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LIBRARY

UNIVERSITY OF CALIFORNIA
DAVIS



THE



RAY SOCIETY



INSTITUTED MDCCCXLIV.







This volume is issued to the Subscribers to the RAY SOCIETY for
the Year 1881.



LONDON:

MDCCCLXXXII.



LIBRARY

UNIVERSITY OF CALIFORNIA
DAVIS



A MONOGRAPH



BRITISH

PHYTOPHAGOUS HYMENOPTERA,

(TENTHREDO, SIREX AND CYNIPS, Linne.)
VOL. I.



BY

PETER CAMERON.



LONDON:
PRINTED TOR THE RAY SOCIETY.



MDCCCLXXXII.



! IBRARY

UNIVERSITY OF CALIFORNIA
DAVIS



PRINTED BY J. E. ADLARD, BARTHOLOMEW CLOSE.



PEEFACE.



THE present work gives a systematic and biological
description of the species of the Hymenopterous
Families Tenth red hi id ce y Siricidce, and Cynipidce, known
at present to inhabit Britain. So far as the two first
families are concerned, this is not the first work on
the British species; for in 1835, in the seventh volume
of his * Illustrations of British Entomology," James
Francis Stephens described the species known by him
to inhabit these isles. Stephens' work is now obsolete,
while since its publication until within the last decade
the plant-feeding Hymenoptera have been altogether
neglected. This is a somewhat curious circumstance,
considering that they are the easiest of all Hymenoptera
to name, that many of them possess elegant and beau-
tiful forms, and many interesting peculiarities of
structure, while their life histories can be worked out
with comparative ease, and afford biological and
physiological problems of the greatest interest for
investigation. The Ciinipidce or gall-flies have been
even more neglected, and only a few fragmentary
papers have been published on the British species.






VI PREFACE.

The published works or papers on the British
species and the workers at the groups being so few, I
cannot hope that the present Monograph is very com-
plete as regards the actual number of British species ;
while, as will be seen, the life-histories of very many of
our commonest species are quite unknown. I cannot
hope either that I have escaped the errors of omission
and commission incidental to a work of this kind,
dealing as it does with little studied and little known
animals ; but such as it is, I hope, that at any rate it
will increase the number of students of these neglected,
but most interesting insects, and thus lead to an
extension of our knowledge of the British species and
their habits.

The literature being thus so scanty, my indebted-
ness is the greater to those gentlemen who have
rendered me assistance by lending me specimens or
giving me information. In this respect my thanks are
especially due to Professor Westwood, F.L.S., Pro-
fessor J. W. H. Trail, F.L.S., Professor Gustav L.
Mayr, of Vienna, the late Professor Zaddach, of
Konigsberg, the late Dr. S. 0. Snellen van Vollen-
hoven, of the Hague, Dr. David Sharp, of Thornhill,
Dr. Buchanan White, F.L.S., of Perth, Messrs. R.
McLachlan, F.R.S., J. E. Fletcher, John B. Bridg-
man, Joseph Chappell, Edward Saunders, F.L.S., E. A.
Fitch, F.L.S., 0. W. Dale, James Hardy, J. J. King,
Thomas Wilson, T. E. Billups, J. G. Marsh, C. G.
Bignall, Richard McKay, the Rev. T. A. Marshall,



PREFACE. Vll

E. A. Butler, Herr Brischke, of Dantzig, and the
late Fredk. Smith, of the British Museum. To
Mr. J. E. Fletcher, of Worcester, I am much obliged
for the great trouble he has taken in procuring me
Iarva3 for figuring ; Mr. W. F. Kirby, of the British
Museum, has given me bibliographical information
which I could not obtain here from the absence of
libraries ; while I have to thank the Secretary of the
Kay Society, the Rev. Professor Thomas Wiltshire,
F.L.S., Professor Rupert Jones, F.R.S., and Mr. J. J.
Weir, F.L.S., for revising the proofs.



GLASGOW;

July, 1882.



A MONOGBAPH



OF THE



BRITISH

PHYTOPHAGOUS HYMENOPTEEA.

VOL. I.



INTRODUCTION.

