericum, oleae.

PULVINARIA camelicola, floccifera,
linearis, vitis.

CEROPLASTES ceriferus, floridensis.

Asprpriotus degeneratus, hederae,
camelliae, spinosus, ficus, mas-
kelli, clavigera, duplex, paeoniae,
dictyospermi.

PARLATORIA pergandei-camelliae, pro-
teus, proteus-virescens.

FIORINIA fioriniae.

CAMPANULA (Campanulaceae).
ASTEROLECANIUM fimbriatum.
AspIpIoTuUS implicatus.

CAMPHORA (Lauraceae).

AspipioTus duplex, ficus, aurantil.

({REEN 83

CANNA (Marantaceae) ‘Indian Shot,’
etc.
PsEupDococcus bromeliae.
LECANIUM nigrum.
CEROPLASTES actiniformis, ceriferus.
Draspts bromeliae.
CAPPARIS (Capparidaceae).
PHENACOCCUS iceryoides.
LECANIUM capparidis.
HEMICHIONASPIS aspidistrae.
ASPIDIOTUS rossi, hederae, niger,
pseudocamelliae.
CAPSICUM (Solanaceae).
ORTHEZIA insignis, praelonga.
IceRyYA purchasi.
PULVINARIA urbicola.
HEMICHIONASPIS minor.
CAREX (Cyperaceae).
ORTHEZIA cataphracta.
EXAERETOPUS caricis.
Luzu.asrts luzulae.
LEcANopsIsS longicornis.
PARAFATRMAIRIA gracilis.
CARICA (Cucurbitaceae) ‘Papaya.’
Lecantum longulum.
DIASPIS pentagona.
AspiIpiotTus orientalis, destructor.
CARISSA (Apocynaceae).
CEROCOCCUS ornatus.
LECANIUM maritimum, oleae, hemi-
sphaericum, longulum.
CHIONASPIS acuminata-atricolor.
POLIASPIS carissae.
AONIDIA pusilla.
ASPIDIOTUS rossi, lataniae.
CARPINUS (Corylaceae) ‘Hornbeam,’
etc.
PHENACOCCUS acericola, aceris.
LEecantum alni-rufulum, ribis, web-
steri, coryli, pulechrum.
PULVINARIA carpini, betulae.
ASpPIDIOTUS ostreaeformis.
LEPIDOSAPHES ulmi.
CARYA = (Juglandaceae)
‘Pecan,’ etc.
PSEUDOCOCCUS jessica.
LECANIODIASPIS tessellata.
LECANIUM canadense, caryae, cary-
arum, pyri.
CHIONASPIS caryae.

‘Hickory,’

84 List of Coccidae affecting various Genera of Plants

CARYA (Juglandaceae)—cont.
ASPIDIOTUS perniciosus, uvae, ob-

seurus.

CARYOTA (Palmaceae).

LecCANIUM tessellatum, signiferum.

CASSIA (Leguminosae).

Icerya seychellarum.

TACHARDIA lacca.

PsEUDOcOCcCUS virgatus.

LecaANtIuM longulum, opimum, tuber-
culatum.

CEROPLASTES cCassiae.

CEROPLASTODES chiton.

CTENOCHITON aztecus.

HEMICHIONASPIS minor,
formis.

CHIONASPIS cassiae.

ASPIDIOTUS tesseratus, victoriae, ori-
entalis.

CASSINE (Celastraceae).

CHIONASPIS elongata.

ASPIDIOTUS piceus,

CASTANEA (Corylaceae) ‘Spanish Chest-

nut.’

PSEUDOPULVINARIA sikkimensis.

LECANIUM armeniacum, quercitronis,
takachihoi, pulchrum, nigrofascia-
tum.

ASPIDIOTUS perniciosus.

LEPIDOSAPHES ulmi.

CASTILLOA (Artocarpaceae).
PsrubDococcus virgatus, crotonis.
Lecantum castilloae.

Inewista castilloae.
Aspipiotus destructor.

CASUARINA (Casuarinaceae).
CALLIPAPPUS bufo, farinosus.
IceRYA purchasi.

FRENCHIA casuarinae, semiocculta.

CYLINDROCOCCUS casuarinae, gracilis,
spiniferus.

SPHAEROCOCCUS casuarinae, ethelae,
lesii.

OURACOCCUS casuarinae.

GOSSYPARIA casuarinae.

ERIOCOCCUS conspersus,
formis, elegans.

RHIzZOCOCCUS casuarinae, pustulatus,
tripartitus, lecanioides, casuarinae-
mancus.

chionaspi-

cypraeae-

PSEUDORIPERSIA turgipes.
PsrupDococcus corymbatus.
PHENACOCCUS casuarinae.
LECANIUM innocens.

POLIASPIS casuarinae.

FIORINIA casuarinae.

AspIDIOTUS casuarinae, cucalypti,
cingulatus, pauciglandulatus, bi-
dens.

AONIDIA paradoxa.

LEPIDOSAPHES casuarinae, striata, lo-
bulatus, complicata.

CATALPA (Bignoniaceae).
CEROPLASTES marmoreus, mexica-

nus.

DIAsPIs pentagona.

ASPIDIOTUS perniciosus, ulmi.

CATTLEYA (Orchidaceae).

Lecantum pseudohesperidum.

Draspts boisduvalli, cattleyae.

Asprpiotus alienus, biformis-cat-
tleyae.

CEANOTHUS (Rhamnaceae).
CEROPUTO yuccae, yuccae-ceanothi.
CHIONASPIS salicis-nigrae.
LEPIDOSAPHES ulmi.

CEARA RUBBER (Manihot glaziovii).
LECANIUM nigrum.

Asprpiotus destructor.

CEDRUS (Coniferae).

ASPIDIOTUS perniciosus, cedri, he-
derae.

CELTIS (Ulmaceae).

LECANIODIASPIS celtidis.

LECANIUM subaustrale, websteri, cel-
tium.

PULVINARIA innumerabilis, tinsleyi,
photiniae.

LICHTENSIA colimensis.

PINNASPIS siphonodontis.

Draspis celtidis, pentagona.

FIORINIA fioriniae

ASPIDIOTUS cueroensis, ancylus, cel-
tis.

PARLATORIA pergandei.

LEPIDOSAPHES mexicana,
mis.

CENTAUREA (Compositae).
GUBERINIELLA serratulae.
ORTHEZIA urticae.

conchifor-

HK. E.

CERASUS (Rosaceae) ‘Cherry,’ ‘ Ever-

green Laurel,’ etc.

KUWANINA parvus.

Lecanium elongatum, armeniacum,
caryae, cerasi, cerasifex, cera-
sorum, rugosum, tiliae, capreae.

Curonaspis furfura.

Draspis pentagona.

ASPIDIOTUS ancylus, forbesi, hederae,
juglans-regiae, ostreaeformis, pa-
tavinus.

LEPIDOSAPHES ulmi.

CERATONIA (Leguminosae).
GUERINIELLA serratulae.
PsEUDOCOCCUS ceratoniae, citri.
LECANIUM corni.

CHIONASPIS ceratoniae.

AsprptoTus hederae, aurantii, dictyo-
spermi, britannicus.

LEPIDOSAPHES ceratoniae, ulmi

CERCIS (Leguminosae).
Lecantumkansasense, nigrofasciatum.
ASPIDIOTUS camelliae.

CEREUS (Cactaceae).

Draspis echinocacti.

Asprpiotus eglandulosus, hederae.

CESTRUM (Solanaceae).

ErtuMm zapotlanum.

LECANIUM nocturnum.

PULVINARIA cestri.

CHAMAECYPARIS (Coniferae) ‘White

Cedar.’

LeEcaNiumM pallidior.

DIAsPIs visci.

CHAMAEROPS (Palmaceae).
CoLOBOPYGA magnani.
Ripersta falcifera.
Lecantum hesperidum.
CEROPLASTES rusci.
Asprp1otus chamaeropsis,

spermi, hederae.

LEPIDOSAPHES pinnaeformis.

CHENOPODIUM (Chenopodiaceae).
ORTHEZIA annae.

Aspiprotus chenopodii.

LEPIDOSAPHES concolor.

CHILOPSIS (Bignoniaceae).
Lecantum chilaspidis.
AsprproTus coloratus.
LEPIDOSAPHES chilopsidis.

dictyo-

GREEN 85

CHLOROPHORA (Moraceae).

LEcANTIUM oleae.

Diaspis regularis.

CHRYSANTHEMUM (Compositae).

ORTHEZIA insignis.

LEcANIUM oleae.

CEROPLASTES cistudiformis, rusci.

AsprpioTus cydoniae-greeni, canari-
ensis.

CHRYSOBALANUS (Rosaceae).

TACHARDIA gemmifera.

Lecanium pseudotessellatum.

CHRYSOPHYLLUM (Sapotaceae).

IcERYA montserratensis.

Lecantum hemisphaericum.

Howaropta biclavis.

AsprpioTus fissidens-pluridentatus.

CINCHONA (Rubiaceae).

PSEUDOPULVINARIA sikkimensis.

LecaNntium viride, hemisphaericum,
nigrum.

PULVINARIA psidii.

Howarptia biclavis.

AspIpiotus cyanophylli, camelliae.

CINNAMOMUM (Lauraceae).

LEecANIUM mangiferae, cinnamomi,
pseudoleae, tessellatum.

PROTOPULVINARIA pyriformis.

CEROPLASTES rubens.

Dtaspts tubercularis.

CHIONASPIS cinnamomi, litseae.

Asprprotus articulatus, longispinus,
dictyospermi, ficus, cistuloides.

PARLATORIA cinnamomi.

CISSUS (Vitaceae).
Crissococcus fulleri.
ASPpIDIOTUS tesseratus.

CISTUS (Cistaceae).

ASTEROLECANIUM fimbriatum.

LECANIODIASPIS sardoa.

Rrperst4 falcifera.

CITRUS (Rutaceae) ‘Orange,’ ‘Lemon,’

etc.

PALAEOCOCCUS rosae.

IcrRYA seychellarum, montserraten-
sis, natalensis, purchasi, okadae,
aegyptiaca.

ORTHEZIA insignis, praelonga.

TACHARDIA aurantiaca.

Psrupococcus citri, filamentosus,

6—3

86 List of Coccidae affecting various Genera of Plants

CITRUS (Rutaceae)—cont.
longispinus, lilacinus, fragilis, vir-
gatus, nipae, bakeri, ryani, citro-
philus, citriculus.

CEROPUTO yuccae, arctostaphyllii.

Lecantum hesperidum, longulum;
perlatum, viride, punctatum, town-
sendi, quercitronis-kermoides, ti-
liae, nigrum, hemisphaericum,
oleae, pseudomagnoliarum, citri-
cola, perinflatum, andersoni.

PULVINARIA aurantii, innumerabilis,
mammeae, psidii, tecta, cellulosa,
okitsuensis, citricola, floccifera.

CEROPLASTES ceriferus, cirripedifor-
mis, floridensis, rubens, sinensis.
rusci.

TAKAHASHIA citricola.

CHIONASPIS citri, euonymi, sassceri.

Howarpta biclavis.

HEMICHIONASPIS aspidistrae, minor.

Diaspis pentagona.

DINASPIS annae.

AsprpiotTus cydoniae, hederae, lata-
niae, perniciosus, duplex, albo-
punctatus, camelliae, — trilobiti-
formis, ficus, articulatus, albo-
pictus, albopictus-leonis, aurantii,
koebelei, personatus, scutiformis,
cocotiphagus, maskelli, dictyo-
spermi, sylvaticus, pedroniformis,
orientalis.

PARLATORIA pergandei, proteus, si-
nensis, ziziphus, oleae.

LEPIDOSAPHES citricola, gloveri, pal-
lida.

CLEMATIS (Ranunculaceae).

PSEUDOCOCCUS capensis.

Lecantum hesperidum, oleae, corni,
persicae, nigrofasciatum.

Asprpiotus hederae.

LEPIDOSAPHES ulmi.

CLIFFORTIA (Rosaceae).
IcERYA natalensis.
PSEUDOCOCCUS segnis.
CLUSIA (Guttiferae).
IcrERYA montserratensis.
GYMNASPIS clusiae.
COBAEA (Polemoniaceae).
LeEcaNIUM nigrum, hemisphaericum.

COCCOLOBA (Polygonaceae).
Lecantum hesperidum.
CEROPLASTES dugesii.

ASPIDIOTUS rossi.

COCCULUS (Menispermaceae).

IcerRyA seychellarum.

LEPIDOSAPHES cocculi.

COCOS (Palmaceae) ‘Coconut Palm.’
IcERYA montserratensis.
ASTEROLECANIUM palmae, lineare.
PSEUDOCOCCUS cocotis, pseudonipae,

virgatus, citri, nipae.

LECANIUM acutissimum, hemisphaeri-
cum, tessellatum.

PARALECANIUM cocophyllae.

CEROPLASTES actiniformis.

VINSONIA stellifera.

CHIONASPIS inday, candida.

HEMICHIONASPIS aspidistrae, minor,

PINNASPIS buxi-alba.

Diaspis boisduvallii-cocois, vandali-
cus.

AspIDIoTUS cydoniae, lataniae, pal-
mae, destructor, ficus, aurantii,
perseae, oceanica, cocotiphagus,
ansel, propsimus, varians, orien-
talis, punicae, personatus, arti-
culatus.

CRYPTASPIDUS nucum.

PARLATORIA greeni.

FIORINIA fioriniae.

LEPIDOSAPHES macgregori, unicolor,
gloveri.

CODIAEUM (Euphorbiaceae).
PsEUDOCOCCUS crotonis, virgatus.
LECANIUM nigrum, longulum, cribri-

gerum.

PULVINARIA thespesiae.

Aspiprotus destructor.

Cryptophyllaspis rubsaameni.

PARLATORIA proteus.

LEPIDOSAPHES newsteadi-tokionis,
pinnaeformis, auriculata.

COFFEA (Rubiaceae).

ORTHEZIOLA fodiens.

ASTEROLECANIUM coffeae.

CEROCOCCUS ornatus.

Sricrococcus sjostedti, gowdeyi.

PsEubDocOcCcUS citri, coffeae, filamen-
tosus, virgatus.

ago

COFFEA (Rubiaceae)—cont.
LACHNODIUS greeni.

RAIZAECUS eloti.

LEcANIUM caudatum, viride, hemi-
sphaericum, nigrum, oleae, hes-
peridum-javanensis, africanum,
subhemisphericum.

Howaroptia biclavis.

ASPIDIOTUS articulatus.

IscHNASPIS longirostris.

LEPIDOSAPHES corrugata.

COLA (Sterculiaceae) ‘Kola-nut.’
Srrcrococcus sjostedti, multispino-

sus, bijubatus.

LECANIUM catori.

COLEUS (Labiatae).

ORTHEZIA insignis.

PsEupococcws citri-colecrum.

CrrRoputo barberi.

LECANIUM depres:um.

CONVOLVULUS (Convolvulaceae).
PsEUDOCOCCUS virgatus.

Rreersta falcifera.

Lrcantum hesperidum, oleae.

CEROPLASTES rusci.

COPROSMA (Rubiaceae),
PsEupococcus glaucus.
CTENOCHITON depressus-minor, per-

foratus, viridis.

Inewista patella.

CHIONASPIS dubia.

LEUCASPIS gigas.

POLIASPIS argentosus.

AsprIpioTus camelliae,

LEPIDOSAPHES pyriformis.

CORDIA (Boraginaceae).

- ORTHEZIA galapagoensis.

LECANIUM mangiferae.

PuLvinaRria floccifera,

PROTOPULVINARIA pyriformis.

Diaspis cordiae.

CORDYLINE (Liliaceae).
PsEubococcus calceolariae.
Levcaspis cordylinidis, stricta.
ASPIDIOTUS articulatus, dictyospermi,

hederae, cyanophylli.

LEPIDOSAPHES cordylinidis.

CORNUS = (Cornaceae) ‘ Dog-wood,’

ete.

PHENACOCCUS aceris.

Xl

GREEN 87
LECANIUM corni, tarsale, coryli.
CHIONASPIS corni, lintneri, salicis,

salicis-nigrae.
ASPIDIOTUS perniciosus.
LEPIDOSAPHES ulmi.
COROKIA.
CrrRococcus corokiae.
INGLISIA inconspicua.
AspipioTus corokiae.
CORONILLA (Leguminosae).
ORTHEZIA urticae.
ASTEROLECANIUM fimbriatum.
AsprpiotTus hederae.
CORREA (Rutaceae).
SPHAEROCOCCUS floccosus.
LEcANIUM hesperidum.
Aspripiotus dictyospermi.
CORYLUS (Corylaceae) ‘Hazel,’ etc.
GOSSYPARIA spuria.
PHENACOCCUS aceris.
LECANIUM corni, corylis, corylifex,
betulae, pulchrum.
ASPIDIOTUS ostreaeformis.
LEPIDOSAPHES u]mi.
CORYNEPHORUS (Gramineae).
RIPERSIA corynephori.
ERIOPELTIS festucae.
CORYNOCARPUS (Myrsinaceae).
IcrRyYA purchasi.
DIASPIS monserrati.
Asprprotus hederae.
COTONEASTER (Rosaceae).
LECANIUM coryli, corni, persicae.
PULVINARIA betulae.
ASPIDIOTUS perniciosus.
LEPIDOSAPHES ulmi.
COURSETIA.
Icrrya palmeri.
TacHARDIA fulgens.
ASPIDIOTUS coursetiae.
CRATAEGUS (Rosaceae)
‘White-thorn,’ etc.
Ertrococcus azaleae, dearnessi.
PHENACOCCUS dearnessi.
Crrococcus koebelei.
Lxecanium bituberculatum,
vense, pyri, nigrofasciatum.
PULVINARIA innumerabilis, occidenta-
lis, oxyacanthae.
Curonaspis furfurus.

‘Hawthorn,’

gene-

88 List of Coccidae affecting various Genera of Plants

CRATAEGUS (Rosaceae)—cont.

Asprprotus forbesi, ostreaeformis,
perniciosus, calurus.

LEPIDOSAPHES ulmi, ulmi-candida.

CROTALARIA (Leguminosae).
Draspis pentagona.
HEMICHIONASPIS minor.

CROTON (Euphorbiaceae).

IcERYA aegyptiaca, braziliensis, mont-
serratensis, caudatum, seychel-
larum.

ORTHEZIA praelonga, insignis.

TaAcCHARDIA albizziae, rubra, lacca.

Psrubococcus longispinus, virgatus,

capensis.

Creroputo barberi.

Sricrococcus dimorphus, diversi-
seta.

LecantuM hemisphaericum, nigrum.
Pounvinaria burkilli.
CEROPLASTES denudatus, ceriferus.
LICHTENSIA lutea.
Asprptotus dictyospermi, smilacis.
PARLATORIA crotonis.
LEPIDOSAPHES citricola, crotonis, la-
sianthi, pinnaeformis, auriculata,
serrifrons.
CRUDIA.
Aonipt1a biafrae.
LEPIDOSAPHES crudiae.
CRYPTOMERIA (Coniferae).
DIASPIS visci.
ASPIDIOTUS cryptomerias.
CUPANIA (Sapindaceae).
PULVINARIA cupaniae.
Aspip1otus longispinus.
CUPRESSUS (Coniferae) ‘Cypress.’
IckeRYA purchasi.
GUERINIELLA serratulae.
PHENACOLEACHIA zealandica.
XYLOCOCCUS macrocarpae.
SPHAEROCOCCUS cupressi.
PsEuDOcoccUS ryani, andersoni, dud-
levi, cupressi.
DIASPIS visci.
CHIONASPIS striata.
Frorrnta fioriniae.
LEUCASPIS cupressi.
ASPIDIOTUS cupressi,
shastae.

coniferarum-

CYANOPHYLLUM (Melastomaceae).

LECANIUM oleae.

AsprpiIoTus cyanophylli.

CYANOTIS (Commelinaceae).

HEMICHIONASPIS aspidistrae.

ASPIDIOTUS excisus.

CYATHODES (Epacridaceae).

Ertococcus multispinus.

Porasprs media.

CYCAS (Cycadaceae).

PsEubococcus longispinus, zamiae.

Lecantum hesperidum, hemisphaeri-
cum, palmae, oleae, acutissimum.

CEROPLASTES myricae, rubens.

DIASPIS zamiae, rosae.

HEMICHIONASPIS minor.

PoLtAsPIs cycadis.

FiortntA fioriniae.

ASPIDIOTUS cyanophylli, hederae, ul-
mi, dictyospermi, aurantii, ficus,
articulatus, rossi, lataniae. orien-
talis, fimbriatus-capensis.

PARLATORIA proteus.

CYDONIA (Rosaceae).

TacHARDIA cydoniae, rubra, angu-
lata.

PHENACOCCUS suwakoensis, aceris.

LECANIUM rugosum, coryli, corni, ni-
grofasciatum.

PULVINARIA betulae.

CEROPLASTES cirripediformis,
densis.

Cuionaspis furfura.

AspIDIOTUS ancylus, cydoniae, for-
besi, perniciosus, camelliae, auran-
tii, africanus, ostreaeformis.

LEPIDOSAPHES ulmi.

CYNODON (Gramineae).

MonopHLEBUS fulleri.

MarGARODES mediterraneus.

Ertrococcus formicicola.

CYNOMETRA (Leguminosae).

Draspts limuloides.

Aontpia_ biafrae.

LEPIDOSAPHES aberrans, tenuior.

CYPERUS (Cyperaceae).

NeEwstTEAD14 floccosa.

ANTONINA australis, maritima.

PsEuDococecUS sexaspinus,

LEcANIUM angustatum.

flori-

E. E. GREEN 89

CYPERUS (Cyperaceae)—cont. Lecantvum distinguendam., corni, hes-
ASPIDIoTUS cladii. peridum.

CYPRIPEDIUM (Orchidaceae). CHIONASPIS salicis, canariensis, ber-
ASTEROLECANIUM aureum. lesii.
AsPIDIoTUS dictyospermi. LEUCASPIS japonica.

CYTISUS (Leguminosae). ASPIDIOTUS camelliae, tasmaniae, he-
PsEvubDococcus aridorum. derae.
PHENACOCCUS ulicis. LEPIDOSAPHES ulmi.

(To be continued.)

90)

NOTE ON THE IMMUNITY OF CHALCID PARASITES
TO HY DROCY ANIC, ACEDe GAs:

By E. ERNEST GREEN.

Wishing to kill a few individuals of a species of Lecanium, for pre-
servation as cabinet specimens, I subjected them to the fumes of strong
hydrocyanic acid gas (in an ordinary cyanide bottle) for a period of
eighteen hours. In spite of this drastic treatment, large numbers of
living Chalcids emerged from the bodies of the Coccids after their
removal from the killing-bottle.

This immunity of internal parasites may have a bearing upon the
treatment of ‘Scale Insects’ in the field, when they are known to be
infested by useful parasites. It would now appear to be possible to
fumigate scale-infested trees, with a fair probability that any Chaleid
parasites that may be developing within the bodies of the Coceids will
escape—to carry on their useful work elsewhere.

VoLUuME IV DECEMBER, 1917 No. 3

ON THE LARVAL AND PUPAL STAGES OF
BIBIO JOHANNIS L.

By HUBERT M. MORRIS, M.Sc. (Mancu.).

(From the Department of Agricultural Entomology,
Manchester University.)

(With Plate If and 12 Text-figures.)

CONTENTS.

PAGE

1. Introduction and Historical Remarks ; : : : 91
2, The Egg : : : : : ; : ; 6 : 92
3. Morphology of the Larva . c 5 . : : 93
(a) Newly hatched larva . z - ; ‘ ‘ 93

(6) Second stage larva : : : i 4 : 95

(c) Fully grown larva : : : : : 95

4. The habits, food, etc. of the Larva . 2 f F : 103
5. Comparison with larvae of other Diptera . . : ~ L04
6. The Pupa . : : : ; : : : ; a LOS
7. Note on the Imago . 3 : < : : 5 eG
8. Economic significance of the Bibionidae . : s LOG
9. Bibliography - “ - 5 : : : ; LOS
10. Description of Plate IT : 5 : : : . = | 109

1. INTRODUCTION AND HISTORICAL REMARKS.

During the early part of 1917 I found in the soil of a permanent
pasture field at Holmes Chapel, Cheshire, a number of what appeared
to be Dipterous larvae of the family Bibionidae, and Dr A. D. Imms
suggested to me that a study of these larvae would form a very interest-
ing piece of work.

Some of these larvae were reared and on emergence the fly proved
to be Bibio Johannis L., for the confirmation of the identity of which I
have to thank Mr H. Bury. To Dr Imms I desire to express my thanks
for his assistance in many ways during the whole course of the investiga-
tion. The work has been carried out in the Department of Agricultural
Entomology, Manchester University.

Ann. Biol. tv 7

92 Larval and Pupal Stages of Bibio Johannis L.

Hitherto there has been no complete account of any Bibionid larva,
but only partial descriptions and fragmentary accounts of the life-
history.

On account of the frequent occurrence of larvae of this family, and
their possible economic importance in certain cases, I have been led to
investigate the present species as fully as possible.

The earliest description of the larva and pupa of any species of Bzbio
met with, is that given by Reaumur (1741). Reaumur describes and
gives figures of the larva and pupa of the “St. Mark’s Fly” (Bibio Marev),
but, as with all other figures of larvae and pupae of this genus seen, the
figures are not sufficiently clear for purposes of identification of species.
De Geer (1776) gave the first account and figures of Bibio Johannis
and in 1832 Lyonet gave a description of Bibio Marci. Bouché in 1834
described and figured the larva and pupa of Bibio hortulanus, and also
figured the mouth parts of the larva, but these figures again are very
indefinite. Westwood in 1840 referred briefly to the larva of this genus
and gave a small figure. In 1872 Beling described the larvae and pupae
of a number of species of Bibio and Dilophus, amongst others those of
Bibio Johannis. Needham in 1902 gave an account of the occurrence
of swarms of the larvae of Bibio fraternus, with descriptions and figures
of the larva and pupa, while Sharp(3) has figured a larva of an un-
named species of Brbio, and has also given a figure of a portion of the
integument of the larva.

In addition to these accounts there are several records of the finding
of larvae of different species of Bzbio in great numbers in a small area (13)
and references to damage done by them to cultivated plants. The larvae
of the different.species of Bebio appear to be very similar, which makes
identification of the larvae difficult.

2. THE EGG.

The egg (Text-fig. 8, p. 112) 1s -63 to -66 mm. long and -13 to -15 mm.
broad. It is cylindrical with rounded extremities, and is approximately
straight. The eggs are not shiny but have rather an opalescent appear-
ance owing to their being covered with small pointed projections. They
are at first of a uniform light straw colour but after a few days a darker
patch appears at each end.

H. M. Morris 93

3. MORPHOLOGY OF THE LARVA.
(a) NEWLY HATCHED LARVA.

The eggs hatched under laboratory conditions in forty-eight days,
on May 30th, which appears to be an exceptionally long period. The
newly hatched larva is from 1:3 to 1-5 mm. in total length, of which the
head measures about -18 mm., with a breadth of -16 to-19mm. The
head is relatively large, yellow brown in colour, and bears a number of
long setae.

The body is almost colourless, the contents of the alimentary canal
showing through as a broad dark line. In shape it is cylindrical, but it
is slightly curved, as in the adult. The body is divided into twelve
seoments, of which the first is the largest. Each segment bears a number
of long slender setae, the length of which varies on different parts of the
segment.

Between the long setae on each segment are a number of smaller
projections on the cuticle, which correspond to the scale-like structures
of older larvae. These projections each consist of a blunt conical base,
bearing a single pointed seta, which is directed obliquely backwards.
Of the long setae those on the sides are the longest, except on the last
and penultimate segments, on which segments those setae situated
dorsally are the longest. Each of the long setae arises from a base
similar to, but larger than, those of the small setae (Text-fig. 11, p. 112).

The young larva bears a single pair of spiracles, which are situated
on the last segment in a corresponding position to that occupied by the
spiracles of this segment in the fully grown larva. At the present stage
each spiracle has only a single opening.

The structure of the spiracles is similar to that of the spiracles on
segments three to ten of the adult larva, but they project very little
from the body.

From the extremity of the last segment the larva is able to protrude
a pair of membranous conical structures, one on either side of the anus.
These structures are protruded by blood pressure, and withdrawn by
means of special muscles attached to them. They assist the larva in its
movements in a similar manner to the pseudopodia of other larvae.

The head at this stage is very similar to that of the full-grown larva.
The antennae, maxillae and labrum show very slight differences from
the adult form. The mandibles are shorter at this stage, and their teeth
are relatively longer. The groups of setae on the mandibles are present,

7—2

94 Larval and Pupal Stages of Bibio Johannis L.

but they are not so well developed as in the full-grown larva, the setae
being shorter and fewer in number.

In the labium, the submentum is rather less stout than that of the
full-grown larva, the anterior projections are longer and sharper, while
between them is a third projection.

Alimentary Canal. The alimentary canal of the young larva is
similar to that of the adult larva. The caeca are rather wider in pro-
portion to their length, and are filled with a yellow fluid. The peri-
trophic membrane is present as a straight delicate tube lying inside the
mesenteron, and extending from its anterior end to about the point at
which the posterior caecum opens into the digestive system. The
Malpighian tubes are similar to those of the fully grown larva, entering
the alimentary canal by a common duct, but the tubes are not enlarged
at their point of union. They are colourless, but contain numerous light
yellow granules.

Tracheal System. From each spiracle of the pair on the last segment
a single short trunk passes inwards, dividing into two on entering the
body. One of these branches passes forwards laterally, giving off a fine
transverse branch in each segment which connects with the main lateral
trunk of the other side ; in each segment, except the second and eleventh,
a short branch is given off which passes outwards to the cuticle, but has
no opening to the outside (Text-fig. 12, p. 114).

From the transverse connective in the first segment, and from the
main lateral.trunks, a number of branches enter the head and are dis-
tributed there.

From the lateral trunks in the eleventh and twelfth segments and
from the transverse connective in the twelfth segment a number of fine
branches are given off which pass to the heart.

The second of the two branches (into which the trunk from the
spiracle divides on entering the body) again divides into a number of
finer branches. Most of these branches are distributed in the twelfth
segment, but one branch passes forwards, and divides into two at the
end of the eleventh segment. The finer of these branches passes to the
loop in the alimentary canal, while the other passes forwards into the
head outside the main longitudinal trunk. This lateral trunk connects
with the branch which passes outwards from the main trunk in an8
segment, except the second and eleventh.

Circulatory System. The heart lies in segment eleven and in the
anterior part of segment twelve; it is continued forward as a dorsal
vessel of slightly narrower calibre, to the anterior end of the body.

H. M. Morris 95

The heart has a small posterior chamber, provided with a pair of
lateral openings by means of which the blood enters. These openings
are closed by means of valves when the heart contracts, thus forcing the
blood along the dorsal vessel. The latter is very thin walled, the nuclei
of the cells of which it is composed bulging inwards into the vessel. The
blood is a colourless fluid containing relatively large colourless corpuscles
which are usually oval in shape.

Nervous System. The nervous system is similar to that of the full-
grown larva. The supraoesophageal ganglion lies in the front of the first
segment with the suboesophageal ganglion beneath it. The first thoracic
ganglion les in the posterior region of the first segment, the second is
similarly situated in the second segment, while the third ganglion lies
rather more forward in the third segment. The eight abdominal
ganglia lie in the posterior half of their segments, except the eighth,
which is in the front of the eleventh segment.

(b) SECOND STAGE LARVA.

The larvae passed into the second stage after nineteen days, under
laboratory conditions. .

This larva is much more like the full-grown larva in external appear-
ance than is the newly hatched form.

The head does not appear relatively so large, while the long setae on
the body have disappeared, the body now bearing processes similar to
those of the fully grown larva. The cuticle also bears scale-like structures
similar to those of the full-grown larva, but somewhat smaller. The
spiracles on the last segment are larger but each has still only a single -
opening. A smaller pair of spiracles is situated on the first segment as
in the full-grown larva, and there is also a still smaller pair of spiracles
on the tenth segment. From this latter pair of spiracles the outwardly
directed branches from the main longitudinal trunks in that segment
take their origin. The tracheal system is similar to that of the first
stage larva, but it has more numerous branches.

The mouthparts are very little different from those of the first stage
larva, but are slightly more like those of the full-grown larva.

(c) FULLY. GROWN LARVA.

(a) External Form. The larva is 10 to 11 mm. long by 1-2 to
1-3 mm. wide and its thickness is a little iess than its width. Of this
length about -9 mm. is the length of the head, which is of slightly less

96 Larval and Pupal Stages of Bibio Johannis L.

width than length. The larva is clearly divided into two distinct
regions, (1) The Head and (ii) The Body.

The Head is very clearly defined and is invested by a shining chestnut-
brown chitinous capsule which is darker and stronger than the covering
of the body. The head can be slightly retracted, so that the posterior
end is covered by the front of the first segment of the body. It is darker
in the anterior half and on that half bears a few long single setae, while
the posterior half, which is lighter, is bare. From the centre of the hind
edge of the head arises a fine dark line which passes forwards and almost
immediately divides into two, which curve outwards to the bases of the
mandibles (Plate II, fig. 5).

The paired appendages of the head are the antennae, mandibles and
the first maxillae. Between and below the maxillae there lies a rather
peculiar shaped plate. This structure probably represents the second
maxillae fused to form a single organ. This plate has another rather
crescent shaped plate lying above it. A similar structure often occurs
in Dipterous larvae. The lower plate is regarded by Miall and Ham-
mond(17) as the sub-mentum, while the upper plate is regarded as the
mentum, which, they consider, has gradually slipped behind the sub-
mentum.

The sub-mentum is dark and strongly chitinised, with a central
lighter area bearing a group of short setae (Text-fig. 7, p. 112).

There does not appear to be any indication of eyes, and the antennae
(Text-fig. 6, p. 112) are small and inconspicuous. The mandibles
(Text-fig. 4, p. 111) are large, strong and dark, and have each two large
_ teeth and two smaller ones. They bear on their inner side a prominent
group of fine setae some of which are slightly branched.

The maxillae (Text-fig. 5, p. 111) are stout and have a distinct
palp. The tops of both palp and maxilla bear a number of setae.

The Body is nearly cylindrical, but is shghtly flattened dorso-ventrally
and normally is curved slightly, the ventral surface forming the inside
of the curve. The body consists of twelve segments, of which the first
is the longest and has rather the appearance of two segments, but the
imaginal discs prove it to be a single segment.

The body bears ten pairs of spiracles which are brown in colour and
are situated, a pair on each segment, on all segments except the second
and eleventh. The spiracles are situated laterally except those on the
twelfth segment which are placed more dorsally than the others. The
spiracle on the first segment (Text-fig. 1, p. 110) is about twice the size-
of those on the third to tenth segments, and that on the twelfth segment

H. M. Morris 97

is about four times the size of those on the third to tenth segments
(Text-figs. 2 and 3, p. 110).

The first segment (Plate I, fig. 1) is divided dorsally into two slightly
raised areas, of approximately equal size, by a transverse groove. On
the first of these areas are six processes, arranged in a transverse row,
those towards the sides being about twice as long as those in the centre.
The ventral side is similarly divided into three areas, of which the second
is below the first dorsal area, but is curved back in front, and a smaller,
roughly triangular, area is formed in front of it, on which are two short
processes. On the second area are two short processes in the centre,
one about four times as long on each side, and one on each side of inter-
mediate length between those at the sides and those in the middle. On
the third raised area are six processes of which the longest, at the sides,
are as long as the intermediate ones on the second area. The spiracle
on this segment is situated laterally and slightly farther back than the
second row of spines on the dorsal side, and projects from the side a
distance equal to its own diameter.

The second segment is divided dorsally into three areas in the same
manner as the first segment. Of these areas the first bears a process
on each side, and the second a row of six processes. Ventrally the same
division is visible, the first area bearing two central processes, and the
second a row of six processes.

The third segment is similar to the second, but bears a pair of spiracles
laterally on the front part of the first raised area. |

The fourth segment is also divided into three areas, and bears on the
front of each side of the first raised area a spiracle, and on the middle
area a transverse row of six processes. Ventrally, it has a row of six
processes on the first area, and another row of six processes on the
second ; the two lateral processes of the latter row appearing behind and
a little below the spiracle.

The fifth to tenth segments are similar to the fourth.

On the eleventh segment the row of six dorsal processes are much
enlarged ; of these, the middle pair are the largest and the lateral ones
one-third the size. About the middle of the ventral side of this segment
is a row of six processes similar to those on the preceding segments.
There is also a lateral process on each side half-way between the dorsal
processes and the front edge of the segment (Plate II, fig. 4).

The four processes on the dorsal side of the twelfth segment are also
much enlarged, and are situated on the hind margin of the segment.
There is, furthermore, a short process on the middle of the side of the

98 Larval and Pupal Stages of Bibio Johannis L.

ventral surface. The spiracles of the twelfth segment are situated half-
way between the lateral processes of the dorsal row, and the front of the
segment. and they project twice as much as the preceding spiracles
(Plate II, fig. 4). These spiracles have each two openings, while the other
spiracles have only one.

The body is covered by a tough cuticle which is actually of a light
brown colour. but the larva appears darker owing to particles of soil -
adhering to it, and to the dark contents of the alimentary canal. The
cuticle bears small irregular shaped scale-like structures, which do not
touch one another. These structures are of various sizes, and the
larger ones are rather conical and bear from one to eight short and
usually backwardly directed spines (Plate I, figs. 7 and 8). On the
bases of the processes, and on the spiracles of the larva, these structures ~
are closer together and give a more scale-like appearance, while on the
processes the spines become considerably longer than elsewhere.

Each intersegmental region bears a row of depressions which vary
considerably in shape. They are placed side by side (Plate II, fig. 6)
and apparently similar structures are situated, often singly, on other
parts of the segments. These depressions are oi a darker colour than
other parts of the cuticle, and are surrounded by elongated spineless
seale-hke structures.

On the twelfth segment the scale-like structures form a closer cover-
ing, which has rather the appearance of a squamous epithelium. The
spines of the scale-like structures on the dorsal surface of this segment
are very much reduced or absent, except on the processes, while on the
ventral surface a single stouter spine is present on each scale. °

From the end of the twelith segment the larva can protrude pseudo-
podium-like structures similar to those of the newly hatched larva, but
at this stage they are relatively smaller.

(6) Internal structure. The Iniegument consists of a chitinous
cuticle, with the hypodermis or chitogenous layer underlying it.

The Cuticle consists of two layers, of which the outer is considerably
the thinner. is of a light yellow colour im sections, and is highly refractive,
except in the head. where the outer layer is of greater thickness than
elsewhere. and is of a brownish yellow colour in sections. The inner
layer, which is relatively thick, appears to be only partially chitinised
and is more readily stainable than the outer.

The Hypodermis appears to be an undifferentiated stratum of proto-
plasm containing scattered oval nuclei which are hard to distinguish,
no cell wall being distinguishable. Below the hypodermis and in contact

H. M. Morris 99 —

with its inner surface, is a layer of flattened, irregular-sized cells. Miall
and Hammond (7) consider that these are the “ Wandering cells.” In
this larva this sub-hypodermal layer of cells appears to be continuous.
The scales consist of a thin stratum of the outer layer of cuticle, which is
not continuous beneath them, the interior of the scale being occupied
by cuticle of the inner layer. The hypodermis does not enter the scales
although it bulges outwards slightly towards their bases. The processes
are of similar structure, the hypodermis bulging upwards barely to the

base.
The Digestive System.

The alimentary canal takes a nearly straight course through the
body from the front of the head to the end of the last segment, but it is
shghtly longer than the body. It is divided into Fore-Gut, Mesenteron
or Mid-Gut, and Hind-Gut, and is provided with salivary glands, caeca
and Malpighian tubes (Text-fig. 9, p. 113).

The Fore-Gut extends from the mouth to the end of the first segment
of the body.

_ The mouth is formed by the labrum above, the mandibles at the sides
and the labium and maxillae below. The inner surface of the labrum
(the epipharynx) bears numerous short setae, the arrangement of which
is shown in Text-fig. 6, p. 112. Some of these setae are probably
sensory while others may assist in holding and cutting the food.

The mandibles are mostly used in taking the food into the mouth.
and are moved in the same, or almost the same plane. but their shape
causes the food between them to be worked against the epipharynx,
which bulges slightly downwards. Just behind the mouth the foregut
dilates shghtly into the pharynz, from the walls of which muscles radiate
to the walls of the head, and circular muscle fibres are present in its
walls.

The Oesophagus (Text-fig. 9) is a straight and narrow tube of simple
structure. It is lined by a chitinous intima, which ‘is considerably
folded. Outside the intima, is an epithelium m which the nuclei can
be seen but not the cell walls. Outside the epithelmum lies a muscular
coat, consisting of a layer of circular fibres, forming a series of transverse
rings. On the outside of the muscular coat is a thin membrane of con-
nective tissue. Towards the middle of the first segment of the body
the oesophagus dilates shghtly, and the intima here becomes stronger
and has the appearance of small groups of teeth. Behind this is a short
region or Gizzard with very strongly developed circular muscles and of

_ 100 Larval and Pupal Stages of Bibio Johannis ZL.

smaller diameter (Text-fig. 9). The oesophagus ultimately joins the
cardia or first portion of the mesenteron, at the end of the first seg-
ment. :

The Salivary Glands. The salivary glands are rather small, and lie
one on either side of the alimentary canal, towards the end of the first
segment. Each gland is hollow and has a lining of protoplasm. Strands
of protoplasm also stretch across the interior of the gland forming a
complicated network in which, as well as in the lining of the gland, are
large nuclei. The salivary duct passes forwards ventrally from the
anterior end of each gland.

The oesophagus is continued a short distance into the cardia, and is
then sharply turned back and passes upwards again to the point where
the epithelium of the cardia begins, forming an oesophageal valve. The
part of the oesophagus forming the valve is very similar in structure to
that of other parts as far as the first bend. It consists of intima,
epithelium, and well-developed circular muscle fibres. The part of the
oesophagus between the two bends is composed of an epithelium of much
larger cells than the other part, without the muscle fibres. The space
between these two parts forms a blood sinus, and is crossed by bands of
connective tissue fibres, and there are also bands of longitudinal muscle
fibres between the two portions of the oesophagus.

The part of the cardia which follows the oesophagus, and surrounds
the valve, consists of deeply staining columnar cells, followed by less
deeply staining cells, and this tissue makes several folds into the cardia.
These folds chiefly involve the epithelium, but also the moderately
developed coat of circular muscle fibres to a small extent. From the
anterior part of the cardia a number of bands of muscle fibres stretch to
the walls of the oesophagus, without resting on the alimentary canal
throughout their length.

From the cardia the three large caeca take origin; the longest, which
lies parallel to the mesenteron and ventral to it, is about 2-5 mm. long.
The other two, which are of about equal length (1-3 to 1-4 mm.), open
laterally from the cardia and are slightly inclined upwards.

The caeca are composed of an epithelium similar to that of the
mesenteron, the cells of which are rather larger and project slightly
into the lumen. Outside the epithelium is a membrane of connective
tissue, but no muscle fibres. The caeca are filled with a finely granular
substance.

The Stomach which follows the cardia has walls of the following
structure, from within outwards:

H. M. Morris 101

1. The peritrophic membrane, which forms a thin-walled tube lying
loose within the stomach from the cardia to near the end of the
stomach.

2. The epithelial layer is composed of cells with rather large and
dark-staining nuclei, and in some parts a distinct “striated margin” was
seen.

3. The basement membrane, outside which is—

4. The muscular coat consisting of poorly developed bands of
circular and longitudinal muscle fibres.

5. The connective tissue, which lies outside the muscular coat.

The thickness of the epithelium varies slightly in different parts of
the stomach, and it gives off protrusions into the cavity which are finely
granular, and feebly staining.

From near‘the posterior end of the stomach a fourth caecum opens
on the ventral side. This caecum is smaller than the others and lies
parallel to the stomach with its closed end forwards. Its walls are of
a similar structure to those of the other caeca, but are considerably
folded near the attached end. The cells of all four caeca show a well-
marked “striated margin.”

The Hind-Gut commences in the ninth segment, but its length is
considerably increased by the formation of a loop. It is divided into
three parts, the clewm, colon and rectum (‘Text-fig. 9).

The Jlewm commences as a slight dilation, and is lined with a layer
of epithelium composed of rather large cells, slightly rounded on the
inside, and bounded by a fine intima. The epithelium rests on a base-
ment membrane, outside which is a strongly developed coat of circular
muscle fibres outside which again are longitudinal muscle fibres, the
whole being covered by a thin connective tissue membrane. The
circular muscles are very close together, each band touching those next
to it. At the commencement of the ileum the circular muscles are
particularly well developed.

The Malpighian tubes are four in number, and at their attached end
they are dilated for a short distance to about twice the diameter of the
remainder of their length.

The four dilated ends join together and join the anterior end of the
ileum by a short common duct, which hes on the left of the alimentary
canal.

The tubes are covered on the outside with a delicate membrane,
inside which is a lining of protoplasm containing numerous large nuclei
which bulge into the cavity of the tube. The nuclei of the dilated part

102. Larval and Pupal Stages of Bibio Johannis ZL.

are smaller than the others but more numerous. The protoplasm con-
tains many fine granules.

The Colon, which follows the ileum, is of rather larger diameter, and
is less muscular than the ileum. It has a fine intima, outside which is a
layer of epithelium rather thinner than that of the ileum. The colon is
invested with circular muscle fibres similar to those of the ileum, but
they are neither so large nor so close together. Externally the colon is
covered with a delicate connective tissue membrane.

The Rectum is of considerably smaller diameter than the colon. Its
epithelium and intima are deeply folded, filling up much of the gut. The
muscular coat is well developed and composed of circular muscles, with
a connective tissue membrane outside them.

The Nervous System. The nervous system of the Bibio Johannis
larva consists of a brain or supraoesophageal ganglion, a suboesophageal,
three thoracic and eight abdominal ganglia. The brain is two-lobed and
lies in the anterior part of the first segment of the body. The two lobes
are distinct but are closely connected.

The suboesophageal ganglion lies directly below the brain, and is
connected with it by short but fairly fine oesophageal connectives, which .
connect its anterior end with the anterior end of the lobes of the brain.
The head is almost entirely filled with the muscles of the mouthparts,
so that the brain is displaced into the first segment. In this latter
region, in larvae near pupation, the rudiments of the adult head may be
also found.

The first thoracic ganglion lies just behind the suboesophageal, and
is nearly as large, the second is close behind it while the third is farther
back. The first ganglion is situated at the posterior end of the first
segment, the second lies in the front of the second segment and the
third in the front of the third segment.

The abdominal ganglia are smaller, and are situated one in each
segment. The first seven ganglia lie in the anterior region of their
respective segments. The last abdominal ganglion is considerably larger
than the others, and is situated toward the hinder region of the eleventh
segment.

In the head is a small frontal ganglion which is connected with the
brain.

The connectives between the ganglia are clearly double throughout.

From the ganglia lateral nerves are given off, the distribution of
which was not studied.

H. M. Morris 103

The Tracheal System.

From each spiracle except those on the last segment a single tracheal
trunk passes inwards, and on passing through the integument it divides
into three branches. One branch at once divides into a number of fine
branches while the other branches connect with the spiracles before and
behind, these connectives also giving off fine branches to the tissues.

From each of the openings of the last pair of spiracles a single trunk
passes inwards, and each one then divides into two branches.

4, HABITS, FOOD, ETC.

The larvae of Bibio Johannis were found near the surface of the soil,
amongst the roots of the grasses of the pasture. The soil near the surface
was very rich in organic matter in all stages of decomposition, as the
field had been pasture for a number of years. The soil was a medium
loam on the surface, but becoming heavier a few inches down.

The larvae were usually found at a depth of not more than half an
inch below the surface, and some appeared to be actually on the surface
of the soil; they were usually in small colonies, in which the larvae were
very close together.

The larvae fed by working particles of soil and organic matter into
the mouth by the rather slow movement of the mandibles.

From examinations made of the contents of the alimentary canal it
appeared that these larvae had been feeding on decaying vegetable
matter only, as only such material and inorganic particles were found.

Several observers record having found the larvae of species of Bibio
in cow-dung, horse-dung (8, 15) and in other situations where there has
been a very high proportion of decaying vegetable matter, as in garden
soil (26) and at the base of decaying tree stumps(19)._ It appears also that
larvae of this genus can feed on the roots of living plants.

The larvae of Bibio Johannis are moderately active and are able to
bury themselves in loose soil fairly quickly, assisted probably by their
backwardly directed processes.

The larvae and pupae, contrary to the experience of Malloch (15) were
not found difficult to rear. They were reared in medium sized glass jars,
partially filled with soil, grass, etc., similar to that amongst which the
larvae were found, the jars being covered with coarse muslin and the
soil kept damp. As it was desired to obtain the fly rather early in the

1 The spiracles have already been described on pp. 96-98.

104. Larval and Pupal Stages of Bibio Johannis ZL.

year, the larvae were kept under cover in a temperature which was
always above that outside.

Although the larvae were found during the latter half of an unusually
severe winter, they appeared but little affected by the cold and did not
descend into the soil to any distance as far as was observed.

No parasites were met with in connection with these larvae, and the
only reference to parasites met with in this family, is that of Malloch (15).
This observer mentions a hymenopterous parasite of whose connection
with this family of hosts he is uncertain. Lyonet mentions finding a
“louse” on a Bibionad larva, and a Filaria inside one.

5. COMPARISON WITH LARVAE OF OTHER DIPTERA.

The structure of the larva of Bibio Johannis indicates that it is very
primitive, the larva having twelve complete segments, a comparatively
large head that cannot be withdrawn into the first segment, and well-
developed mouthparts.

The presence of ten pairs of spiracles is very unusual, and is character-
istic of the family. The fact that the spiracles of the first and twelfth
segments are considerably larger than those of the other segments seems
to indicate a tendency for the larva to become amphipneustic instead of
peripneustic. Of the mouthparts, the most noteworthy is the labium,
which is modified in a similar way to that of Chironomus and Diera-
nota (16,17). Three caeca is an unusual number, many caeca being found
in Chironomus, eight in Anopheles and a few other larvae, four in a
number of species, and two in others.

The posterior caecum is also unusual although Dufour found a
“caecum latéral” in Tipula lunata, which, however, opened from the
intestine and not from the mesenteron as 1s the case in the Bibio Johannis
larva. Four is a common number of Malpighian tubes, but they usually
enter the alimentary canal separately.

The oesophageal valve is fairly primitive, considerably more so than
that of Simulium or Chironomus (16, 17) or Anopheles (12). It considerably
resembles the valve figured by Holmgren(11) in Mycetophila ancylafor-
mans, but is relatively shorter.

The structure of the cardia is also similar to that shown by Holmgren,
in having first a regular epithelium of columnar cells, followed by a con-
siderably folded region. In Bibio Johannis however there is a space
between the two parts of the oesophagus forming the valve, which
contains muscle fibres, and is more like that of Dicranota.

H. M. Morris 105

The peritrophic membrane is very common in Diptera, its length
varying considerably. In this larva as in many others the membrane
appears to arise from the anterior end of the cardia.

In the general features of its morphology the larva of Bibio Johannis
bears a closer resemblance to the larvae of the Mycetophilidae than to
any other group. This resemblance appears to be due to the fact that
the two families are phylogenetically closely related. The possibility,
however, that certain of the characters may be the result of convergence
due to similarity of habitat must not be overlooked.

6. THE, PUPA

The larvae pupated on March 25th, the pupa being formed in an oval
cell of soil, the last larval skin being in the cell with the pupa. The cell
was considerably larger than the pupa, and quite smooth, and looked as
if it had been formed by the larva pressing outwards in all directions.

The pupa is 7 to 8 mm. long, about 2 mm. broad across the thorax
and 1-3 to 1-5 mm. broad across the abdomen.

The cuticle is smooth and white at first, but soon appears darker. as
the parts of the imago darken and show through owing to the trans-
parency of the cuticle. The abdomen throughout is light in colour, as
the abdomen of the imago does not darken completely until after it has
emerged.

The pupa of the female is distinctly larger than that of the male
particularly in the width of the abdomen.

The head is flat below and is pressed down on to the prothorax. The
antenna cases are short and extend little more than half way across the
eyes. On the anterior end of the head is a stout process directed for-
wards, which covers the ocelli of the imago. The cases of the mouth-
parts are distinct. The thorax is short and thick, and the mesothorax
is considerably the largest segment.

The leg-cases lie side by side, touching those of the other side in the
median dorsal line, and extend to about the middle of the first abdominal
segment. The cases of the first pair of legs are wholly visible, those of
the second pair almost so, while only the extremities of the third pair are
left in sight. The remainder is covered by the wing-cases, which do
not quite meet and extend a little farther back than the leg-cases
(Plate II, fig. 3).

Dorsally there is a slight ridge running from the posterior edge of the
mesothorax to the process on the head, and along this ridge the cuticle
splits for the imago to emerge (Plate IT, fig. 2).

106 Larval and Pupal Stages of Bibio Johannis ZL.

The prothoracic spiracles project slightly in a dorso-lateral position.
The boundary between the prothorax and the mesothorax is not marked
on the dorsal side, while ventrally the leg- and wing-cases cover almost
the whole of the thorax. The abdomen is long, straight and slightly
flattened dorso-ventrally and consists of nine segments, the first six of
which are about equal. After the sixth segment the abdomen tapers
slightly, the last segment having the form of a blunt cone. The last
segment bears a pair of stout processes slightly dorsally near its tip,
which are nearly as long as the segment.

Apart from these processes and the spiracles, the cuticle of the pupa
is bare.

The abdomen bears a pair of spiracles on each segment except the
eighth. These spiracles project from slightly before the middle of the
sides of the segments.

7. NOTE ON THE IMAGO.

The adults emerged from the pupa on April 9th and the following
days, but their emergence was probably hastened by the warmer con-
ditions under which they were kept.

The number of individuals of the different sexes, including the pupae
which were preserved as well as the adults which emerged, were, males
20, females 7, showing a considerable preponderance of males.

8. ECONOMIC SIGNIFICANCE OF THE BIBIONIDAE.

There appears to have been a considerable amount of uncertainty as
to whether larvae of this family are destructive to the roots of cultivated
plants. A number of instances are recorded of such damage by certain
species of this family, although Scharov(22) considers them harmless.

Various species are recorded by Theobald 26) as attacking the roots
of oats, grass, lettuces, seedling cabbages and young flower plants, while
hops appear to be particularly badly attacked, especially by Dilophus
febrilis and D. vulgaris (20, 27).

Carpenter (4) reports finding larvae of Bebvo Marci feeding on potatoes,
while Collinge(5) states that Bibro Marci damages tomatoes, young
conifers, seedling ash and young spruce. He further adds that Brbio
Johannis damages larch seedlings and hop roots, and he considers that
these larvae are introduced in manure or leaf-mould. The larvae of
Bibio Marci are also recorded by Gillanders(10) as injuring ash seed-
lings.

H. M. Morris 107

Other records mention Bibio hortulanus larvae as damaging sugar
beet (25), spring barley and wheat(18), the damage in the latter instance
being so severe that many fields had to be ploughed up and resown.

Curtis (6) states that Dilophus febrilis larvae cause much mischief in
gardens. He found them on the decayed portions of planted potatoes
and also on the tubers, and in flower pots.

Larvae of Bibio abbreviatus are reported by Strickland (24) to have
damaged celery plants. The soft tissue between the fibro-vascular
bundles of the stalks was eaten away to a depth of 15mm., and the
larvae also burrowed slightly into the stalks. Owing to the large number
of larvae the damage was extensive. In this case the larvae are thought
to have been brought to the plants in manure.

Some instances of believed damage by the adults of this family are
recorded. Lyonet(14) believed that the adults of Bebio Marci damaged
the buds of fruit trees, and other writers believed that the adults of this
family damage fruit blossom, but it is unlikely that the damage was due
to this cause, the flies being more probably beneficial in assisting pollina-
tion(31). The adults of Dilophus febrilis are mentioned as being believed
to cause damage to hop-cones, but any damage is probably due to their
being dried in the cones (27).

Biblio albipennis, which appears to be very common in the United
States of America, is considered to be harmless. The larvae are said
to feed on dead leaves and stems(7), and they are also mentioned as
having been found feeding on oak galls(9), which appears unusual,
unless the galls had fallen to the ground.

The larvae of Bibionidae appear to occur very commonly in cow-dung
and manure (8, 15) and it seems probable that in many instances the larvae
have been carried to the plants which they were found damaging in
manure. Many of the plants mentioned as being attacked are usually
grown with heavy applications of this material.

Theobald (27) states that vaporite and injections of bisulphide of
carbon into the soil were found to kill the larvae. He also recommends
trapping the larvae by burying old roots in the soil, and then digging
them up early in March and destroying the larvae found feeding on them.
He also found soot and lime effective in dealing with the larvae.

Carpenter (4) states that the larvae “seemed to be but little affected by
the dressings usually applied for killing or repelling underground insects.”
He states that various birds, including domestic poultry, devour the
larvae readily. Brbio larvae of several species have been found in the
food of rooks, starlings and chaffinches (2s).

Ann, Biol. 1v 8

108) Larval and Pupal Stages of Bibio Johannis L.

Spraying infected land with a solution of Chili saltpetre in early
spring, and harrowing in autumn or early spring after spreading quick-
lime on the field are recommended 25), while ploughing deeply and rolling
at the time of pupation, has also been found satisfactory (18), contact
poisons being said to have very little effect.

9. BIBLIOGRAPHY.

1. Bettye, T. (1872). Zweiflugler-Gattungen Bibio und Dilophus. Verhand-
lungen zoologisch-botanischen Gesellschaft in Wien, vol. xxt1, pp. 617-650.

2. Bovucus, P. (1834). Naturgeschichte de Insecten, p. 42, tab. 4, f. 1-10, Berlin.

3. Branpt, Ep. (1881). Recherches sur le systéme nerveux dés larves des Insectes .
Diptéres. Comptes Rendus des séances de l Académie des Sciences, vol. XCIv,
p. 983.

4. Carpenter, G. H. (1913). Reports on injurious Insects in Ireland. Econ.
Proc. Roy. Dublin Society.

5. Couirnan, W. E. (1913). Seventh Annual Report of Hon. Consulting Biologist.

Journ. Land Agents Soc., Oct. (Abstract in Review of Applied Entomology,
1913).

6. Curtis, J. (1860). Farm Insects, p. 467.

7. Davis, G. C. (1894). Bull. No. 116, Mich. Agric. Exp. Station, October, p. 63.

8. Der Gesr, C. (1776). Mémoires des Insectes, T. v1, pl. 27.

9. Durour, L. (1835). Recherches Anatomiques et Physiologiques sur les
Diptéres.

10. GittanpErs, A. T. (1908). Forest Entomology, p. 361. William Blackwood
and Sons, Edinburgh and London.

11. Hotmeren, N. Monographische Bearbeitung einer schalentragenden Myceto-
philidenlarve (Mycetophila ancyliformans n. sp.). Zeitschrift f. wissensch.
Zoologie, UXXxvit. Bd.

12. Inns, A. D. (1907). On the Larval and Pupal stages of Anopheles maculipennis,
Meigen. Journal of Hygiene, vol. vu, No. 2.

13. Lucas, H. (1871). Annales de la Société Entomologique de France. 5 série,
tome 1, pp. Ixvii-lxix.

14. Lyoner, P. (1832). Recherches sur les Insectes (Mém. Posth.), p. 58, pl. 7.

15. Maniocu, J. R. (1917). A Preliminary Classification of Diptera, part. I,
pp. 298-300. Bulletin of Illinois State Laboratory of Natural History, vol. xi,
article ii,

16. Mrauy, L. C. (1899). Dicranota; a carnivorous Tipulid larva. Trans. Ent. Soc.
1893, part III (Sept.).

17. Mraz, L. C. and Hammonp, A. R. (1909). The Structure and Life History of
the Harlequin Fly (Chironomus). Oxford; Clarendon Press, 196 pp., 1 plate
and 127 figs.

18. Mouz, E. and Prerscu, W. (1914). Beitrage zur Kenntnis der Biologie der
Gartenhaarmicke (Bibio hortulanus) und deren Bekiimpfung. Zeits. wissen.
Insectenbiol. Berlin, x, 2 and 3, 1914. (Abstracts in Review of Applied Ent.
1914, and in Haperimental Station Record, 1915.)

THE ANNALS OF APPLIED BIOLOGY. VOL. IV, NO. 3 PLATE II

Pome]

Pe ee

29.

30.

31.

H. M. Morris 109

NEEDHAM, J. G. (1902). Occurrence of Bibio fraternus. American Naturalist,
vol. xxxvi, pp. 181-185.

Ormerop, E. A. (1884). Report on Observations of Injurious Insects, p. 56.

Reaumor, R. A. F. pe (1741). Mémoires des Insectes, tome 5, 1°* partie, p. 70.

ScHaroy, N. (1915). Injurious Insects in Govt. of Astrachan 1912-1914. Pub.
by Entomological Station of Astrachan. (Abstract in Review of Applied
Entomology, 1915.)

SHarp, D. (1909). Cambridge Natural History, vol. v1, Insects, Part IT,
pp. 476-477.

STRICKLAND, E. H. (1916). Agric. Gazetie of Canada, vol. m1, 7, July.

SuDEIKIN, G. S. (1913). Pests of Agricultural Plants in Govt. of Voronezh,
1912. Pub. by Zemstvo, Voronezh. (Abstract in Review of Applied Entomo-
logy, 1914.)

THEOBALD, F. V. (1907-1913). Reports on Economic Zoology.

THEOBALD, I’. V. (1909). Journal of the Board of Agriculture, October, p. 567.

THEOBALD, F. V., McGowan, W., and Lricu, H. S. (1916). Reports on the
food of the Rook, Starling and Chaffinch. Supp. 15 to Journ. of Board of
Agric., May.

WatusH, B. D. and Ritey, C. V. (1869). Plum-tree Insects. Amer. Ent.
vol. 1, 11, July, p. 227.

Westwoop, J. O. (1840). Introduction to the Modern Classification of Insects,
vol. m1, p. 528, and fig. 126, 16.

Witson, H. F. Minor Insect Pests, pp. 195-202, 8 figs. (Abstract in Review
of Applied Entomology, 1915).

10. DESCRIPTION OF PLATE Ill.

ig. 1. Almost fully grown larva of Bibio Johannis, dorsal aspect. sp. spiracle of first

segment; sp., spiracle of sixth segment; sp... spiracle of twelfth segment. 12.

. 2. Pupa of Bibio Johannis, dorsal aspect. ps. prothoracic spiracle. x 12..
. 3. Pupa of Bibio Johannis, ventral aspect. an. antenna case (right); /. leg-case of

right leg of first pair; l., leg-case of right leg of third pair; w. wing-case (right). x 12.

.4, Posterior end of larva, dorsal aspect. 11, eleventh segment; 12. twelfth segment :

sp. spiracle of twelfth segment. x 30.

. 5. Head of larva, from above. ant. left antenna; lab. labrum; m. right mandible;

cl. clypeus. x 60.

_6. Part of an intersegmental region, surface view. x 180.
. 7. Portion of cuticle, surface view. x 180.
g. 8. Ditto, lateral view. x 180.

110 Larval and Pupal Stages of Bibio Johannis L.

Text-figure 2. Left spiracle of sixth

segment of larva. x 790

Text-figure 3. Right spiracle of last segment of larva, x 360.

H. M. Morris 111 -

Text-figure 4. Right mandible of larva viewed from the left. x 180

Text-figure 5. Right maxilla of larva from below. x 180.
p, maxillary palp.

112 Larval and Pupal Stages of Bibio Johannis L.

Text-figure 6. Labrum of larva from below. an, antenna. x 200.

Text-figure 7. Labium of larva from below. — x 200.
m, mentum. sm. sub-mentum.

Vater

Text-figure 8. Egg of Bibio Johannis. x 80.

o>

Text-figure 11. Processes on cuticle of newly hatched larva. 600.
a, Lateral view; b, surface view. s, base of long seta.

“-H. M. Morris 113

{ | se j EY Lominekel é
it fl VA
cs IY fas
\ i _-PC JU ctf EY ae ee

=p il vA ji Ue, hie x. \
CS Sk OS

| lA A i oat A. at

a VER : Ant enti 4 \S
Li

7 Digmeg

Text-figure 9. Alimentary canal of Text-figure 10. Newly hatched larva of Bibio
Bibio Johannis larva. Oe¢es, Oeso- Johannis, dorsal aspect. x90.
phagus. Car, Cardia. Cae, Caeca.

Mes, Mesenteron. P.C. Posterior a
caecum. M.T. Malpighian tu-
bules. Int, intestine. Col, Colon.

114 Larval and Pupal Stages of Bibio Johannis L

ia Sanyal i
ty ~Sp

WS Gar
2 /
iw N

(

Text-figure 12. Tracheal Syste: of newly hatched larva. x 120,
lt, Main longitudinal trunk, ' sp, Spiracle. st, Secondary longi-

tudinal trunk. tc, Transverse connectives. th, Tracheae to the
heart.

TWO EXPERIMENTS IN HOUSE FUMIGATION

By H. MAXWELL-LEFROY.
Imperial College of Science and Technology.

House fumigation with hydrocyanic acid gas or carbon bisulphide is
no new thing and some years ago Mr C. W. Mason and IJ fumigated the
greater part of the new laboratories of the Pusa Agricultural College, a
building over 400 feet long. But in the cases I have had experience of the
difficulties were slight and in the present cases were considerably greater.

In the first case the house was situated in one of the suburbs and was
infested with the house mite (Glycyphagus domesticus, etc.). The use of
paraffin, formalin and sulphur dioxide in single rooms had driven the
mites over the whole house and the lady of the house was in despair,
having struggled without success for some years. It seemed hkely that
only very drastic treatment in every part of the house simultaneously
would succeed and it was necessary that this should not simply mean the
rooms but the floors, staircases, outhouses and even the coalshed.

It is known that hydrocyanic acid gas has a very small power of
penetration in grain and it was fairly certain that it would not penetrate
the floors if simply generated in the room: so carbon bisulphide was used
for floors and at the same time hydrocyanic acid gas was generated.

The house was an ordinary three story detached one with twelve
rooms, no cellars or basement. The houses on each side were less than
twenty yards away. The volume of the house was approximately
31 feet cube or 30,000 c. feet. The individual rooms were not measured
but we tried to fill the whole house evenly and the amounts were allotted
roughly according to the size of the room; all doors were left open inside
the house.

The quantities employed were 40 lbs. cyanide 98 per cent., 40 lbs.
sulphuric, and 54 Ibs. carbon bisulphide. Including larder, bathroom,
etc., 21 lots of cyanide and 23 lots of bisulphide were used as follows:

Cyanide: | lot of 6 lbs. in the hall;
3 lots of 3 lbs. in the larger rooms;
11 lots of 2 lbs. in the smaller rooms;
6 lots of $ lb. in the larder, ete.

116 Two Eaperiments in House Fumigation

Bisulphide: 1 lot of 4 lbs. ;
~ 7 lots of 3 Ibs. ;
14 lots of 2 lbs. ;

1 lot of 1 Ib.

The bisulphide was apportioned according to the floors, landings and
staircases. The procedure was as follows; a list was made of the rooms
and the special places requiring doses either of cyanide or bisulphide:
on this the quantities were estimated, the chemicals were obtained and
the owners went out. With the help of Messrs Davidson and Awati the
fumigation was done between 10.30 a.m. and 1 p.m.

The acid and water was mixed in the yard in proper quantity for
each room in a jug or basin and put there; the cyanide was weighed into
pieces of cloth about 20 inches square and placed beside each basin;
rooms were allotted and signals fixed: the bisulphide was then measured
into jugs and placed beside the cyanide.

All being ready and the sequence of operations fixed for each floor,
we commenced at the top, each pouring his dose of bisulphide down the
floor and standing by with the cyanide: at the signal the cyanide was
dropped into the acid and each man bolted out: in this way the floors
were done: the most difficult was the ground floor, where there were
seven charges of cyanide and nine of bisulphide to be let off by three men
but we emerged without mishap.

The house had been prepared by closing all openings, opening out
cupboards, books, etc., and taking up all carpets; where possible a
plank was taken up in the floor. All fires were out, all chimneys closed,
all gas off.

Success turned on penetration of the floors, which I hoped to secure
by pouring down bisulphide. The strengths were worked out at 1 lb. of
cyanide to 700 cubic feet and 1 lb. of bisulphide to 500 cubic feet,
assuming each to penetrate the whole house. The hydrocyanic prob-
ably never penetrated the floors and the bisulphide did not saturate «
above floor level, so each was much stronger, certainly at first.

The cost of chemicals was:

Si) Sua
40 lbs. cyanide 98 per cent. fused at 1s. 2d. Der gOrne
40 lbs. sulphuric acid coml. at 14d. O95 0
54 Ibs. bisulphide at 4d. O's 50
Su ero)

The house was visited twenty-six hours after the fumigation and the

H. Maxwk.u-LEFroy 117

fumes in the ground floor were then so strong that it was impossible to
stay and IJ had difficulty in getting ott. So the house remained shut
for a total period of sixty-nine hours when it was then opened up.

The occupiers moved in a few days later and the lady of the house,
who had waged war on the mites for years, searched and found live ones
in the books and in one attic. A few days later they were found also on
the banisters and on the piano. Apparently this was all and three
months later the lady of the house wrote: “We shall not need any
further fumigation for the present ; indeed I am hopeful we are practically
free of the mites. I have seen none on the furniture for some time
though I fully expected to in the last week’s warm weather.” Two
months later the house was reported clear entirely.

It seems likely that had the fumigation been repeated fourteen days
later, even on a milder scale, every ultimate mite would then have been
destroyed. It must be remembered that not only is there the egg as a
resistant stage but also the curious hypopial stage, in which the mite
encases itself and passes into a resting stage. In either of these forms
fumigation would scarcely kill all in the most sheltered positions. The
experiment showed (as far as one alone can), that:

1. Cyanide and bisulphide can be used together.

2. The escaping vapours are not offensive to neighbouring houses.

3. Gas escape from an ordinary house is slow.

4. Bisulphide vapour escapes slowly from ordinary ventilated floors
(these not being closed).

5. The cost of fumigation is not excessive.

6. Neither gas damages the contents of a house.

7. A single application at these strengths may be sufficient, by de-
stroying practically all the mites and making further increase impossible.

From observation of the results it appeared as if the bisulphide was
not very effective even at this strength: one larder was treated very
heavily with bisulphide as it contained food that might absorb the
hydrocyanic acid: yet here mites were found.

The second case may be more shortly told. It was a two story
house of 18,000 cubic feet capacity, heavily infested with book-lice
(Psocidae), which were of the usual wingless type found in houses. The
infestation had lasted from April to August and was proving detrimental
to the health of the lady of the house. From an examination made
under the floor, it appeared as if the two foot space below the floor was
not well ventilated, was damp, the beams covered with fungus and the
whole formed the main breeding-place of the Psocids, which came up

118 Two Baperiments in House Fumigation

through the boards and spread over the house. As in the other cases,
partial treatment had driven them from room to room.

Fumigation was done as before but using tetrachlorethane instead
of carbon bisulphide. 12 Ibs. of 130 per cent. sodium cyanide was used,
and 12 lbs. of tetrachlorethane. The cyanide was not weighed but
divided by eye, as it was in lumps, and 10 lots were used in the house,
two small lots in the outside coal cellar and privy. This house was only
semi-detached and I feared gas escape to the next house: but the builder
assured me this was impossible as there was no communication of any sort.

The fumigation was done with the aid of Mr Scott and Mr Lloyd:
forty-eight hours later I visited the house, was able to go straight in
and could detect no smell except that of tetrachlorethane when I re-
moved the paper from the outside ventilators leading from the space
under the ground floor. There was no complaint from neighbours, no
damage to property. The occupiers who were away, returned and have
now reported as follows: the house is completely cleared but reinfection
has been found to be occurring at a dormer window where insects have
been found coming in. This spot has been treated with a miscible wood
creosote and varnish and reinfection has ceased. There has been no
reinfection from the floors at all and no live insects seen in the house.
The cost of treatment was:

£ivs. nde

12 Ibs. cyanide at Is. 6d. 018 0
24 Ibs. acid at 3d. Dee teie 0)
12 lbs. tetrachlorethane at ls. 6d. O18 O
2) 2a

In this case, no particular preparation was made except to open up |
cupboards, etc.: no damage of any kind was done to anything in the
house and the owners are completely satisfied.

In both cases I attribute great weight to the opinion of the lady of
the house, utterly distracted and weary of the plague: and in both cases
residence in the house after treatment has not been followed by a
resumption of the attack.

It is difficult to get cases of this sort but I am satisfied that fumigation
with hydrocyanic acid with carbon bisulphide or tetrachlorethane is a
feasible and effective method even in a town, provided reasonable pre-
cautions are taken. I imagine this fumigation would be effective
against eyery form of insect life except possibly the bed-bug but a house
so infected has not been available.

119

THE LOCUST IN CYPRUS
By W. P. DELANE STEBBING, F.G:S.

The Locust plague in Cyprus which so many early writers have
mentioned and which was one of the problems which had to be grappled
with on the British occupation in 1878, is now almost a thing of the past.
But while locusts are usually thought of as large insects, such as the
Syrian species with its orange body and brown-blotched wings, the one
which has to be dealt with in the island, and was ah annual plague, is
a small indigenous brown-marked species of undistinguished appearance
known as Stavronotus cruciatus. This small locust, which dwells on
rocky and poor land from which, in its larval walking and*hopping stage,
it invades the cultivated areas near by, in its normal state is not
migratory nor is the perfect insect able to take long flights. The
damage it did was due to its general distribution and to ignorance of
the creature’s habits. With Eastern fatalism it was a plague of God
and that was enough, while there was the inability, intensified by a
natural aversion to combine forces, of a poor and sparse population to
cope with it.

Like the poor, this locust is always with the islanders and only pre-
ventive measures continued from year to year could be satisfactory.
The main methods by which the plague has been made negligible are
three :

, 1. Ege collecting—easily done as the egg masses are always laid in
hight soil bordering the fields.

2. Stopping the crawling larval hosts in their progress by trenches
on the further side of which were screens topped with a strip of American
cloth. As they were unable to surmount this they fell back into the
trench where they were suffocated by those coming after; and

3. Sprinkling feeding areas with a bacterial “cultivation” which
gave them an epidemic disease.

It has not been necessary to use the second of these for many years
and the annual expenditure on the first is almost negligible; but as a

120 The Locust in Cyprus

watchful eye has still to be kept on the trouble there are annual grants
for the employment of the third, and a large amount of the “cultivation”
is kept in the Government laboratories. But, along with other war
economies in Cyprus, agriculture has had to suffer, and although it is
said that the locust danger is a thing of the past it is a subject of con-
troversy as to whether the plague has been combatted or if economy has.
had a say in this matter.

In comparison with the Cyprus locust the Syrian migratory species
is a far more formidable creature and its ravages, when it appears, are
so much more serious that many of the older accounts must have referred
to these invasions from over seas. Several of them speak of flocks of a
small bird which suddenly appeared in the island with the insects and
ate up so many that the plague was minimised. Van Bruyn recounts
how “in the year 1668 throughout the island, but especially in the
country round Famagusta, there was such a vast quantity of locusts
that when they were on the wing they were like a dark cloud through
which the sun’s rays could scarcely pierce.”

Early in 1915 news reached Cyprus that swarms of locusts were
ravaging parts of Syria. Then, that numbers had been found along
parts of the coast both north and south of Famagusta in the KE. of the
island, and that one of our cruisers which put in at that port had passed
through a cloud of them’ on her way and had many settle. The first
swarms to arrive were few in number and were not ready for egg laying.
A little damage was done in gardens and, as is the Cypriote nature, a
great-to-do was made about it; but with the aid of Government grants
under the supervision of the Treasury—not the Agricultural Department
as one might expect—-most of the locusts were caught in the early morn-
ing by knocking them off the trees where they clung heavy with the
night dews. This measure for the adult insect is the most effective.
After egg laying had taken place digging over the soil and collecting the
masses was usefully practised, and—after hatching—for both native and
foreign species, spraying with a paraffin mixture, the invention of the
Entomologist to the Agricultural Department. The egg masses collected
came to such an amount that one of the old Turkish storehouses in
Famagusta, formerly a church of Venetian date, was filled with them.
The sticky eggs are laid by the female in a hole which she bores in the
loose soil and form an agglutinated mass covered with grains of earth.

In the latter part of the summer fresh swarms of locusts made their
appearance while others were ravaging Egypt. This time some appeared
on the northern coast while large numbers invaded spots in the southern

W. P. DELANE STEBBING pea

part of the island. Some of these latter did a great deal of damage
among the vines and olives but they were not much inclined to settle
and start egg laying. Each village did as much as it could to keep them
on the move, the inhabitants going out into the fields with sticks and
old tins or anything with which they could make a noise. On the un-
cultivated hill tops piles of brushwood were collected and at the alarm of
a swarm of locusts appearing these were fired so that the drifting smoke
should terrify the insects. At night the scattered fires now rising now
falling in intensity had a rather alarming look from the heights of Troédos
before their necessity was realised. The threatened ravaging of the
Omodhos district, which is one of the richest wine producing districts
of the island, aroused everyone to exert themselves so that little damage
was done at this period. A swarm of locusts appeared over the village
of Omodhos on the afternoon of its great fair and was heralded by the
ringing of its church bells, while departing strangers with their strings
of mules and donkeys were hurried on their way by the beating of tin
cans. Most of the swarms of this plague, which.can have formed only
a minute proportion of the hosts that left the shores of Syria, were
loosely composed and as they did not darken the sun their fluttering
flight was pretty to watch. This flight is very deceptive and made the
writer think that he could catch scores of the first swarm he was among.
But it was very rare for one to alight and without a butterfly-net it
proved impossible to make a capture, although a boy joined in the hunt.
On another occasion at midday a swarm was resting among scrub with
much bare ground but seemed equally wide awake. Although the insects
did not keep in the air no quickness availed to track one to earth
as their flight was too long to keep marking the spot at which some
particular one dropped.

After the birds among natural destructive agencies there is no doubt
that the various species of lizards do an immense amount of good in
keeping down insect life. Their numbers prove this. If a mere man
could not catch a locust the large ugly brown rock and tree climbing
lizard known as Agama stellio could; and an attempt to rob one of his
prey on the slopes of Troddos above the vineyards was frustrated by
his disappearance into a hole. At this level Troédos although tree
covered, evidently had no attractions for locusts as the writer only saw
a couple of other specimens at any height. It was a complete bar
between the cultivated valleys to N. and 8.

The vine growing district south of Troéddos, which consists of a much
denuded belt of decayed volcanic rocks succeeded by a wide limestone

122 The Locust in Cyprus

plateau cut up by deep river gorges, is noteworthy in the possession of
a factory where wine is made on modern methods and spirits are distilled.
The Perapedhi port is well known in the island among the British resi-
dents but the firm being largely German, although under British manage-
ment, and the output gomg to Hamburg meant the closing down of
operations before the vintage of 1915. Up to a late date the manager
hoped to run as usual and to profit by the entry of Greece into the war
on the Alles’ side. This would have meant the flooding of the Alexandria
market with cheap Greek wines, the lowering of the prices of the native
Cyprus wines and the consequent ability of the Perapedhi Wine Company
to buy large quantities at cheap rates from which the firm would have
been able to distil spirit at a good profit. But this was not to be and
the manager, like many others in their outposts of civilisation, left the
island to take up war work in the old country. His garden, which
sheltered a swarm of locusts one morning for a few hours, was a wonderful
example of productiveness under intelligent management, and of what
could be grown in the way of fruit trees which would resist severe
winters. :

The following quotation from the travel observations of Dr Thomas
Shaw on the Syrian locust may close these notes. His life on the
southern shores of the Mediterranean gave him good opportunities of
observing them. “Those,” he says, “which I saw in 1724 and 1725,
were much bigger than our common grasshoppers, and had brown
spotted wings, with legs and bodies of a bright yellow. Their first
appearance was towards the latter end of March, the wind having been
for some time from the south. In the middle of April their numbers
were so vastly increased, that in the heat of the day they formed them-
selves into large and numerous swarms, flew in the air like a succession
of clouds; and, as the prophet Joel expresses it, they darkened the sun.
When the wind blew briskly, so that these swarms were crowded by
others, or thrown one upon another, we had a lively idea of that com-
parison of the Psalmist, of being tossed up and down as the locust.”

MUSSEL BEDS; THEIR PRODUCTIVITY
AND MAINTENANCE

(THE MUSSEL BEDS OF CARDIGAN BAY)

By FRANK 8. WRIGHT.
Zoology Department, University College of Wales, Aberystwyth.

The present paper deals with some of the results of my observations
on the mussel beds of Cardigan Bay, from September 1915 to August
1917. These investigations were carried out on behalf of the University
College of Wales, Aberystwyth, and included an experimental trans-
plantation of mussels on a fairly extensive scale, in the estuaries at
Aberdovey, Barmouth, and Portmadoc. The Cardigan Bay mussel beds
had become greatly depleted through over fishing, which, in conjunction
with pollution troubles, had brought the fishery to a very low ebb. The
work has included outdoor observations, as well as more detailed work
in the Jaboratory. Although the Sea Mussel (Mytilus edulis, L.) has
received a great deal of attention in the past, and, therefore, some of
the facts, per se, contained herein may not be new, yet it is believed
that their presentation in an especial manner may be useful. The
Jaboratory work has been of a somewhat detailed character, and, although
a great deal of time has been devoted to it, much of it remains unfinished.
I refer more particularly to that portion which deals with the food
material of Mytilus, which, while it bears more or less directly upon the
subject-matter of the present paper, cannot be more than touched upon
here. It is hoped to embody these results in a separate paper at a later
date.

The beneficial results to the Cardigan Bay mussel fishery which have
resulted from the restocking of the beds (in the spring of 1916, and, less
extensively, 1917), as well as the possibility of carrying out the investiga-
tions, are due to grants from the Board of Agriculture and Fisheries.

The work was confined mainly to the Dovey Estuary. It is within
easy distance of Aberystwyth, the mussel beds there are easily accessible,
and a room was used as a laboratory within a few yards of the shore.

This paper is published by kind permission of the Board of Agri-
culture and Fisheries.

Ann. Biol. 1v 9

124 Mussel Beds; their Productivity and Maintenance

CARDIGAN BAY AND ITS ESTUARIES.

The following account of Cardigan Bay and its more important
inlets is, in the main, abridged and otherwise modified from Mr C. L.
Walton’s description in the first Report on Investigations towards the Im-
provement of Fisheries in Cardigan Bay and its Rivers, published in 1913
by the University College of Wales, Aberystwyth.

Cardigan Bay occupies a considerable portion of the west coast of
Wales. It is bounded on the north by the southern shores of Carnarvon-
shire, and its central portion comprises the entire coastlines of Merioneth-
shire and Cardiganshire, while its southern limit is the North Pembroke-
shire coast. It may be said to lie eastward of a line drawn from
Braich-y-Pwll in Carnarvon to Strumble Head in Pembroke, which two
places are distant some fifty-five miles from each other. The total
length of the coastline between these two points is about 140 miles.
The whole area is relatively shallow, the thirty fathom limit lying just
westward of the line mentioned above. Several causeways or spits
(Welsh, Sarm, a paved roadway) project out to sea in the northern half
of the Bay, often for several miles. Their landward ends are uncovered
at-low water. Such are Sarn Badrig, Sarn y Bwch, and Sarn Cynfelyn.
High and steep cliffs bound the shores of the Bay, except where they are
interrupted by the numerous river valleys, and the larger estuaries.
We shall omit any mention of the former, as they do not concern us in
this place, and confine ourselves to the Estuaries in which the mussel
beds are found, namely the Estuary of the Glaslyn and Dwyryd rivers
at Portmadoc, the Mawddach Estuary at Barmouth, and the Dovey (or
Dyfi) Estuary at Aberdovey. It is in these places that the sea mussel
finds the conditions suited to its habits. Patches of mussels occur at
various places on the coast, where freshwater influence is felt, but, as
the shellfish always remain stunted in growth, they are of no economic
value. They might be employed to replenish depleted beds, if necessary.

The tidal sweep, assisted by the south-westerly winds on the west
coast, is very strong. Where it meets the rivers, large storm beaches
have accumulated,.and, fronting the estuaries, sand bars (and sometimes
dunes, as at the seaward end of the Dovey Estuary). This tidal sweep
causes great alteration of the beaches from time to time, the stone and
shingle being transported in a northerly direction along the coastline.
C. L. Walton has shown how this factor has had an adverse effect on the
fauna in certain parts of Cardigan Bay!?.

1 “The Shore Fauna of Cardigan Bay,” Journal of the Marine Biological Association
of the United Kingdom, Vol. x, No. 1, November, 1913.

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126 Mussel Beds; their Productivity and Maintenance

THE Dovey Estuary (see Map).

It is necessary to give here a brief description of the Dovey Estuary,
and of its mussel beds.

The estuary is a large inlet (some five miles in length), which divides
the counties of Merionethshire and Cardiganshire. Its area is approxi-
mately five and a half square miles. The north shore is rocky and
steep, but, on the south, it is bounded by that low-lying tract which
we may term the Dovey Flats. A large sand bar lies across the entry
of the estuary, and restricts it to a relatively narrow channel or neck.
Such an estuary is termed a “ bottle-neck.” Within, its condition may
best be described as sand-logged, and, consequently, with the exception
of the actual channel (or channels) of the river, it is very shallow.
Through the great stretches of sand, the river pursues a meandering
course to its outlet. Its channel is subject to considerable alteration
from time to time, through the agency of the banks of shifting sand.
The stable sandbanks are populated by an abundance of cockles and their
associates.

Although relatively shallow, it is yet obvious that a very large
volume of water is contained in the estuary at high tide. This, having
to ebb and flow through one comparatively narrow outlet, is apparently
never wholly changed; for instance, within the estuary, the tide will
have risen appreciably before it is able to check the outgoing current.
Therefore matters constituting a possible source of contamination to
the mussels may remain in the channel for a long time.

The river impinges at several points on the north shore, including
nearly the whole of that portion fronting the town of Aberdovey and its
neighbourhood, and westwards to the Wharf. The current formerly
ran along the shore from Trefri to Penhelig Point (east of Aberdovey),
but, at the present time, only a shallow gutter marks this old channel.
For the most part, these places have been cleared of sand, and they are
either rocky, or else covered with stony beaches. This portion of the
foreshore shelves moderately gently to low-water mark of spring tides,
and then very abruptly to the bed of the river. It is upon such rocky
and stony areas (from about low-water mark of ordinary tides downwards),
here of limited extent, that the mussel beds are situated. The sea
mussel needs hard ground on which to anchor itself; but, where the
current is not very swift, and there is a muddy bottom (as at Portmadoc),
they are able to maintain themselves by becoming embedded in the
mud, or by clinging to each other in clusters.

F. S. Wricut 127

The history of the Aberdovey mussel beds (and, indeed, of the Cardigan
Bay beds in general), is difficult or impossible to trace. It 1s safe to say
that they have suffered many vicissitudes, as, with the slightest de-
flection of the river channel, portions of the beds are always liable to
be covered by the sand, and their population killed. Such accidents
have happened time and again; yet the current that destroys one bed
may uncover another stony area, that, within a short time, affords
a holdfast for a very populous colony of mussels.

The fishing grounds at Aberdovey, then, may be said to comprise a
strip of the foreshore on the north shore of the estuary from Trefri Point
to the Shipping Wharf, as well as portions of the river bed, etc. Their
continuity is broken by occasional patches of sand, but, roughly, the
length of the beds may be stated at one mile. Relative to the width
of the inlet, this strip is a narrow one, and, in places, exceedingly so.

In all these situations, the mussel thrives satisfactorily, finding an
abundance of food material, the necessary degree of freshwater influence,
and other conditions suited to its habits.