THE term " Phytophagous " is applied to the Insects
described in the present work to signify that most of
them are plant-feeders, and not that they form a homo-
geneous section of the Order Hymenoptera to which
they belong. Nor, indeed, is the term strictly correct,
for many of the species in one group the Cynipidce
are animal parasites ; while this family differs
structurally from the other families described, in
having the abdomen attached to the thorax by a narrow
pedicle only having it appendiculated or petiolate
the abdomen in the other section, that containing the
Tenthredinidce and Siricidce, being joined to the thorax
by its entire width, or sessile. The latter groups,
furthermore, differ from all other Hymenoptera (includ-
ing the Cynipidce) in the peculiar structure of the
ovipositor, and in the larvae having legs on the thorax.

The four families of Tenthredinidce, Siricidce, Ce-
phidce, and Oryssidce (Holonota, Foerster*) form thus

* Ueb. d. syst, Wertli d. Fliigelgeaders b. d. Hymen., p. 19.
VOL. I. 1



2 THE IMAGO THE HEAD.

a well-marked section, and together have been
variously called Phytiphaga in allusion to their habits,
Sessiliventris, in allusion to the form of the abdomen,
and Securifera or Serrifera, after the form of the ovi-
positor. We may distinguish the groups as follows :

Abdomen joined to the thorax by its entire width. Trochanters with
two joints. Anterior wings with a lanceolate cellule. Larvae with legs
on thorax only, or on thorax and abdomen. Sessiliventris*

I. Fourth body-segment (metathorax) fissured in the middle at its
apex, antennas placed above the clypeus, and above the lower part of
the eyes. Anterior wings with at least three cubital cellules.

A. Anterior tibiae with two spines at the apex. Prothorax email.
Tenthredinidce.

B. Anterior tibiae with one spine. Prothorax large.

1. Antennae subclavate, abdomen compressed. Middle lobe of
mesonotum not reaching to scutellum. Tibiae spined. Ovi-
positor short. Cephidce.

2. Antennae of uniform thickness. Middle lobe of mesonotum
reaching to scutellum, and separated from it by a transverse
line. Ovipositor long. Siricidce.

II. Fourth body-segment not fissured. Antenna? inserted below the
clypeus and the eyes. Ovipositor semi-spiral. Anterior wings with
two cubital cellules. Oryssidce.



1st. Family.

1. THE IMAGO.

The Head.

The head is always broader than long, but never
broader than the thorax ; it has never a globular form,
and usually is more or less concave behind. The eyes
are large, sometimes projecting, and situated on the
sides, rarely occupying much of the inner portion of
the head. They may (Sciopteryx) or may not reach to
near the base of the mandibles. The vertex is flat
with Lyda, depressed with some Tenthredina, and thick
and somewhat rounded with Dolerus, &c. ; the three
ocelli are placed in a triangle on it. The vertex has
sometimes well-marked sutures, as has also the front ;
while immediately below the ocelli there is sometimes

* The other division of the Hymenoptera is called Petioliventris.



THE AXTKNN/R. 3

a raised five-angled field the pentagonal or frontal
urea which is especially well defined with the
latina.

There are three of these furrows on the vertex, one on
either side of the ocelli, and one between, running in
the direction of the central ocellus, but this middle
furrow is not always present. Other furrows proceed
from below the ocelli, round the base of the antennae
the frontal furrows.

With Hylotoma, Nematus, &c., there is a projecting
ridge (sometimes with afovea the antennal ' fovea in
its centre) between the antennas the antennal tubercle.

The clypeus is large, and is either deeply incised
or truncated at the apex. The labrum is transverse,
rounded, and often hairy at the apex. In rare cases
the apex of the clypeus is slightly indented as in
Gladius viminalis (PI. XV, fig. 3 b).

The antennce. The antennae are placed immediately
over the clypeus. They are seldom (save in the case
of some male insects) much longer than the abdomen,
and may be, as in Perga, not much longer than the
head. With most species they taper slightly in thick-
ness towards the apex, while the joints decrease in
length, with those species which have them nine-
jointed ; the third joint being as a rule the largest.
The Gimbicides have them clavate or subclavate, the
apical joints forming a more or less distinct club.
Some species of Attantus and Tenthredo have them also
to a certain extent thickened at the apex, while others
have them more or less fusiform. The two basal
joints (forming the scape) are more globular than the
others, besides being the shortest. The remaining
joints may be of equal thickness throughout (as is more
often the case) or may be produced beneath into blunt
teeth (Lophyrus), or projecting processes (Tarpa). In
Pinicola (Xyela) the third joint is greatly developed,
much thickened, and fusiform in shape. Some species
of Lyda have the third joint enlarged and thickened,
and there may be, between it and the second, a small



4 THE TROPHI MANDIBLES.

intermediate joint. A few genera of Hylotomina have
the large apical joint deeply grooved.