In the three estuaries there are certain beds (often of large extent
and occasionally supporting a crowded mussel population), where the
shellfish grow moderately well, while yet never attaining a marketable
condition. Such mussel beds will be described hereafter as “scars”
(skears), for want of a more convenient term. They generally differ in
several respects from the Lancashire mussel beds, properly so designated,
however. The population of the Cardigan Bay scars remains poorly
fleshed, and their shells, while usually free of Balanus, are for the most
part very thin and fragile. The last statement applies only to such
beds as become dry at long intervals. Otherwise the mussels are often
stunted or deformed, thick-shelled, and thickly encrusted with Balanus.
The repeated wetting and drying to which they are subjected cause the
shells to become rough and unsightly. When the chitinous outer shell-
layer (the periostracum) is lost, the prismatic layer becomes visible,
which, because of its colour, has caused such mussels to be called “ blue
nebs” among fishermen. A large scar (probably several acres in extent,
although, for various reasons, its exact area is difficult to ascertain),
or bed of seed mussels occurs at Aberdovey, towards the Bar. It occu-
pies a portion of the north bank of the river, as well as of its bed, and
stretches from a short distance below the Wharf to within about half
a mile of the Bar. A portion of this bed, on the north shore, becomes
uncovered at exceptionally low spring tides, and this place is known

locally as Ro-ddu.

128 Mussel Beds; their Productivity and Maintenance

It will be interesting to note briefly the
manner in which portions, at least, of this scar
were formed, and how the mussels maintain
themselves there (Fig. 2). The substratum is of
moderately firm, clean sand, the surface of which
is somewhat broken up into sand ripples. The
steep (lee) faces of these front in an east-north-
easterly direction. Against these ridges, cockle
shells (which have been transported downstream
by the river current from the extensive beds
within the estuary), have accumulated, together
with stones, water-logged wood, etc. On these
materials, spat liberated by the mussels higher
up the river has settled, and continues to settle
year by year. As the shellfish develop, their
byssus fibres fasten the whole together with a
certain degree of firmness. As individual mussels
die, they become covered by sand, and their
shells afford a still better anchorage to their suc-
cessors. Thus the bed is composed of a number
of small colonies of mussels, clinging to the
steeper sides of the sand wave ripples, and
sheltered from the direct influence of the tidal
current from the sea. Whether the whole of this
somewhat “ragged” bed presents the same aspect
is doubtful, but there is reason to believe that its
deeper portions, which are always submerged, are
rather more densely populated.

Lying, as it does, in the narrow neck of the
estuary, where the tidal currents race most
strongly!, portions of the scar are probably al-
ways covered more or less with sand. This sand
may be simply washed over it in quantity, from
the river bed, or from banks of shifting sand,
or else deposited from that held in suspension

South -wesk.

Mussels maintain themselves in the shelter

No scale.
afforded by the lee face of the Sand-Ripples, Boulders, ete., and are affixed to shells, stones and other objects which have collected there.

Direction of sncorng currerel from the Sed.
Boulder

Anchorage of Shells, Stones. Debris Se, i eee,
Diagrammatic Section across a portion of the Ro-ddu ‘*Scar”’ (Seed Bed).

ae by the current, which is considerable (see para-
Saye. ; : : :
Ci graph on this subject in another place).
$ ge Although the sea mussel is an animal of
= é F ° ° ¢
Sy rapid growth, yet, considering the relatively small
- 3 fox
33 ey 1 Captain Enoch Lewis, of Aberdovey, informs me that,
Ss

during spring tides, the current in the seaward portion of the
estuary reaches a speed of about three miles an hour.

F. S. Wricur 129

extent of the fishing grounds dealt with in the present paper, it will
be understood that these will soon become depleted unless restocked
from time to time. It is not legal to take mussels of a size less than
21 inches, except in certain places (see the Bye-Laws of the Lancashire
and Western Sea Fisheries District), and, from the time of the dis-
charge of the ovum, probably three years will elapse before this size
is attained, even under favourable conditions. The ova discharged
by a single female of Mytilus during the spring and summer months are
estimated to number from 10,000,000 to 15,000,0001, the vast majority
of which are destined to perish in various ways. So much so indeed,
that, in order that the beds may be fished from year to year, it is
necessary to restock them at the close of each fishing season—a matter
of comparative ease.

Myticulture is practised in several different ways”, but the only one
that need be mentioned here is the system of bedding, as practised in
Britain. Ina limited degree, transplantation has often been carried out
by the fishermen concerned, and others, and accounts descriptive of the
operations have appeared from time to time. Briefly, the shellfish are
removed in quantity, from certain beds (seed beds), where they do not
fatten, and redeposited in other situations where growth and fattening
proceed with rapidity. Beds of seed mussels are usually present in the
vicinity of the fishing grounds, and form nurseries or reservoirs from
which they may be restocked when necessary.

The present paper is an attempt to discover the maximum produc-
tivity of mussel beds,—we might say the ideal productivity, and, like
most other ideals, the present one might perhaps be regarded as un-
attaimable. Yet, even if this should prove to be the case in practice,
it is necessary to formulate a working hypothesis, and I venture to
believe that an output such as is described later is well within the range
of possibility. In its attainment, the chief factor to be taken into con-
sideration is that the population may secure a sufficiency of food material ®,
although there are other complicating factors to be considered. The
degree of restocking necessary to maintain a maximum yield from the
fishing grounds is also dealt with, etc. The data from which most of
the subject matter of the present paper has been written, was collected

1 These figures apply to the American sea mussel, which is, however, of the same
species. See article by I. A. Field in The American Museum J ournal, October, 1916.

2 See article by Professor W. A. Herdman in the Report for 1893 of the Lancs. Sea
Fisheries Laboratory.

3 See article by I. A. Field in The American Museum Journal, October, 1916.

130 Mussel Beds; their Productivity and Maintenance

during many visits to the Aberdovey (and other) mussel beds. The
economic aspect has always been kept in view, but many of the facts
contained in the following pages are probably new, or not vet published,
and therefore they may possess some degree of scientific value in other
respects also.

In concluding these remarks, I shall quote an article by Professor
Irving A. Field, whose works are so often mentioned in the following
pages: “In the light of our present knowledge it is proper to say, when
viewing a shoal of mussels, ‘there is one of the greatest organisations
in nature for making flesh food by a short and rapid process.’ Surely
the humble mussel is fulfilling a benevolent mission in the world?.”

Acreage of the Aberdovey Mussel Beds.

It is not necessary to describe in detail the various beds, where, at
Aberdovey, the marketable mussels are fished. It has been said already
that they lie on the north shore, towards the seaward end of the estuary,
where the slope is often very abrupt. This may be anything up to 50°,
such being the slope of the river bank (here of solid rock) at Penhelig
Point, just east of Aberdovey. In attempting to estimate the dimen-
sions of the beds, therefore, it is not sufficient to discover merely their
length and breadth, but the angle at. which the river bank slopes has
also to be taken into consideration. These several factors were borne
in mind during my endeavours to discover the present superficial area
of the fishing grounds, early in the present year (1917). Despite all care
to ensure a reasonable degree of accuracy, the figures given below must
be understood as being merely approximate. In fact, they are probably
considerably below, rather than above, the actual figures.

The approximate total area of the Aberdovey mussel beds is 76,000
square feet (= nearly 1? acres).

(This does not include the great scar towards the Bar.)

The above figures were obtained from a personal knowledge of the
ground, and information supplied by the more experienced fishermen,
the whole matter being carefully checked on a large scale map, and in
other ways.

Population of the Scars or Seed Areas.

In an endeavour to estimate the maximum potential productivity
of mussel beds, when their.area is known, it is necessary to find the
greatest number of individuals of a given size able to live and thrive
per square unit of measurement in natural conditions. Obviously, all

1 J, A. Field in The American Museum Journal, October, 1916.

EF. S. Wricur 131

the individuals in such a unit will not be of the same dimensions, but, in
practice (and when checked by other methods) the results have proved
fairly accurate.

I found that the only place which fulfilled most of the requirements
stated above, as well as certain others to be detailed presently, was the
Ro-ddu seed area, at Aberdovey. At low water of spring tides, certainly,
many areas bearing mussels are readily accessible, but in the majority
of them the individuals are very unevenly distributed. It has been said
before that the mussels with which we are chiefly concerned here are
those from 2” to 23” in length, as, at Aberdovey, the average growth made
by a two-inch mussel during the close season is about half an inch
(actually 5%”).

Therefore, the conditions required in order to obtain this “ population
factor” were, not only the greatest number of individuals in, say, one
square foot, but that all within such unit of measurement should be
between 2” and 23” in length.

The sea mussel is fixed in a variety of ways (Fig. 3); if in clusters, the

long (antero-posterior) axis may lie in any plane without inconveniencing
the shellfish, and the same may be said of it when attached to stones
and other solid objects. When, however, it is found living on sandy or
muddy bottoms, and more especially when crowded together, or if any
force of current is experienced, it generally lives with its anterior or
“head” end buried in the substratum, the posterior, or siphonal end,
projecting slightly above the surface. The mussel apparently favours
these conditions, and I have noticed that newly transplanted mussels
soon gather mud and sand around themselves, as described above. In
sluggish streams especially, such a posture confers certain advantages
with regard to feeding. The siphons will thus be slightly raised above.
the level of the floor, and, therefore, in a better position to receive the
detritus and other food material which washes about there, than if they
were more elevated. In this way, a bed of mussels will retard food
particles passing through it.
This condition prevails on the Ro-ddu Scar, which is occasionally
accessible at very low spring tides. By actual count of the individuals
(all from 2” to 24” in length) falling within one square foot, I found that
the population factor in this place lay somewhere between 121 (11 x 11)
and 144 (12 x 12). These figures represent crowded, though not ex-
cessively crowded, conditions?.

1 For details of overcrowded conditions on mussel beds, etc. see article by Andrew
Scott and Thomas Baxter, ‘‘ Mussel Transplantation at Morecambe,” in the Report for 1905
of the Lancashire and Western Sea Fisheries Laboratory.

132 Mussel Beds; their Productivity and Maintenance

Posterior.

Anterior

SS
—

ventral. gf

Fig. 3. Fixation of Mussels, Growth Marks. &c.

a. Mode of anchorage in a muddy or sandy substratum exposed to currents. 6, c. Mode
of fixation to vertical surfaces,—solitary and crowded conditions. d. Mussel, with ridges
on shell denoting its age. The thick numbered lines are “ winter marks,’’— therefore,
the individual figured is five winters old. It is a ‘‘seed’’ mussel, from the Ro-ddu
“Sear,” Aberdovey. The right side (valve) is shown.

F. S. WriGcur 133

Can we, then, take this result as our ideal population factor, as it
stands, and can this numerous population be expected to flourish? In
order to determine this point, in view of what is known with regard to
the abundant food supply available for the mussel, I conducted the
following check experiment. A band of thin iron, 13” in depth, was bent
into the shape of a square foot, in which were placed mussels, “head”
end downwards, 23” in the vertical axis, until the measure was well
filled. Sufficient space was allowed for each individual to function.
They were then counted, and were found to number 121 (11 x 11)
individuals. This result is in close agreement with the rougher totals
obtained in natural conditions on the Ro-ddu seed bed. Therefore, such
a number can live and thrive on the fishing grounds, and it may safely
be taken as the population factor desired. The poor condition of the
mussels on the seed beds is due to a special cause, or a combination of
causes, which will be considered immediately.

Such a population obviously cannot be distributed homogeneously
over the whole of the fishing grounds, but, even if portions of it have
been too thickly restocked, a certain degree of readjustment will take
place. The diatoms, and other organisms, vegetable detritus, etc., on
which Mytilus feeds are present in practically inexhaustible quantity,
and every individual in even a populous colony will be able to procure
an ample supply of food material for its needs, unless, that is, badly
overcrowded conditions cause the water currents to become obstructed
in certain cases.

I have examined a large number of mussels from the seed areas (more
especially those from Ro-ddu Scar, Aberdovey), as well as from the fishing
grounds, at different seasons of the year, with regard to their stomach
content. Some very interesting, and apparently contradictory facts
were noted in this connection, but upon consideration, these will be
found to be in accordance with the conditions in which the mussels live.

I have found, for instance, that the stomach content of the seed
mussels (poorly fleshed mussels) is generally equal to, and sometimes
greater than, that of individuals from the actual fishing grounds, although
scientists and others have not hesitated to call the former starved indi-
viduals. Also, the organisms, etc., present were, if anything, in greater
variety in the case of the mussels from the scars. This state of things
needs some explanation, but this attempt to account for the poor flesh:
content of the seed muscles must be regarded as tentative. As the
beds at Aberdovey are very sharply defined, I confined these observa-
tions to this place, for the most part.

134 Mussel Beds; their Productivity and Maintenance

The Conditions of Infe on the Scars or Seed Areas.

In his book, Life in the Seat, J. Johnstone, discussing the views of
Piitter and others, suggests the possibility that the respiratory and other
tissues of certain aquatic animals assist in the assimilation of certain
foodstuffs held in solution in the medium in which they are bathed.
That, in fact, it may be proved in the future that such tissues function
as the chief means? in the nutrition of a large number of forms. In the
same connection, he calls attention to the relatively large extent of the
“so-called respiratory surface of the mollusc or ascidian...,” both seden-
tary forms in which, as might be supposed, “the respiratory function is
much less important than it is in the case of a warm blooded animal,”
because, in them, metabolism proceeds more slowly. He further dis-
cusses the possibility of the “anal respiration” of certain of the micro-
crustacea as being, partially at least, nutritive in character. This
hypothesis is a fascinating one, but the experiments of Moore, Edie, and
Whitley on the nutrition and metabolism of marine animals* seem to
disprove Piitter’s results. Lobsters (to mention one instance) were
kept in seawater, which was regularly renewed, in tightly closed vessels.
All plankton was removed from this water before it was introduced into
the vessels. The lobsters lived as long as seven months under these
conditions. At the end of this time, they frequently registered an in-
crease in weight, but this was found to be due to what may be described
shortly as a water-logging of the tissues. As an alternative explanation
of the large respiratory surface shown by the types mentioned above
(sedentary types), among others, the following suggestion is made. The
rate of oxidation in many aquatic animals is very low, a fact which has
received somewhat belated recognition. Yet, even so, a relatively large
volume of water has to be treated by the organism in order to supply its
needs. It is fairly certain that, for various reasons, feeding is often
interrupted for longer or shorter periods. Therefore, the taking in of
food must be so adapted as to allow of a reserve being accumulated to
enable the organism to survive during periods when the supply is cut off.
This would go far towards explaining the large respiratory surface in

1 Cambridge University Press.

2 Others regard vegetable detritus as the most important element in the food of Wytilus
and some other forms.

3 See article in the Report for 1913 of the Lancs. and Western Sea Fisheries Laboratory :
“The Nutrition and Metabolism of Marine Animals: the Rate of Oxidation and Output
of Carbon-dioxide in Marine Animals in Relation to the Available Supply of Food in Sea-
Water,’ by Professor Benjamin Moore, FE.R.S., Edward 8S. Edie, B.Sc., and Edward
Whitley, M.A.

F. S. Wrient — 135

the forms under discussion, because in them (most Lamellibranchs,
Ascidians, etc.) the cilia of the gill epithelium alone serve as the mechanism
of the respiratory streams. A large gill-surface means that a larger
volume of water can be treated by those forms possessing it.

Even if the validity of Piitter’s theory of “osmotic” nutrition be
fully conceded, it does not help us much to understand the poor flesh
content of the seed mussels. It must be stated again that, as the
Ro-ddu Scar is situated near the narrow neck of the estuary, and conse-
quently all the water entering or leaving it has to pass over the bed, any
such dissolved food material that may be present higher upstream will
have to pass here on its way seaward.

Fouling of the Beds, ete.

_ The toxic effect of noxious matters liberated in the course of meta-
bolism by large and crowded assemblages of animals,—products of
excretion and metabolism,—must now be considered briefly. This
factor may be taken as explaining, in some degree at least, the poor
condition and high mortality of mussels in those beds which, besides
being very crowded, are situated in a sluggish current, where waste
products may remain and accumulate to the detriment of the population t.
When the shellfish are several layers deep, such a condition of things
will probably be intensified. On the Ro-ddu Scar, however, the animals,
though very closely packed, are never overlain by their congeners.
Because of this, in conjunction with the great tidal scour to which the
place is subjected, the patches of mussels, and the sand in their vicinity,
are always remarkably free of noxious substances. Mussel excreta may
certainly be detected at times, but in quite negligible amount.

Food Material.

The plentiful and varied nature of the food in the stomach content
of mussels from all situations (diatoms, protozoa, detritus, etc.) proves
that there is no lack of suitable aliment. Each mussel (as has been
explained), in the seed beds will have free access to the water currents,
except in certain circumstances to be considered presently. The paucity
of diatoms and other organisms, in material collected by means of the
tow-net near the mussel beds, compares in an interesting manner with
the stomach content of Mytilus, with its wealth of organisms. It must
be borne in mind, however, that the greater number of diatoms, etc.,

1 See article by R. L. Ascroft. “Mussel Beds and Mud Banks,” in the Report for 1898
of the Lancs. and Western Sea Fisheries Laboratory.

136 Mussel Beds; their Productivity and Maintenance

entering the mouth of the tow-net, pass out again through the meshes
of the silk or other fabric of which the net is fashioned. As the food
supply is ample, we are forced to conclude that, for some reason, the
individuals are not always able to avail themselves of it.

Silting of the Beds.

It has been said in the foregoing that parts of the mussel nursery
situated towards the Bar at Aberdovey appear to be always covered by
sand to a greater or less depth,—not necessarily the same portions all
the time. I have never visited this place without observing patches of
it in this condition, the buried mussels lying beneath from one to about
four inches of sand. As this place dries only at exceptionally low spring
tides, when the volume of water entering and leaving the estuary is
much greater than normal, we may infer that this “sanding” process is
worse at such times than during neap tides. Surface tow-nettings, taken
at various states of the tide, reveal the large amount of sand always
carried in suspension by the current, both at Aberdovey and in the other
estuaries. On the other hand, the sand probably remains longer over
any given place during the lesser tides than during springs, when patches
covered by one tide may be cleared by the next. The direction and
force of the wind are other factors which have considerable influence in
this silting process. From some preliminary (incomplete) experiments
which I carried out at Aberdovey, under artificial conditions, during the
summer of 1916, I found that mussels, despite all care, succumbed in
from four to five days when covered by sand. Not only was this the
case, but, with even the slightest covering of this material, the mussels
made no effort whatever to raise themselves above it, or otherwise to
free themselves. Yet a vigorous stream from the exhalent siphon would
have cleared them, as the individuals were in a position favourable to
such action. This dilemma seems to be one in which the foot might
be employed with advantage if it is capable of being utilised as an aid to
movement in the adult stage. I have not observed it to be used for this
purpose, except in very small individuals, at any time. Although diffi-
cult of proof, I am inclined to the view that Mytilus behaves in a similar
manner when covered by sand in natural conditions. That is, it remains
passive, with its normal life processes slowed down, until the sand is
removed by the current, or till death supervenes. Fishermen often
assert that mussels are able to raise themselves above accumulating
mud or sand by the lengthening of their byssus strands, which are at-
tached to underlying stones and other substances. What really happens

F. S. Wricut . 137

is that, as one generation dies and becomes buried (or, perhaps, becomes
buried and dies), a new generation grows up, which anchors itself to the
shells of its predecessors. So the bank grows, each successive generation
accumulating more silt, and, in this manner, covering those beneath!.
It is not improbable, however, that in natural conditions, it may survive
for a somewhat longer period than that mentioned above. Whatever
future research may prove to be the true facts, 1 am convinced that the
above factors account, in a large degree, for the poor flesh content of
those shellfish living on certain beds which are liable to silting. Covering
by sand causes feeding to be interrupted, often for fairly extended periods,
whereas, in better situations, it proceeds ceaselessly. There must be
a considerable amount of sand held in suspension in the water near the
bed of the river, and it is suggested that, often for some hours during
each tide, this factor is serious enough to prevent the mussels feeding.
They are compelled to remain closed in order to prevent the entrance
of sand into the branchial cavity. The views expressed above receive
a certain degree of confirmation (although perhaps this is not very
definite) from the evidence afforded by the mussel’s orientation with
regard to the current, when this is a swift one. My curiosity and
scepticism were aroused by the following paragraph, as my own experience
had led to results opposed to the views stated by its author. In an
inaugural address to the Malacological Society”, B. B. Smith Woodward
says: “ Mytilus, which also comes of a family having a long pedigree,
has not a particularly stout test capable of resisting heavy blows, but
it meets the waves with its outwardly directed, sharp, wedge-shaped
shell and cleaves them instead;....” On the Ro-ddu bed, however,
where the mussels are buried head foremost in the sand in order to
secure a holdfast, I found that, in the majority of cases, the valves, or
sides, opposed the currents. Thus, one valve faces upstream, and the
other downstream. In this manner, they are probably able to feed for
rather longer periods than would be the case if they were placed as stated
in the quotation, because of the sand danger. Mussels may, and do,
-meet the current with their sharp siphonal extremity, but this is probably
because they have little choice in the matter, or because the velocity of
the current is not great. The quotation is, without doubt, very mis-
leading.

As Mytilus does not appear to thrive in purely marine conditions the

-

1 See also article by R. L. Ascroft, op. czt.
2 «What Evolutionary Processes do the Mollusca Show?” Proceedings of the Mala-
coloyical Society. Vol. viz, Part 5, June 1907.

138 Mussel Beds; their Productivity and Maintenance

more seaward (generally) situation of the seed areas may possibly be a
factor to be considered in attempting to account for the light weight of
their population. Remembering that the sea mussel is essentially a
brackish water animal, it is probably safe to say that its “condition”
varies with the difference of freshwater influence.

Growth-Rate of the Sea-Mussel.

The growth-rate of Mytilus will be considered here mainly from the
economic standpoint, leaving points of more purely scientific interest
for another occasion. One point of general interest, and some import-
ance, must be noticed in this place, namely the amount of growth made
by Mytilus during the first year of its life, in its natural habitat. These
observations were made on a suitable portion of the foreshore, near the
fishing grounds, at Aberdovey, near low-water mark of spring tides, and
they extended over a considerable period. Certain stones were carefully
watched, as circumstances permitted, upon which mussel spat was likely
to settle (the spawning time probably commences at the end of April,
or during May). In due course, young Mytili were seen to have affixed
themselves thereon, and in July of the following year (1917) they had
attained a size varying from }” to 3”.

During the course of fonenlantaton work in Garden Bay, for two
successive years, it has been found that a large proportion of the seed
mussels measured about two inches in length. It was desired to ascer-
tain the growth made by these during the close season, which, at Aber-
dovey and Barmouth, extends from April 1 to October 31 inclusive,—
a period of.seven months. At Portmadoc, the close season begins a
month later, and ends a month earlier, than at the above named places.

Various means were tried of marking large numbers of two-inch
mussels, as for instance, by the application of spots of specially prepared
paint. This pigment not only hardened under water, and is known to
have adhered for some considerable time to the shells, but it left the
mussel] so marked quite uninjured. The attrition of water-borne sand,
however, removed all trace of it in the course of time, and to my disap-
pointment, not a single marked mussel has been recovered from any of
the beds. As a check experiment, some cages of galvanised iron wire
were constructed at the same time, and these were deposited in the river
at Barmouth. Some of them were recovered at the commencement of
the next fishing season, and the surviving mussels were carefully mea-
sured. As the cages would seem to have been affected by the shifting
sand that has lately covered portions of the Barmouth mussel beds, the

F. S. Wricur 139

results obtained are not of great value. Other cages, more carefully
constructed, were placed in the river at Aberdovey, and have not yet
been recovered. It is feared that a recent “creep” of the foreshore may
have buried them.

Despite these setbacks, however, some valuable data has been amassed
with regard to the growth of Mytilus during the close season. Upon
removal from the poor areas (seed beds), the transplanted mussels make
such rapid shell, as well as flesh growth, that usually a distinct ridge
is formed on the shell, which marks off its older portion from the newer
growth. When removed from a poor to a better situation, this mark
is so definite and unmistakable, that it is impossible to doubt its
meaning (Fig. 3). At the commencement of the fishing season (7.e. after
the transplanted mussels had spent about seven months on the fishing
beds), I examined a large number of individuals, which, from certain
unmistakable indications, had been brought from the poorer situations.
The average increase in length made by a two-inch mussel in this time
was found to be rather more than half an inch (actually ,”).

16

Growth Rate of the Sea Mussel.

Length
Size of Locality When trans- When re- Average increase in | of growth | Number
mussel c planted covered length period in | examined
ays
2” (5:1 cm.) | Ro-dduseed | March 30, Several
bed 1916 | hundreds
24” (6-4cm.) | Near Literary Nov. 15, | }” (actually 3,”) | 231 | Several
Institute, | 1916 hundreds
Aberdovey

Now let us consider the increase in cubic content which this growth
in length represents,—reckoning the latter at half an inch. The fol-
lowing figures were obtained by placing in water a large number of
individuals (sometimes singly, sometimes more than one), in a partially
filled measuring glass graduated in cubic centimetres. In each case,
the valves were carefully tied with cotton to keep them in apposition,
as any water entering them would have resulted in too low a reading.
A number of shells were also treated in a similar manner, and the
readings for them, being deducted from the total mass including the
shells, give the correct figures for the valve content. This of course
includes flesh, air, water, etc.

Ann. Biol. iv 10

140 Mussel Beds; their Productivity and Maintenance

Average Cubic Content of Mytilus as measured by
Water Displacement.

Length

5 Cubic con- Displace- Actual cubi ;
) : | place c cubic =
aida tent (includ- | ment ofshell| content of Increase | °f aa eB ee
ing shell) only valves | period i
. days
2” (5-1 em.) 10 c.c. 3:3 ¢.c. 6:7 c.c. | Several hundreds

17°5 c.c. 10-8 c.c.* 231 Several hundreds

24’ (6-4cem.) 22-5 cc. 5-0 c.c.

* This represents an increase of, roughly, 161 %.

Weight Experiments.

A considerable number of mussels was utilised in the determination

of the figures given below. The average weight probably varies con-
siderably at different seasons of the year, and, during the summer
months especially, I have found that mussels are often poorly fleshed
and of light weight. They increase in weight in autumn and winter.
The figures here represent the weights of fairly heavy, unspawned indi-

viduals.
Average Weight of Mussels in Shell (Live Weight).
— . om |
Size of Weight | | pees Named a
Size o ‘eight (in- | ics : . | of growth) Number |
mussel cluding shell ~ Locality Date Increase pent in examined Remarks
| | days |
Rea Er ae ade NR | = aH ;
2” (5-lem.) | 14 gms. | Ro-ddu seed bed, | March 30, Several | Unspawned
Aberdovey 1916 | | hundreds | (fairly heavy)
| | individuals
2 a SEES ie ta : BLE
23” (6-4em.) | 30 gms. | Fishing grounds, | Nov. 15. | 16 gms.* 231 | Several | Fairly heavy
| Aberdovey 1916 | _ hundreds mussels

* This represents an average increase in weight of about 114 %.

Average Weight of Soft Parts (Flesh Content).

In the case of a soft bodied creature like the sea mussel, which secretes
an abundance of mucus, it will be understood that it is difficult or even
impossible to determine accurately what is organic matter and what
not, in the fresh condition. A rough method of estimating the flesh
content is, therefore, of no use whatever. Special methods have to be
employed, and these have to be followed with great care if the results
are to prove of any value.

F. S. Wricart i41

In order to determine the readings given below, a number of mussels
of the required measurement were heated until they maintained a
constant weight in an air oven at a temperature of 100° to 105°C. The
shells and byssus fibres were of course removed. At the conclusion of
the period of desiccation the weights of the residues were determined by
a balance, and the average weight calculated.

I am greatly indebted to Dr T. Campbell James, of the Edward
Davies Chemical Laboratory, U.C.W. Aberystwyth, who kindly worked
out these results, and who is responsible for the figures given in the
following table.

Average Dry Weight of Organic Matter (Flesh Content).

7 |
SE Average weight r —
Si of dry organic | Locality Date Increase Pare Remarks
matter (flesh) | | |
| — =
2” (5-1. em.) | 0-949 gms. Ro-ddu seed bed, | Mid April. 6 | Unspawned
Aberdovey | 1916 | mussels
d i
‘ls (Ee ie
23” (6-4cem.) | 2-027 gms. | Fishing grounds. | November. | 1-:078* gms. 6 | Heavy
Aberdovey 1917 | | | mussels

* Therefore, the approximate increase in flesh content made during the close season
ne HIRO

The Maximum Potential (Ideal) Productivity of the
Aberdovey Mussel Beds, and its Money Value.

At Aberdovey, theoretically, a “bag” of mussels, as packed for
export, contains one hundred pounds of the shellfish. Actually, it
weighs about 125 lbs. in order “to allow for the decrease of weight
consequent on the loss of moisture during transit to the various market
centres.”

It was necessary to estimate, approximately, the number of mussels
of different sizes contained in a bag of 125 lbs. In order to do this,
several pounds of each of the sizes required were weighed, and the
number per bag calculated from the figures so obtained.

We have seen already that 121 mussels each 23” in length can thrive
in a space of one square foot. Let us assume that the Aberdovey beds
are populated to this extent. We see that, in order to fill one bag
with 21” mussels, the total population of nearly fourteen square feet
is required. The estimated total area available for mussel culture at

10—2

142 Mussel Beds; their Productivity and Maintenance

Aberdovey is some 76,000 square feet!, which, if stocked to its utmost
capacity, would number a population of 9,196,000 individuals?. This
number would suffice to fill, roughly, about 5659 bags.

Number of Mussels contained in a bag of 125 lbs. as determined by weight.

26 ; Number
Size of Approximate no. per es ae Num .
mussel bag of 125 Ibs. Locality Date Ena Remarks

2” (5-1 em.) | 3260 individuals | Wallat Penhelig.| July 19. 8 lbs. | Old and thick-
Aberdovey 1917 shelled mussels

23” (6-4cem.) | 1625 individuals | Wall at Penhelig,| July 19, 6 lbs. | Old and thick-
Aberdovey 1917 shelled mussels

22” (7 em.) | 1312* individuals | Fishing grounds, | August 4, 6 lbs.~ | Thin-shelled
Aberdovey 1917 mussels

* This number is probably too high. The shells of these individuals were less thick
and consequently lighter than those of the other sizes given. By actual count of the
mussels (averaging about 23’) in a measure, three of which the fishermen count as one
bag, | estimated that about 1100 individuals of this size went up to make a bag of 125 Ibs.

The average price per bag received by the fishermen throughout the
season may be taken at about five shillings,—sometimes rather less
and often above. Therefore, taking this sum as the unit value per bag,
the whole yield, as calculated above, should represent a value in money
of something near £1414. Os. 0d.8

If twenty men were regularly employed in the mussel fishery at
Aberdovey throughout the fishing season of five months, counting this
period as twenty weeks, this sum of money, if equally distributed,
should mean that each man would earn a wage of £3. 10s. Od. per week.

It must be admitted that such an intensive yield might prove im-
possible of realisation in practice, but the difficulties are not so insuper-
able as they appear on a casual consideration. Returns not very far
short of the figures given above might reasonably be expected if the

1 This does not take into account walls, piles, etc., which afford a holdfast to hosts of
mussels of all sizes.

* Thus, the progeny of a single female mussel. if all survived, would suffice to populate
the entire fishing beds at Aberdovey ! (see paragraph in another place).

3 It is estimated that about thirty tons of mussels were exported from Aberdovey
during the season 1916-17. At 5s. per bag, this represents a value of only £150. Had the
demand held, a much greater quantity could have been marketed, and, therefore, the
river is fairly well stocked for next season’s fishing. Cooperation between the fishermen
is the great need of the local mussel fishery.

FE. S. WriGHT 143

necessary amount of restocking is carried out with due care. A good
deal of space would be occupied by individuals below the legal size,
down to very minute mussels which have developed from the spat.
These, however, would occupy the interstices between the larger mussels,
to a considerable extent, and, at all events, the space which they occupy
would be compensated by those larger mussels living in clusters, and
by the increased superficial area of the ground resulting from inequalities
in its surface.

Restocking the Beds (Transplantation).

We shall assume that, at the close of the fishing season, the beds
have been exhausted of mussels of the legal size (two and a quarter
inches, and above). It is now necessary to estimate the amount of
transplantation requisite in order that the maximum yield may be
maintained in the following autumn, and the distribution among the
fishermen each his proper share in this work.

In the first place, it is necessary to gauge how far the beds are already
stocked with mussels below the legal size, which have either not been
brought up in the course of fishing, or else have been thrown back when
the men cleaned their catches. This is a somewhat difficult matter, as
obviously conditions will vary in different areas. Still, knowing some-
thing of the rapidity of the mussel’s growth rate, it will probably not
be very wide of the actual state of things if we assume that one-fourth of
the area is intermittently stocked in this way. Therefore, three-fourths
of the ground will need to be replenished by means of transplantation.
This, at Aberdovey, represents some 57,000 square feet, and, if we aim
at placing 121 individuals (in this case each of 2” in length?), it in-
volves the removal and deposition of 6,897,000 individuals. This number
would fill, roughly, 2122 bags, and represents 106 tons of shellfish.

Most of the boats used in this fishery, at Aberdovey and elsewhere,
are fairly large ones, each capable of carrying one ton or slightly over.
This means that, if the maximum amount of transplantation is carried
out, a boat, under the most favourable conditions, would need to make
one hundred and six journeys with its maximum load of one ton® of
seed mussels. A single boat could only procure this large cargo during
a very low spring tide, when the seed bed dries, and the mussels are
simply shovelled into it. If gathered by means of a rake, it would
scarcely be possible for a single boat, with a crew of one, to procure

1 Asa 2’ mussel will increase to 21” in seven months, this growth has to be allowed for.

2 This amount was often exceeded during the transplantation experiments at Aber-
dovey, even when the crew consisted of one person only.

144 Mussel Beds; their Productivity and Maintenance

more than half this quantity per tide. But if, as we have supposed to
be the case, twenty men were working at the fishery, and that all of them
assisted in the transplantation, removing one ton per tide per man,
the whole amount could be removed in, roughly, ten journeys per boat.
The scar may be supposed to dry for about four or five days during
low spring tides, or, even if it does not actually dry, the depth of water
covering it will be negligible, and, therefore, the whole operation could
be carried out in the space of two spring tides. If additional assistance
were forthcoming, the time occupied would be further lessened. Thus
boats from a neighbouring pert might be requisitioned for a few days,
their owners assisting; such services to be repaid in kind later. The
mussels should be transplanted prior to spawning.

Some Destructive Influences, ete.

It has been mentioned before, that mussel beds, when affected by
strong currents, are liable to much destruction through becoming under-
mined, when large masses become detached. These felted masses are
swept out to sea and destroyed. Thewastage of spat is simply incredible,
if, indeed, it is to be regarded as wastage. Myriads of creatures feed
upon the larvae, both in the brief free-swimming stage and after fixation.
I beheve that frost has been known to destroy large numbers of mussels
in beds subject to its influence, but I am unable to quote any authority
for this statement, at the moment. I have not remarked such an effect
in Cardigan Bay.

The chief fish consumers of young mussels are those belonging to
the Pleuronectid family,—Plaice, Dab and Flounder. Skate are caught
near the seed areas at Aberdovey, and it is not unlikely that they feed
upon the thin-shelled population of these areas.

Fishermen assert that Herring Gulls, Oyster Catchers, etc., favour
a dietary of mussels, and, certainly, whenever the Ro-ddu area becomes
dry, large numbers of these birds resort to it.. Scott adduces evidence
confirmatory of this statement, and found traces of mussels in gulls’
excreta, while Field gives a list of birds feeding on mussels in America?.

Several carnivorous molluscs attack the mussel, but the only one
that need be mentioned here is the Dog Whelk (Purpura lapillus L.),
which may sometimes be detected in the act. Mussel shells bearing a
neatly drilled hole are not uncommonly found?,—clear testimony of the
attacks of a gastropod culprit.

' See article by I. A. Field in The American Museum Journal, October, 1916.
> Thid.

F. S. WrieHt 145

In the branchial chamber of large mussels there is frequently present
a small crab (Pinnotheres pisum). An examination of the stomach
content of several of these crustacean “messmates” of Mytilus revealed
the presence therein of the diatoms and other materials! utilisable by
the mussel itself as food, but diverted by the crabs to their own use.
I have remarked that it is never (or very rarely), found within the
valves of the seed muscles, which, as we have seen, are poorly nourished.
This is significant, because, as they are frequent in mussels from the
fishing grounds, it would appear that the partnership is a profitable one
from the crab’s point of view. I have noticed that, in certain-cases,
where the female Pinnotheres had attained a relatively large size, it
would seem to have exerted considerable pressure on portions of the
mantle lobes, and upon the shell beneath. In some instances, this
pressure had caused the nacreous or pearly layer to be dissolved away,
probably by the action of pathogenic matters secreted by the cells of
the mantle at the points affected. Thus, the presence of Pinnotheres
(although it may not be parasitic in the strict meaning of the term), is
probably more or less harmful to its host. By fishermen and dealers
alike, Balanus-encrusted mussels are regarded with great disfavour,

‘because, by rendering the appearance of the shellfish unsightly, their

market value is considerably reduced. My own observations tend to
show, however, that, so far from being an unmitigated nuisance near
mussel-beds, Balanus may actually prove of some benefit to young
mussels. The spat tends to settle (or, rather, to remain) on stones, etc.;
which are encrusted by numbers of Balanus, while other stones in the
vicinity, although to all appearance equally suitable, are frequently
barren. A Balanus-covered surface certainly offers a good attachment,
and I have frequently remarked young Mytil: growing up and thriving
actually within the “parapet” of Balanus, the original tenant of which
had died. I have no doubt that large numbers of larval Mytili receive
their start in life through the agency of the Balanus colonies. The
nauplius and cypris stages of Balanus larvae are not uncommonly
present in the stomach content of Mytilus, and they probably form a
not inconsiderable part of its food in spring and early summer. ‘The
Common Starfish (Asterias rubens, L.) is a notorious enemy of the mussel.
It is occasionally found on the seed beds at Aberdovey, and elsewhere
in Cardigan Bay, but, being anything but numerous in these situations,
it cannot be classed us a serious pest.

» The Food Value of Sea Mussels, by 1. A. Field, Government Printing Office, Wash-
ington, U.S.A.

146 Mussel Beds; their Productivity and Maintenance

During my examination of the stomach content of Mytilus, I found
that Nematodes were present in a large number of individuals. The
matter is being investigated, and these thread worms may prove to be
true parasites.

The above will suffice to show that, as regards animal foes, the amount
of damage wrought in the Cardigan Bay mussel areas is inconsiderable.
Indeed, their activities may be regarded as positively beueficial in their
effects, inasmuch as they serve to thin the crowded population of the
scars to some small extent.

C. L. Walton! has found that mussels adherent to vertical rock faces,
piles, etc., break away and fall to the ground when they attain a length
of 23” to 33’, and a weight in correspondence. It is suggested that
this happens only where the mussels are subjected to frequent changes
of medium, and not when always bathed in water.

Seaweed, when present in quantity near mussel beds, is often the
cause of a high rate of mortality among the shellfish, which are apt to
become smothered beneath masses of it. “ Kel Grass” (Zostera-sp.) and
the commoner Ulvae may be cited in this connection. This source of
danger, again, is rarely or never serious in Cardigan Bay.

Industrial pollution of rivers and estuaries may sometimes affect
mussel beds in an adverse manner. At the present time, I am investiga-
ting the probable effects of plumbism on mussels from Aberystwyth
Harbour, 99 % of which show a singularly uniform malformation in
shell growth.

The greatest calamity to which mussel beds are subjected, how-
ever, is that of becoming :silted over by shifting sand. Whole beds are
often destroyed in this manner, as referred to in the foregoing.

Sand is also important in this connection in quite a different way.
In August 1917, I received a sample of fairly large mussels from the
entrance to the Harbour at Pwllheli. The shellfish were fairly well
fleshed, but extraordinarily light in weight. This was owing to the fact
that the attrition of water borne sand and shingle had worn away a
large part of the two outer shell layers. Practically, only the inner-
most (pearly) layer remained to protect the animal at the anterior end,
and, although this was relatively thick, it is improbable that, in such
conditions, many individuals would survive for any great length of
time.

1 The Food Value of Sea Mussels, by 1. A. Fieid, Government Printing Office, Wash-
ington, U.S.A.

F. S. Wricut 147

THE Portmapoc MusseEL BeEps.

Description of the Fishing Grounds.

The mussel beds at Portmadoc are situated in the River Glaslyn,
near Portmadoc, and, lower down the river, at Borth-y-Gest, there are
certain small mussel-bearing areas. The latter are not important at
the present time, and need not be described here.

The chief beds lie (a) at Llyn bach (above the Ffestiniog railway
bridge), (6) in the Dock, and, turning sharply in a north-easterly direction,
the latter bed follows (c) the “ gutter” or channel behind the New Quay.
Scattered beds of small extent exist in the vicinity of the Slate Wharf
and Ballast Bank, rather lower down stream.

The current here is comparatively tranquil, and, for the most part,
the mussels maintain themselves on the substratum (mixed sand and
mud) in bunches or clusters. The population in all the above areas is
very abundant. Extensive seed beds adjoin the fishing grounds.

Acreage of the Portmadoc Mussel Beds, ete.

The figures given below were estimated from a large scale map of the
district, and checked from my own knowledge of the fishing grounds.
These occupy the more or less level bed of the river, and, therefore, it is
not difficult to gain an approximate idea of their superficial area by
such methods. This is, roughly, 400,000 square feet (rather above
nine acres). ;

Assuming, as before, an ideal population of 121 mussels per square
foot over the whole of this surface, we get the large total of 48,000,000
individuals (24”’ in length). This figure represents a total of 29,784 bags
(approximately), and, in terms of money, a sum of £7446. Os. Od.
Reckoning, as for Aberdovey, the amount of transplantation necessary
to maintain this large production, we find that 1t involves the deposition
of 554 tons (nearly). It would not be possible to procure this large
amount of seed in Portmadoc itself, and, therefore, this factor might be
regarded as governing the output of these beds. Near Pwllheli, however,
there is a very large seed bed, the population of which is available to
restock the Portmadoc fishing grounds, if necessary.

Should intensive myticulture ever be practised in this country,
methods will have to be devised in order to increase the amount of space
available for the settlement of spat. The plan of mapping out the many
beds of poorly nourished mussels on various parts of the coast has been

148 Mussel Beds; their Productivity and Maintenance

suggested. Some of these are fairly populous, and they exist wherever
the influence of freshwater is felt, and there is suitable ground. These
beds should be surveyed, and their population estimated, in order to be
prepared for the possible failure of the usual sources of seed mussels.
These small colonies are stocked automatically by the spat liberated by
mussels in their vicinity, but more favourably situated. They represent
a very small proportion of that which is washed out to sea and destroyed
in various ways. They form a never failing, if not very considerable,
source for the replenishment of the fishing grounds, which, by means of
low stakes, or by diverting the stream to flow over a greater area of
beach, could doubtless be considerably developed with a small outlay.
This matter deserves serious attention. That the seed beds (generally
more seaward in situation) may fail is no remote contingency, and such
has been the case at Barmouth durmg 1916 and 1917. The winter
storms and spring floods have resulted in serious damage being done to
the beds, and several years may elapse before they regain their former
dense population. ;

THE BarmMoutH MussE.L FISHERY.

With regard to Barmouth and its mussel fishery, only a few words
can be said in this place. The beds are of small extent, and always
covered by a considerable depth of water. Since they are also situated
on steeply shelving banks, their area is difficult to estimate exactly.
If well stocked, they might give a maximum yield of mussels to the
value of £300 or £400. These figures, however, are not based upon
actual calculations, but, when all the factors are taken into consideration,
they are probably not very wide of the potential production.

PURIFICATION OF MUSSELS.

Most (and probably all) of the rivers and estuaries of Great Britain
suffer from sewage and industrial pollution, in varying degrees. Sewers
and drains empty into them, and also the effluents from factories and
works on their banks. The sewage is often permitted to escape in an
untreated condition, and this is the state of-affairs that prevails in the
Cardigan Bay estuaries, which, on the other hand, suffer very little from
industrial waste products. This condition of things is obviously very
unsatisfactory when considered in relation with the mussel beds, and
extensive bacteriological analyses of water taken in relation with the
fishing grounds reveal the presence of bacteria resembling those found

F. S. Wriqgut: 149

in the human colon (Bacillus coli communis etc.), often in numbers too
great to be ignored. Mussels may also contain through inhibition of
contaminated water, “ Bacillus typhosus (producing enteric fever), and,
possibly B. enteritidis (producing Gaertner poisoning). These last are,
luckily, much more rare in this connection. Even though we-need not
place implicit trust in the findings of bacteriological science, which has
to rely upon indirect methods or reactions in its determinations of these
minute organisms, yet we see that the matter is serious enough. It is
probable that (admitting the validity of their identification), their
sojourn in the mussels’ digestive tract, or in salt or brackish water,
may have so changed the character of the bacteria as to render them
generally harmless to man, or, at least, less harmful.

It will be remembered that, in a previous paragraph, it was stated
that the water in the Cardigan Bay estuaries was never wholly changed
in any one tide. Thus, impurities washing about in the river bed may
remain there for a considerable time, and the significance of this factor
now becomes apparent. Under such conditions (which affect the areas
now being discussed), the occurrence of, for example, a single case of
enteric, could bring about an immediate cessation of the fishing in the
place affected. Therefore, it becomes necessary to effect the purifica-
tion of the shellfish in order to safeguard the industry, no less than in
the interests of the public health.

A crude method of “purification” is sometimes practised by the
fishermen at certain places. After cleaning (“spinning’’) the mussels,
they are placed in bags, which are left to wash for a day or two in the
tide, where the water bathing them is known to be reasonably free from
contamination. This rough method cannot be said to have the desired
effect, for reasons now to be stated. According to recent views, any
bacteria which the mussel may harbour are present in the animal’s
rectum; that is, in the faecal matter not yet extruded by the animal.
Now, although mussels treated in the manner described above will
speedily excrete such waste products, these, being retained by the
closely woven fabric of the sacking, only serve to re-infect the shellfish.

Mussel purification tanks are projected to be erected (one is already
in use at Barmouth), in connection with the Cardigan Bay mussel beds,
under the supervision of the Lancashire and Western Sea Fisheries
Committee. They are solidly built concrete structures, in several com-
partments, on the wooden grids on the floor of which the mussels are
placed, in layers not exceeding three deep. They are designed to fill
over the top at about high water of neap tides, when the mussels will

150 Mussel Beds; their Productivity and Maintenance

rest under a depth of about two feet of clean sea water. As the faecal
matter is ejected, it falls through the gratings on to the cemented floor
beneath, which slopes away to outlet pipes of large diameter. The water
is allowed to escape when the tide is low, and carries, as it flows out, the
excretory products. Exhaustive tests (bacteriological and others) are
varried out before the site of the tank is decided upon, in order to ensure
the purity of the water gaining access to it. The shellfish remain in the
structure for the space of forty-eight hours, and they are then put into
bags bearing the lead seal of the Committee, to show that they have
undergone treatment.

Another method, now being experimented with in this country,
employs certain chemical substances, which cause the mussels to eject
speedily all waste matters, and at the same time sterilises the water.

The capacity of these structures is limited to present day needs, and,
therefore, if the industry is to be developed to its utmost limit, as out-
lined in the present article, these purification arrangements must be so
designed as to expand with it. ;

In this article, it has been attempted to show the means whereby
suitable “ground” in estuaries may be made to produce a greatly in-
creased yield of mussels. Great efforts are being made in the U.S.A.
to popularise this shellfish as an article of food, in view of its high nutri-
tive value. In Europe, no such efforts are required, as its value has
long been recognised. It is hoped that representative persons living in
settlements where mussels are fished regularly will take up the matter,
and encourage the fishermen to keep the beds well stocked, work well
worth the doing, from the standpoint of food production as well as in
other ways. In the small seaside communities of Cardigan Bay, for
instance, the mussel fishery forms practically the sole source of income
to a fair number of men, who would otherwise be unemployed for long
periods during which there is no other work for them to do. In these
places, however, the industry, which has been shown to be capable of
very considerable development, suffers because of the utter lack of
cooperation between its members, and means must be devised to over-
come this evil. A frequent cause for complaint by the fishermen is that
they have no security of tenure, which however seems unavoidable.
They ask to be granted the leasehold of portions of the beds, in which
case, they assert, they would undertake to keep their respective “small
holdings” stocked to their fullest capacity. This is open to objection,
however, even were it possible to accede to their wishes. Most of our

F. S. Wrieur PD

British mussel beds are liable to much destruction from time to time,
through silting and other causes. Thus, the leasing of portions of the
mussel beds would simply give cause for further dissatisfaction. Co-
operation between themselves, on the other hand, and their prior claim
to the limited accommodation afforded by the mussel-cleansing tanks,
would render their molestation by outsiders an impossibility. At the
present time, most fishermen (on the west coast of Wales, at least),
cannot be made to realise that regularity of supply creates a steady
market.

I have now to thank those gentlemen who have kindly assisted me
during the progress of the work, and in the preparation of this paper.
I am greatly indebted to Dr J. Travis Jenkins, the Superintendent of
the Lancashire and Western Sea Fisheries Committee, for much advice
and assistance. Mr W. E. Whitehouse, and Mr C. L. Walton, both of
the U.C.W. Aberystwyth, have also greatly assisted me in many ways.
I have to thank Captain Enoch Lewis, of Aberdovey, for allowing me
the use of a room as a laboratory.

LITERATURE CONSULTED

(See also text and notes).

Buxstropeg, Dr H. Timpreiy. Report on Shellfish other than Oysters in Relation
to Disease. London, His Majesty’s Stationery Office, 1911.

DuruacuHer, F. W. On the Drift of Sewage in the Dovey Estuary in Relation to the
Mussel Beds. (With Chart.) Report of the Lancashire and Wesiern Sea Fisheries
Laboratory at the University of Liverpool, 1913.

—— On the Drift of Sewage in the Estuary of the Mawddach in Relation to
the Mussel Beds. (With Chart.) Jbid.

DuR.LAcHER, F. W. and Watton, C. I. Notes on the Inshore Fisheries of Cardigan
Bay. Zoological Dept., Univ. College of Wales, Aberystwyth, June 1915.
Frevp, Irving A. The Sea Mussel Industry. Reprinted from the Transactions of

the American Fisheries Society for 1913. (A very interesting and useful paper.)
—— The Ultimate Sources of Marine Food. Transactions American Fisheries
Society for June, 1916. Vol. xiv, No. 3. (See also references to the works of
this author in the present article.) :

Futiarton, J. H. The Clyde Mussel Beds. Tenth Annual Report of the Fishery
Board for Scotland, for 1888.

On Buchéot Mussel Culture and the Buchédt Experiment at St Andrews.
Ninth Annual Report of the Fishery Board for Scotland, for 1890.

HerpMan, W. A. and Scort, A. Note on an elongated variety of Balanus crenatus
on certain mussel beds. Report of the Lancashire and Western Sea Fisheries
Laboratory at the University of Liverpool, 1913.

HeERpMAN, W. A. Public Health Bacteriology in the Lancashire and Western Sea
Fisheries District. (Refers to the duration of life of certain pathogenic bacteria
in the sea.) bid. 1911.

—— Notes on the Spawning and Food of Mytilus. Ibid. 1892, 1900,

152 Mussel Beds; their Productivity and Maintenance

JOHNSTONE, JAMES. Bacteriological Investigations in Relation to Shellfish Pollution
by Sewage Matter. (Deals with mussels from the Mersey and Lune Estuaries.)
Ibid. 1904.

Bacteriological Investigations in Relation to Shellfish Pollution. (An inter-

esting account of certain purification experiments carried out at Conway.) bid.

1908.

Report on the Examination of Various Mussel Beds in Lancashire and Wales
during the year 1913 (illus. by charts and plates). (A useful account of bacterio-
logical analyses of water and mussels from various sources.) bid. 1913.

—— Report on some Mussel Beds in Lancashire and North Wales as regards their
Liability to Sewage Contamination. (A valuable paper on bacteria in relation
to the mussel beds. It describes the indirectness of bacteriological methods.
It should be consulted by all interested in this matter.) bid. 1912.

— Shell Fish and Sewage Contamination. The Cardigan Bay Mussel Order.
Ibid. 1915.

—— Shell Fish and Sewage Investigations. Ibid. 1917.

— Report on Various Bacteriological Analyses of Mussels from Lancashire and
Wales. Ibid 1906.

—- The Methods of. Cleansing Living Mussels from Ingested Sewage Bacteria.
(An account—illustrated—of certain analyses of Cardigan Bay mussels.) bid.
1914.

— The Spawning of the Mussel (Mytilus edulis). Ibid. 1898.

Keiioc, JamEs |. Shell-Fish Industries. Contains a short account (illus.) of
certain ‘“‘members of the mussel family” which act as pests in oyster culture in
the U.S.A. New York, Henry Hold and Co., 1910.

Lesour, M. V. The Mussel Beds of Northumberland. (Contains references to para-
sitic Trematodes.) Report on thé Scientific Investigations of the Northumberland
Sea Fisheries Committee, 1906.

—— The Mussel Experiment on the Coquet. bid. 1901.

— On Mussel Cultivation on the Coast of Northumberland. bid. 1900.

Notes on Northumbrian Trematodes. (Illus.) Jhid. 1905.

PrTerRsEn, ©. G. Jon. and JensEN, P. Boysen. Valuation of the Sea, vol. t (1911).
Report of the Danish Biological Station to the Board of Agriculture, 1911.
Copenhagen.

Scorr, ANDREW. Note on the Spawning of the Mussel. Report of the Lancashire
and Western Sea Fisheries Laboratory at the University of Liverpool, 1900.

Mussels and Mussel Beds. (Gives an account of conditions obtaining on
certain mussel beds, and of their fauna.) Jbid. 1895.

—— Sex Gulls and Shell-Fish Beds. Ibid. 1915.

Scorr, ANDREW, and Baxter, THomas. Mussel Transplantation at Morecambe.
(An interesting and useful paper—illustrated—giving an account of eget 3
experiments at Morecambe.) bid. 1905.

Storrow, B. Mussel Culture. Report on the Scientific Investigations of the North-
umberland Sea Fisheries Committee, 1913.

——- Transplantation of Mussels at Holy Island. bid. 1910-11.

Watton, C. L. (and others). Report on Investigations towards the Improvement
of Fisheries in West Wales. Published by the Zoological Dept. of the Univ.
College of Wales, Aberystwyth, 1914.

Waiter, Pature J. The Conway Mussel Fishery. Report on the Puffin Island Bio-
logical Station, 1894-5.

—— Mussel] Bed on Perch Bank, Carnarvon Bar. Ibid.

—— The Sea Fisheries of North Wales. Jbid. 1892-3.

—— The Sea Fisheries of North Wales. (Read before the “Liverpool Welsh
National Society,” March 21, 1891.)

VoLUME IV MARCH, 1918 No. 4

USTULINA ZONATA (LEV.) SACC. ON
HEVEA BRASILIENSIS

By A. SHARPLES, A.R.C.8., D.LC.,
Mycologist.

Department of Agriculture, Kuala Lumpur, Federated Malay States.
(With Plates III—VIII and 1 Text-figure.)

INTRODUCTION.

Pests and diseases on rubber plantations have caused little anxiety
up to date. Scares due to attacks by Fomes lignosus (Klotzsch) and
White ants (Termes gestrov) were prevalent before 1908, but in the general
management of Malayan plantations pests and diseases have been con-
sidered a minor detail. There are certain estates where preventive
measures had to be undertaken because of specific “White ant” or
‘“Fomes” attacks, but these areas are strictly localised. Up to date, no
general scheme for combating pests and diseases on rubber plantations
could be put forward, for the trees have been extraordinarily free from
insect and fungus troubles. Investigations carried out over the last two
years indicate that more attention, especially to fungus diseases, will be
necessary in the future. A general scheme of treatment may now be
recommended with an assurance that money spent on routine disease
work will be amply repaid.

HISTORY OF PESTS AND DISEASES ON THE PLANTATIONS.

The pioneer rubber planters in Malaya mostly obtained their ex-
perience on the tea and coffee plantations in Ceylon and the tea planta-
tions of India. The failure of the coffee crop in Ceylon owing to the
attacks of Hemaleia vastatriz left a lasting impression, and in the early
days of rubber planting, planters were inclined to believe many exag-
gerated reports of damage caused by various agencies. The root disease
caused by Fomes lignosus (Klotzsch) was at first regarded as a potential
exterminator of young rubber; about the same time the F. M. 8. Govern-
ment offered a $5000 reward for the best cure for “‘ White ant” attacks.

Aun. Biol. tv 1]

154 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

This money wasneverawarded. Experience taught that “ Fomes” attacks,
even in the worst affected places where it may cause heavy losses, could
be treated, and that attacks by White ants created little material differ-
ence in the long run on the majority of plantations. After these scares,
a period of indifference to rubber pests and diseases set in until 1912,
when the rapidity of spread of “ Pink disease” throughout the peninsula
stimulated enquiry into the necessity for vigorous treatment. The work
of Rant (7) and Brooks and Sharples (2) proved the incidence of the disease
and the probable causes of spread, and vigorous preventive measures
based upon the work mentioned showed that “Pink disease” could
be controlled by concerted effort. Since this time, a large number of
plantations have passed the ten years stage and many of the old trees
have been killed by fungi attacking the roots. The symptoms have been
classed under various headings by Malayan planters ie. “ Wet-feet,”’
“Brown-root disease,” “Dry-rot,” etc. As a result of work carried out
over the last two years these general terms can now be assigned to
specific fungi. This contribution deals with the dry collar-rot on old
rubber caused by Ustulina zonata (Lev.) Sacc.

HISTORY OF DRY COLLAR-ROT.

Brooks (1) in 1915 made the first important contribution to our know-
ledge on the subject of U. zonata as a fungus causing a root disease of
plantation rubber. Previous to this, Massee(3) in 1910 published photo-
graphs and a description of a fungus, Butypa caulivora (Mass.) growing
on a dead tree of Hevea brasiliensis, taken from the Singapore Botanic
Garden by Mr H. N. Ridley. The photograph of the diseased wood shows
the typical symptoms of a tree attacked by Ustulina zonata. It is prob-
able this fungus was responsible for the death of the tree, E. caulivora
growing as a saprophyte on the dead tissue. Numerous saprophytic fungi
are always to be found on trees killed by U. zonata which are in an
advanced state of decay. Petch(4) in 1910 records a case of U. zonata
growing on an old Hevea which had died of root disease, and states that
“apparently the disease was caused by this fungus, though the evidence
was rather doubtful.” Later in 1914 he says() “ This fungus is a common
cause of root disease (7.e. of Tea) in Ceylon, though not on Hevea.” He
records several cases of U. zonata on Hevea brasiliensis in fields where the
trees have been planted among tea which has subsequently been allowed
to die out. In 1916 Reeves(8), the Mycologist to the Rubber Growers’
Association in Ceylon, published some observations on U. zonata with
reference to rubber trees, and found the disease common in Ceylon.

A. SHARPLES 155

There is, as yet, no report of this fungus being found on rubber in Java or
in Sumatra.

Brooks obtained the fructifications and as a result of his observations
established U. zonata as the cause of a collar-rot on H. brasiliensis. An
account of his observations in Malaya up to the end of 1914 is given()
when he left for England. At the beginning of 1915 specimens were
obtained which necessitated a more complete investigation. This work
was carried on through 1915-1916 and various side issues are still under
consideration. A general account (10) on economic lines was published in
1916; the following article includes all observations made since 1914 up
to the present date.

Petch(5) records several hosts for the fungus: Tea, Cassia Nodosa,
Benya ammomilla, Casuarina montana, Molia Dubra, Lafoensia Vandel-
liana, Denis Robusta, Citrus Decumana, Albizzia Molluccana, and
Grevillea sp.

FIELD OBSERVATIONS ON DRY-ROT AND COLLAR-ROT.

In Malaya, the disease is found on old plantations in every. part of the
peninsula; the fungus is not localised in its distribution as is the case with
Fomes lignosus (Klotzsch). It attacks old rubber trees in the region of
the collar; only in advanced cases does the fungus spread up the stem,
and it seldom reaches more than three or four feet above soil level. In
one case, however, the fungus has been found travelling from the collar
up through the heartwood of the stem into the lower branches, some
twelve feet high; externally the tissues appeared healthy except for about
two feet above soil level. The fungus travels down through the heartwood
of the lateral roots in the same way. The diseased wood in an advanced
case is found to be dry and tindery, like touchwood, and running through
the diseased tissues conspicuous black lines are to be seen. When the
bark is removed, these black lines can be observed in some cases on the
outer surface of the wood and, if the lines are followed carefully, it will
be seen that they form thin plates of black tissue inside the wood, the
edges showing as black lines on the exterior. A longitudinal section
taken through the collar of a diseased tree shows these black lines run-
ning irregularly in the rotting tissues, often forming circles surrounding
dark coloured patches of diseased wood (PI. ITI, fig. 1).

There is no external mycelium associated with roots suffering from
this disease, though fan-shaped, white patches of a felt-lhke mycelium
may sometimes be observed on the exterior of the wood when the bark
is removed. The absence of external strands of mycelium distinguishes

11—2

156 Ustulina Zonata ( Lev.) Sacce. on Hevea Brasiliensis

this disease from that caused by Fomes lignosus, while the black, rhizo-
morphic strands between the bark and wood of trees attacked by
Sphaerostilbe repens serve to distinguish those affected by this fungus.
The typical dry-rot in the collar caused by Ustulina zonata cannot be
mistaken, the wood in advanced cases falling to pieces under the pressure
of the fingers.

This root disease is common on most of the older plantations in the
F. M. 8. though its presence is unsuspected. The fungus works slowly and
insidiously, the crown of leaves becoming thin as it progresses in the
collar. The diseased tissue is usually confined to one side of the collar,
and from this side latex cannot be obtained. The opposite side may give
a good yield and tapping is continued till the amount of latex obtained
begins to diminish. When this stage is reached the tree soon dies and has
to be taken out.

The dry collar-rot has been found occasionally on trees 5-8 years old,
but it is only typically developed on trees over 10 years of age. A large
number of magnificent trees in the older properties have been killed by
this fungus. Cases are quoted later where large areas have been rendered
useless owing to attacks by Ustulina zonata and other root fungi.

Fructifications are found on diseased roots, usually near soil level.
They are closely adpressed to the stem; when young the flat plate-like
fructifications are soft, rather leathery, whitish in colour and greenish-
white at the edges. Later they darken and become brittle and closely
resemble exuded patches of coagulated latex attached to the stem, which
have blackened owing to exposure and oxidation. In this condition they
are easily overlooked. When the fructifications develop near ground
level, they are often difficult to detect as they become splashed with mud
after a shower of rain.

OBSERVATIONS IN FIELD ON RELATION BETWEEN SHOT-HOLE
BORER (XYLEBORUS PARVULUS) AND USTULINA ZONATA.

In the report of the Director of Agriculture, F. M.S. for 1914,
H. C. Pratt, Government Entomologist, writes:

“ Xyleborus parvulus. This beetle was first noticed in this country as
attacking rubber in 1909. It occurred only in one district. The instance
was undoubtedly due to the pollarding of a large number of trees. Many
of these pollarded trees were attacked, and in a few cases adjacent trees
which had not been pollarded were bored. Since that time this district
has always lost a few trees each year from what would appear to be the
attacks of this insect. During 1914 there was a remarkable increase in

A. SHARPLES 157

the number of cases reported to the Department of Agriculture, and there
has been a corresponding increase in the districts in which it now occurs.
It is instructive to find that all estates which are affected were either
thinning-out the number of trees to the acre or had just fimished this
work.”

The practice of planting trees to the number of 150-200 an acre on
rubber plantations renders necessary the cutting out of large numbers
when they reach the age of 6—7 years. During the thinning, attacks by
boring beetles on the permanent trees become prevalent. Early in 1915
a living specimen of a rubber tree attacked by borers was obtained. This
specimen (A) showed the insects active along one side of the stem ex-
tending from three feet above ground level to a height of twelve feet.
The roots were healthy. Sections through the attacked parts showed that
the borers were penetrating through rotten wood. Running irregularly
through the rotten wood were black lines very similar to those observed
in a typical case of dry collar-rot (Pl. ITI, figs. 3 and 4).

Immature fructifications of an Ustulina sp. were obtained on the
surface of the attacked parts. On a neighbouring dead tree (B) attacked
by borers, typical specimens of Ustulina fructifications bearing a conidial
layer were observed in various stages of growth upon the bark; in close
proximity numerous saprophytic fungi were growing. Sections of this
tree showed more advanced symptoms than those found in specimen (A);
these symptoms were identical with those found in the dry collar-rot of
Hevea brasiliensis caused by U. zonata. A fungus was isolated from the
affected wood in specimen (A) which proved to be practically identical
with cultures established from typical dry collar-rot trees.

It would appear from the above that there is some connection be-
tween U. zonata and attacks by boring beetles. Much evidence to support
a close connection can be advanced. Several estates in the F. M. S. were
troubled during 1915 with leaf fires. Owing to a heavy wintering the
leaves formed a layer several inches thick on the ground, and when dry
the leaves are easily fired. In the areas through which the fires passed
the bark of the trees was scorched and boring beetles quickly entered,
though the latex streamed freely. On one estate, every tree in a nine-
acre block of rubber, nine years old, had to be removed; four other
estates encountered the same trouble on a smaller scale. In every tree
entered by the borers the same symptoms described for specimen (A)
were observed; the insects were penetrating actively a rotting portion of
the wood through which black lines ran irregularly. Some time was spent
trying to find scorched trees attacked by the fungus only. Specimens

158 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

were obtained showing but five or six boreholes and the fungus working
actively in the wood, but no case was found where borers were entirely
absent. In the great majority of the trees, the association of insect and
fungus was very pronounced. The fungus was carefully isolated from
several of these trees and was identical with the cultures obtained from
specimen (A).

Further supporting evidence for the connection between Ustulina
zonata and attacks by boring beetles was obtained in an experiment
described (9). In this experiment the bark of twenty-four rubber trees
was scraped in order to see whether this treatment rendered them more
hable to insect and fungus attacks. The laticiferous system was not
injured in any way, the scraping being performed to compare heavy
scraping—the cork-cambium being removed—and light scrapimg—the
cork-cambium being left intact as far as possible. Five trees of the total
treated were quickly attacked, three by borers. Two of the three trees
attacked by borers showed traces of Ustulina zonata in the bark five
weeks after the insects entered. In one tree, the fungus made beautiful
progress and daily observations were made. An interesting point is that
the borers disappeared after the first fortnight and the rate of growth of
the fungus in the wood of the stem and collar could be directly com-
pared. PI. IV, fig. 5is a photograph taken four days after the trees were
scraped and shows the latex streaming down the trunk from the holes
made by the beetles. Fig. 6 shows the surface of the wood exposed with
the typical black lines formed by the fungus. Pl. VIII, fig. 21 shows a
section through the diseased part six months after the scraping, and
a comparison with Pl. VII, fig. 19,*which represents a typical artificial
inoculation at the collar about six months old, shows that the rate of
growth of the fungus in the stem and collar is almost the same.

This experiment (9) indicates that the important protective layer in
rubber trees is the outer layer of corky cells, and if this layer is injured,
they are liable to attack by boring beetles. The lJaticiferous layer affords
comparatively little protection against borer attacks beyond preventing
the entry of the first few insects. The first comers trying to enter were
trapped in the streaming latex, but later arrivals succeeded in entering
through places prepared by their predecessors. On the estates troubled
with leaf fires the scorching of the bark did not interfere with the pre-
sumed protective function of the laticiferous system of the trees, for the
latex streamed freely from the holes made by the borers.

The above evidence affords a convincing explanation of the preva-
lence of borer attacks at the time of thinning out. When a tree is felled

A. SHARPLES 159

its branches come in contact with and bruise the branches and trunks of
neighbouring trees, wounding the outer corky layers. Through these
places boring beetles enter and the fungus U. zonata may be taken in by,
or quickly follows the insects. The fungus penetrates the wood quickly,
for the insects bore to every part of the tree carrying small pieces of
diseased tissue, so setting up innumerable centres of infection. The fructi-
fications form on the surface of the diseased parts, and spores from these
are blown about the plantation. The rubber logs and stumps lying about
the thinned-out areas form suitable growing places, as does any rotting
soft-wood timber, and thus the fungus obtains suitable conditions for
perpetuation and spread.

When a tree attacked by borers is examined, the typical symptoms
caused by U. zonata can nearly always be demonstrated. The association
is probably due to the fact that a tree penetrated by borers is very liable
to attack from common wound-fungi. Ustulina zonata is a wound para-
site on Hevea brasiliensis, and is also one of the commonest causes of
rotting in soft-wood timber in the plantations. Its prevalence on the
plantations in rotting timber and stumps increases its chances of attack-
ing rubber trees whenever a suitable opportunity occurs. The fungus
often gains an entry through wounds caused by the breaking of large
branches. In these cases, there is always a copious exudation of latex for
a lengthy period as fresh areas of healthy bark are attacked during the
progress of the fungus. It passes much more quickly through the wood
than the bark. It would appear that Ustulina zonata does not easily
attack rubber trees unless an exposed wood surface, or a convenient path
to a wood surface, as in trees penetrated by borers, is provided.

Fructifications are found on all parts of the stem and branches where
the fungus is working in the tissues. “Stag’s head” in rubber trees is a
well-known phenomenon and is usually attributed to Diplodia sp., the
cause of “ Die-back.” On two occasions the fruit-bodies of U. zonata have
been observed growing on these dead branches taken from the topmost
parts of the tree. When the fungus gains an entry through wounds
caused by the breaking of large branches, a large quantity of fruit is
usually produced about the place of entry; the later blackened stage of
the fructifications are often masked by a copious exudation of latex from
the diseased portions.

It is possible that borers may directly transfer spores to the trees they
enter. Insects suchas White ants, Red ants, etc. walking over the flat plate-
like fruit-bodies when the latter are producing spores would carry away
numerous conidia or ascopores attached to their appendages. Fructifi-

160 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

cations in the conidial stage have been found showing traces of insect
markings; whether the latter were feeding on the spores is doubtful, but
it was obvious they had spent some time upon the surface, judging from
the intricate tracings.

Several cases of old trees hollowed by White ants and attacked by the
fungus have been found (PLIV,fig. 8). These trees were all twelve years old;
some had been successfully treated with the White-ant pumping machine
at the age of eight years. The number of trees found attacked by White
ants and U. zonata is comparatively small when compared with those
attacked by boring beetles and U. zonata, or the number of old trees
suffering only from the fungus attack. In a consideration of treatment
and spread of the fungus, the White ant question appears to be of minor
importance.

DESCRIPTION OF THE FUNGUS.

The development of the fruit-bodies of U. zonata has been carefully
studied in the laboratory. Brooks’ (1) description of Malayan specimens
is incomplete because up to the time of his departure he had not seen the
fructifications in the early stages. It may be stated here that the Malayan
specimens correspond in every respect to the description given by
Petch(4) for those of Ceylon.

The common fructification commences as a small yellowish-white
plate closely adpressed to the bark. The plate increases in size and the
surface darkens to a greenish-grey colour. This change in colour is due
to the formation of a thick conidial layer. In the Laboratory this stage
persists for about a week, and during this period the stroma is soft and
easily cut. Owing to the disappearance of the conidia] layer, the stroma
becomes darker; as it ages it takes on a leathery consistency and ulti-
mately becomes quite brittle and black. Typical young specimens in the
field show a well-defined zoning on the surface (P1.1V, fig. 7 and P1.V, fig. 9)
but those developed in the Laboratory did not show a conspicuously zoned
surface. When fully developed the plate-like fructifications are several
inches in diameter. A number of these plates may fuse together; large
plates formed by fusion of smaller ones have been found covering an
area of the stem three feet in length and nine inches broad.

When the flat plate-like fructifications are broken across, the tissues
are found to be arranged in distinct layers. The accompanying diagram
(after Brooks) illustrates the different layers.

On the upper surface (a) represents the remains of the conidial layer.
Brooks did not observe the conidial layer in the specimens obtained by

A. SHARPLES 161

him in Malaya, though it appears a constant feature. It is very transitory
as observed in the Laboratory; 4—5 days is the actual time between its
appearance and the dispersal of the spores. (b) is the upper black zone,
composed of compact tissue very similar to that composing the black lines,
as seen in a diseased collar. (c) is a white loosely compacted zone in
which the globular perithecia are formed. (d) is a broader band, grey
in colour and leathery in consistency. (e) is the black zone on the under
surface, which is continuous at the margins with the black zone towards
the upper surface.

The globose perithecia communicate with the exterior by very narrow
channels. The first formed elements of the perithecia can be recognised
in suitably stained sections very early in the development of the fructifi-
cation, long before the production of conidia. These elements stain more
deeply with protoplasmic stains than surrounding ones and appear as
small circular patches of spirally running hyphae.

In the early stages of development, the black zone is not present in
the fructification. Whilst the stroma is still soft and yellowish, the walls
of patches of cells of the loosely compacted layer, irregularly distributed,
but at the same depth, become impregnated with carbonaceous material.
Later, the walls of the cells of the loosely compacted layer intervening
between the black patches become impregnated with similar material,
their cell contents darken, and a continuous black, brittle zone is formed.
It is a very characteristic zone, and can be used as a rough diagnostic
feature when studying the variable forms of fructifications produced by
this fungus. This zone is always present in the “ Xylaria” forms of the
fungus; many true Xylarzas are found on rubber trees killed by U. zonata,
but these do not show the black carbonaceous zone to which the fructifi-
cation of U. zonata owes its brittleness. The greenish-grey conidial layer
is formed about the time the black zone is completed, while the fructifi-
cation is still rather soft and leathery. In many cases observed, the
conidial layer is restricted to the younger, growing edges of the fructifi-
cation, while the older parts in the middle are showing the ostioles of the
perithecia. The hyaline conidia are abstricted abundantly from the

162 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

apices of hyaline hyphae compacted to form a smooth surface. They
measure four microns by two.

The perithecial openings can be observed as minute black spots almost
immediately after the disappearance of the conidial layer. By this time
the black zone is continuous, and the spore chambers are developed just
below this zone in the more loosely compacted tissue. The asci are numer-
ous, with paraphyses. The ascospores, when first delimited from the
remainder of the protoplasm in the ascus, are hyaline, with no special
contents. Later, they darken, become almost black, with two or three
oil drops. They are slightly curved, inequilateral and lie to end in the
ascus. The ascospores are 28-32 microns by 7-10 microns. They exude
through the openings of the perithecia under moist conditions, looking
like small drops of ink. When the amount of moisture fails, the exuded
spore masses spread out over the surface, resembling black patches of
dust surrounding the perithecial openings. Only on one occasion did the
ascospores germinate readily; these were obtained immediately after ex-
trusion from a fructification developed in the laboratory. Placed in
potato mush agar in damp chambers they germinated in twenty-four
hours, several germ tubes being put out along the side of the spore, none
from the ends. The tubes grow vigorously and branch profusely.

The conidia germinate more easily, but do not produce a copious
mycelium on potato mush agar in damp chambers. Conidia placed
directly on slants, however, produce just as vigorous a mycelium as is
formed from sowings of ascospores. Cultures are not easy to obtain from
spores developed in the field, though the fungus can nearly always be
obtained in pure culture from the black lines formed in the diseased
tissue.

There is as much variety in the form of the specimens from Malaya as
in those from Ceylon described by Petch. There is a solitary stalked form
(PI. V, fig. 11), the conidial layer being produced only on the top and con-
tinued a short distance down the sides. In some cases, these stalked forms
may be aggregated to form a compact plate, the heads of the stalks becom-
ing hexagonal in shape owing to mutual pressure. This approximates to
the typical Kretschmaria form, the common Kretschmaria coenopus (Fr.)
closely resembling this form of U. zonata, but the ascospores of the latter
are much larger. There is another form which has not yet been found to
produce spores; this closely resembles a foliose lichen (PI. VI, fig. 14).
PI. V, fig. 10 shows a photograph of a fructification with the lichenoid type
at the edges, gradually passing into the plate-like form with hexagonal
heads; the commoner flat plate-like form was growing up from beneath

A. SHARPLES 163

the stalked form. In the photograph the growing over the stalked form
masks the presence of the commoner form.

CULTURE EXPERIMENTS,

The Ustulina fructifications found on specimen (B) differed from those
previously found in the F. M.8., for a typical conidial layer was formed
as in specimens described from other countries. A further difference was
observed, for the fungus attacking the wood in specimen (A) was isolated
and the pure cultures lacked the typical zoning (PI. VI, fig. 17 4) of those
obtained by the isolation of the fungus from the rotting tissues at the
collar. Again the bored trees showing this fungus were killed very
quickly while the collar-rot proceeds very slowly.

Owing to these differences, critical cultural experiments were under-
taken to decide whether there were two distinct species of Ustulina
capable of attacking rubber, Ustulina zonata causing a collar-rot and
another species distinct from, but closely related to Ustulina zonata,
causing a stem-rot in conjunction with boring beetles.

TYPICAL CULTURES OBTAINED FROM COLLAR-ROT.

Pure cultures were first established after numerous failures by taking
a small portion of one of the black lines from the collar under sterile
conditions and placing it on a block of sterilised Hevea wood in a culture
tube. Several days after sowing a greyish mycelium began to grow and
spread out slowly over the surface of the block, remaining closely ad-
pressed. As the growth continues, the mycelium turns black, forming a
thin crust. If the cultures are allowed to develop for several weeks and
the blocks taken out and cut open, black lines similar to those formed in
the tissues in cases of collar-rot are seen in the middle (PI. VIII, fig. 23).

Small pieces of the black crust from the wood blocks were taken and
used to inoculate flask cultures of potato mush agar. A white flocculent
mycelium first developed; after three or four weeks the surface of the
jelly was covered with a black crust similar to that developed over the
wood blocks. The crusts in these cultures showed a typical zonation,
dark and light zones being formed owing to a thicker aggregation of
hyphae at one part than another.

CULTURES OBTAINED FROM STEM OF SPECIMEN (A).

A description of symptoms shown by this specimen is given above.
The trunk of the tree was sent into the Laboratory and the affected
portion cut into sections. The boundary between diseased and healthy

164 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

wood was well marked by a diffuse brown discoloration, and after twenty-
four hours in the Laboratory, a copious white mycelium appeared at this
junction. Pieces of this mycelium used to moculate flask cultures of
potato agar gave rise to cultures which, except for the absence of zoning,
corresponded to those obtained from the collar-rot caused by Ustulina
zonala.

Other cultures were started by placing small portions of the black
lines developed in the rotten portions of the wood in sterile damp cham-
bers. In two days hyphae began to grow out; after four days the small
pieces of diseased tissue with the attached mycelium were taken and
placed in flask cultures; similar non-zoned cultures to the ones described
were ultimately obtained.

The boreholes made by the insects through the rotten wood were
filled with fungus mycelium. Small portions were taken to imoculate
other flasks and again non-zoned cultures resulted.

The non-zoned cultures are characterised by a peculiar folding of the
crust which forms on the surface, due to unequal growth in different
directions. This folding is seen especially well when the culture medium
is rather soft; when hard the folds radiate out from the centre in a more
or less even manner.

CULTURES FROM SCORCHED TREES.

Stems of the trees attacked by borers, from estates which were
troubled with leaf fires, were taken to the Laboratory and the fungus
isolated from them. Specimens from two estates were treated and
typical non-zoned cultures were obtained starting from small pieces of
the black lines.

CULTURES FROM CONIDIA AND ASCOSPORES.

From another estate which suffered similar damage owing to a leaf
fire a rubber log was obtained carrying a large fructification twelve inches
long and four inches broad on the stem. Over the greater portion of the
surface the smooth conidial layer was present. After two days in the
Laboratory the ascospores began to be extruded from the perithecia over
about one square inch of the stroma. Cultures were obtained from the
ascospores by setting a few of these in flask cultures. Non-zoned cultures
resulted.

Cultures are difficult to start from conidia. Numerous foreign spores
fall on the flat fructifications, and these develop more quickly in cultures
than those of Ustulina zonata, with the result that the latter is crowded

A. SHARPLES 165

out. Cultures were successfully established from conidia by carefully
rubbing away the upper layers of old spores with a sterile needle, using
young spores from beneath to inoculate test-tubes of potato-mush agar.
These cultures when transferred to flasks showed an interesting transition,
indicating that the zoning of the cultures is variable, depending largely
on external conditions. PI. VI, figs. 15-17 show a series of photographs
of flask cultures originating from the conidia. Figs. 15a and 158 show
a culture zoned on both surfaces. Fig. 164 shows the zoning on the upper
surface, but the photograph of the under surface 16B shows that the
zoning does not extend through the substance of the culture as in a
typically zoned one. Fig. 178 shows the under surface of a non-zoned
culture, exactly similar to the under-surface shown in Fig. 16B while
Fig. 174 shows the typical under-surface of a zoned culture.

The action of the light on the zoning was tested by inoculating flask
cultures with small pieces of the crust taken from a zoned one. These
cultures were allowed to grow for a few days till the zoning became
apparent in all of them. At this stage some of those showing two or
three rings were placed in the dark, the other allowed to stand in diffuse
hight in the Laboratory. The latter developed into zoned cultures. In
those placed in the dark the zoning stops immediately. The zoning of
the fungus in pure culture is not constant, but can be varied by chang-
ing the conditions under which it is growing.

Fructifications were not obtained in pure culture till the end of
1916. It was then found that if sufficient water is placed in the culture
tube to cover the cotton wool and partially immerse the wood block, the
fungus immediately commences to produce growths resembling fructifi-
cations. The top end of the wood block must project slightly above the
surface of the water and be kept comparatively dry in order to provide a
suitable place for inoculation. The fungus quickly strikes away, and
growing down the block through the water produces thin, black plate-
hke structures resembling the plate-like fructification found in nature.
The fungus grows through the cotton wool and in one case produced the
“Kretschmaria”’ form on the lower end of the wood block. Two or three
weeks after the “ Kretschmaria”’ form was noticed, small protuberances
appeared on the upper end block which finally took on the “ Xylarial”
form; these were black stalked with a small greenish-grey head. The
latter colour was due to the production of the typical conidial layer.
Slants were started from these conidia, and typical cultures obtained.
Thus the whole cycle of the life history has been obtained with the
exception of the ascospore stage.

166 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

Fertile fructifications have not yet been obtained in agar cultures.
Small rhizomorphic-like strands which attain a height of }’’ above the
surface of the culture are often found (Pl. VII, fig. 18). These strands
resemble the individual components of the lichenoid form of the fungus.
They grow about in the culture medium in a very irregular manner, and
are doubtless comparable with the black lines running through the rotten
wood of plants affected with U. zonata.

These experiments prove that Ustulina zonata is the fungus largely
responsible for the death of trees attacked by borers. Attacks by boring
beetles would not prove serious if other agencies were not concerned. The
connection between the insects and this fungus, which is the cause of one
of the most serious diseases on old rubber we shall have to contend with
in Malaya, renders the question of the control of collar-rot a difficult
one. It is obvious, however, that strict attention must be given to all
trees, stumps or logs in which borers are working.

FUNGUS IN THE WOOD.

The progress of the fungus in the tissues is well shown by Fig. 19,
which shows an artificial inoculation at the collar. The fungus advances
from the point of inoculation into the wood and spreads more quickly in
this than in the bark. The wood assumes a brown colour as the fungus
advances, this discoloration extending fairly evenly in-the vertical and
lateral directions. Attention may be called to the apparent zoning shown
by the discoloured tissues.

The brown wood is permeated with thin hyaline hyphae largely con-
fined to the medullary rays and fibres of the wood. The vessels are com-
paratively little affected; only when the black lines cross the vertical
path of the vessels are hyphae noticeable in them.

The fungus causes a drying of the affected tissues; the wood becomes
crumbly and falls apart under the pressure of the fingers in advanced
cases. The black lines of fungus tissue appear as the affected wood dries.
These lines are formed by the aggregation and massing of hyaline hyphae;
this aggregation always commences in the medullary rays (PI. VII, fig. 20).
Later, tracts of connecting cells between the rays become filled with
similar tissue, and a continuous line is formed. Carbonaceous material
is deposited in the cells after aggregation, and as time passes it is often
difficult to detect their origin. The elements bordering the lines are
crowded with hyaline hyphae.

The.slow progress of the fungus in the root system is connected with
its method of penetrating the tissues. The vessels are the routes along

A. SHARPLES Tov

which quick travelling fungi, such as Diplodia cacaoicola (P. Henn) and
Corticium salmonicolor (Zimm.) proceed, and the hyphae of these fungi
are always specially noticeable in the vessels. C. salmonicolor is note-
worthy in this respect, for as 1t passes along the vessels the living cells
bordering them produce tyloses (2) in an attempt to stop the progress of
the fungus. The vessels in wood attacked by U. zonata seldom show these
ingrowths; Brooks(1) also calls attention to this absence of tyloses.

BLACK LINES IN ROTTING WOOD.

The tendency for fungi to produce black lines similar to those de-
scribed for U. zonata is a noteworthy feature in the tropics. All rotting
soft-wood logs on the plantations show these lines when the wood is cut.
These lines are an important diagnostic feature to the planter, and more
certain knowledge of the fungi forming lines in rotting soft wood on the
plantations is desirable. A special investigation is under weigh, results
of which are not yet to hand.

INOCULATION EXPERIMENTS.

The inoculations described by Brooks(1) indicate that the fungus will
easily enter the collar of a rubber tree through wounds, but cannot enter
a healthy unwounded tree. On very young unwounded seedlings, he
obtained successful artificial inoculations, but similar trials on woody
plants were unsuccessful.

Usually a fungus is limited in its infective capacity to either the
aerial or underground portions of a plant, i.e. a fungus causing a root-rot
will not attack the stems and branches of a particular host, and vice versa.
A priori considerations lead to the conclusion that a wound parasite on
roots might easily attack branches through wounds, but experimental
evidence was desirable. The inoculation experiments to be described
settle this question, and also bring evidence to support the result arrived
at by culture experiments and field observations which proved that
U. zonata is the organism causing the rotting of the tissues in rubber
stems and branches attacked by borers.

Roots were inoculated with the fungus (U, s) isolated from the stem
and branches, and branches were inoculated with the fungus (U, 1)
isolated from the roots.

Expt. 1. Hight seedlings were inoculated on 17. vi. 15. These plants
were six months old, and had developed a woody stem at and for about
eight inches above the collar. Four were inoculated with (U, r) four with
(U, s). The inoculations were made by placing small pieces of rubber

168 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

wood on which the fungus was growing in pure culture in slight cuts
made with a sterile knife, either in the collar or woody parts of the stem.
Control plants were kept; these were treated in the same way, but small
pieces of newly sterilised wood were placed in the cuts. The results are
placed in tabular form below.

Date U (r) at U (r) in U (s) at U (s) in
examined collar in stem collar in stem
No. 1* 2% 3* 4* 5% G6 TF 8F
24. vii. 15 soe + as je af ses
27. vii. 15 us ee sic aor ese ee +
29. vii. 15 By ees + ;
11. viii. 15 + ae eee =
Dk Lb bie aig oe + + 5 aa 535
6.55.15 Sah ae aie ee sae - ase +

* Nos. 1, 2, 3 and 7 were dead on the date of examination. The death symptoms were
typical, the leaves suddenly wilting. When the plants were cut open at the point of inocu-
lation the progress of the fungus for one or two inches above and below this place was
clear, and black lines were forming in the diseased tissues from the wounded places.
No. 5 gave a similar result, but the plant was examined before the leaves wilted. Nos. 4
and 8 showed the fungus progressing in the tissues on the date of examination, while No. 6
completely recovered. Cuts made in control plants all healed quickly.