The number of joints varies : Cimbicides have from
five to seven ; Hylotoma has only three, namely, two
small ones at the base, and a very long terminal one.
Mne must be regarded as the normal number, that
being the number with Tenthredina (with a few
exceptions) and Nematina. The exceptions are the
Phyllotomides which have fewer joints (Goenoneura with
seven or eight) or more (Phyllotoma ten to sixteen
joints). Pinicola again has twelve- jointed antenna ;
LopTiyrus seventeen to twenty-three; and Lyda twenty-
two and upwards.*

Male insects have the antennas often differently
shaped from those of the female ; being often hairy,
pectinated, &c., as explained further on.

The mandibles. These are as a rule short and thick,
broad at the base, and tapering (sometimes bulging out
first) to a blunt point at the apex. In Hylotoma and
some Nematina there is only the apical tooth (PI. X,
fig. 10), but other genera have them toothed or in-
dented along the edge as well, and in some cases the
basal part has a jagged edge. This is more especially
the case with carnivorous species (Tenthredo, &c. 9
PL XII, figs. 13, 16), while again certain males
(Trichiosoma) have long, sharply-toothed mandibles,
which they use in fighting among themselves.

The form of the maxilla (PL X, fig. 3) does not offer
any striking features, nor does it afford good cha-
racters which can be used in classification. The outer
lobe (PL X, fig. 3, 2) is more or less rounded at the
apex, and contracted in the middle, or quadrate at the
apex as in Allantus. The inner lobe (1. c.,) is very short
with Hylotoma, with which it scarcely projects beyond
the base of the outer ; in Lyda it is slightly longer ;
with Nematus it ends in a sharp point, which reaches

* When the number of joints exceeds the normal number (9) they
tend to vary in the same species, so that the number of joints cannot
always by itself be regarded as a specific character.



THE MAXILLA PALPI. <5

to near the top of the outer lobe ; this being the case,
too, with Tenthredo, only it is longer. Generally the
parts are more or less membranous, especially at the
apex.

The maxillary palpi vary only in the relative size
and length of the different joints, and in number (at
least, so far as European species are concerned) they
are uniform, namely, six. In Fenusa there is indeed
a short intermediate joint at the apex of the third,
according to Hartig, but it is doubtful if it can be
regarded as a distinct joint, nor does it exist in all the
species. Curtis,* too, mentions a species having only
five in the maxillary and three in the labial palpi ; but I
have not been able to verify this observation, as he does
not mention the species, further than saying that it is
allied to Selandria.

The basal joints are horny; the apical are more
membranous and lighter coloured, while they may be
provided with short hairs. The basal joint is the
smallest, the second somewhat larger, and the third is
one of the longest. The fourth, again, is often very
small Cimbex, Cladius and not unfrequently the
joints, from the second, may be pretty much of the
same length Dolerus, Athalia, Tenthredo.

The labium (PL X, fig. 2) is deeply cleft into three
nearly equal lobes, which are rounded at the apex and
generally of the same size and form. The middle lobe,
however, may be larger than the others and truncated
at the top. Tenthredo scalaris has a little conical
point on the centre of the middle lobe. Some forms
have the parts widely separated and well marked, but
with Hylotoma, Tenthredina, &c., they are closely
pressed together.

The labial palpi have usually four joints. With
Cimbex the third joint is thickened and bulged out, and
the fourth knob-like at its outer edge. With other
species (Emphytus, &c.) the third is smallest, while
with Hylotoma they increase in size from the base.

* B. R, 764.



6 THE THORAX.

With Nematus, again, there is no great difference in
size. Pinicola appears to have three-jointed palpi.

Save with Tar pa the labium and maxilla are incon-
spicuous. In Tarpa they are long and projecting.

The Thorax.