Expt. 2. In this experiment, similar inoculations were carried out on
five year old, untapped trees growing in an area clear of all rotting
timber. Eighteen trees were inoculated, nine with U (r), nine with U (s).
Six each of U (r) and U (s) were made at the collar, the bark being lifted
with a sterile knife, and a small piece of culture wood inserted. Six
inoculations were made in the branches, three with U (r), three with
U (s). These were made by cutting deeply into the cortex and inserting
similar pieces of culture wood as those used in the collar inoculations.
Inoculations made: 22. vi. 15, and examined: 1. 1. 16.

Tree U(r) at Tree U(r)in Tree U(s)in Tree U (s) at

No. collar No. branches No. branches No. collar Remarks
] + 7 + 10 + W3o- + Lost may be taken
2 + 8 + ll - 14 - as unsuccessful
3 + 9 + 12 + 15 a
4 “+ mas ae sare ree 16 Lost
5 - — Rae rae ae 17 +
6 Lost ae sive ae bes 18 Lost

The tabulated results of Experiment 2 show that twelve out of
eighteen inoculations were successful. The branch inoculations were
uniformly good, both with U (7) and U (s). Seven out of twelve root
inoculations were successful. Considering the difficulties attached to
root inoculations, this result is most conclusive.

A. SHARPLES 169

The rapidity of the healmg of the wounds in the control plants is
noteworthy. In Experiment 1, observations were continued for some
time comparing Nos. 4 and 8, in which cases the fungus penetrated slowly
about the wounded part, and the control plants where sterilised slips of
wood were placed in the cuts. Healthy callus healed the wounds in the
controls in two months, while the wounds in Nos. 4 and 8 showed no
signs of healing after three and four months. Compared with No. 6,
which recovered completely, the cuts in the controls healed much more
rapidly. The control plants in both experiments continued to flourish.

These inoculation experiments confirm the conclusions arrived at by
field observations and cultural experiments. The capacity of Ustulina
zonata to attack either the roots or aerial parts of rubber trees through
wounds can no longer be doubted. The fungus makes very appreciable
progress in the tissues in six months’ time as is indicated by the photo-
graphs shown, PI. VII, fig. 19 and Pl. VIII, fig. 21. The common occur-
rence of this fungus on the plantations renders it a matter of extreme
import that vigorous measures should be undertaken to prevent its
spread. The measures to be adopted will now be considered.

SOURCES AND MANNER OF INFECTION.

Petch (4) states that Ustulina zonata is the cause of the commonest
root disease of Tea in Ceylon, and that its prevalence is due to the
practice of growing Grevillea among tea and cutting it out later for fire-
wood, or when it has grown too big. The same applies when Albizzia
moluccana is planted through tea, and afterwards felled. The Grevillea
and Albizia stumps left in the ground are rotted away owing to the
action of fungi, and U. zonata is the commonest one growing in them. In
the same way, this fungus appears to be one of the chief agents causing
the rotting of rubber stumps and logs left in the plantations after thin-
ning-out.

On the tea plantations, the fungus enters the Grevillea and Albizzia
stumps and grows down them into the lateral roots. The roots of the
tea bushes in contact with these infected laterals are quickly attacked.
The same method of spread operates in the rubber plantations after the
thinning-out period if the stumps of the cut trees are left in the ground.
Lateral roots of infected trees have been traced to old rubber stumps
left after thinning, on which the fructifications of the fungus were
developing. Further, on the badly affected plantations noted up to date,
the stumps of the rubber trees were not removed after thinning-out.

There is, in Malaya, a wide-spread dispersal of the fungus through the

Ann. Biol. tv , 12

170 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

plantations by means of the spores after the thinning-out period. The
fungus enters permanent trees attacked by boring beetles and quickly
kills them, and the stumps and felled logs form excellent material in
which the beetles and fungus may work together. But the fungus alone
can enter and grow through any soft-wood timber without the aid of the
insects.

All trees attacked by boring beetles should be immediately cut out
and destroyed, as they represent one of the worst sources of infection.
Strict attention should be given to trees scorched by fire, and if borers
attempt to enter, a coating of tar and crude oil (80 per cent.—20 per cent.)
should be applied over the scorched surfaces. In the case of scorched
trees resulting from leaf fires, the burnt areas are usually situated near
ground level, and can be easily treated with the tar mixture. A second
coating should quickly follow the first. Scorching of higher branches
resulting from burning of piles of timber is not so easily treated, but as
far as observation goes, these branches are not often attacked by the
insects; in any case they can be cut away from the main stem quite
easily.

The cases of leaf fires noted this year—1916—support the observa-
tions made in 1915 and given above. One interesting case was noted: an
estate was visited four days after the fire and borers were already at
work on half a dozen trees not badly scorched; latex was exuding freely
from the boreholes.

At the time of thinning-out a tremendous increase of suitable food
material for the fungus becomes available. Practically all stumps and
felled logs of rubber if left lying about the plantation for any length of
time show signs of Ustulina zonata. The fructifications develop on the
surface of these logs and stumps, and for a short period corresponding to
the weekly one observed in the Laboratory, a copious supply of spores
(conidia) is produced and blown about the plantation by the wind.
Later, the ascospores ripen, and these are distributed amongst the trees
by various agencies.

The spores come to rest in wounds in the collar and lateral roots of
the permanent trees and under suitable conditions germinate. The fungus
develops slowly, and several years later when the trees are passing the
ten years’ limit, some begin to show a thin crown of leaves. If the collar
is now cut open, the characteristic dry-rot will be found. 2

The fungus is also found on rotting jungle timber and on old jungle
stumps left in the plantations after burning-off. It is not so common in
the early years as it is during or after the thinning-out period, though

A. SHARPLES 171

many cases have been found recently of roots of four year old trees per-
meated and killed by this fungus. The jungle stumps and timber repre-
sent one of the sources from which the fungus commences, for fructifica-
tions have been obtained from old jungle stumps (PI. II, fig. 2) and
characteristic symptoms have been observed in lateral roots of jungle
stumps exposed in areas treated for Fomes lignosus.

It is probable that healthy jungle trees are attacked by this fungus,
and spores may be blown from the jungle into the plantations. It is
impossible to take the measures to prevent the spread of the fungus from
this source. On a clean estate, there is little danger to be anticipated, and
in the general scheme of treatment it may be considered negligible.

TREATMENT.

This consideration of the sources and manner of infection indicates
that present day plantations may be divided into three groups. The
treatment accorded to each group varies with age. The groups are as
follows:

(A) Young plantations not thinned out.

(B) Plantations thinning-out with trees not ten years old.

(C) Plantations with trees over ten years of age.

(a) Control measures against the collar-rot caused by Ustulina
zonata may be initiated by enforcing strict sanitation methods from the
time of planting up. The clearing of the ground of rotting timber and
the treatment of jungle stumps is the first and immediate measure to be
undertaken. This will largely prevent trouble from White ants and
Fomes lignosus, as well as minimising that likely to ensue from attacks
of Ustulina zonata. Special attention should be paid to the eradication
of the lateral roots of jungle stumps to prevent contact infection from
both Fomes lignosus and Ustulina zonata. This can be secured best by
following up the laterals from the stumps to a depth of two feet below
the surface. At this point they should be cut through and separated
from the parent stump. Clearing timber and eradicating stumps or lateral
roots is costly, and the difficulty of the undertaking fully appreciated.
Though many of the larger stumps will have to be left standing, yet it is
possible to clear any estate to such an extent that trouble from root
diseases may be reduced to a negligible quantity.

On estates badly affected with Fomes semitostus, the elimination of
stumps and timber, as far as is practicable, has been fully recompensed.
General treatment on these lines could not be advised previously, for
large numbers of estates are free from “ Fomes” troubles, but few will

122

172 Ustulina Zonata (Lev.) Sace. on Hevea Brasiliensis

escape attacks by Ustulina zonata. This fungus appears likely to cause
damage on most old properties.

(6) Plantations thinning-out with trees not yel ten years old.

Estates about to thin out from which no jungle stumps have been
removed or timber cleared, should attempt to follow the advice given
under (a). On all estates the method of thinning-out should follow the
same lines as treatment advised for clearing land at the beginning. One
tree should be cut, and the stump, lateral roots and logs removed and
destroyed immediately. A sharp watch should be kept over the thinned.
area for signs of borer attacks on standing trees and those attacked should
be cut out and destroyed quickly. This treatment prevents the multipli-
cation of boring beetles by destroying their breeding grounds.

PERIOD AFTER TREES ARE TEN YEARS OLD.

On most old plantations in Malaya, this disease will be found to be
responsible for the death of numerous trees. In a previous publication (10)
the writer stated that it might be possible to treat old trees attacked at
the collar by cutting out the diseased tissues and running a pillar of
concrete up the middle. Since then, this method has been tried, but from
the planters’ point of view is unsatisfactory because of the expense,
Therefore, if diseased trees are found in an advanced state of decay, they
should be cut out immediately, care being taken to remove all diseased
laterals to prevent contact infection. The greatest damage on old planta-
tions arises from infection of roots of healthy trees by contact with
diseased laterals of neighbouring trees; the recognition of this fact must
not lead to a minimisation of the dangers of spore infection.

Fructifications are common on the surface of the diseased tissues at
the collar. They develop quickly, so a constant watch should be kept on
attacked trees, if left standing. Two examinations a week would be
advisable, and immediately fructifications are observed, a tin of kerosene
oil should be obtained and the fruit-body gathered and immersed in the
oil. This will help to prevent the spread of the fungus about the plan-
tation by means of wind-borne spores. Wounded lateral roots on trees
over six years old showing above the surface of the soil are convenient
places of entry for the fungus. Such roots showing black lines below the
wounds should be cut off if they can be spared.

Many managers see difficulties in the amount of burning which is
required. Burning, however, is carried out successfully all the year round
on many estates in the treatment of “ Pink Disease,” with little damage
to the permanent trees.

A. SHARPLES ~ 1s

FUTURE POLICY AND CONCLUSION.

It is an accepted fact that pests and diseases are a constant menace
to all plantation industries. The pctential dangers to the Rubber Plan-
tations in Malaya are becoming more manifest each year, and the menace
is doubly dangerous because of the comparative immunity of the planta-
tions up to date, which has lulled responsible persons into a false sense of
security. Many significant facts have been brought to light during the
last two years. A few cases of serious attacks of root disease in rubber
plantations might be quoted:

(a) On one estate, a block of 6-7 acres of sixteen year old rubber was
examined—sixty trees to the acre. A casual inspection revealed 120 trees
attacked by U. zonata. More have since been found.

(b) The Government estate behind the offices of the Department of
Agriculture at Kuala Lumpur carries about seven acres of fifteen years
old trees. A fair number of cases of U. zonata were known, but only one
small group of six trees was known to be affected with “wet root-rot?.”
To obtain specimens and observe the disease below ground, this group,
together with the neighbouring trees, was opened up. It was obvious
from the commencement that the subterranean spread was much greater
than at first anticipated. Two hundred and twelve trees were opened up,
and forty per cent. showed diseased roots (i.e. wet root-rot). The matter
was so serious that at the request of the Advisory Committee to the
Department of Agriculture, the whole of the seven acres of old rubber
had their roots exposed. Over the whole area, in which 700 trees were
examined, twenty per cent. showed diseased roots.

(c) A third illuminating case was noted some months ago. A wind
storm, locally known as “Sumatra,” swept over a portion of one estate,
and a large number of seventeen year old trees were blown over. Of these
prostrate trees, only three showed healthy roots; these were without tap
roots. A few of the fallen trees had been treated previously for U. zonata,
but by far the great majority which were not suspected to be suffering
from root disease, had U. zonata attacking the roots. A few cases of
branch infections with U. zonata and a few roots with wet root-rot, were
also found. When the place is cleared, huge gaps must be left in the
wind swept area. The manager is quite certain that any other portion of
the old rubber subjected to a similar storm would show a larger number
of unsuspected cases of root disease. This, and the case quoted im-
mediately above, shows the insidious spread of these root fungi on old

“1 Belgrave, W. N. C. ‘A Root disease of Plantation Rubber in Malaya.” Agr. Bull.
Fed. Malay States, Vol. tv. No. 11. Aug. 1916.

174 Ustulina Zonata (Lev.) Sacc. on Hevea Brasiliensis

rubber, and it is impossible to urge too strongly the necessity for im-
mediate and strenuous measures to keep them under control.

A further complication arises: during the last six months, serious out-
breaks of different manifestations of so-called Bark Canker have been
found in widely separated districts in Malaya. The important point in
combating diseases of renewing bark is that the trees should be assured
proper ventilation. The more light and air penetrating to the trees, the
_ less chance of epidemics of Bark Canker. If Bark Canker becomes general
in Malaya, thinning-out will have to be undertaken to the irreducible
minimum number of trees per acre commensurate with profitable working.
When estates are forced to this position, the menace of a bad attack of
root disease is obvious.

A critical period approaches for the plantation rubber industry in
Malaya. No immediate danger promises though the menace of disease
becomes more prominent every year. Fungus diseases will, in the long
run, provide the limiting factor, preventing the expansion and hindering
the progress of the industry. The logical conclusion drawn from facts
as they present themselves is that if preventive measures are not 1m-
mediately adopted, fungus diseases may prove the ultimate ruin of
an industry, which with careful foresight and administration, should
smother all competitors for decades.

The future policy to be adopted in Malayan rubber plantations must
be one of two: either

(a) An attempt to keep the present plantations healthy as long as
possible, or

(b) A re-planting scheme at an age between 20-30 years.

The profits gained by a rubber plantation depend upon the average
yield of dry rubber per acre per annum. There is little evidence regarding
average yields to be obtained from a consideration of present day estates
approaching the age of twenty years, and that available is contradictory.
Some old areas yield remarkably well, while others give comparatively
poor yields. There are reliable records (6) of a thirty-seven year old tree
giving 392 lbs. 7 ozs. of total rubber in five years, a yearly average of
78 lbs. 8 ozs. There are also reports of old trees in Malaya giving enor-
mous yields, but these cannot be claimed to be authentic. There appears
no reason why plantation trees in Malaya should not approach the above
standard, and if such yields are possible the policy of rendering the
present plantations as permanent as possible should be adopted. At the
same time it will be advisable to move cautiously, for observations on one
estate, run on up-to-date lines, lead to the conclusion that the yields on

A. SHARPLES 175

the present plantations with 50-60 trees per acre, begin to decrease after
the trees are twenty years old. It must be remembered, however, that
these old areas passed through the “boom” period when the only ques-
tion considered was that of a maximum yield without any regard for the
health of the tree, and it is not possible to hazard what effect such treat-
ment would have. Further, root diseases on this area are giving a great
amount of trouble, causing continual losses. The question of the per-
manence of the old trees is closely linked with the possibility of root
diseases causing the death of large numbers. These diseases in rubber
plantations can be reduced to a negligible quantity if the land is cleared
before planting up is commenced, and though the result of clearing plan-
tations now in bearing is more problematical, the estates undertaking
this will be fully recompensed by freedom from fungus disease.

If the fungi causing root-rots on old trees become active so as to
endanger the plantations at thirty years, a fresh planting scheme must
be considered. There are two alternatives:

(a) Re-supplying old areas.

To re-supply successfully the stumps, lateral roots and logs of all the
old trees would have to be burnt off and the ground allowed to lie fallow
for at least twelve months, or a subsidiary crop might be grown on the
land during this period. If clearing was not thoroughly undertaken, the
root-rot fungi would find conditions more favourable for perpetuation
and spread than in the previous years, and an exaggerated recurrence of
thinning-out conditions would result. Instead of the root-rots becoming
serious at ten years old, they might be expected to prove serious much
earlier, and numerous young trees would be killed by these fungi.

(b) Planting new areas.

New contiguous areas opened up near old areas containing diseased
trees are doomed to failure unless the latter are cleared. Presumably, the
old areas would be gradually abandoned, and in the interests of economy,
the rotting trees would be allowed to remain. Such areas would prove to
be centres of infection, and it is extremely probable that the new areas
would be quickly infected. The parasitism of these fungi may increase in
vigour with time, and as observations show, young plants are easily
attacked under suitable conditions.

FUTURE RESEARCH.

The evidence favours an endeavour to keep the present plantations
active until age prevents the old trees from yielding, profitably. Many
magnificent looking trees are poor yielders; this fact together with

176 Ustulina Zonata (Zev.) Sacc. on Hevea Brasiliensis

possible losses from disease has been the great stay for the argument
that more trees should be kept to the acre than are absolutely necessary.
This is an obvious but clumsy way of insuring a profitable yield, but until
a better method is suggested it must remain in force. An optimum
number of trees per acre is the ideal—this postulates average yielding
trees and few or no losses from disease after the ten years limit is reached.
Rubber estates developed with a due regard to hygienic principles need
not fear losses from disease as far as present knowledge goes; this state-
ment obtains more support the further investigations are carried.

Fears for the future should not lead rubber people to favour the
retention of trees in excess of the optimum, but should stimulate them
to insist upon responsible persons finding the ways and means of sur-
mounting the difficulties by approaching cognate problems from different
perspectives. The solution lies in the adoption of an intensive scheme of
scientific research.

Two lines call for immediate attention: (a) physiological investigation
to enquire into the réle played by latex in the metabolism of the tree;
(b) seed selection investigations with a view to improving yields of latex
and at the same time obtaining trees more resistant to fungus attacks.
The inception of these investigations would mark a new departure in
tropical research. Up-to-date, practical investigations have been all that
were asked for; the problems have been so many and the workers so few
that immediate matters have had to be hurriedly dealt with, and little
attention has been paid to the future. The position is worse because of
the lack of correlation in scientific investigations and the difficulty
investigators find in meeting and discussing cognate problems from the
experience gained in different countries. Rubber research needs cen-
tralisation and reorganisation, which would enable immediate practical
matters to be grappled with, and would also institute pure scientific
investigations with a view to rendering the industry a permanent corner-
stone in the edifice of National Industry. With proper foresight and
efficient administration, the rubber industry of the Middle Kast should
remain largely under British control, and should fear no competitors.
On the other hand, if the present methods continue, the result may be
disastrous. The present time is ripe for a departure from archaic ideas,
and if all interested parties can be brought together to reasonably
discuss the situation, the outcome is assured.

I am indebted to Mr F. de la Mare Norris, Asst. Ag. Inspector, F. M.S8.,
for the drawing of Fig. 20 and to E. W. King, Esq., Visiting Agent to the
Kuala Lumpur Rubber Co., for the photograph included as Fig. 2.

on

10.

A. SHARPLES Li 7

REFERENCES.

Brooks, F. T. A Disease of Plantation Rubber caused by Uslulina zonata.
Bull. No. 22, Dept. of Agriculture, F. M.S. and New Phytologist, vol. x1v, Nos.
4 and 5.

Brooks, F. T. and Sarees, A. Pink Disease. Bull. No. 21, Dept. of Agri-
culture F. M.S.

Masses, G. Fungi Exoticii. Kew Bull. p. 251, 1910.

Percu, T. Root Diseases of Tea. Circs. and Ag. Jour. of Roy. Bot. Gard. Ceylon,
vol. v, No. o, Oct. 1910.

Percu, T. The Fungus-diseases of Hevea brasiliensis. Rubber Receuil, Inter-
national Rubber Congress and Exhibition, Batavia, Sep. 1914, pp. 116-129.
Percu, T. Tapping of an old Hevea trea at Henaratgoda. Bull. No. 13, Dept.
of Agriculture, Ceylon, Sep. 1914.

Rant, A. Ueber die Djamoer-Oepas Krankheit und ueber das Corticium
javanicum Zimm. Bull. du Jard. Bot. de Buitenzorg, 2nd sér. No. tv, 1912, pp. 1—
48.

Reeves, A. T. Ustulinazonata. Art. vit, page 26, Report of Consulting Chemists
in London to the Rubber Growers’ Association, 2 July, 1916.

SHarpies, A. Bark Scraping and Bark Affections. Ag. Bull. Fed. Malay States,
vol. m, No. u, Aug. 1915.

SHareues, A. Ustulina zonata—a fungus affecting Hevea Brasiliensis. Bull.
No. 25, Dept of Agriculture, F. M.S. 1916.

EXPLANATION OF PLATES.

PLATE-Ill. ~

. 1. Typical specimen of dry collar-rot on ten year old tree caused by U. zonata.

(4 nat. size.)

.2. Flat Plate Fructifications of U. zonaia on old jungle stump left in Plantation.

(Photograph by E. W. King, Esq.)

. 3. T.S. of Spec. (A) (see text) attacked by U. zonata and shot-hole borer. (4 nat.
size.) 5
. 4. L.S. of same showing bore-holes and black lines. (4 nat. size.)

PEATE VIN:

.5. Photograph of scraped tree taken four days after scraping—showing latex exuding

from bore-holes. (4 nat. size.)

. 6. Same tree with bark removed exposing outer surface of wood—note black lines,
ete.
. 7. Lateral root carrying typical fructification of U. zonata. Note white patches of

mycelium in bark; the black lines and zoning on the plates. (} nat. size.)

. 8. Hollow White-ant tree with U. zonata. The two black lines indicate the limits

of the wood attacked by the fungus. (+ nat. size.)

; 178 Ustulina Zonata (Lev.) Sacc. on Hevea Brasiliensis

PLATE V.

Fig. 9. Showing typical flat, zoned fructification. (3 nat. size.)

Fig. 10. Common variation—consisting of stalked individuals aggregated to form a
compact mass. At the edges a lichenoid form can be seen, while old plate fructifications
are present below but cannot be brought up in the photograph. (4 nat. size.)

Fig. 11. Isolated individual stalked (Xylaria) form—darker area at top indicates the spore
bearing part. (Nat. size.)

Fig. 12. Microphotograph of longitudinal section of Fig. 11. The layer above the black
line at the top is the spore bearing (conidial) layer.

PEATE Vir

Fig. 13. Another specimen of aggregated stalked form passing into lichenoid type at
edges. (4 nat. size.)

Fig. 14. Lichenoid form of U. zonata in young condition. (Nat. size.)

Fig. 154. Upper zoned surface of culture started from conidia.

Fig. 158. Under surface of 154—zoning extends through substance of culture.

Fig. 16a. Upper surface showing false zoning of culture started from same source as
154 and 15x.

Fig. 168. Under non-zoned surface of 164.

Fig. 17a. Typical zoned culture from collar-rot tree (under surface).

Fig. 178. Showing typical under-surface of non-zoned culture started from same source
as 154 and 16a.

PLATE VII.

Fig. 18. Petri dish zoned culture showing attempt to produce lichenoid form.

Fig. 19. Photograph of section of tree artificially inoculated at the collar. Indicates
progress made by fungus in seven months. (} nat. size.)

Fig. 20. T.S. of wood of H. Brasiliensis attacked by U. zonata. Black lines commencing
to form in medullary rays (m).

PLATE VIII.

Fig. 21. L.S. of scraped tree, see Figs. 5 and 6, indicates progress of fungus in stem in
seven months time. (4 nat. size.)

Fig. 22. Sections of lateral roots showing U. zonata travelling in the middle. External
tissues apparently healthy. (+ nat. size.)

Fig. 23. Blocks of rubber wood on which cultures of U. zonata have been grown. Split
open to show black lines in middle. (Nat. size.)

THE ANNALS OF APPLIED BIOLOGY. VOL. IV, NO. 4 PLATE III

IV

VOL. IV, NO. 4 PLATE

THE ANNALS OF APPLIED BIOLOGY.

THE ANNALS OF APPLIED BIOLOGY. VOL, IV, NO. 4 PEATIEY V

Fig. 11

Fig. 12

Fig. 10

VOL. IV, NO. 4 PLATE VI

THE ANNALS OF APPLIED BIOLOGY.

5.

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PLATE VII

THE ANNALS OF APPLIED BIOLOGY. VOL. IV, NO. 4

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THE ANNALS OF APPLIED BIOLOGY. VOL. IV, NO. 4 PLATE VIII

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179

A STUDY OF THE CAPSID BUGS FOUND ON

APPLE TREES.

By F. R. PETHERBRIDGE anp M. A. HUSAIN}.

School of Agriculture, Cambridge.
(With Plates [IX—XI.)

CONTENTS.

Introduction
Methods :
Capsids found on apple ae Sate ce distingoishiiae
features .
Plesiocoris rugicollis (Fieb. )
Synonymy
Adult
The egg
Instars .
Table of measurements
Table of duration of each stage
Habits
Time and nature of ae
Cause of injury
Control
Summary of the life- fiatory of a compat
Orthotylus marginalis (Reut.)
Psallus ambiguus (Fall.)
Atractotomus mali (Mey.)
The enemies of capsids
The food of apple-dwelling caps
References . :

1, INTRODUCTION

PAGE
179
181

184
185
185
185
186
189
191
192
193
194
196
198
198
199
201
203
204
204
204

The damage done to apples by bugs of the family Capsidae has now
become a very serious trouble to fruit growers in this country and
a detailed knowledge of those found on apple trees is therefore of
immediate importance. This work was undertaken at the suggestion of
Fryer who has, during the past few years, made observations on these
insects (11, 12, 12a),

1 Mr Husain wishes to thank the Government Grant Committee of the Royal Society
for the grant given to him to carry out this work.

180 A Study of the Capsid Bugs found on Apple Trees

The problem has been studied mainly from an economic standpoint,
our main object being to find out the amount of damage caused by each
species, to study their life-histories and the nature and cause of the
injuries done to the leaves, shoot and fruit by the various stages.

Problems of great biological interest and possibly of economic impor-
tance have arisen during the course of this work which we have been
unable to investigate owing to pressure of time. One season is a very
short time to study all the aspects of such a problem as this, and we hope
if circumstances permit to continue this work next season. Our justifi-
cation for the publication of this rather incomplete paper is in the hope
that the observations contained in it may be of immediate use in helping
to control this serious pest, and also that under such abnormal con-
ditions as exist at the present time, the authors may be tnable to
continue this work, in which case the observations made may be of
some help to future investigators.

A large number of the Capsidae live on the juices of plants which they
suck by means of their long rostra, and it is probably as a consequence of
this that so many of them have been recorded, some rightly and others
wrongly, as plant pests. In America the following have been recorded as
damaging fruit trees:

Heterocordylus malinus Reut.
Lygidea mendax Reut.

Lygus pratensis Fab.
Neurocolpus nubilus Say.
Paracalocoris colon Say.

Fryer points out that of these only Lygus pratensis is present in this
country.

In England the following among others have been recorded as
damaging apple trees:

Alractotomus mali Mey.
Lygqus pratensis Fab.
Orthotylus marginalis Reut.
Plesiocoris rugicollis Fall.
Psallus ambiguus Fall.

Lygus pratensis is recorded as producing dimples on apples, whereas
the others are recorded as damaging the leaves, shoots and fruit.

As Fryer has pointed out (11) there is a great deal of confusion
as regards the real pest and the status of the various capsids found so
commonly in affected orchards. Unfortunately the presence of a species

F. R. PETHERBRIDGE AND M. A. HUSAIN 181

on damaged trees seems to have been regarded as sufficient evidence to
record it as the cause of the trouble.

Theobald 24-28) repeatedly mentions Atractotomus mali, Orthotylus
marginalis and Psallus ambiguus as the culprits. Schdyen (21) mentions
Orthotylus marginalis, Plesiocoris rugicollis and Psallus ambiguus as doing
damage in Sweden. We do not know on what evidence these state-
ments are based as no details are given, but we have found that it is
possible to visit an orchard in which the apples have been badly marked
by Plesiocoris rugicollis after this species has disappeared and when
one or more of the other three species are still present. We think
therefore that very probably the damage has been attributed to the
wrong species. It is of course possible that in Sweden the injury might
be done by a species which is harmless in this country, but in the absence
of direct evidence this should be regarded as doubtful.

Fryer has pointed out that Plesiocoris rugicollis is the more serious
pest and has shown by direct experiment that it causes the typical
damage to the leaves, and that Psallus ambiguus does not (12). Fryer and
Petherbridge also showed by direct experiment that Plesiocoris rugicollis
damages the fruit and shoot and that Psallus ambiguus and Atractotomus
mali do not(12a).

Our experiments and observations show that Plesiocoris rugicollis
causes marked damage to the leaves, shoots and fruit and is responsible
for most of, if not all, the damage in the Wisbech district, and that
Atractotomus mali, Orthotylus marginalis and Psallus ambiguus although
they feed on the juices of the apple do not cause any apparent damage to
the varieties badly marked by Plesiocoris rugicollis. In no case have we
found either of these three species causing any visible damage to apples.

The life-histories of a number of forms have been worked out in
America (6, 7, 16, 18, 29) but very little work has been done in that direction
in this country.

2. METHODS.

Observations were made during the season of 1917 chiefly in badly
attacked orchards at West Walton near Wisbech where the bugs used for
experimental work were also obtained. Observations were also made in
unattacked orchards near Cambridge.

April 14th is the earliest record of the hatching of P. rugicollis (12)
so we started our visits to Wisbech at the beginning of April but
obtained no young capsids during the whole of this month. Twigs of
apple were brought back and searched for eggs. We could not find the

182. A Study of the Capsid Bugs found on Apple Trees

eggs by means of a surface examination even after cleaning the twigs
with dilute potash, but were able to find them by peeling the bark
when the eggs remained sticking to it. We kept a number of these twigs
in water in the laboratory in the hope that young larvae would hatch out
from some of the eggs. Fortunately we were rewarded by getting a number
of young P. rugicollis larvae (one of which we observed emerging from an
egg) from shoots brought in at the end of April.

These started to hatch on May 5th. Up to this date no capsid larvae
had hatched at Wisbech, but a visit on May 7th revealed the presence of
many newly hatched larvae. The young leaves of the shoots on which
they were found were marked with brown spots.

As we were unable to identify the young capsids until later on
we classified them under the headings A, B, C, etc. The larvae and
nymphs were taken to the laboratory, carefully examined, classified and
some of them measured and drawn. Some were preserved, others piaced
singly on shoots in cages, and others put into sleeves on apple trees, each
sleeve containing a single bug. Young bugs were brought in three or four
times a week and the development in the laboratory checked by the
stages found at Wisbech. All the different stages found were placed on
shoots in cages and sleeves and their behaviour noted. We were thus able
to find out which of the species did damage and at what stages the
damage was done to the leaves, fruit and young stems. Precedence was
given to P. rugicollis in our observations as this was soon found to be
the only culprit. Altogether we had over fifty cages of P. rugicollis and
about an equal number of the other bugs. We sleeved about fifty P.
rugicollis, and a large number of the other bugs each in a separate sleeve.
We sleeved some P. rugicollis singly on black currants and plums, and
also took some larvae and nymphs of P. rugicollis which were damaging
black currants at Histon and sleeved them at different stages on apples.

The sleeves gave very good results and there were very few casualties.
We were successful in rearing them in cages, but there were more deaths
on account of their drowning or falling:down at night. At first we
put the twigs in beakers of water with a bug on each twig, but they often
crawled down the twigs and got drowned. We then kept the twigs in
small flasks of water, plugging the mouth of the flask with cotton wool
and placed it in a large beaker covered at the top with a piece of
muslin. These cages proved fairly successful, the chief drawback being
that the bugs often fell down into the beaker and had to be replaced
two or three times a day. The shoots were changed every two or three
days in order to keep conditions as normal as possible. In spite of the

F. R. PETHERBRIDGE AND M. A. HUSAIN 183

difficulties encountered we were able to carry through to the adult stage
three individuals of P. rugicollis which hatched in the laboratory. From
the cage cases we got a complete record of the times of moulting and
the duration of each instar which on comparison proved very similar to
those under normal conditions at Wisbech. All doubtful cases were
discarded and the figures given in Table II (p. 192) are those about which
there is no doubt.

The records of the life-history in the cages in the laboratory were
compared with the sleeve cases at the farm and with those under normal
conditions at Wisbech and were found to agree closely, in the laboratory
the hatching and certain moults were in some cases a day or so ahead.
We failed to find P. rugicollis copulating in spite of the fact that we put
males and females together on shoots in the cages. We tried to watch
the process of egg laying, but in spite of careful watching we were
unsuccessful. For this purpose we had lengths of glass tubing about one
inch in diameter, closed at one end by a piece of muslin and at the other
by a cork with a hole in it. An apple twig with a 9 P. rugicollis on it |
was introduced in the tube and the end put through the hole in the cork;
the basal end of the twig being outside was placed in water and so kept
fresh. A later examination of these twigs showed that eggs had been laid.
Some of these twigs with eggs were dissected and photographed.

During the early part of the experiment shoots of Bramley’s Seedling,
Karly Victoria (Emneth Early), Grenadier, Keswick Codling, Lord Gros-
venor and Worcester Pearmain were used in the cages, but later on,
owing to the difficulty of getting twigs, we had no time to find out the
varieties used.

P. rugicollis caused characteristic markings in every case. Details
of these markings are given under the description of the injury done by
this species.

Psallus ambiguus, Orthotylus marginalis and Atractotomus mali were at
first put on shoots of Keswick Codling and Bramley’s Seedling and later
on several other varieties, but as far as we could see they did not change
the appearance of the leaf or fruit and certainly did not cause any mark-
ings of a similar nature to those caused by P. rugicollis.

The drawings were done by means of a camera lucida.

A large number of measurements of the different parts are given as
the length of a larva or nymph is very variable according to its food
supply, a well-fed larva being much longer than a starved individual as
in the latter the basal joints of the abdomen become telescoped. Owing
to this we subdivided P. rugicollis into A and B and expected to get two

184 A Study of the Capsid Bugs found on Apple Trees

different species. The measurements of the antennae and legs are not so
variable.

An account of the life-histories of the various species is given below.

3. CAPSIDS FOUND ON APPLE TREES.

In this country apple trees harbour a fairly large number of the
different genera of the Capsidae. From orchards near Wisbech and
Cambridge we collected seven different genera and two species of one
genus whilst other observers have recorded other species, e.g. Lygus
pratensis.

The following is a list of the species found:

District Numbers Remarks
Wisbech very abundant affected orchards on apples and
Plesiocoris rugicollis ~ F eaane
| eenides x af not found on apples but abundant
on currants
Orthotylus marginalis | Wesbeok it + affected orchards
| Cambridge a i unaffected orchards
Peach { Wisbech £28 - affected orchards
i (Cambridge abundant unaffected orchards
Airacictonus alk { Wisbech few affected orchards
(Cambridge fair number unaffected orchards
Phytocoris ulmi and { Wisbech few affected orchards
Phytocoris populi | Cambridge - unaffected orchards
sat aay ne ieee { Wisbech Pr affected orchards
a sti eg ee on Cambridge . unaffected orchards
Tee te ins { Wisbech abundant affected orchards
Z Ph RO eset | Cambridge pe unaffected orchards

As pointed out above, of these eight species, Plesvocoris rugicollis is
the only one which we have found marking the leaves, shoot or fruit and
therefore we shall deal with this species in greater detail. The adults of
all these genera can be easily identified (Saunders, Heteroptera), but it is
not always possible to recognise the genus in the earlier stages.

The following characters may be useful in identifying the young stages

of the above species:

Plesiocoris rugicollis hatch in April or early in May.
Yellowish green becoming greener at each successive moult.
Terminal joint of antenna pinkish brown.
Lips of dorsal abdominal gland well marked.
Mark the leaves with brown spots.

F. R. PErHERBRIDGE AND M. A. Husain 185

Orthotylus marginalis hatch about a fortnight later than P. rugicollis.

Slightly smaller, orange yellow in first stage, later greenish yellow with
bluish tinge, especially marked on lower surface.

Large orange coloured dorsal abdominal gland with faint lips.

Terminal joint of antenna smoky orange. More hairy than P. rugi-
collis.

Psallus ambiquus hatch about the same time as P. rugicollis.

Smaller, orange yellow. Terminal joint of antenna smoky orange,
and very hairy.

Atractotomus mali (Pl. X, fig.11) hatchabouta month laterthan P. rugicollis.

Small, red, two basal joints of the antenna very much thickened.

Phytocoris populi hatch nearly a month later than P. rugicollis.

Large. Antennae and posterior legs long. Mottled, ground colour
white with yellow and brown spots; thorax with dark broad lateral
bands. Antennae and legs banded and covered with long hairs.

Phytocoris ulmi differs from the preceding in being very much darker.
The spots are green, brown and black.

Pilophorus perplexa. Dark reddish brown and bear a marked resem-
blance to ants with which they are usually found in association.
Head large flattened posteriorly and overlaps the front margin of
pronotum. A narrow white band across the anal margin of pro-
notum and a wider white band across the anal half of tergite I.
Terminal joint of antenna white.

Aetorhinus angulatus hatches nearly a month later than P. rugicollis.

Small, slender, yellowish green, recognisable by its very long antennae
and black bases of the tibeae.

4, PLESIOCORIS RUGICOLLIS (FIEBER).
SYNONYMY.
Lygus rugicollis Falléri. Mono. Cimi. p. 76, 1818.
Phytocoris rugicollis Falléri. Hem. Svec. 1. 79. 6.
Capsus rugicollis Schaff. Wanz i. 80-98, Fig. 299.
Phytocoris marginalis Zelt. I. L. 271, 5.
Plesiocoris rugicollis Fieb. Kur. Hem. 272.
Reuter Cap. 2. 43.
Lygus rugicollis Doug. and Scott. E. M. M. tv. 50.

Aputt (PI. X, fig. 10).
The genus Plesiocoris Fieb. consists of only one species. The adult
Plesiocoris rugicollis is elongate oval; bright green; head, front part of
Ann. Biol. 1v 13

186 A Study of the Capsid Bugs found on Apple Trees

pronotum, sides of elytra and legs yellow. Sparsely pilose. Hlytra sub-
parallel in g and comparatively more rounded in 9.

Head small, with large, dark red, compound eyes, nearly touching the
pronotum and projecting slightly beyond its lateral margins. Vertex
carinated posteriorly.

Pronotum with a very distinct narrow yellow collar and two very
prominent callosities just behind it. Strongly rugose. Posterior margin
not emarginate and covers the mesonotum. Sides straight.

Elytra green with yellow margin; sparsely covered with short thick
almost black hairs. Membrane hyaline, two cells with green nervures and
with a clouded area round the inner angle of the large cell.

Antennae medium length; covered with short thick black hairs and
longer and finer light hairs; basal joint green and thicker than the other
joints. Second joint longest; lower portion green, upper half dark.
Terminal joint three-quarters the length of the third joint, both together
shorter than the second; both dark. When cleaned and mounted in
balsam terminal and sub-terminal joints pinkish brown.

Legs yellowish green, with short brownish hairs. Tibia with fine
brownish spines. Tip of tibia dark and thickly covered with hairs which
become thicker and longer as they approach the tip. Tarsi 3-jointed,
covered with fine hairs; two basal joints sub-equal, terminal longest;
tips dark with curved claws and a pair of transparent arolia.

THe Hee.
Time of egg-laying.

The females of P. rugicollis brought from Wisbech from about
the third week of June to the beginning of July were enclosed in glass
tubes with apple twigs, and were observed to have laid eggs in these
shoots. In spite of a careful watch, the actual process of egg-laying
escaped observation. It may be that the eggs are laid during the early
hours of the morning. There is no doubt that they are laid after long
intervals, as in a number of cases there were only two or three eggs after
a female had been on the twig for over a week. During the egg-laying
period the bug keeps feeding on tender leaves and soft terminal parts of
the stems which show the characteristic purple-brown spots. It would
be interesting to find out the number of days that a female takes to
develop eggs after fertilisation and the time taken to lay all the eggs.
We are inclined to think that egg-laying continues all through the later
part of the life of an adult female.

F. R. PETHERBRIDGE AND M. A. Husain 187

Position of eggs.

The eggs laid in the laboratory were carefully compared with those
dissected out of the twigs brought from Walton, and their identity
confirmed by comparison with the eggs dissected out of a female. In all
cases the eggs were laid in the present year’s soft stem, in many cases
very near the apex and in some cases at the thickened bases of the twigs.
They were laid indiscriminately in lenticels or in slits made for the pur-
pose in other parts of the stem, preference, however, was given to a
wound that had become soft, as shown by the presence of a number of
eggs in such situations (PI.IX, fig. 3). They were usually laid singly, but
in some cases more than one egg was found at the same level both in
lenticels and wounds. In the latter situation the number may increase
to five or six.

After a little practice the position of an egg can be easily detected
either as a small brown spot or a little slit in the stem, and under magnifi-
cation one can easily see the brownish cap of the egg with its whitish rim
(see P] IX, fig. 2). Only a small portion of the cap ifanyis above the surface
of the stem. The long hairs of the stem, to a large extent, conceal the
position of the egg which is often made more obscure by the hairs sticking
together on account of the exudation of sap from the wound made in the
stem, and by the liquid from the body of the female. After a few months
the growth of green algae and particles of dust make it impossible to
detect an egg by an external examination of a shoot. But if the bark is
peeled off carefully the eggs may be detected on the inner side as they
usually come off with it. There are no processes extending out from the
egg cap.

Direction of the egg in the stem.

The eggs are laid with their long axes more or less radial to the stem
and often penetrate the xylem and in young stems reach the pith. Some-
times they are more tangential and lie wholly in the bark, this is par-
ticularly the case when a number of eggs are laid at the same level with
their caps close to each other on the surface. They lie somewhat obliquely
with their concave side facing the apices of the twigs and the blunt end
situated in front of the cap (see PI. IX, fig. 1). Only in one case was an egg
found with its convex side towards the apex of the twig (Fig. 3). The
greatest diameter of the egg cap is in line with the long axis of the
shoot and only in one case when the egg was laid in the scars of the
previous year’s bud scales was the long axis of the egg cap at right angles
to the long axis of the stem. This can be explained on simple mechanical

13—2

188 A Study of the Capsid Bugs found on Apple Trees

erounds. The female must have a strong hold on the stem for the action
of its ovipositors and for this it seems necessary that she should hold on
in the direction of the stem and not crosswise. Moreover it is easier to
separate the fibres of the xylem than to cut across them and a longitudinal
slit does not interfere with the growth of the surrounding parts and the
egg remains in a fresh condition. The tissue around the egg remains in a
healthy condition, except probably around the collar of the egg.

From the position of the egg it would appear that the female faces
the base of the twig when ovipositing, and this is borne out by the
structure of the ovipositor which is concave on the dorsal side [i.e. pos-
terior side when ovipositing] and by actual observation on the position
of an egg which was carried about by a female (its laying in tissue
somehow or other interfered with) with its convex side directed ventrally.
The direction of the egg shows that the ovipositor acts almost vertically
to the stem only a little upward in direction. We cannot suggest any
reason for the female facing towards the base of the shoot for oviposition.

Structure of the egq.

The egg has been described by Fryer (12) as somewhat resembling the
rubber portion of a fountain pen filler. It is markedly curved along its
length, with one end bluntly rounded and thick, and gradually narrowing
towards the opposite end forming a neck-like region and slightly ex-
panding into a cap at the top end (see Pl. IX, fig. 4 A). The egg is cream
coloured, the surface is smooth and glistening and the shell is strong and
elastic. The body of the egg is slightly flattened by the fibres of the
plant pressing against it. This part of the egg is thus oval in cross-section
becoming almost circular in the region of the neck. The cap is dark
brown in colour and strongly chitinized. It shows strongly marked
longitudinal striations a]l round, which are probably hairs that hold the
cap to the egg-shell and at the base of it are seen a few scale-like mark-
ings. The function of these markings is obscure. The opening of the egg
is closed by a strong oval disc, brown in colour and showing curious
processes on both surfaces. The outer rim of the cap is whitish with
radially arranged lamellar-like structure when seen from above.

As mentioned above, the egg dissected out of a twig is flatter than one
dissected out of a female. It measures 1-4 mm. in length, 0-3 mm. at its
greatest width, and 0-25 mm. in the region of the neck.

In the body of a mature female the eggs lie in longitudinal direction,
all with their caps pointing forwards. The whole body is practically full
of eggs, which reach right up to the prothorax. The largest number

F. R. PETHERBRIDGE AND M. A. HUSAIN 189

dissected out of one female was fourteen, but it is probable that the
actual number is more than this.

The eggs live in the shoots all through the winter and the young
larvae hatch from them the following April or May.

DESCRIPTION OF THE INSTARS.

Instar I (P1.1X, fig.5). Length 1-1-1-4mm., small, slender, fragile, semi-
transparent. When just hatched pale yellow, turning greenish and darker
in a few hours. On the head and thorax are smoky patches interrupted
on the thorax by a mid-dorsal pale line which bifurcates on the head at
the level of the eyes. The smoky colour is in the chitin whilst the actual
colour of the bug is due to pigments in the tissues of the body.

Head relatively large, marked longitudinal groove just in front
of vertex; yellow, with smoky shades interrupted by a Y-shaped
pale line. A row of short thick black hairs is present on the vertex
and a few longer hairs on the front of the head. Eyes, compound,
large, deep carmine in colour, nearly touching the pronotum.

‘Thorax increases in width up to the metathorax.

Pronotum almost rectangular, anterior margin slightly curved,
angles rounded. Light green with smoky patches interrupted by
mid-dorsal pale line. Row of hairs on posterior margin and a few
irregularly scattered hairs.

Mesothorax with smoky patches; broader than prothorax.

Metathorax shortest and broadest, smoky patches narrower.

Abdomen pyriform, slightly longer than broad; greatest breadth
across segments II-IV. (In a well-fed individual the abdomen is dis-
tended and almost circular in cross-section; but in a starved specimen
it becomes flatter and the first two abdominal segments become
telescoped.) Yellowish green, with a pale line extending from segments
IlI—X, smoky patch on segment I. A large circular yellow area is
present in the mid-dorsal region of segment III. This is the pocket-
shaped dorsal abdominal gland seen through the cuticle; its orifice
is between segments III and IV; the anterior lip is the black thickened
part of the anal margin of tergite III. The anterior part of tergite IV
opposite this is dark and the two lips enclose a light coloured area.
A row of thick short black hairs on each tergite, longer on segments
VITI-X; segment IX also has a number of small hairs. Whole
abdomen covered with a fine fur of setae.

Appendages.

Antennae medium-sized, slender, at first pale yellowish green,

190 A Study of the Capsid Bugs found on Apple Trees

later dusky. Terminal joint yellow at base, changing into orange,

pinkish brown, orange and yellow towards the tip. This pmkish

brown colour is characteristic of all the instars of this species.

Terminal joint longest; 14 times that of the third joint and

slightly thicker. It is thickly covered with hairs, other joints

fewer hairs.

Legs short, thick, at first pale, then turn yellowish green and
dusky, tarsi almost black. Femora light green with a few black
hairs slightly longer than those on the body. Tibia slender with
more and longer hairs. Tarsi 2-jointed, the terminal joint being
the longer. Two black curved claws with transparent aroliae.

Proboscis greenish yellow with a black tip; reaches to about
the middle coxae.

Instar IT (P1.1X, fig. 6). Length 1-5-2-2 mm. Resembles Instar I in
shape. At first yellowish with transparent appendages but soon becomes
darker. The body is distinctly greener than Instar I. The smoky shades
present on the head, thorax and abdomen are now absent. The pale mid-
dorsal line on the abdomen and thorax bifurcating on the head is stil]
present.

Characteristic differences. Nearly double as long. Terminal joint
of antenna slightly longer than joint II; joint II distinctly longer than
joint III. Posterior margin of mesonotum slightly emarginate.

Head large, no groove present; yellow with Y-shaped pale line
present. Eyes deep red, and the number of facets has increased.

Thorax, shape as Instar I.

Pronotum trapeziform, anterior margin slightly narrower than
the posterior; two callosities present.

Abdomen pyriform; longer than broad. No smoky shade on
segment I. The yellow mid-dorsal abdominal gland is still present
on segment IIT and its lips are well marked.

Appendages.

Antennae medium sized, slender—colour as in Instar I; basal
joint thickest; terminal joint longest, slightly longer than joint IT.

Legs similar to Instar I but longer.

Proboscis reaches to about the middle coxae, colour as in
Instar I.

Instar III (P1. X, fig. 7). Length 2-1-2-8 mm. Outline and colour
as Instar II; mid-dorsal line faint.

Characteristic structural peculiarities. The second joint of the antenna
has increased relatively more than the other joints. Terminal joint of

F. R. PeETHERBRIDGE AND M. A. HUSAIN

191

antenna now shorter than the second joint which is the longest; the third
joint shorter than the fourth. Wing pads, small thickened lobes at the
posterior angles of meso- and metanotum, the former being slightly larger.
The wing pads become darker when the nymph is about to moult. Other
characters similar to Instar II, the yellow spot on the abdominal seg-
ment III being rather faint.

Instar IV (Pl. X, fig. 8). Length 1:33-1:99 mm.

Characteristic structural peculiarities. A further increase in the relative

TaBLE I. PLESIOCORIS RUGICOLLIS (MEASUREMENT IN MILLIMETRES).

|
| Instar IV

Instar V

Instar I | Instar II Instar III | Adult
Lifes | {= 2
Length “21 34 | -43 “52 54 56
Head | width 4 52 64. | = -79 9 99
| Distance be- -26 “34 39 =| -45 “5 5
|| tween eyes
: _ (| Length | 21 “26 31 “4. 6 =
Prothorax || Width 38 BD 69 86 1-15 =
(| Length 14 “19 -28 43 67 =
pcan || Widtli 48 6 -36 = — -—
_ {| Length 12 ‘14 SII7/ 7 “19 =
Meine orae | | Width 49 | -66 -88 — — —
: {| Length — — — 85 1-7 =
Wings =| Width a Sy ht ey ase 1-8 a
{| Length 43—-73 8-1-29 | 1-1-1-47 | 1-33-1-9 | 1-9-2-37| —
ei bdomieny i) Sprideh 57 69 95 1:3 1-7 ae
Total length) 1-J-1-4 | 1-5-2-2 | 2-1-2-8 2-7-3°4 | 3-64-27 | 5-9-6-0
1 14 “17 *22 29 38 55
2 -20 +34 “54 86 1:3 1-81
3 17 26 40 57 -76 ‘91
A i]
ntennae | 4 Bil -40 “45 +52 -57 -70
Total length) -82 1:17 161 | 2-24 3-01 | 3-8
= ——= | — ——|__ =_—=—
p Femur -25 “41 52 69 ‘78 1-29
Leg I Tibia “34 -46 -66 “83 1-1 1-6
Tarsus “19 24 28 “34 43 58
| Femur “31 46 6 83 1-1 1-48
Leg II Tibia | +38 7515) -78 1-09 1-48 1-82
Tarsus 2 25 28 | sag) 5 62
Femur +36 47 -69 94 1-2 1-85
Leg III Tibia “45 69 -98 1-5 1-95 2-92
| Tarsus +22 29 34 | 45 595) 68
( 1 16 -20 26 32 “41 | -49
i 2 13 18 21 27 aa | a4
Resa 3 aT 13 16 24 31 | 42
4 18 21 27 0 | 82 41 53
Totallength -56 70), ou 1-] 1:39 1-84

192. A Study of the Capsid Bugs found on Apple Trees

length of the second antennal joint; the third joint is now longer than
the fourth. A change in the shape of the thorax, owing to the increase
in size of the wing pads which now reach the second abdominal segment.
Other characters as in Instar ITT.

TABLE IJ. PLESIOCORIS RUGICOLLIS.

Dates of hatchings Durati f | Records of hatchings and
Stages and of the various een er 2 moults obtained in the
instars Ee laboratory
Hatching *May 5th—13th | — — —_
Instar I present from Hatching Ist moult
May 5th-18th 6 days 5. v. 17 ILE Sys Aly
5. v.17 Le weal a
5. v.17 1 vale
Instar IT present from 1st moult 2nd moult
May 11th—23rd 4—5 days ll. v.17 14. v. 17
Msve Pi 15. v. 17
aS eked 15.00 VY
Ue Ven lel 16. v. 17
12. v.17 isoweudh
Instar II] present from 2nd moult 3rd moult
May 15th—28th | 6 days aS eal 20. v. 17
| 15. v. 17 Po a li
Instar IV present from 3rd moult 4th moult
May 20th—June 3rd 5-7 days 20. v. 17 26. v. 17
20. v. 17 25. v. 17
24, v.17 30. v. 17
24. v.17 Sloe LT
25. v.17 31. v. 17
31. v. 17 6. vi. 17
Instar V present from 4th moult 5th moult
May 25th—June 9th 6-7 days 25. V. 17 eye ily)
| 28. v.17 4, vi. 17
| Sleeve 6. vi. 17
Adult | present from
| June Ist—July 21st about 6 weeks = —

Instar V (Pl. X, fig. 9). Length 1-9-2-37 mm.
Characteristic peculiarities. Colour greener than in previous stages;
second joint of antenna very long, nearly equal to the third and fourth
together. Wing pads larger and reach the fourth abdominal segments.
Yellow spot on abdominal segment IIT not noticeable. Other characters
as in Instar LV.

* Fryer records these larvae as hatching before April 14th in 1913.

F. R. PETHERBRIDGE AND M. A. HUSAIN 193

Hapits.

Plesvocoris rugicollis hatches out after the buds of the apple have
opened and about 16-17 days before the flowers are in full bloom. Very
soon the young larvae move to the opening buds and begin to feed on
the tender opened or half-opened leaves which at this stage are not more
that about an inch in length. On the opened leaves they usually feed from
the upper surface more especially on each side of the mid-rib of the basal
half of the lamina (see Pl. XI, fig. 12). They also feed on the upper surface
of the rolled opening leaves and here they are partially concealed. Every
leaf where they feed soon shows the characteristic brown spots. On being
disturbed they run away very quickly and conceal themselves either in
the curled leaves or the axils of the opened leaves. It is difficult to shake
them off a branch at this stage, even when falling from one of the upper
branches of a tree they hardly ever reach the ground but obtain a hold on
one of the lower twigs either by means of their sharp claws or by ex-
truding the posterior part of their alimentary canal which secretes a
sticky fluid. The hairs on the leaves and stems of the apple seem to help
them in regaining their hold as they are more easily shaken off the black
currant. The later instars are more easily shaken off. At all stages they
run very quickly but seem to be more active during the younger stages.
They dodge like a squirrel by running to the opposite side of the stem
and it is often difficult to catch them.

They share with other insects the habit of cleaning their antennae by
means of the hairs at the ends of the front tibiae after which they often
rub their tibiae against each other. They moult in any situation, cast
skins having been found on both surfaces of the leaves, on the petioles
and on the stems. When ready to moult they become very sluggish and
stop feeding. Moulting takes place by a longitudinal slit in the mid-
dorsal region of the thorax, this being preceded by a throbbing in the
region of the callosities on the pronotum. The thorax and part of the
head and abdomen come out first, followed by the legs and antennae and
lastly by the rostrum. After moulting the bugs feed voraciously, making
repeated stabs at the leaf at the rate of about fifty per hour.

The adults are easily shaken from the trees.

In walking through an infested orchard we have never seen them flying
from one tree to another, but they can fly a fair distance when disturbed.
When shaking them from a tree into a Bignell beating tray they often
fly back again into the tree before reaching the tray and some of those
which reach the tray fly back to the tree again. In the laboratory they

194. A Study of the Capsid Bugs found on Apple Trees

usually flew towards the window in an almost horizontal direction, but
some flew upwards and a few reached the ceiling.

TIME AND NATURE OF INJURY.

In 1917 a very severe and prolonged winter was followed by a
warm spring, the former retarding the opening of the buds and also
the hatching of P. rugicollis. Fryer records them as hatching before
April 14th in 1913 and in 1916 a few newly hatched bugs were found on
April 25th. In 1917 the first markings were seen on May 7th, but under
warmer conditions in the laboratory a few hatched on May 5th. At this
date the buds were opening rapidly, the diameter of well-opened buds
being about one inch and a half, with the outer leaves about an inch long.
The first attack started immediately after hatching and in a day or two
a large number of buds showed the characteristic purple brown markings
on their leaves. The number of attacked buds continued to increase
rapidly on account of new larvae which kept hatching until May 13th
and also because the earlier hatched larvae moved from one bud to
another. It is probable that the hatching period, May 6th—May 13th,
is shorter than the normal period owing to the warm condition obtaining
at this period in 1917.

In some varieties and notably Lord Derby the leaves remained curled
much longer than in other varieties and provided more shelter for the
bugs. The time of full bloom of Early Victoria, Lord Grosvenor and Lady
Hollendale was on May 25rd, i.e. about seventeen days after the bugs
started to hatch and during this time the leaves were the source of food.
In some varieties, e.g. Grenadier, the opened leaves were soon used up as
a source of food and were very badly damaged, the bugs then began to
feed on the closed part of the buds. This variety received a very bad
check from the marking of the young leaves which did not expand to any
extent (see Pl. XI, fig. 14 B).

When the fruit set the bugs were mostly in the fourth instar, some
third and fifth instars also being present. These bugs began to mark the
fruit on May 28th, very soon after setting. All the last three nymph
stages and the adults damage the fruit. In cages in the laboratory they
did not show any marked preference for the fruit but fed upon leaves and
fruit alternately and seemed to be quite satisfied to feed at the place
where they were put, except on old leaves.

They did not attack the fruit after it was over an inch in diameter
but turned their attention to the young leaves and succulent part of the
stem. When the adults appear the fruit is a fair size and not much

F. R. PETHERBRIDGE AND M. A. HUSAIN 195

damage is done to it by them, but the adults do most of the damage to
the shoots. Where the young stem is attacked a brown fluid oozes out,
the stem often cracks and is in some cases killed. When the terminal
shoot is killed several of the buds below form shoots and a very thick tree
results, especially when young trees are attacked. Most of the damage to
the fruit is done by the Instars IV and V.

Wherever a P. rugicollis in any stage sucks a leaf a purplish brown
spot appears after a short time, at first round but soon becoming
irregular. The spot becomes irregular by spreading to the nearest small
veins which form the boundaries of the spot and thus the shape of the
marking is determined by the small veins between which the puncture is
made. The area covered by the spot becomes thinner and sinks below
the normal level of the surface of the leaf.

In older leaves the marking does not spread much but remains as a
small spot. In all cases cork formation takes place round the seat of
injury. When the puncture is very deep the whole of the mesophyll is
affected, but in some punctures from the upper surface only the upper
part of the mesophyll was injured and in some punctures from the lower
surface only the lower part of the mesophyll turned brown. In many
cases the epidermis over the brown spot appeared to be normal. Sections
of injured leaves show that the mesophyll dies first and the epidermis
afterwards. A badly damaged leaf sometimes remains shrivelled and
eventually dies. Some badly damaged leaves do not die but remain
crumpled and deformed, the dead tissue falling out and leaving a number
of holes with a brown margin. In several trees of the variety Grenadier
the leaves were so badly punctured that very little growth was made
until late in the season. In a mild attack the leaves may grow fairly well
whilst showing the small brown marks. Occasionally a vein is punctured
and a brown spot results.

The injury to the fruit varies with the variety. In the slower growing
varieties like Lady Hollendale and Worcester Pearmain the damage is
enormous and badly marked apples do not grow even to one-quarter of
their normal size and often fall off. In the quicker growing varieties like
Bramley’s Seedling and Early Victoria the fruit grows out of the injury
more, and although corky markings and peculiar shaped apples may
result, the reduction of the crop is not nearly so marked.

When a bug punctures the young fruit a small drop of fluid exudes
from each puncture. These drops eventually dry up and leave a brown
mark in the fruit (see Pl. XT, fig. 13). The tissue around the seat of injury
forms cork and is therefore prevented from making normal growth,

196 A Study of the Capsid Bugs found on Apple Trees

dimpled or malformed fruit resulting. In a young apple the injury extends
several cells below the cuticle, but in an old apple there is no discolora-
tion of the flesh under the cork layer.

Punctured apples in their late stages show a russetting due to the
brown cork scars and in some varieties they crack badly. Practically all
the damage to the fruit is done before it reaches an inch in diameter,
probably because later on it is too hard to be easily punctured. In one or
two cases adults were found dead with their probosces inserted into the
tissue of medium-sized fruits. Cork formation follows the punctures in
leaves, fruit and young shoots.

THE CAUSE OF INJURY.

It has been suggested (1, 14) that the injury done by a capsid is due to
the mechanical laceration of the tissues by the barbed stylets of its
rostrum. There is no doubt that the ends of the stylets are barbed and
that the bug does puncture the plant repeatedly, but how far this lacera-
tion is responsible for the brown spots or any other external sign of
damage is difficult to say. A number of different capsids were found
feeding on the same trees but only in the case of P. rugicollis was any
visible damage done.

The stylets of all these capsids are very similar and it seems to us that
the cause of the damage is chemical rather than mechanical, the salivary
injection from P. rugicollis being lethal to the tissue of apple trees whilst
that of the other species is not. This is supported by the fact that it is
the mesophyll and not the epidermis which shows the first signs of injury,
and dead mesophyll may be present under a healthy epidermis, and
again the damaged area may spread for some time after laceration has
taken place.

This brings us to an interesting biological problem. The injury done
to a plant may be mechanical or physiological, and although the final
result to the plant may be the same it seems necessary to distinguish
these two kinds. The term “mechanical injury” might be used to include
the wounding of plants by eating away parts of them or by sucking the
juices. The term “physiological injury” might mean the injection of
some material into the plant which kills the tissue or brings about ab-
normal growth. The same species might be responsible for both mechani-
cal and physiological damage.

It seems probable that in the case of Plesiocorus rugicollis the
mechanical injury is of little consequence. Psallus ambiguus and
Orthotylus marginalis were sometimes as numerous as that species and

F. R. PETHERBRIDGE AND M. A. HUSAIN 197

yet the injury caused by their sucking the juices was of no importance.
An insect that causes mechanical injury would probably do so to all
plants that it feeds on but it is possible that the injection of an insect
that causes physiological injury might affect different plants in different
ways and even be harmless to some plants and also much less harmful
to some varieties of plants of the same species.

It is interesting to find that certain pests are specific in their attacks
whereas others infect a large number of plants. Lygus pratensis is known
to attack fifty different species of plants(7). Plesvocoris rugicollis was
formerly known to attack Salix and Alnus but it now attacks apple,
black and red currants and under experimental conditions has been made
to attack plums. This interesting change in the diet of a species is
possibly comparable with mutations in the morphological characters and
may be due to some physiological mutation in the organism. It is possible
that P. rugicollis may in the future extend its host plants and so become
a still more serious pest.

The change in its diet is difficult to explain but 1t may be due to a
very simple cause. Larvae cannot fly and when just hatched do not
appear capable of travelling far, and their only chance of living seems to
be to suck the juice of the plant on which the eggs are laid. They get
used to this diet and so do not change it readily. Suppose a fertilised
female to be blown on to a new host and not capable of reaching her
former host, she may lay eggs there and if she can live on the juices
of this host the larvae which hatch from these eggs will probably be
able to live on the tissues of the host on which their mother could live,
and in any case are unable to reach the original host of their mother.
Actual experimental evidence is wanting, but we know that nymphs can
be made to change their hosts, e.g. apple to plum, and black currant to
apple, and it would be interesting to see if P. rugicollis could be made to
lay eggs on a species other than that on which it was reared.

The facts that apples and willows are found interlacing and only the
willows attacked by P. rugicollis and also apples and black currants
interlaced with only the latter attacked show that it normally lays its
eggs on the host on which it has fed and does not readily change its host
when that host is capable of providing it with food.

In the Wisbech district P. rugicollis lives on willows, apples, black
currants and red currants, whereas in certain districts near Cambridge
it does not live on apples but does on the other three. Larvae from black
currants near Cambridge were sleeved on apple trees and although they
did not feed readily at first eventually became used to their new host

198 A Study of the Capsid Bugs found on Apple Trees

and completed their development. They begin to feed more readily if
transferred in the early larval stages than in the later stages. Larvae from
apples also reached the adult stage when sleeved on black currants. In
an orchard at Great Eversden where for several years black and red
currants have been attacked, this year the rows of apples near them,
Worcester Pearmain, are also attacked.

The black currant leaves are much thinner than apple leaves and
consequently the brown marks caused by the bugs soon fall out and
leave holes with a brown margin.

Larvae of P. rugicollis when sleeved on plum caused a few markings
but did not live long. The injury was similar in appearance to that of
black currant.

Taylor 3) and Collinge(5) attribute the dimples in apple fruit to the
eggs of Lygus pratensis which are also laid in the stalk of the fruit which
may consequently fall off. This is not the case with P. rugicollis.

CONTROL.

It has been shown by experiments (12, 12 and some carried out
in 1917 by one of us) that P. rugicollis can be kept in check by
spraying with “soft soap and nicotine.” The amount of soft soap neces-
sarily varies with the hardness of the water, 1-0 per cent. or even less is
sufficient for soft water but it may be better to use more than this for
hard water. 0-05 per cent. of nicotine (98-99 per cent.) is sufficient. This
wash kills the bugs very quickly in all stages except the egg stage.

In order to have its maximum effect the wash should be applied just
after all the bugs have hatched and spraying may continue for some time
after the fruit has become marked. It is necessary to spray with a
powerful jet and for this purpose a high pressure pump and a fairly coarse
nozzle should be used. The trees should be thoroughly drenched and
sprayed in a downward direction, keeping the nozzle fairly close to the
opening leaves.

As the eggs are laid in the young shoots, trees from an infested nursery
should not be planted in non-infested areas.

5. SUMMARY OF THE LIFE-HISTORY OF A CAPSID.

Although these bugs do not undergo a sudden change at any moult,
yet each stage possesses characteristic features. The following is a brief
summary of these peculiarities founded on the study of the capsids dealt
with in this paper and others that have come under our notice and will
be applicable to a large number of species.

F. R. PETHERBRIDGE AND M. A. HUSAIN 199

Instar I, Smoky shade on dorsal surface of head, thorax and first
abdominal segment, interrupted in the region of the thorax by a mid-
dorsal pale line which continues on the head and bifurcates at the level
of the eyes (see Pl. IX, fig. 5).

Longitudinal groove present on the head.

Terminal joint of antenna the longest.

Instar II+ (Fig. 6). No smoky shade.

Terminal joint of antenna slightly longer than the second.

No wing pads.

Instar ITI (Pl. X, fig. 7). Small but distinct wing pads.

Second joint of antenna the longest.

Instar IV (Fig. 8). Wing pads reach second abdominal segment.

Second antennal joint relatively longer.

Instar V (Fig. 9). Wing pads reach fourth abdominal segment.

Second antennal joint still longer.

All these instars have 2-jointed tarsi.

6. ORTHOTYLUS MARGINALIS REUT. (NASSATUS FALL. ET AUCT.).

This species hatches about a fortnight later than P. rugicollis and
Psallus ambiguus. The adult resembles P. rugicollis in its green colour
but can be readily distinguished from it by the absence of a collar and
the two callosities on the pronotum; it is moreover covered with fine
white hairs. The eyes nearly touch the pronotum.

The antennae are slender, medium sized, with the basal joint some-
what pale in both sexes, and the terminal joint with no pink colour.

A very distinct orange spot is present between the last two pairs of
coxae.

Male with asymmetrical genital forceps, that of the left side having
two conspicuous prongs.

It is mentioned by Theobald (24, 28) and Schéyen (21) as a pest of apples
but we find no evidence for this. We have found it in considerable
numbers in uninjured orchards.

The egg of Orthotylus marginals is smaller than that of P. rugicollis,
being only 0-95 mm. in length. It resembles the rubber part of a fountain
pen filler with the open end flattened laterally.

It differs from the egg of P. rugicollis in that the transverse section of
the cap is much longer than it is wide and the cap itself is convex.

It is slightly curved in the region of the neck (cf. PI. IX, figs. 4 4 and B).

1 Crosby and Leonard’s (7) third and fourth stage are alike and what they describe
as second stage is really the third.

200

A Study of the Capsid Bugs found on Apple Trees

We dissected out eggs from a female but did not find any eggs in the
stems. Females were put on shoots in cages but we were unable to find

any eggs in these shoots.

The eggs are undoubtedly laid in the stems because the larvae hatch
out on the twigs.
Instar I. Length 1-17—1-26 mm.
In shape very similar to Instar I of P. rugicollis but smaller and dis-
tinguishable by the bright orange-yellow dorsal abdominal gland, which

Tas_eE III.

ORTHOTYLUS MARGINALIS (MEASUREMENTS IN MILLIMETRE).

Instar I Instar If Instar I) InstarIV InstarV,; g 9
ae | Spee | = | |
Length 24 |. -31 | 39 52 5) 58 +6
Head | Width 38 5 63 ‘79 90 94 1-02
ead 1 Distance | 2 28 39 “45 52 44 -52
bet. eyes

(, Length U7 Mu. 224 31 39 ‘58 85 —

Prothorax || Width “a | ORR -66 83 1-2 LS
f (| Length 13 18 25 41 “62 = =
Mesothorax || Width 45 -66 “85 ats ae = ae
Metathorax Length 08 alii “15 Aly aHL7/ —- —
eee { Leneth — == = = 1-6 4:8 os
Weeee (| Width = = zt 1-2 1-9 214 =
{| Length -55—69 | .-76—-95 | -86-1-16 | 1-3-2-0 | 1-9-2-0| — =

Abdomen || Width 48 75 1-0 Ll 1-5 a
Total length | 1-17-1-26| 1-6-1-8 | 1-9-2-4 | 2-7-3-5 | 3-9 6-23 —

Segment | “i 13 “18 “28 “39 “50

eeacear PD Neecdi7a AY), 2°CRG 46 +82 13 1-85

Hit ey els -22 “34 ‘58 -79 1-02

mntounee haba 31 39 47 55 -66

| Total length | 67 96 1:37 2-12 | 333 4-03

(| Femur 24 “37 5 Pik 1:0 1-25

Leg I || Tibia -26 4 By 8 Ll 1-46

| Tarsus 15 18 25 29 38 46

(| Femur “24 “4 5, “82 ell 1-46

Leg I .| Tibia 29 45 63 94 13 1-72

(| Tarsus 15 “18 25 +32 “41 47

| Femur 29 45 56 1-0 15 2-00

Leg III - | Tibia 34. 6 93 1-4 2-0 3-00

|| Tarsus ‘17 27 “31 40 “52 63

(1 a! -18 2 24 “34 “44 51

pandas a 2 -08 15 19 27 36 44

rides asi 3 07 -12 17 23 +29 40

| 4 ‘17 19 21 29 37 -42

FE. R. PETHERBRIDGE AND M. A. Husain 201

is easily seen by the naked eye through the chitin. Lips of this gland very
light brown and not so noticeable as in P. rugicollis.

Yellowish green in colour, eyes dark red with a white margin round
them. Thorax and abdomen covered with long white hairs. Antennae
light orange with a dusky chitin; terminal joint of same colour, not pink
as in P. rugicollis. Other characters typical of first Instars (see p. pus

Instar II, Length 1-6-1-8 mm.

Peculiarities typical of Instar IT (see p. 199), otherwise as Instar I
except for a slight bluish tinge, especially underneath.

Instar III. Length 1-9-2-4 mm.

Peculiarities typical of Instar III (see p. 199), otherwise as previous
instar.

Instar IV. Length 2-7-3-5 mm.

Peculiarities typical of Instar IV (see p. 199), otherwise as previous
instar.

Instar V. Length 3-9 mm.

Peculiarities of Instar V (see p. 199), otherwise as previous instar.

The last three instars have a definite bluish tinge.

7. PSALLUS AMBIGUUS (FALL.) (OBSCURUS D. AND &.).

This species hatches out about the same time as P. rugicollis.
A large number were found in the orchards at West Walton. They are
very shy during the first two stages and lie concealed in the axils of
the leaves and it is very difficult to see them and still more difficult
to dislodge them by beating or shaking. They were found equally
frequently in damaged and undamaged buds, and their behaviour in
cages and in sleeves definitely proved that these were not associated with
the injury done to the leaves and fruit. They were present at the Uni-
versity Farm, Cambridge, and at Histon where there was no trace of
damage. We found them too frequently on apple shoots brought for
our cages, but never found any damage on these and consequently we
regard this species as harmless. One fact is very significant and requires
elucidation. As pointed out above the larvae of Psallus ambiguus lived
for weeks on absolutely dried shoots with no leaves and several of them
reached the fourth instar stage. This suggests that their source of food
may be something other than plant juices. There were present on these
twigs, eggs and nymphs of the apple sucker (Psylla mali) and also eggs
and young of the red spider (Tetranychus sp.). There is no doubt that
they do suck plant juices as we have seen them doing so, but we have also

Ann. Biol. tv 14

202. A Study of the Capsid Bugs found on Apple Trees

seen them sucking the dead bodies of other capsids and it seems probable
that they may be carnivorous and consequently beneficial.

The duration of each instar is very much the same as in the case of
P. rugicollis.

Instar I. Length 1-0-1-4 mm.

Yellow, eyes crimson with a white edge round them.

Thorax and abdomen covered with long white hairs.

TaBLE IV. PSALLUS AMBIGUUS (MEASUREMENTS IN MILLIMETRES).

Instar I | Instar II Instar III InstarIV)| Instar V Adult
(Length 24 | 31> | 23h ee 43
| Width ‘37 -48 ‘57 69 Hi” 8 ‘86
Head , | Distance 28 “31 “34 “4 “45 45
between
| the eyes
wits (li uengthe Pell coda 26 29 43 AR) lee
Ere rae) aerate te 37 51 59 «| «6-760 «| «10 | 16
2 (Length “12 7 92h A Sat ese
Mesothorax \| Width 45 6 | .68 ie ea ial
(| Length ‘ll 12 AS of Sed, 1 pss =
Metathors = 1" “width 51 67 15 | — | — —
‘| Length as cs el TT ON Bed 3-41
Wins | Widthofbody) — "a - 1-1 1:5 | 1:8
= | in the region
of wings
Abdomen !| Length 48-62] -8-88 | -94-1-1 | 1-3-1-6 | 1-7-1-9 |
(| Width 56 68 +85 1-2 1-4 =
Total length | 1-0-1-4 | 1-6-1-8 | 2-1-2:3 | 2-6-3-1 | 3-28-3-6 | 4-5
1 07 14 16 2 28 36
| 2 | 15 298 =|) 64 | 6 “85 1-17
A J 3 13 -22 31 “4 “52 58
UE 4 25 31 28 32 36 4
| E. ie E s =e
{| Total length | -60 95 1-15 1-52 271 sh ene
Femur 27 +34 41 Ne agit! 7 } 9
Leg I Tibia 3 36 ‘5 | +54 “81 11
Tarsus “16 19 | "22 | 427 3 “36
{ Femur -28 36 ‘51 63 | 9 1-0
Leg II | Tibia | Ve8e 43 SBS: > | 2 Ll | 1-4
| Tarsus | -16 19 23 28 35 38
| Femur 39 ‘41 63 8 1-1 | 1-4
Leg III | Tibia | -43 5 79 Ll 1:62 | 21
Tarsus “19 “23 -28 +36 “49 | 58
1 16 20 27 3 41 45
: 2 12 15 19 27 38 41
Proboseis | 3 09 12 18 23 30 36
4 18 21 27 3 40 45

F. R. PETHERBRIDGE AND M. A. Husain 203

Yellow dorsal abdominal gland with faintly marked lips.

Antennae pale orange with a dusky shade in the chitin; terminal
joint of same colour, not pink as in P. rugicollis.

Other characters typical of first Instars.

Instar II. Length 1-6-1-8 mm.

Peculiarities typical of Instar II (see p. 199), otherwise as Instar I.

Instar III. Length 2-1-2-3 mm.

Antennae darker, basal joint darkest.

Head yellow; thorax and abdomen greyish yellow with a green tinge.

Kyes dark red with a white margin.

Peculiarities typical of Instar III (see p. 199), otherwise as Instar II.

Instar IV. Length 2-6-3-1 mm.

Peculiarities typical of Instar IV (see p. 199), otherwise as Instar IIT.

Instar V. Length 3-28-3-6 mm.

Peculiarities typical of Instar V (see p. 199), otherwise as Instar IV.

Adult. Length 4-5 mm.

Oval; 3 dark brown; 2 varies from grey to dark brown, cuneus always
reddish.

Body covered with long pale hairs which easily rub off.

No collar on pronotum.

8. ATRACTOTOMUS MALI (MEY.).

This species has been accused of doing great damage to the apple in
Suffolk and Hereford (26) but in all our experiments we have found it to
be quite harmless. It was not found in any great numbers either at
Wisbech or at Cambridge, but the trees on which they were found in
fair numbers, two or three on one shoot, showed no marks or signs of
injury. While one P. rugicollis larva would cover two or three fair sized
leaves with brown spots in one night, two even three or four nymphs kept
in cages for days on the same shoot did not mark them. We regard this
species as quite harmless.

Instar V (Pl. X, fig. 11). Small, broad, ovate nymph, with deep dark
red colour, very dark on the anterior part of pronotum, wing pads and
two basal antennal joints.

Antennae medium sized with two basal joints very thick and dark red,
thickly covered with black hairs.

The two terminal joints cream coloured with a faint tinge of orange
in the terminal joint.

Femora red, tibiae upper half red, lower half and tarsi pale.

Proboscis reaches the second coxae.

Peculiarities typical of Instar V.
14—2

204. A Study of the Capsid Bugs found on Apple Trees

9. THE ENEMIES OF CAPSIDS.

We gave very little attention to this side of the subject but we never
found any insect attacking capsids. We found a cimicid Anthocoris
sylvestris sucking the dead bodies of capsids at various stages and we
also saw several species of capsid sucking the dead body of the same or
different species. It is possible that Anthocoris sylvestris and also some
species of capsids, e.g. Psallus ambiguus, are capable of killing live capsids,
but we have never observed them doing so.

The young capsids are so active except at moulting that they would
probably escape from such enemies as those which attack aphis. We
found dead capsids on the trees and on healthy shoots in cages but we
were unable to assign a causal organism.

10. THE FOOD OF APPLE-DWELLING CAPSIDS.

Both the nymphs and adults of Plesiocoris rugicollis live mainly on
the juices of the leaves, stem and fruit of various species of plants, but
they have been seen sucking dead individuals of the same or another
species. Where they suck another bug a blackish mark is formed. This
is also true of Psallus ambiguus, Orthotylus marginalis, Atractotomus mali
and larvae of Phytocoris ulmi. Atractotomus mali has been recorded as
attacking caterpillars of Hyponomeuta (13, 20), and in one case we found
a large number of adults near a nest of these caterpillars. Such large
numbers were never found together in any other place.

Psallus ambiquus feeds on plant juices but it can live for several weeks
on dried twigs on which nymphs and adults of Psylla mali and young
forms of Tetranychus sp. were present. No definite observations were
made as to its carnivorous nature, but Rymer Roberts writes that “a
nymph of Psallus ambiquus fed on Aphis avenae and also on two syrphid

eggs.”
11. REFERENCES.

Awati, P. R. Proc. Zool. Soc. Lond. 1914, p. 685.

Brittain, W. H. The Canadian Horticulture. Dec. 1915.

Rev. App. Ento. Dec. 1916.

CaEsar. Ent. Soc. Ontario, 1912, p. 102.

CoLLINGE. Journal Eco. Biol. vol. vit. p. 64.

CrosBy. Cornell Uni. Bull. No. 291, 1911.

CrosBy and LeonaRD. Cornell Uni. Bull. No. 364, 1911. Give a long list of
literature on Capsidae.

Dovetas and Scorr. <A Catalogue of British Hemiptera, 1876.

Fauuert, C. F. Monographia cimicum sveciae, 1818, p. 76.

Freser, F. X. Die Europiiischen Hemiptera Halbfliigler, 1861, p. 272.

Fryer, J. C. F. Preliminary notes on the damage of apples by Capsid Bugs.
The Annals of App. Biol. vol. 1. no. 2, 1914.

Fryer, J.C. F. Journal Board of Agriculture, Jan. 1916.

Sl Saree ten oie

fj —
NPS 00.

THE ANNALS OF APPLIED BIOLOGY. VOL. IV, NO. 4 PLATE IX

MAH del

THE ANNALS OF APPLIED BIOLOGY, VOL. IV, NO. 4 PLATE X

cia ed Dd) Pitan fp
ee SY
PL RU OL res

MAH det

THE ANNALS OF APPLIED BIOLOGY. VOL. IV, NO. 4 PLATE XI|

F. R PETHERBRIDGE AND M. A. Husain 205

12a. Fryer, J. C. F. and Petuersrines, F. R. Journal of the Board of Agriculture,

April, 1917.

13. GrarD, A. Sur un Hemiptére Atractotomus mali (Mey.) parasite dechenilles
d’Hyponomeuta malinellis. Bull. de la Soc. Ent. de France, 1900.
14. Horne, A. S. and Lerroy, H. M. Effects produced by sucking Insects and
Red Spiders on Potato foliage. The Annals of App. Biol. vol. 1.
15. pues moe Observation on the oviposition of certain capsids. Jour. Geo.
nt. ;
16. Lkonarp. Immature stages of Plagiognathus politus Uhler and Compylomma
verbosci Henick-Schaeffer. Jour. New York Ent. Soc. vol. xxi.
17. OscHantn, B. Verzeichnis Palaearktischen Hemiptera. Bd. 1. Heteroptera,
p. 733, 1909.
18. Parrot and Hopakiss. New York Agr. Exp. Sta. Bull. No. 368, 1913.
19. Reuter. Hemiptera Gymnocerata Europae. xxtt. No. 2. Acta Societatis
Scientiarum Finnicae.
20. —— Food of Capsids. Ent. Month. Mag. vol. xiv. pp. 121-127, 1903.
21. Scnéyen. Beretning on Skadeinseketer og plantisygdommer i land og havebrukt,
1914.
22. Soravgr, P. Handbuch der Pflanzenkrankheiten, Bd. ut. p. 630, 1913.
23. Taytor, EK. P. Jour. Geo. Ent. vol. 1. p. 371.
24. THEOBALD, F. V. Report on Economic Zoology, 1910, p. 37.
25. — _ Report on Economic Zoology, 1912, pp. 23-25.
26. — Journal of the Board of Agriculture, 1913, p. 112.
27. —— Report on Economic Zoology, 1913, pp. 27-33.
28. Report on Economic Zoology, 1914.
29. WesstEeRand Stoner. Life history of Calocoris rapidus. Jour. New York Ent.
Soc. vol. Xx. pp. 229-234, 1914.
EXPLANATION OF PLATES.
PLATE IX.
Fig. 1. Egg of Plesiocoris rugicollis in situ.
Fig. 2. Surface view of the cap of an egg of Plesiocoris rugicollis in situ.
Fig. 3. Eggs of Plesiocoris rugicollis in situ.
Fig. 4. A. Egg of Plesiocoris rugicollis.
B. Ege of Orthotylus marginalis.
Fig. 5. Plesiocoris rugicollis, Instar I.
Fig. 6, = =f lhe
PLATE X.
Fig. 7. Plesiocoris rugicollis, Instar III.
Fig. 8. 35 + ae ae
Fig. 9. a 7 att eis
Fig. 10. : », Adult.
Fig. 11. Atractotomus mali, Instar V.
PLATE Xl.
Fig. 12. Apple leaves marked by Pleszocoris rugicollis.
Fig. 13. Young apples marked by Plesiocoris rugicollis.
Fig. 14. Two apple trees (variety Grenadier).

A. Sprayed and showing normal growth.

B. Unsprayed and showing a severe check to the growth of the leaves due to Plesio-

coris rugicollis.

206

NOTES ON THE STRAWBERRY LEAF BEETLE
(GALERUCEHELLA TENELLA LINN.).

By H. C. EFFLATOUN, F.E.S., M.R.A.C.
(With 3 Text-figures.)

Specimens of the larvae of this strawberry beetle, recetved by Mr F. V.
Theobald were given to me to describe and follow out the life-history.
The following are some notes I have made in regard to the various stages.
It is hoped that, later, fuller details of the bionomics of this insect will be
ready for publication. The insects bred in the laboratory of the South
Eastern Agricultural College were sent to Prof. Theobald from County
Monaghan, Ireland, where they had done much damage.

LARVA.

Length, one-eighth to one-sixth inch. Colour, dirty greenish yellow,
head black. All the segments of the body, with the exception of the head,
pronotum and anal segment, have a pair of elongate, transverse, thickish
stripes, the cephalad stripe being larger than the caudad one. The stripes
on the meso- and metanota are separated as shown in the figure. The
dorsal segments are transversely furrowed. Each segment of the body,
with the exception of the thoracic region (pro-, meso- and metanota) have
four shining black tubercles on each side. These tubercles vary in size,
the largest being near the transverse stripes. The pronotum is free from
markings or tubercles and is uniformly dark brownish-grey. The meso-
and metanota have two tubercles instead of four on each side; the inner
pair are somewhat round, while the outer pair are much larger and some-
what crescent-shaped. The terminal segment is brownish-grey and more
hairy than the rest of the body. There are three pairs of true (segmented)
legs, which are black, on the three first segments of the body. Hach*bears
two sharp claws. The anal segment possesses a large and simple process
or proleg by means of which the larva progresses after the manner of one
of the Geometridae. The body is covered with more or less numerous
yellow hairs.

H. C. EFFLATOUN 207

PUPA.

About one-tenth inch in length: dark yellowish-brown and slightly
hairy. There are fourteen black spines on the dorsum of the cephalic
region, each spine arising from a dark papilla, and eight smaller spines on
the thoracic region.

- The abdominal region has seven distinct segments, the first six of
which carry a pair of large, black and shiny tubercles, a pair of small
spines in the centre, and another pair of slightly larger spines on the
sides. The lateral spines on the sixth segment are stouter and larger than
the others. The antennae, instead of curling down between the legs, on
the ventral side, extend outwardly and are curved round the back of the
legs.

IMAGO.

Length, one-ninth to one-seventh inch. The colour varies slightly
from dull yellow to pale brownish. The head has a broad black stripe
across it and the head itself is yellow. The third joint of the antennae is
longer in proportion than the second. The thorax has a small, more or
less round depression on each side and is yellowish in colour with a dark
furrow in the centre. The tubercles on the forehead are distinct and
shiny. The punctures of the elytra are not deep but present a granulated
and shiny appearance. The suture and margin of the elytra are yellow
and the shoulders are dark. The ¢ has the fifth segment (ventral) of the
abdomen slightly impressed at the apex, the same segment being almost
entire in the 9. The legs are pale; the antennae yellowish and dark at
the apex. “The series in the British Museum shows some variation with
regard to markings” (1) and “occasionally the elytra are marked with a
more or less dark band” (2).

NATURE OF DAMAGE.

Both the larva and the imago damage the leaves of strawberries in
exactly the same way. They eat the lower and upper epidermis and the
soft underlying tissue, leaving the opposite layer of epidermis intact.
The leaves then present a curious and characteristic spotted appearance.
If the leaves are left exposed to weathering conditions they may then
present a different appearance; they will appear as if regular holes had
been eaten out of them and thus errors may arise when trying to identify
the insect related to the damage.

The larvae from which the adults were bred were fully mature so that
no observations were made as regards their habits, moults, etc.; pupation

208 Notes on the Strawberry Leaf Beetle

began the day following their arrival and this took place underground
without the formation of a cocoon.

Date of pupation: June 21st—24th.

Adults hatched: July 22nd to 26th.

The beetles, on hatching, were in a fairly active condition but it took
them from three to six days to harden. At the least sound or noise the
beetles feigned death and dropped to the ground where they soon
burrowed and disappeared out of sight. They were hardly ever observed
to feed in the daytime. They fed mostly during the nights and early
mornings, when quite a few did not seem to be disturbed, either by noise
or even by handling their pot-plant.

This is not the first time that the species has been reported as injurious
to the strawberry plant. Ormerod(3) received information of damage
done by it from Hundred Acres, Wickham, Hampshire, with a note that
they were destroying the strawberry plants in that neighbourhood, and
that it was considered a new pest in the locality. Mr Theobald has re-
ceived it this year from Buckinghamshire also.

Lampa (4) records it from Sweden.

Sacharov (5) records it for the first time in Russia as injurious to
strawberries. “The beetle winters,” he says, “underneath old leaves on
the beds of strawberries; with, the arrival of warm weather the insects
appear and feed on the young leaves, and oviposit during April and May.
The eggs are deposited by the female in a hole gnawed by it in the leaf,
3-10 eggs being laid in such a hole. The egg-stage lasts 12-14 days.”

Anal proleg
(side view).