The thorax forms a compact mass, and is usually
slightly broader than the head, and of the same width
as the abdomen. The prothorax (PI. X, fig. 1, 17) is
small, the only portion visible from above being that
part often denominated the " collar," a part which ,
from its being separated from the lower or leg-bearing
portion, has by some been regarded as a distinct
piece. The " collar " (pronotum) is firmly united to the
mesothorax, from which it is not readily detached.
Looked at from the side it is somewhat triangular as it
issues from the base of the mesothorax, where the wings
are inserted, towards the head, and from that curves
down towards the legs ; the same being the case on the
inner side, so that it becomes quite narrow at its lower
part (PI. XY, fig. 11 a). The episternum (1. c. I) is
shorter and stouter than the " collar," and slightly
broader at the bottom than at the top. It is much freer
in its attachment than the pronotum, and comes away
easily, carrying the legs and head with it when pulled
from its attachment. The prosternum is a small piece
situated between the episternum and the two coxae
(PI. XY, fig. 7, prosternum of Dolerus).

The mesothorax is very large compared with the two
other portions. The scutum and scutellum form one
piece, the latter being generally flat and but slightly
raised above the scutum, but is usually sharply cut off
from the metanotum by the ridge which separates the
latter from the mesothorax. The mesonotum is divided
by depressions into three parts, a triangular one in
front and one on either side, the first being called the
"front" or "middle" (PI. X, fig. 1, 18), and the
others the " lateral " lobes of the mesonotum (PI. X,



THE METATHORAX. 7

fig. 1, 19, :20). The middle lobe never reaches to
the scutellum, from which it is sometimes separated
by a deep depression. Close to the prothorax, and
where the wings are inserted, are two overlapping
horny points, often differently coloured from the sur-
rounding parts, called tegulce.

The epistcrnuiii is a small three-angled piece situated
below the front of the wings. The mesosternum and
i era are well developed, and their usual form may
be seen by a reference to the figures (PL XV, fig. 11,
i/, //). The mesojphragma is made visible by remov-
ing the metanotum which lies over it. At its base it
stretches from one side of the thorax to the other, but
it narrows towards its apex, which curves down into
a sort of hook form, the apical part being split in two
(PI. XV, fig. 6, j from above, d from the side).

The metathorax forms a narrow ring, and is never
larger than the basal segment of the abdomen. It is
separated from the mesothorax above by a deep
depression. On its front edge, and close to the scu-
tellum, are two white bead-like horny points, called
ccnchri (PI. X, fig. 1, 22), which are usually un-
protected, but with Li/da are covered with overlapping
hoods. Immediately behind this ring (which has a
distinct metasternum) there is, separated from it by a
groove, another arc which has no ventral continuation
(PI. XV, figs. 6, 12 a, 13 c) and bears a stigma (fig.
126). The precise signification of this segment has
been much discussed, some considering it to form part
of the abdomen, while others look upon it as belonging
to the metathorax. There can be little doubt that it
is a distinct segment, and if we regard the thorax as
being made up of three segments, then it would have
to be regarded as part of the abdomen ; but, on the
other hand, it seems clear that functionally it forms
part of the thorax, it having the muscular system, &c.,
identical with the three preceding segments, besides
being much more intimately bound with the thorax
than with the abdomen. In other words, the thorax



8 THE LEGS.

is to be regarded as composed of four segments,* a
\>iew which holds good likewise with the larvae, whose
fourth segment (which is never provided with legs like
the succeeding segments) ministers to the thorax
rather than to the abdomen, or the part of the body
subserving to nutrition. Latreille called it the " seg-
ment mediale," a term which is appropriate enough,
but probably it is best to call it the fourth thoracic or
body segment.

The legs have two-jointed trochanters (PI. X, fig.
8, 1), and have on the apex of the tibiae (including
the front pair, a character which distinguishes them
from all other ffymenoptera) two spurs (calcaria) (PL
X, fig. 1, 24). The calcaria are absent in the
exotic genus Pacliylota. In length the legs are vari-
able, but they are never of excessive length or thick-
ness, nor is one part ever much developed in propor-
tion to the others. The spurs are sharp-pointed and
minutely-toothed with Dolerus, Cladius, &c. ; tubercle-
like with Cimbex and Lophyrus; while with many genera
(Emphytus, &c.) the point of the outer spine is dilated
at the end into a fleshy prong. The posterior calcaria,
are always simple and sharp-pointed, and one is longer
than the other. Hylotoma, Lyda, and Tarpa (among
European genera) bear one or more spines (PL X, fig.
1, 25) on the two hind tibia?, or one on all the
legs, as with Lyda pratensis, &c. Hylotoma has one
on each of the two posterior tibiae, Tarpa two on the
same parts ; some forms of Lyda have one on the
anterior and three on the two posterior. Pinicola,
again, has three on each of the two posterior tibiae.
The tarsi are five-jointed. The joints are unarmed
with Phyllotoma, but, with most of the other genera,
they are provided with leaf-like expansions on the
underside, called patella (PL X, fig. 6, 1). The
claws on the apex of the tibiae are either equally cleft

* See Audouin, Ann. d. Sc. Nat., i, 1824 ; Latreille, Regne An.
v; Westwood, Int. ii, 92; Reinhard, B. E. Z., 1865; Palmen, Zur
Morphologic des Tracaeensystenas, 98.