Fig. 1. Larva of @. tenella.

H. C. Erriatoun

cael et

Ventral view. Dorsal view.

Fig. 2. Pupa of G. tenella Linn.

Fig. 3. Upper surface of leaf damaged by G. tenella.

209

210 Notes on the Strawberry Leaf Beetle

REFERENCES.

THEOBALD, F. V. (1909). The Insects and other Allied Pests of Orchards, Bush
and Hothouse Fruits and their prevention and treatment, p. 459.
Fow ter, Rev. Canon (1890). The Coleoptera of the British Islands, vol. 1v, p. 330.
OrmeEROD, E. A. (1898). Handbook of Insects injurious to Orchards and Bush
Fruits, p. 249.
Lampa (1907, 1908). Upps-prakt. Ent. vol. xvu, pp. 3-5, and vol. xvi.
pp. 80-81. :
SacHarov (N.). Hntom. Stat. of the Astrachan Society of Fruit Growers, Market
Gardeners and Agriculturists, Astrachan 1913.
and
SacHarov, (N.) and SHEMBEL, (S.). Report on the activity of Entomological
Station in 1913 (Astrachan).
and
SacHarov, (N.). The Injurious Insects, noticed in the Govt. of Astrachan from
1912 to 1914. From the report of the Station for 1914.

SoutH EASTERN AGRICULTURAL COLLEGE,
Wve, Kent.
October 1st, 1917.

—_— 7 es”

211

OBSERVATIONS ON PIMPLA POMORUM RATZ.,
A PARASITE OF THE APPLE BLOSSOM WEEVIL
(INCLUDING A DESCRIPTION OF THE MALE BY
CLAUDE MORLEY, F.Z.S.).
By A. D. IMMS, M.A., D.Sc.,
Reader in Agricultural Entomology, Manchester University.

(With Plate XII and 5 Text-figures.)

CONTENTS.

PAGE

1. Introductory Remarks . : : : ; : eral
2. The Female : ; . - - : : 4 ae ae
3. The Male. : - : - peels
4. Observations on the Biology of the Species é : - 214
5. The Young Larva , " : : . : : Se edly
6. The Fully Grown Larva. : : . els
7. Comparison with Larvae of other ieenasonniae a . . 220
8. The Male Pupa . 222
9. The Female Pupa 223
10. Efficiency as a Parasite : : 223
11. Remarks on other Parasites of A sionon us pomorum . 225
12. Summary of General Conclusions 225
13. References to Literature 226
14. Explanation of Plate . 227

1. INTRODUCTORY REMARKS.

Towards the end of May, 1916, I received several consignments of
apple blossom buds attacked by Anthonomus pomorum. These were
kindly sent at my request by Mr J. C. F. Fryer, Entomologist to the
Board of Agriculture, who obtained them from an orchard at Chatteris,
Cambridgeshire, where the weevil is often abundant. It is a well-known
fact that A. pomorum is a most difficult pest to control on account of its
concealed habits of feeding when in the larval stage, which greatly mili-
tates against the effective application of insecticides. The female weevil
deposits her eggs in the blossom buds of the apple before they open,
and, see to Theobald (1909, p. 106), the young larvae hatch out in
from 5-7 days. The blossoms commence to expand but rarely fully open,
further growth ceases, and the brown shrivelled petals form a kind of
dome-like cap over the receptacle. If one of these so-called “capped

212 Observations on Pimpla pomorum

blossoms” be opened the small white apodous larva of the weevil will be
found in the centre. In many cases the larva of the weevil will be found
to be dead, or weakly, and accompanied by a smaller larva not very
unlike it in appearance. This latter larva in most instances will prove to
be that of Pimpla pomorum, which forms the subject of the present
investigation.

During the past year I have carried out a preliminary investigation
of the parasites which attack the apple blossom weevil, in the belief that
a possible method of control might eventually be afforded by the utiliza-
tion of these natural agencies. In this connection it is noteworthy that
Marchal (1907, p. 15) quotes the experiments of Decaux who was im-
pressed by the multitude of ichneumon flies, or Braconids, which came
out of apple buds attacked by A. pomorum. Instead of immediately
burning these buds as was usually done, Decaux preserved them in boxes
covered with gauze, raising the latter from time to time to allow of the
escape of the parasites. In 1880 he put this method into use and collected
in Picardy five hectolitres of buds from 800 apple trees. By this means,
it is stated, that more than a million Anthonomi were destroyed and
about 250,000 parasites liberated which, in the following year, were
valuable aids in the destruction of the weevils. The orchards treated
were surrounded by cultivated fields and consequently isolated from
neighbouring fruit plantations. It sufficed to repeat the same operation
during the following year, in order to prevent serious damage from the
weevil during the succeeding ten years, so thoroughly had the parasites
done their work.

The results obtained during one year’s preliminary investigation con-
firmed my surmise that the apple blossom weevil is, in certain localities,
at any rate, in this country, equally heavily parasitised. Owing to the
great difficulties in obtaining labour entailed by the War, it has not been
found possible to prosecute these investigations any further at present,
as very considerable quantities of affected blossoms are needed from
various parts of the country. Nevertheless, the facts already observed
are, I think, of sufficient importance to merit publication. I must express
my indebtedness to Mr Claude Morley, who examined a pair of the adult
ichneumons submitted to him and identified them as belonging to the
species Pimpla pomorum Ratz.

2. THE FEMALE.

This species was first described by Ratzeberg (1848, p. 96) from
females bred by Reissig from Anthonomus pomorum in pear blossom

A. D. IMs ANB}

which is an infrequent host plant for the latter. Subsequently both sexes
were reared from the same weevil by Nordlinger, and Ratzeberg later
adds (1852, p. 103) that Reissig bred both sexes from apple blossom. In
1912, Catoni recorded having reared considerable numbers in the Trentino.
As adequate descriptions of this sex are given by Schmiedenknecht
(1906, p. 1084) and Morley (loc. cit. p. 76), it is neither desirable nor
necessary to add anything further so far as the female is concerned.
Morley states that examples of this sex are one of the commonest of
all Ichneumonidae in Britain in the early spring. There are, however,
very few records apparently due to the fact that the imsect was not
recognised as being a British insect until 1889 when Bridgman established
its identity. Up to the present, it is known from certain of the southern
and south-eastern counties, but further collecting and observation will
doubtlessly reveal its distribution to be more widely spread.

3. THE MALE.

Although the female is an abundant insect very little has been known
concerning the male. Ratzeberg surmised that an example bred by
Nordlinger, along with females of this species, probably belonged to it;
similar males and females were afterwards reared by Reissig. In 1912
Catoni reared a number of males from the Anthonomus in Italy but
apparently was unaware of their seeming rarity. I know of no further
records concerning this sex. Ratzeberg’s description is very brief and
inadequate but, since it was the only information available, is copied by
Schmiedenknecht (1906, p. 1085) and Morley (1908, p. 77). During the
course of the present investigation I have bred out a considerable number
of examples of this sex and as the result I am able to include herewith

a full description thereof which has been drawn up and forwarded to me
by Mr Claude Morley.

DESCRIPTION OF THE MALE oF PiwpPLaA (EPIURUS) POoMORUM RaTz.,
BY CLAUDE Mortey, F.Z.S., ETC.

Head with the face and short cheeks immaculate black; mandibles
and palpi pure white. Antennae filiform and not apically attenuate,
nigrescent testaceous and about half the length of body, pale beneath
with the scape and pedicellus pure white below. Thorax with short white
humeral callosities before radices, but the collar not in this instance (as
is stated by Ratzeberg) pale; metanotal areae wanting, at most the basal
indicated; metathoracic apex impressed before a longitudinal carina on
either side; spiracles circular. Abdomen linear and not very strongly

214 Observations on Pimpla pomorum

punctate; basal segment distinctly punctate laterally ; third segment dis-
tinctly a little longer than broad (as in P. wlicicida, Morl.; Hntom. 1911,
p- 161, ¢ 9 and herein my character for their distinction given at Revis.
Ichn. Brit. Mus. 111. 1914, p. 82, fails in the 3 sex); the deeply impressed
thyridii, and the third to fifth segments especially basally, pale castane-
ous; the sixth to eighth narrowly whitish apically; valvulae incon-
spicuous. Anterior legs and hind trochanters white, with onyches and
onychii of the intermediate tarsi nigrescent; front femora entire and not
emarginate beneath; hind coxae and femora pale testaceous; hind tibiae
white, with apical third and a band before base connected by an internal
striga nigrescent; pulvill large, but shorter than claws; calcaria and
basal third of metatarsus white. Wings with the radix and tegulae white,
stigma pale luteous; basal nervure continuous through median; areolet
nearly twice as broad as long, emitting the oblique second recurrent
nervure from very near its apex; nervelet obsolete; nervellus hardly
geniculate and intercepted by the weak spurious nervure at its lower
third or fourth.

This male has hitherto been mixed in Britain with that of P. puncti-
ventris Thoms. which name is inserted in errore at Ichn. Brit. 11. 1908,
p. 81.

In the above description Morley describes the scape and pedicellus
of the antennae as being pure white below. From an examination of
eight examples these joints were seen to be stramineous in every case,
so possibly there is some variation in this respect. As the sexual differ-
ences are very marked in this species I append below an enumeration of
the most characteristic features afforded by a comparison of a number of
male and female examples.

MALE FEMALE
Scape of antennae stramineous ventrally Scape of antennae fuscous ventrally
Thorax black Mesothorax, ‘the greater part of the pleurae,

and a pair of apical spots on the meso-
thorax, red
Abdomen minutely punctate, testaceous Abdomen coarsely punctate, dark brown or
or infuscate almost piceous
First abdominal segment oblong First abdominal segment not longer than
apically broad

4. OBSERVATIONS ON THE BIOLOGY OF THE SPECIES.
The larva of this Ichneumon lives entirely external to its host, which

may be either in the larval or pupal stage of development. Whether it
is the larva or pupa that is destined to furnish the food-supply of the

A. D. Imus 215

Pimpla, depends upon the time of oviposition by the latter. The earliest
hatched larvae meet with larval weevils only, but the later examples
will, more often than not, find the host in the pupal condition. Which-
ever occurs the life of the parasite is the same. Its young larva is usually
to be found on the dorsal side of the host larva, with the mouth-parts
immersed within the tissues of the latter. The position occupied by the
parasite is not constant since the latter was found attached to its host
in the following situations: to the fourth tergum; between the eleventh
and twelfth terga; to the eighth tergum; between the third and fourth
terga; to the second tergum; to the sixth tergum and, in one instance,
between the twelfth and thirteenth sterna.

If it be the pupa that is attacked, the parasite was invariably ob-
served to select the anal extremity of the latter. Half-devoured pupae
were often met with, the abdomen being largely shrunken away, though
the remaining portion of the host appeared to be quite fresh, and ex-
hibited no signs of discoloration or putrefaction. Under these circum-
stances, it appears not unlikely that the parasitic larva may inject some
kind of secretion into the tissues of its host, serving as an antiseptic
arresting decomposition.

Only a single parasite was found in relation to each individual host,
and a good deal of overlapping of the development stages was found to
occur—a feature which is far from rare among hymenopterous parasites.
Thus, on May 25th, I found Pimpla larvae 2 mm. long, half and fully
grown larvae, larvae commencing to spin their cocoons, and fully formed
pupae from among less than fifty examples of the Anthonomus.

When fully fed, the larva spinsa slight silken cocoon, which is ovoid
in shape, measuring on an average 6 mm. long and 2 mm. in diameter
(Text-fig. 5). The cocoon can be readily detected within the cavity of
the affected apple bud; the silk of which it is composed is white, or, in
some instances, the outer fibres thereof are pale brown in colour. When
examined under a low power objective, the fibres can be readily observed
to be arranged for the most part in a circular manner around girth of
the cocoon. The whole structure, and the interstices between the threads,
is varnished over with a very thin and transparent layer of glutinous
secretion.

Under laboratory conditions, the first example issued on June 17th,
1916, and was a male, the actual time being twenty-three days from the
date of commencement of spinning the cocoon. From the above date
onwards, until July 5th, a large number of the parasites emerged, the
first female appearing on June 21st.

216 Observations on Pimpla pomorum

It is noteworthy that all of some eighty unparasitised examples of
the host weevil, reared during this investigation, emerged from the pupa
prior to the appearance of the Pimpla, none issuing later than June 13th.

After the emergence of the perfect insects, the subsequent life of the
species isa mystery. It is perfectly clear that there is no available supply
of the larvae or pupae of the weevil until the following year. It appears
improbable that the adult parasite awaits a period of about ten months
for the reappearance of its larval host. Most probably it utilises an
alternative species, and passes through a second annual generation,
though what that host is likely to be is hard to predict.

A further point of interest is the fact that the parasite occurs in dis-
tricts where Anthonomus pomorum is unknown. For example in Suffolk,
according to Morley (1908, p. 77), this weevil is absent, nevertheless the
parasite is a common insect in that county, and may be frequently
beaten out of Coniferae. Nothing, however, is known regarding the host
which it utilises on such occasions.

In this connection some clue may possibly be afforded if we take into
account the various hosts utilised by other species of the genus Pimpla.
There is no doubt whatever that Lepidoptera are usually selected and,
out of the forty British species of Pimpla, which are enumerated by
Morley (1908, pp. 51-118), the vast majority have been bred from various
members of this order of insects. The most usually parasitised species are
Retinia buoliana, R. resinana, Tortrix viridana, Orgyia antiqua, Odonestis
potatoria and Clisiocampa neustria. Many other species, however, serve
as hosts and great variation is exhibited in the size of the host selected.
Thus Pimpla rufata Gmeb. has been bred from Tortrix viridana and the
relatively gigantic Sphinx ligustri; and P. instigator Fab. from Psyche
viciella and Smerinthus populi! Outside the order Lepidoptera there are
few reliable records; four British species of Pimpla have been bred from
the egg masses of spiders and about six species have been reared from
Coleoptera, almost exclusively Curculionidae. With the exception of
Pimpla pomorum these latter species have been reared from Lepidopterous
hosts also. Of the species known to parasitise Anthonomus pomorum the
following host records are enumerated by Morley (1908, pp. 60, 81, and
99). Pimpla graminellae has been reared from Odonestis potatoria, Epippi-
phora scutulana (or EB. pflugiana) and Clostera reclusa. Pimpla sagax has
been reared from Retinia buoliana, R. resinana, R. turionana, Coccyx
cosmophorana, Tischeria complanella, Conchylis posterana, and Ixtho-
colletis trifasciella. Morley (loc. cit. p. 81) also records an example bred
on April 26th from dried heads of Centaurea mgra gathered beneath

A. D. Imus vA De

fir trees. He suggests the gall-forming Trypetid Urophora solstitialis as
its host, “unless of course its presence there was purely accidental and
its true association were with the overhanging conifers, in which case it
would surely have shown itself in the jar in the course of the preceding
month.” In my opinion it is more probable that one or other of the
several species of Lepidopterous larvae which inhabit the flower heads
of Centaurea is the host in question. Pimpla examinator Fab. has been
bred from Retinia buoliana, Liparis chrysorrhoea, and many other Lepi-
doptera. Pimpla pomorum is exceptional in that it has only been bred
with certainty. from Anthonomus pomorum. From analogy with other
species of its genus it 1s probable that it utilises Lepidopterous hosts also,
although it is remarkable that it has not so far been reared therefrom.
Morley states that he has invariably beaten it from Pinus sylvestris and
Picea excelsa in fir woods about Bentley in Suffolk. This suggests that
Retinia buoliana or other pine infesting Tortricid may prove to be one of
its hosts. In the absence of pine trees (as in the Chatteris locality, Cam-
bridgeshire) certain of the commoner Lepidopterous larvae feeding on
apple, hawthorn and other plants, may not unlikely prove to be para-
sitised by this species.

As a general rule the parasites of exposed hosts—in other words host
insects not sheltered by a cocoon, or in a bud, leaf or stem—live in-
ternally. Howard has remarked (1913, p. 161) that it is very rare to find
an external Hymenopterous parasite on an unprotected host insect, and
it occasionally happens that the same species of parasite, in its larval
stage, will feed exteriorly upon a protected host and interiorly upon an
unprotected host. So little is known concerning the biology of the genus
Pimpla that it is impossible to assert how far the ecto- and endoparasitic
habits prevail, as both protected and exposed hosts may be utilised by
one and the same species. A thorough investigation of the economy of
members of this genus is likely to yield results of considerable biological
interest and importance.

5. THE YOUNG LARVA.

The smallest larva met with measured 1-1 mm. long (Plate XII, fig. 1)
and, although I have had no opportunity of examining the newly hatched
individual, I have little doubt that it does not differ from the latter in any
essential details of its morphology. It is pearly white in colour, and differs
from the fully grown larva in the following among other features.
(1) The relatively large size of the head, which is completely exserted,
and incapable of any withdrawal into the first trunk segment. It

Ann. Biol, tv 15

218 Observations on Pimpla pomorum

measures -22 mm. long and -24 mm. broad, the ratio of the length of the
head to the total length of the larva being as 1 : 5-4; in the fully grown
larva the ratio is 1: 8-3. The antennae are equal

in size to those of the fully grown larva, and are oCsO
consequently of a much greater relative size. (2) The Bye
dorsal curvature of the body is much less pro- ©

nounced. (3) The labial and maxillary papillae are _
represented in each case by a group of six or seven Tig.) Papiiiac from the
minute cuticular structures on either side (Text- Jabium of a young
fig. 1). (4) The body segments are more rounded are Meee
and uniform in character, and the dorsal pseudopodia are not yet formed.
(5) The tracheal system is incompletely developed, and nine pairs of
spiracles are present, the minute vestigial second pair not yet being
evident.

6. THE FULLY GROWN LARVA.

When fully grown the larvae vary from whitish, or dull cream colour,
to pale brownish white or pink, and measure when alive from 4-5 to
5 mm. in length, with an average maximum breadth of 1-25 to 1-5 mm.
They are elongate fusiform in shape, narrowing towards the two ex-
tremities, and more so at the anal than at the cephalic end. The dorsal
surface is more prominently arched than the ventral (Plate XII, fig. 2),
and the cuticle is studded with numerous minute conical chitinous
papillae. These structures have an average diameter of -004 mm. and
give the cuticle, under a low magnification, the appearance of fine
shagreen; those on the dorsal region are slightly larger than elsewhere.
A few short setae occur and, for the most part, are grouped in the form
of a loose circlet around the middle of each segment. A well-defined
head is present followed by thirteen sharply.demarcated body segments,
which are related to one another in length in the following proportions:
6-7: 6:5-6:6:7: 7-8: 8-9: 8-9: 7-8: 6-7: 5: 3-4: 3. Owing to the
variable amount of contraction or extension which the segments undergo,
these ratios are not capable of more exact determination. The head
differs from the remainder of the body in being enclosed in a smooth
and slightly thicker chitinous investment; it is, moreover, usually a little
darker in colour. It is about as broad as long, measuring -6 mm. in
either direction. On the dorsal] aspect, it has two ovoid or somewhat
pyriform infuscate markings, which are placed alongside the middle line,
parallel with the longitudinal axis, Definite though vestigial antennae

A. D. Imus 219

are present; they are peg-like in form and measure -049 mm. long and
‘007 mm. wide across the middle region (Text-fig. 2).

The mandibles (Text-fig. 3) closely resemble one another. At its base,
each is flattened and plate-like and measures -07 mm. in breadth;
apically it is drawn out into a straight spine-like piercing tooth, beset
with minute spines along a portion of its antero-posterior margins. The
mandible measures, from the apex of the tooth to the condyle, -11 mm.
in length.

—_

Fig. 2. Right antenna of a fully grown ‘Fig. 3. Right mandible of a fully grown
larva: highly magnified. larva. x300.

Fig. 4. Ventral view of the labium and Ist maxillae of a fully grown larva; x 600.
1, labium: m, 1st maxilla (left): p, sensory (?) papillae. The dotted lines indicate the
position of the underlying head skeleton.

The mouth is bounded dorsally by the labrum, laterally by the first
maxillae, and its floor is formed by the labium. The labrum is an oblong
transverse plate, slightly curved and measures -13 mm. from side to side,
and -04 mm. in the antero-posterior direction. The first maxillae (Text-
fig. 4) are extremely simple and their ventro-lateral margins are closely
applied to the sides of the labium. No traces of galeae or laciniae are to
be found, neither is there any division into basal sclerites. Near to its
outer free margin each maxilla carries a papilla (p) arising from a divided
basal ring of chitin measuring -015 x -011 mm. This structure occupies
the same position as the group of small papillae found in the young

15—2

220 Observations on Pimpla pomorum

larvae. The labium (1) is ovoid in form and measures -14 mm. in length
and -10 mm. broad (Text-fig. 4). Its free margin is simple and undivided;
a pair of papillae (p), similar in form and size to those found in the first
maxillae, are also present. These are similarly represented in the young
larvae by a pair of groups each comprising seven minute papilla-like
structures. From their position and constancy of occurrence, these struc-
tures suggest their possibly being the vestigial counterparts of the labial
and maxillary palpi, and have been regarded as palpi by Cushman in his
description of the larva of Thesolochus conotracheli (1916, p.853 and Fig. 8).
The fact that in Pimpla pomorum, at any rate, they are represented in the
young larvae by groups of minute papillae, militates against this inter-
pretation of their morphology.

The trunk segments are separated by deep, well-defined intersegmental
grooves, and segments 4 to 10 have the tergal region raised in such a
manner as to form a row of transverse mid-dorsal tubercles or pseudo-
pods. These are only slightly developed and are more noticeable from a
lateral rather than from a dorsal view (Plate XII, fig. 2). Ina similar way,
the lateral regions of the same segments are slightly produced outwards to
form rounded mamilla-like swellings. Ten pairs of spiracles are present,
and are situated on the first, second, and fourth to eleventh segments.
The first pair is placed on the posterior region of its segment, near the
intersegmental groove separating it from the succeeding segment. The
second pair of spiracles is vestigial and non-functional. These spiracles
are very small and hard to detect; they occupy a position on their seg-
ment similar to that of the preceding pair. No spiracles are present on
the third segment, while the remaining eight pairs are situated far for-
wards on their respective segments.

7. COMPARISON WITH LARVAE OF OTHER ICHNEUMONOIDEA.

In the possession of a well-defined head and thirteen body segments
the larva of Pimpla pomorum conforms to the usual type found among
Ichneumonoid larvae. This same number of segments has been found to
obtain in a number of species, notably by Xambeu (1898)! in Pimpla
oculatoria Grav., by Seurat (1899) in P. mexicana, by Giraud (1863) in
P. detrita Holmg. (graminellae Grav.), by Ratzeberg (1844) in Exochilium
(Anomalon) circumflecum L., by Riley (1888) in Thalessa lunator Fab.,
by Berthoumieu (1894) in Ichnewmon rubens Fons., by Morley (1903) in

1 Xambeu mentions (p. 239) twelve segments in P. oculatoria, the hindmost being
“prolongé par un mamelon rétractile”; the latter structure, however, appears to be the
reduced thirteenth segment.

A. D. Imus 221

Exetastes cinctipes Retz., by Wardle (1914) in Hypamblys albopictus Grav.,
by Cushman (1916) in Thersolochus conotracheli Riley, by Klapalek (1889)
in the curious larva of Agriotypus, by Cushman (1913), and subsequently
by Smith (1914) in Calliephialtes, and also by Seurat (loc. cit.) in the
following species: Mesochorus vittator Zett., Anilasta ebenina Grav. et
Thom., Xylonomus praecatorius Fab., and Phymatodes variabile. Newport
(1855) similarly recognised thirteen segments in the larvae of Paniscus
virgatus Foure., and Anthophorabia (Mellitobia) retusa Newp., while Graf
(1917) figures a similar number in the larva of Bassus gibbosus Say.
Apparent exceptions to this rule are often difficult to explain, and very
possibly in some instances the small thirteenth segment has been over-
looked. Thus Timberlake (1912) only recognised twelve segments in the
larva of Limnerium validum (Cress.) and Morley (1914) mentions a
similar number in Paniscus cephalotes Holmgr. In Ichneumon atropos
Curt. Newport (loc. cit.) detected fourteen segments, including the anal
process, but the latter structure is most probably an outgrowth of the
thirteenth segment and this species would therefore conform in possess-
ing the usual number of segments. In Spilocryptus cambicis Tschek.
Morley (1907) states there are twelve segments, apparently including
the head in his enumeration; in the onisciform larva of Mesostenus ob-
noxius Gray. this same observer (1906) found only nine segments.

In the retention of ten pairs of spiracles the larva of Pimpla pomorum
exhibits a primitive feature not hitherto recorded, so far as | am aware,
in any other species of Ichneumonoidea. Laboulbéne (1858) noticed nine
pairs of spiracles in the larva of Pimpla Fairmairvi and the same number
has been observed by Giraud in P. detrita Holmgr., by Xambeu in P.
oculatoria Grav., by Ratzeberg (1844) in Ichnewmon pisorius L., by
Berthoumieu in J. rubens Fons., and by Seurat in Pimpla mexicana,
Anilasta ebenina, Xylonomus praecatorius, Mesochorus vittator, and Phy-
matodes variabile. The vestigial second pair of spiracles is very small,
being easily passed over, and it is not improbable that, in certain cases,
it has been overlooked by previous observers. It is noteworthy that ten
pairs of spiracles are also present in the newly hatched larva of the honey
bee, but in this species they correspond, according to Nelson (1915), to
the second to eleventh segments inclusive.

In the presence of body hairs, and the absence of either a caudate
appendage or anal vesicle, the larva of Pimpla pomorum exhibits features
that are characteristic of Ichneumons leading an ectoparasitic mode of
life.

222 Observations on Pimpla pomorum

8. THE MALE PUPA.

In describing the pupa, whether male or female, one meets with the
very real difficulty of selecting from the few characters which it affords,
those which appear to be of diagnos-
tic value. In hardly a single instance
do we find a description of an Ichneu-
monid pupa sufficiently detailed to
be of value for comparative purposes.
So far as the present species is con-
cerned, I have only dealt with those
morphological features which appear
likely to prove of generic or specific
value. Of these, the characters
afforded by the abdominal spines
appear to be important.

In the male pupa (Plate XII, fig. 3)
the head is a little wider than the Fig. 5. Cocoon showing the emergence
thorax across the widest region, with pele eee By tne ee
the frontal surface inclined obliquely
downwards. The mouth-parts are wholly ventral in position, with the
first maxillae and labium lying parallel with the longitudinal axis of the
body, and near to the surface of the prosternal region. The antennae
curve over the anterior surface of the head, closely applied to the inner
margins of the eyes, and lie for the remainder of their length on the
ventral side of the body. Their apices extend backwards as far as the
fourth abdominal segment. The extremities of the anterior tarsi reach
as far as the apices of the middle tibiae; the second pair of legs are wholly
invisible dorsally and their extremities reach to the middle of the second
tarsal joint of the hind legs; in the third pair of legs the apices of the
tarsi extend slightly further backwards than those of the antennae. The
fore-wings completely overlie the hind-wings and exclude them from
view; they reach backwards as far as the extremity of the first tarsal
joint of the middle legs. Seven segments are evident in the abdomen but
the seventh or hindmost segment is of a composite nature and apparently
consists of two partially fused pupal segments. The first segment is
devoid of spines, while the second to fourth segments are each armed
with a single pair of small ventral spines. The fifth segment is provided
with four ventral and two dorsal spines; the sixth segment has a circlet
of spines of which usually six are ventral in position, four are lateral and

A. D. Imus 295

four dorsal. The apical region of the abdomen is prolonged posteriorly
into a pair of short appendages, which are imperfectly two-jointed, and
rounded at their extremities. On either side of these appendages, is a
pair of papillae, each carrying a conspicuous curved spine, considerably
longer than the spines on any of the preceding segments; a pair of smaller
spines are also present ventrally.

Length 5 mm.; maximum breadth across the thorax 1-5 mm.

9. THE FEMALE PUPA.

The female pupa (Plate XII, fig. 4) differs from the male pupa in that
the antennae extend as far backwards as the sixth abdominal segment
while the hind legs reach to the seventh segment. The terebra is folded
back over the dorsal side of the abdomen, its apex reaching to the middle
of the first segment. The latter is unarmed, but the second and third
segments are each provided with a pair of small dorsal spines. The fourth
segment has four similar dorsal spines and two ventral spines; vestiges
of a second and outer pair of ventral are also present. The fifth segment
is armed with four dorsal, two ventral and two prominent lateral spines
—one on either side. The sixth segment has usually six ventral, four
dorsal and large lateral spines. The seventh or apical segment is pro-
vided, on either side, with a pair of large curved ventro-lateral spines as
in the male, and, furthermore, is prolonged backwards in the form of a
pair of unjointed appendages each surmounted by a conspicuous spine.

Length 4-25 mm. to 4-45 mm.; maximum breadth across the thorax
1-5 mm.

10. EFFICIENCY AS A PARASITE.

Between May 25th and 29th, 1916, 1270 apple buds, harbouring the
weevil in various stages of development, were separately examined under
a binocular microscope. Among these infested buds 349 contained larvae
of Pimpla pomorum. This gives a ratio of parasitism working out at
27-4 per cent., which is a relatively high one, and remarkably near to
that found by Decaux to be efficient in France in the control of the
weevil by means of species of Braconidae. A further 605 buds gave in-
conclusive results, and are not included in this enumeration. Many of
them were either attacked by mould or were empty, or contained dead
or sickly hosts, without certain indications of being parasitised by the
Pimpla. The appearances in many cases suggested that the parasite had
been present, but had died along with the host. Mould favoured by wet
weather, appeared often to kill the latter when parasitised, and the
parasitic larva usually died also as the result. When the petals of the

224 Observations on Pimpla pomorum

unopened buds were not tightly closed, the mould appeared to gain access
more readily.

The effect of the parasitism on the host is complete, the latter dying
in every instance whether it be in the larval or pupal stage. It is prob-
able, therefore, that Pimpla pomorum is an important natural aid in the
control of the apple blossom weevil in this country. The high rate of
mortality which I have shown it exacts from its host, together with the
general fact of its biology, clearly supports this contention. Measures
involving the preservation and increase of the parasite, along lines
similar to those conducted in France, are fully worthy of adequate trial
as an accessory means of controlling the weevil. The utilisation of natural
enemies in the control of injurious insects has led to highly encouraging
results in America, Italy, France and elsewhere; nevertheless, it is a
method which can only be advocated after a thorough scientific enquiry
into the life-economy of each particular species and its parasites. In the
case of the apple blossom weevil, among the various measures recom-
mended for dealing with this insect is that of jarring the trees, which
causes the affected apple blossoms to fall readily. Frequently, many fall
in the natural course of events without the trees being shaken. The
blossoms are then collected and burnt. With the expenditure of very
little extra time and labour the blossoms, after being collected, might
easily be placed in boxes and saved. Shallow well-fitting wooden boxes
are best for the purpose, and not more than six layers of blossoms should
be placed in a single box, as they rapidly decompose and rot in damp
weather. The lids of the boxes should have as large an area as possible
replaced by cheese cloth or butter muslin, to allow of the admission of
air and light. If, however, the finest holed perforated zinc be used the
boxes will then serve their purpose for a much longer period without
trouble. All that is necessary is to examine the boxes daily from about
the beginning of the second week in June, removing the lids thereof for a
few minutes to enable the parasites to fly away once they commence
appearing. It is advisable to jar the box sharply before doing so, in order
to cause those weevils which may have crawled up the sides to loose their
foothold and so prevent their escape. By this means the greater number
of the weevils are imprisoned within the boxes and eventually die, while
the parasites are berated to continue their beneficial mission. Experi-
ments were conducted in order to ascertain whether it be possible to
utilise gauze of such a mesh which would allow of the liberation of the
parasites, and the retention of the beetles, and thus obviate the necessity
for the periodical removal of the lids of the boxes. Owing to the relatively

A.D. Imus 225

large size of the parasites, compared with the size of the host, it was
found that the parasites did not readily issue through a mesh which, at the
same time, was small enough to imprison the host weevils. The method
of collecting the affected blossoms followed by the burning of the same,
is open to a good deal of doubt as to its advisability on account of the
large number of beneficial parasites which are destroyed at the same time.

11. REMARKS ON OTHER PARASITES OF ANTHONOMUS POMORUM.
A useful summary of hymenopterous parasites recorded from this
host is given by Elliott and Morley (1907 and 1911) and further records
are quoted by Catoni (1912). Several of the statements, however, are of
doubtful value as they probably refer to parasites of Aphids and other
insects and have no closer connection with Anthonomus than the fact
that the host food-plant was apple in each case. Among these doubtful
records may be included A panteles (Microgaster) albipennis Nees, Bracon
varvator Nees, Asaphes vulgaris Walk. (Chrysolampus aeneus Ratz.),
Encyrtus flavomaculatus Ratz. and Pteromalus (Habrocytus) saxeseni
Ratz. (Thoms.). Brischke, however, has bred Pimpla examinator Fab.,
P. sagax Htg., and Apanteles (Microgaster) lacteus Nees from this host.
Apanteles (Microgaster) impurus Nees was frequently bred by Reissig
from apple blossom infested by the weevil and has also been reared by
Catoni. According to Ratzeberg (1848, p. 84), Nordlinger bred a single
male of Campoplex latus Ratz., and it is stated that Goureau has bred
Pimpla graminellae Gray. from the same host. Catoni (1912, p. 149) has
also bred Meteorus ictericus (Nees) and Habrocytus fasciatus Thoms.

During this investigation Pimpla pomorum was the only parasite
which I bred from the Anthonomus. Whether or not any of the above
species are likely to prove of value from the economic point of view is
doubtful. Males of Pimpla examinator are common in this country though
no certain records of the female appear to be known. P. sagax has not
often been met with while, according to Morley, there are but few reliable
records of P. graminellae.

The species of Apanteles are well-known natural enemies of Lepi-
doptera and the extent to which they may parasitise insects of other
orders requires fuller investigation before we are able to formulate definite
conclusions with regard to their economic significance.

12. SUMMARY OF GENERAL CONCLUSIONS.
1. Pimpla pomorum Ratz., in its larval stage, is an ecto-parasite of

the Apple Blossom Weevil (Anthonomus pomorum) attacking both pa
and pupae of the latter.

226 - Observations on Pimpla pomorum

2. The larva of this Ichneumon is composed of a definite head and
thirteen trunk segments; no caudal process or anal vesicle is present.
Ten pairs of spiracles are evident but the pair situated on the second
segment is minute and vestigial.

3. Pupation takes place within a slight silken cocoon spun within
the cavity of the unopened apple buds. The adult Ichneumons com-
menced to emerge on June 17th, and an average of twenty-three days
was occupied from the time of spinning the cocoon.

4. The male insect was met with in considerable numbers for the

first time, and its identity made certain. Hitherto nothing has been
known of this sex beyond Ratzeberg’s surmise that a male Pimpla bred
by Nordlinger belongs to this species and that Catoni has reared it in
Italy. A full description of the male by Mr Claude Morley is included in
the present paper.
__5. After emergence in June, the biology of this species during the
rest of the year is unknown. Most probably it passes through a second
generation and utilises certain species of Lepidoptera as hosts. In
localities where Anthonomus pomorum is unknown both generations
probably parasitise Lepidoptera.

6. From among 1270 apple buds gathered at Chatteris in Cambridge-
shire, and infested by the Apple Blossom Weevil, Pumpla pomorum was
found to effectively parasitise the latter to the extent of 27 per cent.
This ratio of parasitism is relatively high, and agrees very closely with
that found by Decaux to obtain among Braconid parasites of the same
host.

7. It is suggested that measures involving the preservation and in-
crease of this parasite, along lines similar to those conducted in France,
should be given an adequate trial; it is likely that they may prove of
value as an accessory means of controlling the weevil.

13. REFERENCES TO LITERATURE.

BertHoumrEt, G. V. (1894). Ichneumonides d’ Europe et des pays limitrophes. Ann.
Soc. Entom. France, pp. 241-274.
Catont, G. (1912). Parassiti dell’ Anthonomus pomorum (L.) osservati in valle di Non
(Trentino). Boll. del Lab. di Zool. Gen. e Agrar. Portici, vol. v1, pp. 148-150, 2 figs.
Cusuman, R. A. (1913). The Calliephialtes parasite of the Codling Moth. Journ. Agr.
Res. Washington, vol. 1, pp. 211-237, Pl. 20 and 14 text-figs.
—— (1916). Thersilochus conotracheli, a Parasite of the Plum Curculio. Journ.
Agric. Res. vol. vi, pp. 847-856, pl. cix and 8 text-figs.
Ettrort, E. A. and Mortey, C. (1907). On the Hymenopterous Parasites of Coleo-
ptera. Trans. Entom. Soc. Lond. pp. 7-75.
—— (1911). Ibid. First Supplement, T.E.S. pp. 452-496.

THE ANNALS OF APPLIED BIOLOGY. VOL. IV, NO. 4 PLATE XII

te ae

(

A. D. Imus Papal

Giraup, J. (1863). Notice sur les Deformations galliformes du Triticum repens.
Verh. z.-b. Ges. Wien, pp. 1251-1288.

GraF, J. E. (1917). The Potato Tuber Moth. U.S. Dept. Agric. Bur. Entom., Bull.
427, 56 pp., 45 figs. and one map.

Howarp, L. O. (1913). Proc. Entom. Soc. Washington, vol. xv, p. 161.

KiapaLek, F. (1889). Agriotypus armatus (Walker) Curtis: its Life-history and
geographical distribution. Hnt. Month. Mag. vol. xxv, pp. 339-43, 7 figs.

LABOULBENE, A. (1858). Histoire d’un Ichneumon parasite des Araignées (Pimpla
fairmairii). Ann. Soc. Entom. Fr. Sér. 3, T. 6, pp. 797-817.

Marcuat, P. (1907). Utilisation des Insectes auxiliares entomophages dans la Lutte
contre les Insectes nuisibles a l Agriculture. Ann. Inst. National Agronom.
2e Sér. T. vi, 74 pp. and 26 figs.

Morey, C. (1903). On the British Species of Tryphonidae-Macrochili. Ent. Month.
Mag. vol. Xxx1x, pp. 157-164.

—— (1907). The Ichneumons of Great Britain, vol. u, Cryptinae, pp. xvi + 348.
—— (1908) Ibid. vol. m1, Pimplinae, pp. xvi + 324.
— (1914). Ibid. vol. v, Ophioninae, pp. x + 400.

Netson, J. A. (1915). The Embryology of the Honey Bee. Princetown Univ. Press,
pp. iii + 282, 95 text-figs and 6 pls.

Newport, G. (1855). The Anatomy and Development of certain Chalcididae and
Ichneumonidae, compared with their special Oeconomy and Instincts: with
Descriptions of a new Genus and Species of Bee Parasites. Trans. Linn. Soc.
vol. xxI, pp. 61-77, pl. VIII, and pp. 85-93, pl. IX.

RATZEBERG, J. T. C. (1844-52). Die Ichneumonen der Forstinsekten. Berlin, vol. 1,
1844: vol. o, 1848: vol. m1, 1852.

Ritey, C. V. (1888). The Habits of Thalessa and Tremex. Insect Life, vol. 1, pp. 168—
179, pl. I, text-figs. 36-39

SCHMIEDENKNECHT, Q. (1906). Opuscula Ichneum. fase. xtv.

SeuraT, L. G. (1899). Contributions a létude des Hyménoptéres entomophages.
Ann. Sci. Nat. Zool. 8° Sér. T. x, pp. 1-59, pls. I-V.

Smiru, H. 8. (1914). Calliephialtes in California. Monthly Bull. State Comm. Hortic.
Sacramento, vol. 11, pp. 195-211, figs. 57-71.

THEOBALD, F. V. (1909). Insect Pests of Fruit. Wye, pp. xvi + 550 and 328 figs.

TIMBERLAKE, P. H. (1912). Technical Results from the Gipsy Moth Laboratory.
V. Experimental Parasitism: A Study of the Biology of Limneriwm validum.
U.S. Dept. of Agric. Bur. Entom. Techn. Ser. 19.

VOLLENHOVEN, S. VAN (1861). Bij de Afbeelding der Larve en Pop von Rhyssa per-
suasoria. Tijdschr. ned. entom. Ver. T. 4, pp. 176-77, Pl. XII.

Ward te, R. A. (1914). Preliminary Observations upon the Life-histories of Zenillia
pexops B. and B. and Hypamblys albopictus Grav. Journ. Econ. Biol. vol. 1x,
pp. 85-104, pls. [V-VII and one text-fig.

XAMBEU, Capt. (1898). Moeurs et métamorphoses de Pimpla oculatoria Grav. Le
Naturaliste, pp. 239-240.

EXPLANATION OF PLATE XII.

Fig. 1. Young larva of Pimpla pomorum seen from the right side, x 62.
Fig. 2. Fully grown larva seen from the right side. x 26,

Fig. 3. Female pupa, lateral view. x 26.

Fig. 4. Male pupa, lateral view. x 26.

228

A LIST OF COCCIDAE AFFECTING VARIOUS
GENERA OF PLANTS.

By E. ERNEST GREEN, F.ES., F.ZS.

(Continued from page 89)

DACRY DIUM (Coniferae).
CTrENOCHITON dacrydii.
DACTYLIS (Gramineae).
PsEubDococcus walkeri.
Crropuro volynicus.
Luzuxaspts luzulae.
DAHLIA (Compositae).
PsEubDococcUS affinis.
PULVINARIA psidii.
DALBERGIA (Leguminosae).
MonopuHuesus dalbergiae, octocau-
data.
TACHARDIA lacca.
LECANIUM expansum.
Asprpiotus trilobitiformis, lataniae,
simillimus, transparens.
DALEA (Leguminosae).
CEROPLASTODES daleae.
DAMMARA (Coniferae).
PsEuDococcUS aurilanatus.
DANAE (Liliaceae).
Frorinia pellucida.
DANTHONIA (Gramineae).
Ertococcus danthoniae.
DAPHNE (Thymeliaceae).
Ruizococcus gnidii.
PsEUDOCOCCUS similans.
LECANIUM magnoliarum.
ASpIDIOoTUS caldesii, hederae, camel-
liae, lataniae.
DASYLIRION (Bromeliaceae).
LECANIODIASPIS yuccae.
Psrupococcus dasylirii.
DATURA (Solanaceae).
PsEUDOCOCCUS virgatus.
Asprptotus hederae.

DAVALLIA (Filices).
HEMICHIONASPIS aspidistrae.
LEPIDOSAPHES ocellata.

DAVIESIA (Leguminosae).
PULVINARIA tecta.
ASTEROLECANIUM stypheliae.
CHIONASPIS nitida.

PoLtAspiIs nitens.
AspipiotTus hederae.
LEPIDOSAPHES casuarinae.

DEBREGAESIA (Urticaceae).
Psrupococcus debregaesiae.
CEROPLASTES ceriferus.
HEMICHIONASPIS mussaendae, mi-

nor.

DENDROBIUM (Orchidaceae).
Levucaspis stricta.
AspIpiotus dictyospermi.
LEPIDOSAPHES cocculi.

DENDROCALAMUS (Gramineae).
ASTEROLECANIUM bambusae,

natum.
ANTONINA bambusae.
CHIONASPIS angusta.

DENDROPHTHORA (Loranthaceae).
PULVINARIA dendrophthorae.

DERRIS (Leguminosae).
LEPIDOSAPHES dilatilobis.

DESCHAMPSIA (Gramineae).
ERIopELtis festucae.

DESMANTHUS (Leguminosae).
CERONEMA africana.

DEUTZIA (Philadelphaceae).
ASPIDIOTUS perniciosus.

DEVERRA (Umbelliferae).
Curonaspts bilobis.

coro-

E. E. GREEN 229

DIANELLA (Liliaceae).
Levucaspis cockerelli.
PARLATORIA proteus.

DICHAPETALUM (Chailletiaceae).
ASPIDIOTUS maeandrius.

DICHOPSIS (Sapotaceae).

IcERYAE seychellarum.
Vinsonta stellifera.

DICTYOSPERMA (Palmaceae).
PINNASPIS buxi.

AsPIpioTus dictyospermi, articulatus,
ficus.

DIELYTRA (Fumariaceae).

Lecantum hesperidum.

DILLENIA (Dilleniaceae).

Lecantum cocophyllae.

DILLWYNIA (Leguminosae).
LECANIUM pingue.

PULVINARIA contexta.
POLIASPIS exocarpi.

DIOON (Cycadaceae).
POLrAsPIS cycadis.
DIASPIS zamiae.

DIOSCOREA (Dioscoreaceae).
Aspipr1otus hartii, destructor, trans-

DIOSMA (Rutaceae). [parens.
LrEcaAniIvuM oleae.

ASPIDIOTUS camelliae.

DIOSPYROS (Ebenaceae).

IceryaA seychellarum.

Lecantopiaspis tessellata.

PHENACOCCUS pergandei.

CEROPLASTES ciripediformis.

PULVINARIA citricola.

LECANIUM corni, bicruciatum.

Dtaspis pentagona.

ASPIDIOTUS perniciosus, dictyosper-
mi, duplex, aurantii, orientalis.

PARLATORIA pergandei-phylanthi.

DIPTEROCARPUS (Dipterocarpaceae).
TACHARDIA lacca.

DIRCA (Thymeliaceae).

CxHronaspPis lintneri.

DISPORUM (Liliaceae).
Asprprotus hederae.

DISTICHLIS (Gramineae).
SPHAEROCOCCUS distichlium.
Ertococcus salinus.

DISTYLIUM (Hamamelideae).
CuTonaspPIs latissima.

DOBERA (Salvadoraceae).
Drnaspis reticulata.
DODONAEA (Sapindaceae).
WALKERIANA senex.
PULVINARIA dodonaeae, thompsoni,
psidii.
DOLICHOS (Leguminosae).
CEROPLASTODES cajani.
Inquista bivalvata.
Lecantum longulum.
DOMBEYA (Sterculiaceae).
IcERYA jacobsoni.
DOODIA (Filices).
ALECANOPSIS filicum.
DORYCNIUM (Leguminosae).
ASTEROLECANIUM fimbriatum.
DOVYALIS (Flacourtiaceae).
Howarpta biclavis.
CEROCOCCUS ornatus.
DRABA (Cruciferae).
ASTEROLECANIUM fimbriatum.
DRACAENA (Liliaceae).
Lecantum hesperidum.
HEMICHIONASPIS dracaenae, aspidis-
trae.
PINNASPIS buxi.
CHIONASPIS tangana.
Asprprotus lauretorum, tinerfensis,
dictyospermi, lataniae, hederae.
Levcaspris cockerelli.
DRIMYS (Magnoliaceae).
INGLIsIA patella.
PSEUDOPARLATORIA parlatorioides.
LEPIDOSAPHES drimydis.
DRYANDRA (Proteaceae).
CERONEMA dryandrae.
AspIpIoTus dryandrae.
PARLATORIA dryandrae.
DRYMUS.
ASPIDIOTUS moreirae, pisai.
DRYPETES (Euphorbiaceae).
Lecantum hemisphaericum.
DURANTA (Verbenaceae).
PULVINARIA psidii.
LECANIUM oleae.
ORTHEZIA insignis.
DURIO (Malvaceae).
CHIONASPIS durionis.
DYSOXYLON (Meliaceae).
CHIONASPIS dysoxyli.

230 List of Coccidae affecting various Genera of Plants

DYSOXYLON (Meliaceae)—coni.
Asprpiotus dysoxyli.
LEPIDOSAPHES pyriformis.

EARINA (Orchidaceae).
CTENOCHITON elongatus.

ECHINOCACTUS (Cactaceae).
Draspts echinocacti.

ECHITES (Apocynaceae).
PHENACOCCUS mangiferae.
Asprprotus trilobitiformis.

EDGEWORTHIA (Thymeliaceae).
PsEubDococcus edgeworthiae.

EHRETIA (Boragineae).
ASPIDIOTUS replicatus.

ELAEAGNUS (Elaeagnaceae).
Lecanium bicruciatum, persicae,

hesperidum, nigrofasciatum.
CEROPLASTES floridensis.
CuHrionaspis difficilis, elaeagni, vitis.
DIASPIS crawil.
AsprpioTus camelliae, britannicus,
rossi.
AonIpIA elaeagni.
LEPIDOSAPHES citricola, crawii, ul-
mi.

ELAEIS (Palmaceae).
CEROPLASTES actiniformis.
HEMICHIONASPIS marchali.
ASPIDIOTUS elaeidis.
IscHNaspPIs filiformis.

ELAEOCARPUS (Tiliaceae).
Ertococcus pallidus.
PsEvbpococcwus scrobicularum.
Lrcanium formicarii.
ERIOCHITON spinosus.
CTENOCHITON elaeocarpi, flavus.
INGLISIA ornata.
HEMICHIONASPIS scrobicularum.

ELAEODENDRON (Celastraceae).
FrortntA elaeodendri, plana.

ELAPHRIUM (Burseraceae).
CEROPLASTES ceriferus.

ELLIPANTHUS (Connaraceae).
CHIONASPIS vitis.

ELYMUS (Gramineae).

RIPERSIA smithii.

ELYTROPAPPUS (Compositae).
SPHAEROCOCCUS africanus.
PsEuDOococcUS elizabethae.

EPACRIS (Epacridaceae).
Ertococcus multispinosus-laevigatus.
LECANIODIASPIS microcribraria.

EPHEDRA (Gnetaceae).
PsEubococcus ephedrae.
LicutEensia ephedrae.
PHILEPHEDRA ephedrae.

Storzra striata.

Fiurepia ephedrae.

Dryaspis ichesii.

Levucaspis ephedrae.

Aspripiotus trabuti, ephedrarum.
PARLATORIA ephedrae.

EPIDENDRUM (Orchidaceae).
ASTEROLECANIUM epidendri.

EPIGAEA (Ericaceae).

ASPIDIOTUS epigaeae.

ERANTHEMUM (Acanthaceae).
Icrrya seychellarum, sulfurea.
LECANIUM hemisphaericum, depres-

sum.
PULVINARIA jacksoni.

EREMOPHILA (Myoporaceae).
ASPIDIOTUS coralinus, hederae.

ERICA (Ericaceae).

ORTHEZIA maenariensis, urticae.
ASTEROLECANTUM fimbriatum.
Errococcus devoniensis, ericae.
RrperstA_ halophila.
PsEUDOCOCOUS ericicola.
PULVINARIA ericae.

LrcANtum oleae, hemisphaericum.
Drasprts ericicola.

CHIONASPIS salicis.
ADISCODIASPIS ericicola.
Asprpiotus hederae, bavaricus.
LEPIDOSAPHES ulmi.

ERIGERON (Compositae).
PsEUDOCOCCUS neomexicanus.
CEROPLASTES cultus, cuneatus.

ERIOBOTRYA (Rosaceae).

IceRyA purchasi.

CEROPLASTES vinsonii.

Draspis pentagona.

AspIDIOTUS dictyospermi, aurantii.

PARLATORIA Oleae, pergandei.
ERIODENDRON (Malvaceae), ‘Silk

Cotton.’
ASPIDOPROCTUS giganteus.
LECANIUM intimum, nigrum.

ee ee

HK. E.

ERIODENDRON (Malvaceae)—cont.
Aspip1oTus pedroniformis.

ERIODICTYON (Hydrophyllaceae).
PsEvDococcus yerba-santae.

ERIOGONUM (Polygonaceae).
Errococcus palmeri, eriogoni.
PsEuDOcoccUS maritimus.

ERIvuM eriogoni.

ERYTHEA (Palmaceae).
COMSTOCKIELLA sabalis.
HEMICHIONASPIS aspidistrae.

ERYTHRASPIS.

ASPIDIOTUS camelliae, erythraspidis.

ERYTHRINA (Leguminosae).
PsEUDOCOCCUS crotonis.

Lecantium tenebricophilum, oleae.
PULVINARIA maxima.

ERIOcHITON theae.

Draspis pentagona.

AspIpioTus dictyospermi, pustulans.
LEPIDOSAPHES erythrinae.

ERYTHROPALUM (Olaeaceae).
LECANIUM cocculi.

EUCALYPTUS (Myrtaceae).
MoNnoPHLEBUS fortis, crawfordi, craw-

fordi-levis, crawfordi-pilosior.
GUERINIELLA serratulae.
CALLIPAPPUS australis, immanis.
APIOMORPHA attenuata, bauerleni,
calycina, conica, duplex, minor,
ellipsoides, floralis, helmsii, kar-
schi, maliformis, munita, munita-
tricornis, ovicola, ovicola-glabra,
ovicoloides, pedunculata, phare-
trata, pileata, pomiformis, rosae-
formis, rugosa, sessilis, sloanei,
strombylosa, thorntoni, thorntoni-
nux, umbellata, urnalis, variabilis,
urnalis-schraderi, cucurbita, dip-
saciformis, excupula, fletcheri.
OPISTHOSCELIS conica, fibularis, glo-
bosa, maculata, mammularis, mas-
kelli, nigra, pisiformis, serrata, spi-
nosa, subrotunda, verrucula.
ASCELIs attenuata, echiniformis, prae-
mollis, schraderi.
WARBURTONIA frenchi.
LECANIODIASPIS eucalypti, frenchi,
convexus, newmani.
GOSSYPARIA confluens.

GREEN

231

Ertococcus confusus, coriaceus, eu-
calypti, simplex, simplex-dealba-
ta, tepperi, tricarinatus, serrati-
lobis, crofti, apiomorphae, gre-
garius, irregularis, picta, tessel-
latus.

SPHAEROCOCCUS elevans, obscuratus,
pustulans.

SPHAEROCOCOPSIS inflatipes.

Ovrococcus cobbii, eucalypti.

LACHNODIUS eucalypti, lectularius.

PsEubDococcus lobulatus.

TACHARDIA melaleucae.

LECANIUM oleae.

CTENOCHITON eucalypti.

CERONEMA caudata.

PULVINARIA maskelli.

CHIONASPIS assimilis, ethelae, eu-
geniae, formosa, eucalypti, frenchi,

angusta.
ASPIDIOTUS extensus, perniciosus,
camelliae, subrubescens, rossi,

acaciae, eucalypti, alatus, con-
fusus, rubribullata, subrubescens-
corticoides, rossi-victoriae, fuscus,
tasmaniae, miniatae, ficus, am-
plius, cyanophylli, articulatus,
personatus.

MASKELLIA globosa.

LEPIDOSAPHES cordylinidis, grisea,
lidgetti, bicornis, eucalypti, bi-
cornis-alba.

Frorrnza lidgetti.

EUCHARIS (Amaryllidaceae).
ASTEROLECANIUM aureum.
HEMICHIONASPIS minor.

EUGENIA (Myrtaceae).

LLAVEIA primitiva-pimentae.

CAPULINIA jaboticabae, craterifor-
mans.

ERIOIDES cuneiformis.

CARPOCHLOROIDES viridis.

STICTOLECANIUM ornatum.

Lecanium tessellatum, jaboticabae,
bicruciatum, psidii, mangiferae.

PULVINARIA eugeniae, psidii, grab-
hami.

CEROPLASTES fairmairii,
rubens.

VINSONIA stellifera.

formosus,

232 List of Coccidae affecting various Genera of Plants

EUGENIA (Myrtaceae)—cont.

EDWALLIA rugosa.

CHIONASPIS eugeniae.

Frorinta fioriniae.

Asprpiotus fimbriatus, virescens,
hederae, ficus, camelliae, de-
structor, personatus.

ODONASPIS pimentae.

LeprposaPHES rubrovittatus, ungu-
lata.

PARLATORIA Oleae, proteus.

EUONYMUS (Celastraceae).

LxEcanium oleae, coryli, nigrofascia-
tum, capreae.

PULVINARIA camelicola, euonymi,
innumerabilis, betulae, floccifera.

Dtaspis pentagona.

CHIONASPIS citri, euonymi, acumi-
nata, salicis.

ASPIDIOTUS euonymi, perniciosus,
aurantii, rossi, camelliae, cictyo-
spermi, ficus, lataniae.

PaRLATORIA theae-euonymi.

EUPATORIUM (Compositae).
ORTHEZIA insignis.
ASTEROLECANIUM fimbriatum.

EUPHORBIA (Euphorbiaceae).

PALAEOCOCCUS rosae.

Icrrya euphorbiae.

WALKERIANA euphorbiae.

ORTHEZIA urticae.

ASTEROLECANIUM fimbriatum.

PsEUDOCOCCUS virgatus, longispinus.

Lecantum longulum.

CEROPLASTES euphorbiae.

Crrococcus alluaudi.

DIASPIS conservans, barrancorum,
antiquorum.
Asprpiotus _ trilobitiformis-darutyi,

ferox, magnus, euphorbiae, fissus,
taorensis, Jenticularis, biformis,
hederae.
CRYPTASPIDIOTUS austroafricanus.
LEPIDOSAPHES ulmi.
PARLATORIA mangiferac.
EUPHRASIA (Scrophulariaceae).
ASTEROLECANIUM fimbriatum.
EURYA (Ternstroemiaceae).
L&EcANIUM ochnaceae.
PULVINARIA aurantii, psidii.

EURYA (Ternstroemiaceae)—cont.
Aspipi1otus duplex.

LEPIDOSAPHES euryae.

EURYCLES (Amaryllidaceae).
Caronaspts dilatata.

EUTERPE (Palmaceae).

Draspts_ boisduvallii.

EVODIA (Rutaceae).
CHIONASPIS acuminata.
DINASPIS permutans.

EXCOECARIA (Euphorbiaceae).
Lecantum longulum.

CEROPLASTES excoecariae.

EXOCARPUS (Thymeliaceae).
Crrococcus bryoides, bryoides-

stellatus.
PsEvubococcus hibbertiae.
CEROPLASTODES melaleucae.
POLIASPIS exocarpi.
Aspipi1otus junctlobius.
LEPIDOSAPHES casuarinae, subspicu-
[lifera.

FABIANA (Solanaceae).

PULVINARIA argentina.
CEROPLASTES longiseta.
Asprpiotus fabianae.

FAGONIA (Zygophyllaceae).
ASPIDIOTUS nigra, hederae.

FAGRAEA (Loganiaceae).

LECANIUM psidii.
Draspts fragraeae.

FAGUS (Corylaceae) * Beech.’
COELOSTOMIDIA assimilis, pilosa.
PHENACOLEACHIA zealandica.
Crrococcus fagi.
Facisuca triloba.
PuatyPyG@a fagi.
Ertococcus _ fagicorticis,

raithbyi, aceris.
Ruizococcus intermedius, maculatus,
pulchellus, totarae, cavellei.
Cryprococcus fagi.
PsEubDococcUS iceryoides, obtectus,
aceris, newsteadi.
RIPERSIA fagi.
PULVINARIA innumerabilis, betulae.
INGLISIA fagi.
AspIpioTus ancylus, forbesi, ostrei-
formis, perniciosus.
LEPIDOSAPHES ulmi.

pallidus,

EK. E. GREEN

FATSIA (Araliaceae).
PULVINARIA psidii.
PROTOPULYINARIA japonica.
FERONIA (Rutaceae).
ANOMALOCOCCUS cremastogastri.
FESTUCA (Gramineae).

Errococcus festucae.

RreersrA festucae.

TRIONYMUS californicus.

ERIoPEttis festucae, lichtensteinii.

FICUS (Moraceae).

ASPIDOPROCTUS verrucosus.

Drostcua maskelli, lichenoides.

MOoNOPHLEBUS octocaudata.

IcERYA aegyptiaca, maxima, pur-
chasi, seychellarum.

GUERINIELLA serratulae.

TacHArDIA lacca, fici, longisetosa.

ASTEROLECANIUM pustulans,

LECANIODIASPIS africana.

ANOMALOCOCCUS cremastogastri.

ERrococcus crispus, lagerstroemiae.

PsEubDococcus ficus, longispinus,
setosus, adonidum, citri, crotonis,
virgatus, virgatus-madagascari-
ensis.

PHENACOCCUS mangiferae.

Strcrococcus formicarii.

Lecanium ficus, longulum, depres-
sum, nigrella, plebeium, nigrum,
ficinum, oleae, persicae, tessel-
latum, crassum, hesperidum, de-
solatum, hemisphaericum, formi-
carii, expansum, expansum-java-
nicum, ramakrishnae, carpenteri.

HEMILECANIUM imbricans.

PULVINARIA ficus, psidii, psidii-
philippina, jacksoni, cupaniae.

LicHTENSIA lutea.

CEROPLASTES floridensis, rubens, rusci,
townsendi-percrassus, ficus, quad-
rilineatus, gowdeyi, coniformis,
ceriferus, galeatus.

Draspis gennadii.

Scuizaspis lobata.

CHIONASPIS manni, fici.

Howarpta biclavis.

HEMICHIONASPIS aspidistrae, minor,
fici, minima.

LeEvcaspis japonica.

Ann. Biol. Iv

FICUS (Moraceae)—cont.

ASPIDIOTUS cyanophylli, cydoniae,
camelliae, trilobitiformis, articu-
latus, ficus, aurantii, africanus,
sylvatica, fossor, obsita, orien-
talis, dictyospermi, personatus,
lataniae.

AonipiA planchonioides.

GYMNASPIS ficus.

LEPIDOSAPHES citricola, ficus, fici-
folii, mexicana, minima, pinni-
formis, conchiformis, luzonica.

Iscunaspis filiformis.

FILICES ‘Ferns.’

TESSAROBELUS guerinii.

ORTHEZIA cheilanthi.

ERrococcus insignis.

MACROCEROCOCCUS superbus.

PsEupococcus longispinus.

Rrrersta filicicola.

LEcANIUM tessellatum, hesperidum-
alienum, cockerelli, filicum, hemi-
sphaericum, mori, diversipes,
oleae, longulum.

PULVINARIA mammeae, floccifera.

CEROPLASTES rubens,

CTENOCHITON depressus.

ALECANOPSIS filicum.

CHIONASPIS dilatata, dubia.

HEMICHIONASPIS aspidistrae.

PoLtiasPIs media.

LEPIDOSAPHES phymatodidis, ocel-
lata, desmidioides.

FILICIUM (Burseraceae).

TACHARDIA albizziae.

FLACOURTIA (Flacourtiaceae).

PsEuDococcus longispinus.

Dtaspis pentagona-flacourtiae.

Howarpia biclavis.

PARLATORIA cingala,

FOUQUIERIA (Tamaricaciae).

Lecaniodiaspis rufescens.

FRAGARIA (Rosaceae) ‘Strawberry.’

IcERYA genistae.

ORTHEZIA insignis.

Draspis rosae.

ASPIDIOTUS perniciosus.

FRAXINUS (Oleaceae) ‘ Ash.’

FonscoLoMBiA fraxini.

PHENACOCCUS aceris, pettiti.

16

234 List of Coccidae affecting various Genera of Plants

FRAXINUS (Oleaceae)—cont.

LECANIUM cerasifex, fraxini, oleae,
nigrofasciatum, corni, robiniae-
subsimile.

PuLVINARIA fraxini, betulae.

ERICERUS pela.

DIAspIs pentagona.

CHIONASPIS salicis.

ASPIDIOTUS ancylus, juglansregiae-
albus, perniciosus, townsendi,
vagabundus, pyri. ;

LEPIDOSAPHES ulmi.

PARLATORIA Oleae, affinis.

FRENELLA (Coniferae).
Ertum frenellae.

FREYCINETIA (Pandanaceae).
PsEUDOCOCCUS moptanus.

FUCHSIA (Onagraceae).
PsEupococcus citri, longispinus.
JEROPLASTES albolineatus.
ASPIDIOTUS camelliae.
LEPIDOSAPHES Jactea.

FUMARIA (Papaveraceae).
MACROCEROCOCCUS superbus,
CEROPUTO superbus.

FUNTUMIA (Apocynaceae).
PULVINARIA psidii.

CEROPLASTES ceriferus.

Cutonasptis funtumiae, lutea.

FURCRAEA (Amaryllidaceae).
Lxecanium hesperidum, depressum.
ASPIDIOTUS furcraeicola, hederae.

GAERTNERA (Loganiaceae).
Frortnta scrobicularum.
GAHNIA (Cyperaceae).
LEpPIDOSAPHES cordylinidis.
GALIUM (Rubiaceae).
ORTHEZIA urticae.
Psrupococcus pulverarius.
ASPIDIOTUS niger.
GARCINIA (Guttiferae).
LECANIUM zonatum.
PULVINARIA psidii.
CEROPLASTES rubens.
VINSONIA stellifera.
ASPIDIOTUS greeni, dictyospermi,
rossi, rossi-ferrandii.
Frorinia frontecontracta.
PARLATORIA proteus.

GARDENIA (Rubiaceae).
Drostcua maskelli.
ORTHEZIA insignis.
Lecanium viride, hemisphaericum,
hesperidum, oleae.
PROTOPULVINARIA longivalvata.
CEROPLASTES ceriferus.
Howarpta biclavis.
Asprprotus articulatus,
tayabanus.
GARRYA (Cornaceae).
AsprIprotTus hederae.
GARUGA (Amyridaceae).
TACHARDIA lacca.
GAULTHERIA (Ericaceae).
HEMICHIONASPIS minor.
GAYLUSSACIA (Ericaceae).
ASPIDIOTUS perniciosus.
GEIJERA (Rutaceae).
FIoRINIA geijerae.
Aspipiotus hederae, rossi.
GELONIUM (Euphorbiaceae).
Ineuista chelonioides.
CHIONASPIS varicosa.
Frortyta proboscidaria, saprosmae-
gelonii.
GELSEMIUM (Loganiaceae).
ASPIDIOTUS hederae.
GENIOSTOMA (Loganaceae).
CTENOCHITON elongatus.
GENISTA (Leguminosae).
IcERYA genistae.
ASTEROLECANIUM fimbriatum.
LECANIUM genistae.
Draspis pentagona.
CHIONASPIS salicis.
Asprpiotus hederae, niger.
LEPIDOSAPHES ulmi.
GERANIUM (Geraniaceae).
ORTHEZIA urticae, cataphracta.
ASTEROLECANIUM fimbriatum, pustu-
lans.
PsEUDococcUS bechuanae.
Draspis pentagona.
GIGANTOCHLOA (Gramineae).
ASTEROLECANIUM bambusae.
ANTONINA bambusae.
ODONASPIS canaliculata.
GLAUX (Primulaceae).
ORTHEZIA urticae.

hederae,

HK. EK.

GLEDITSCHIA (Leguminosae).
PsEuDOCOcCcUS burnerae.
LECANIUM cynobati, rugosum, oleae.
Draspis pentagona.

Cutonaspis ortholobis, gleditsiae,
spinicola.

Asprpiotus forbesi, fernaldi, afri-
canus, ostreaeformis.

GLOBULARIA (Globulariaceae).
ASTEROLECANIUM rehi, fimbriatum.
CRYPTOPHYLLASPIS bornmulleri.
Asprp1otus labiatarum.

GLYCINA (Leguminosae).

LECANIUM wistariae.

GLYCOSMIS (Rutaceae).

Vinsonia stellifera.

GNETUM (Gnetaceae).
PSEUDOPARLATORIA cristata.
CRYPTOPARLATORIA uberifera.

GOODENIA (Goodeniaceae).

ICERYA aegyptiaca.

GOSSYPIUM (Malvaceae) ‘Cotton.’
Crrococcus hibisci.

PsEubDococcus citri, virgatus, per-
niciosus, filamentosus, corym-
batus, longispinus.

PHENACOCCUS gossypii.

LECANIUM nigrum.

PULVINARIA jacksoni, maxima.

INGLISIA malvacearum.

HEMICHIONASPIS minor, townsendi,
aspidistrae-gossy pu.

GOURLIEA (Leguminosae).
PsEUDOCOCCUS percerosus.

GRAPTOPHYLLUM (Acanthaceae).
PsEuUDOCOCCUS vVirgatus.

LECANIUM nigrum.

Iscunaspts filiformis.

‘GRASSES’ (Gramineae).
MoNOPHLEBUS fulleri.

WALKERIANA africana.

IceryA pilosa, purchasi.

MARGARODES hamelii, newsteadi, per-
ingueyi, ruber, papillosus, niger.

ORTHEZIA cataphracta, graminis,
martelli, urticae.

NEwWSTEADIA floccosa.

MAcCROCEROCOCCUS superbus.

Ertococcus graminis, greeni, in-
signis, kemptoni, quercus, nativus,

(GREEN 935

ruber, tenuis, formicola, salinus,
festucae, inermis.

Psrupococcus arecae, calceolariae,
graminis, herbicola, hibernicus,
neomexicanus-alkalinus, nubicola,
poae, roseotinctus, salinus, segre-
gatus, walkeri, calceolariae-minor,
bantu, elongatus, natalensis, soci-
alis, mallyi, caffra, flagrans, tim-
berlakei, aridorum, citri, pulver-
arius, kandyensis.

PuHENacoccus cholodkovskyi, grami-
nicola, graminis.

CEROPUTO calcitectus, volynicus, su-
perbus.

NATALENSIA fulleri.

Rrpersta festucae, halophila, mon-
tana,porterae, salmonacea, subter-
ranea, tenuipes, tomlini, trichura,
corynephori, sporoboli, libera, ory-
zae, smithii, occulta, globata.

TRIONYMUS petrisii, nanus, cali-
fornicus, violaceus, insularis.

RIPERSIELLA kelloggi, maritima.

Gkococcus radicum.

Micrococcus similis.

ANTONINA graminis, parrotti, pur-
purea, indica, phragmitis, natal-
ensis, transvaalensis, maritima.

LEecaNiIuM anthurii, tenuivalvatum.

LEcANopsIS brevicornis, longicornis,
formicarum, butleri.

Luzunaspts luzulae.

SperRMococcus fallax.

EXAERETOPUS Caricis.

ERIOPELTIS festucae, lichtensteinii,
brachypodii, coloradensis.

PARAFAIRMATRIA bipartita, gracilis.

ACLERDA californica, digitata, ob-
scura, subterranea, signoreti.

DraspPis uncinati.

Eprpraspts subterranea.

CHIONASPIS herbae, natalensis, gra-
minis, spartinae.

HEMICHIONASPIS aspidistrae.

Asprpiotus bilobis, hederae, grami-
nella, sacchari, marlatti, panici.

OpoNnASPIS janeirensis, graminis, ru-
thae.

LEPIDOSAPHES ampelodesmae.

236 List of Coccidae affecting various Genera of Plants

GREVILLEA (Proteaceae).
WALKERIANA cinerea.
ASPIDOPROCTUS maximus.
ASTEROLECANIUM pustulans.
PsEupococcus grevilleae, filamen-
tosus, citrophilus.

Erium globosum, newmani.

Lecantum longulum, hemisphaeri-
cum-hibernaculorum.

HEMICHIONASPIS minor.

Howarpta biclavis.

Asprpiotus hederae, camelliae.

LEPIDOSAPHES grevilleae.

GREWIA (Tiliaceae).

TACHARDIA lacca.

ERIUM newmani.

Tyxiococcus formicarii.

LECANIUM oleae.

Tneuista castilloae.

CHIONASPIS vitis.

Frorrnta tumida, secreta.

CRYPTOPHYLLASPIS occultus, occul-
tus-elongatus.

GRINDELIA (Compositae).
PaLAEococcus townsendi.
LECANIUM assimile.

GRISELINIA (Cornaceae).
LEUCASPIS gigas.

GRISLEA (Lythraceae).
ASPIDIOTUS moorei.

GROSSULARIA (Grossulariaceae).
LECANIUM armeniactm, coryli, cyno-

bati, rehi, ribis, persicae.
PULVINARIA occidentalis.
FIORINIA grossulariae.
Asprpiotus forbesi, perniciosus.

GUAIACUM (Zygophyllaceae).
PALAEOCOCCUS rosae.
LEcANtUM tessellatum.
CEROPLASTES floridensis.
ASPIDIOTUS aurantii.

GUAZUMA (Sterculiaceae).
TACHARDIA rotundata.
Ertococcus aurescens.
LECANIUM nigrum.
HEMICHIONASPIS minor.

GUETTARDA (Rubiaceae).
Howarpta biclavis.

GUTIERREZIA (Compositae).
PaLAakococcus townsendi,

ORTHEZIA nigrocincta.
TACHARDIA glomerella.
Ertococcus tinsleyi-cryptus.
PsEUDOCOCCUS gutierreziae, neomexi-
canus.
ASPIDIOTUS gutierreziae.
GYMNOSPORIA (Celastraceae).
LECANIUM gymnospori.
AspIpDIoTUS gymnosporiae, laureto-
rum.
GYNANDROPSIS (Capparidaceae).
CHIONASPIS gynandropsidis.

HABROTHAMNUS (Solanaceae).
PsSEUDOCOCCUS citri.

HAKEA (Proteaceae).
PaALAEOCOCCUS australis, rosae.
ASTEROLECANIUM hakeae.
Ertococcus hakeae.

LEcANIUM depressum.

PULVINARIA maskelli-viminariae.

AUSTROLICHTENSIA hakearum.

CHIONASPIS eugeniae.

Asprpiotus hakeae, comperei,
acaciae-propinqua.

Aonrpra rotunda.

GyYMNASPIS perpusilla.

PARLATORIA petrophilae.

LeprmposapHeEs defecta-tincta.

HALOXYLON (Chenopodiaceae).
PULVINARIA orientalis.

HAMELIA (Rubiaceae).
ORTHEZIA insignis.

HARPULLIA (Sapindaceae).
TACHARDIA albizziae.

HAROGANA (Guttiferae).
STicTococcus gowdeyi.
Iveutsta conchiformis.

HEBERDENIA (Myrsinaceae).
Asprptiotus lauretorum.

HEDERA (Araliaceae) ‘Ivy.’
IcERyA purchasi.

ORTHEZIA urticae.

ASTEROLECANIUM hederae, fimbria-
tum.

PSEUDOCOCCUS citri.

PHENACOCCUS hederae, aceris.

Lecanium hesperidum, maculatum.

Frurepta oleae.

LICHTENSIA viburni.

EK. E. Green ap

HEDERA (Araliaceae)—cont.

Dtaspis bromeliae.

AspIDIoTUS cydoniae-crawi, hederae,
lauretorum, camelliae, ficus, dic-
tyospermi, britannicus.

HEDYCARPUS (Euphorbiaceae).

LeEvcasPIis stricta.

HEDYCARYA (Monimiaceae).

CTENOCHITON viridis.

HEDYOTIS (Rubiaceae).
Cutonaspis hedyotidis, galliformens.
HELIANTHEMUM (Cistaceae).

NEWSTEADIA floccosa.

ASTEROLECANIUM fimbriatum.

LECANIODIASPIS sardoa.

CrRococcus eremobius.

LEPIDOSAPHES ulmi.

HELIANTHUS (Compositae).
Puenacoccvus helianthi.
Asripiotus helianthi.

HELICHRYSUM (Compositae).

Crrococcus bryoides.

Ertococcus sordidus.

LECANIUM oleae.

ASPIDIOTUS niger.

HELICONTA (Musaceae).
Draspis boisduvallii.
HEMICHIONASPIS aspidistrae.

HELICTERES (Sterculiaceae).
CErrococcus indicus.
ERtococcus paradoxus-indicus.

HELIOTROPIUM (Boragineae).
DIaspiIs pentagona.
CHIONASPIS major.

HEMICYCLEA (Euphorbiaceae).

TACHARDIA albizziae.

LECANIUM expansum.

AonrpiA echinata.

HERACLEUM (Compositae).

ORTHEZIA urticae.

HERNIARIA (Caryophyllaceae).

MARGARODES polonicus.

HETERODENDRON (Sapindaceae).

TACHARDIA melaleucae. .

Asprpiotus hederae.

HEVEA (Euphorbiaceae).

ASTEROLECANIUM pustulans-seychel-
larum.

PsEupococcus virgatus.

LECANIUM nigrum.

(Shs)
~I

VINSONIA Stellifera.
Cutnoaspis dilatata.
HEMICHIONASPIS aspidistrae.
AsPIDIOTUS cyanophylli, destructor,
transparens, ficus, personatus.
PARLATORIA proteus.
LEPIDOSAPHES rubrovittatus.
HIBBERTIA (Dilleniaceae).
PsEubococcus hibbertiae.
HIBISCUS (Malvaceae).
ConcHASPIS angraeci-hibisci.
ASTEROLECANIUM pustulans.
Crerococcus hibisci.

PsEupococcus bromeliae, cocotis,
filamentosus.

Lecanium hesperidum, depressum,
nigrum.

PULVINARIA cestri, citricola.
ERICERUuS pela.
CEROPLASTES ceriferus, dugesii, ficus.
INGLISIA malvacearum.
Strcrococcus diversiseta.
Diaspis bromeliae, pentagona.
Howarpta biclavis.
HEMICHIONASPIS minor, mussaendae,
aspidistrae.
Asprp1otTus longispinus, perniciosus,
cydoniae.
PARLATORIA chinensis.
HIERACEUM (Compositae).
MaRGARODES polonicus.
ORTHEZIA urticae.
ASTEROLECANTUM fimbriatum.
CreropuTo pilosellae.
HIPPEASTRUM (Amaryllidaceae).
PsEUDOCOCCUS citri.
HIPPOCREPIS (Leguminosae).
ASTEROLECANIUM fimbriatum.
HIPPOPHAES (Elaeagnaceae).
PHENACOCCUS aceris.
CHIONASPIS salicis.
LEPIDOSAPHES ulmi.
HIPTAGE (Malpighiaceae).
LEcANIUM tessellatum, viride.
HOHERIA (Malvaceae).
Ertococcus hoheriae.
CHIONASPIS dysoxyli.
LEvcAspPIS stricti.
HOLACANTHA (Simarubaceae).
Draspis toumeyi.

238

HOMALOMENA (Araceae).
PINNASPIS buxi.

HOMOGYNE (Compositae).

ORTHEZIA cataphracta.

HORDEUM (Gramineae).
PsEubococcus hordei.

HOSTA (Liliaceae).

HEMICHIONASPIS aspidistrae.

HOWEA (Palmaceae).

LecaniuM tessellatum.
Frorinta kewensis.

HOYA (Asclepiadaceae).
PsEuDococcus hoyae.

HUMBOLDTIA (Leguminosae).
Lacunopius humboldtiae.

HUMULUS (Urticaceae) ‘Hop.’
ORTHEZIA urticae.

PHENACOCCUS aceris.

HURA (Euphorbiaceae).

LEcANIvUM oleae, hurae.
CEROPLASTES cirripediformis.

HYALIS (Compositae).

PsEUDOCOCCUS mendozinus.

HYDRANGEA (Saxifragaceae).
LECANIUM persicae, magnoliarum-

hortensiae.

HYGROPHILA (Acanthaceae).
PsEuDOococCcUS viridis.

LEcANIUM nigrum, oleae.
PULYINARIA obscura.

HYMENAEA (Leguminosae).
LICHTENSIA zapotlana-townsendi.
Howarpta biclavis.

HYMENANTHERA (Violaceae).
PULVINARIA maskelli-novemarticu-

lata.
CrENOCHITON hymenantherae.
LEPIDOSAPHES hymenantherae.

HYMENOCLEA (Compositae).
ORTHEZIA sonorensis.
Psrubococcus hymenocleae.

HYPERICUM (Guttiferae).
ASTEROLECANIUM fimbriatum.
Lecantum pulchrum.
ASPIDIOTUS privignus, camelliae

labiatarum.

HYPHAENA (Palmaceae).
CHIONASPIS pseudonivea.
ASPIDIOTUS fissidens-constricta.

HYPOCALYMMA (Myrtaceae).

5]

List of Coccidae affecting various Genera of Plants

TACHARDIA convexa.

SpHAEROCOCCUS pulchellus.
HYPTIS (Labiatae).

Diaspis pentagona.
HYSSOPUS (Labiatae).

ASPIDIOTUS rossi.

IDESIA (Flacourtiaceae).

PULVINARTA idesiae.

ILEX (Aquifoliaceae) ‘Holly.’

PaLagococcus pulcher.

Lecanium _ hesperidum,
nigrofasciatum, oleae.

CERONEMA japonica.

CEROPLASTES floridensis,
rubens, rusci.

Dtaspis_ penzigi.

PINNASPIS javanica.

Asprptotus britannicus, hederae,
camelliae, ficus, perseae, laure-
torum, paeoniae, dictyospermi.

PARLATORIA theae-viridis.

ILLIGERA (Combretaceae).

ASPIDIOTUS replicatus.

IMPATIENS (Geraniaceae).
CEROPLASTES floridensis.
INDIGOFERA (Leguminosae).

HEMICHIONASPIS chionaspiformis,
minor.

INGA (Leguminosae).

IcERYA montserratensis.

TACHARDIA ingae.

ASTEROLECANIUM pustulans.

CEROPLASTES confluens.

IPOMOEA (Convolvulaceae).

ORTHEZIA insignis.

PSEUDOCOCCUS citri.

Lecanium hesperidum, batatae.

PULVINARIA urbicola.

CEROPLASTODES Cajani.

CEROPLASTES cirripediformis.

HEMICHIONASPIS minor.

Asprpiotus cyanophylli, excisus.

IRIS (Inidaceae).

ASPIDIOTUS dictyospermi.

IXORA (Rubiaceae).

LECANIUM mangiferae, hemisphaeri-
cum, maritimum, hesperidum,
viride.

PULYVINARIA ixorae,

notatum,

grandis,

E. E. GREEN 239

IXORA (Rubiaceae)—cont. JUNIPERUS (Coniferae).

Aspipiotus trilobitiformis, articu- Ertococcvs gillettei.

latus. PsEUDOCOCCUS juniperi, vovae.
LEPIDOSAPHES ixorae. Draspis juniperi, carueli, atlantica,
IscHnaspts filiformis. visci.

CHIONASPIS striata.
AONIDIA juniperi.

JABOTICABA (Myrtaceae). CRYPTOPARLATORIA leucaspis.
Asprpiotus trilobitiformis. ASPIDIOTUS maderensis.
JASMINUM (Oleaceae). CRYPTASPIDIOTUS mediterraneus.
IcerRYA purchasi. FIORINIA juniperi.
ASTEROLECANIUM pustulans. LEPIDOSAPHES juniperi.
PHENACOCCUS ornatus. JUSTICIA (Acanthaceae).
LEcANIUM hesperidum, mangiferae, ORTHEZIA insignis.
acuminatum. LECANIUM hemisphaericum, nigrum,
Diaspis pentagona. viride.
CHIONASPIS euonymi. Cutonaspis longispina.

Howarpta biclavis.
Asprpiotus lataniae, forbesi, per- KENNEDYA (Leguminosae).

sonatus, dictyospermi, aurantii, IcrRyA purchasi.
rossi, hederae, trilobitiformis, bri- Aspipiotus kennedyae.
tannicus. KENTIA (Palmaceae).
PaRLATORIA blanchardi. PsEuDOcOccUS pseudonipae, nipae.
Iscunaspis filiformis. Draspis_ boisduvallii.
JATROPHA (Euphorbiaceae). Frortnta pellucida.
LLAVEIA axin. Asprpiotus hederae, dictyospermi,
PsEUDOCOCCUS virgatus. ficus.
LECANIUM nigrum. PARLATORIA proteus.
HEMILECANIUM imbricans. KHAYA (Meliaceae).
HEMICHIONASPIS minor. Dtaspis senegalensis.
JOSSINIA (Myrtaceae). KIBARA (Monimiaceae).
PULVINARIA grabhami. Myxorecanium kibarae.
JUGLANS (Juglandaceae) ‘Walnut.’ KIGELIA (Bignoniaceae).
PsEuDococcus bakeri, citrophilus. ASPIDIOTUS lataniae.
Lecantum cockerelli, juglandifex, KNIGHTIA (Proteaceae).
juglandis, oleae, coryli. Ertococcus multispinus.
PutyinariA betulae. KOELREUTERIA (Sapindaceae).
DIAspPiIs pentagona. PULVINARIA horii.
Curonaspis furfura, ortholobis. KRAUNHIA (Leguminosae).
Eprpraspis lepéri. LECANIUM corni, persicae.
ASPIDIOTUS aesculi-solus, forbesi, ju- KUNZEA (Myrtaceae).
glandis, juglans-regiae, pernicio- Ertrococcus leptospermi, araucaria-
sus, ulmi. minor.
LEPIDOSAPHES juglandis, ulmi, multi- KYDIA (Malvaceae).
pora, conchiformis. TACHARDIA lacca.

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“THE ANNALS OF
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THE OFFICIAL ORGAN OF THE ASSOCIATION
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CONTENTS OF Vor. IV, Nos. 1 anp 2

Frit Fly (Oscenus va seers: Winter Wheat. = F. R. PETHER-
BRIDGE ake tate =

Some Farm Insects fetal in the Abersstvyth Are, 1913-1916. eat aaa
By C. L. Watron, M.Sc. fe es :

A Note on Agricultural Oecology in Mia- Wels. By 0. L. War ae
TON, M.Sc. .

On a Disease of the Beech ee a Bini Pelion Wett. By :
R. J. Tazor, B.Sc., and Kate Barratt, M.Sc. (With Plate I.)

The Life History and Economy of the Cheese cpr any. NELLIE B.
Ears, B.Sc. (Lond.). ee:

Investigation of Bulb Rot of Narcissus. Part 1. The pee of the
‘Disease. By E. J. Wetsrorp, F.L.S. (With Five Text-Figures.)
Notes on a Plague of Psocids in a Factory. By Ke A. HarpER ~

Gray, M.A., B.Sc. (Agric.), M.Sc. 3 ae.
A Bacterial Blight of Pear Blossoms occurring in South Africa. By Bots
Eruet M. Dorper, M.A., D.Sc., F.L.8. (With 7 Text-Figures.) ‘Sve
A List of the Coccidae affecting various Genera of Plants. By j
E. Ernest GREEN
Note on the Immunity of Chaleid Painsiter to o Hydocyanie Acid Gas. |
By E. Ernest GREEN | : ; ; ; at

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ys Soa

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THe NATIONAL IMPORTANCE OF CHEMISTRY. By W. J. Pops, F.RS,
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CONTENTS OF Vot. IV, No; 013-28

On the Larval and Pupal Stages of Bibio Johannis L. By Hinde
M. Morats, M.Sc. (Manch.). (With Plate II and 12 Text-Figures.)
Two Experiments in House Fumigation. By H. Maxweti-LeFRoy
The Locust in Cyprus. By W. P. Drtane Srespine, F.G.8.
Mussel Beds; their Productivity and Maintenance. By Peane 8.
WRIGHT . ; : ; ; Mea es CAS

arene

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Edited by A. C. SEWARD, F.R.S., Master of Downing College, Cambridge.

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THE ANNALS OF
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EDITED BY

WITH THE “ASSISTANCE OF

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CONTENTS OF Vot. IV, No. 4

Ustulina Zonata (Lev.) Sacc. on Hevea Brasiliensis. By. A. SHARPLES, sae
ARCS. D.C. (With Plates III—VIII and 1 Text-figure.) _

A study of the Capsid Bugs found on Apple Trees, By F. R.
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Notes on the Strawberry Leaf Beetle (Galerucella tenella Linn.).
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SCIENCE AND THE NATION

Essays by Cambridge Graduates
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Right Hon. Lord Moulton, K.C.B., F.R.S.

" Edited by A. C. SEWARD, F.R.S., Master of Downing College, Cambridge.

It is the aim of the authors of these essays to present the results of
"experience in scientific investigation, to illustrate by concrete examples the
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_ to the layman the position of research as a factor in national prosperity.
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ies Extracts from Press Notices

aa ues! ‘One ‘of the most important and most illuminating of recently published volumes on the place

_ of science in national life.... The admirable essays contained in the volume give assurance that the
-men who are chiefly vesponsible for the direction of scientific instruction in this country have the
- root of the matter in them, that British science is sound and vigorous at its centre, and that what
is mainly required is the intellectual and financial support of the nation as a whole.’’—Leading
Si Article in Glasgow Herald

REL This is a fascinating book, and it fulfils its purpose admirably of helping ordinary people to
grasp the value of scientific research.. .. The essays are the clearest popular exposition with which
we are acquainted | of the achievements of modern science in the service of man. »”_TInquirer

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