THE WINGS. 9

(bifid) (PI. XY, fig. 10), simple (1. c. fig. 8), or with a
minute tooth not far from the apex (PL XV, fig 9).

Croesus has the basal joint of the tarsus flattened
into a plate-like expansion, the posterior tibiae being
also thickened towards the apex. Some species of
Nematus have the apex of the hinder tibise thickened,
and often grooved on the inner side.

The icings are (with one exception*) always present,
and four in number, the two anterior being much the
larger pair. They are broadest at the apex, which is
rounded (PI. X, fig. la). In texture they are mem-
branous. The front border (the costa) is thickened,
and towards the apical third of the wing is a thickened
spot called the stigma (PI. X, fig. 1 st), which is often a
conspicuous object, especially when it projects above
the costa, as it does with Pachylostica.

Generally the wings are hyaline and often iridescent,
but with some species they are coloured, either in
patches or throughout, the usual colour in either case
being black, although with many exotic forms it is
bluish; and, in the latter case, it has occasionally a
metallic lustre, the wings themselves being of a thicker
texture than usual.

Proceeding from the base of the wing towards the
apex, but seldom reaching much beyond the stigma,
are four nervures, while from the neighbourhood of
the base of the stigma, other two nervures run to the
apex in a slightly curved fashion. Intersecting these
transverse nervures, are shorter longitudinal ones, so
that, in this way, enclosed spaces are formed, to which
the term cell or cellule has been applied. As the form
and position of these nervures are remarkably constant,
and, as the presence of a particular arrangement of the
nervures carries along with it peculiarities in other
parts of the animal's structure, great attention has
l3een paid to them, especially as to their use in the
definition of genera. In this relationship the cells
formed by the transverse nervures which run from the
* Pompholyx, Freymouth, which has the 9 apterous.



10 NERVURES.

base of the stigma to tlie apex called the radial and
cubital respectively, and a cell at the bottom of wing
the lanceolate cellule, are the most important.

The following are the designations of the various
nervures and cellules adopted in this work, with the
various names applied to them by different writers on
Tenthredinidce,* and a reference to the plate will make
their position clear to the student.

Nervures.

1. COSTAL or COSTA (PL X, fig. 1 a) = Radius, Hartig ;
Vena marginalis, Foerster ; Randader and Randnerve,
Zaddach.

2. SUBCOSTAL (PI. X, fig. 1 b) Gubitus, Hartig; Vcnu-
submarginalis, Foerster; Post-costa or Nervus post-
costalis, Thomson ; Unterrandrierve, Zaddach.

3. MEDIAN (PI. X, fig. 1 c),= Vena media, Hartig,
Foerster ; Gubilus or Nervus cubitalis, Thomson.

4. ANAL (PI. X, fig. ld) = Vena postica, Hartig,
Foerster ; Nervus branchialis, Thomson.

5. ACCESSOEY (PI. X, fig. 1 e) = N. humeralis,
Thomson.

6. INFEEIOE (PL X, fig. 1 /).

7. RADIAL (PL X, fig. lo) = N.marginaUs, Thomson.

8. CUBITAL (PL X, fig. l^>) = jV~. submarginalis,
Thomson.

10. BASAL (PL X, fig. II) (behind the figure 8 in
left wing letter omitted in right side, see PL XV, fig.
1 b) Margino-discoidalis, Andre.

11. 1st TEANSVEESE MEDIAN (PL X, fig. 1 q, behind
figure 12 on left wing, see PL XV, fig. lc)=N.
transversus ordinarius, Thomson; Vena transverso-hume-
ralis, Foerster ; N. medio-discoidalis, Andre.

12. 2nd TEANSVEESE MEDIAN (PL X, fig 1 li) =N. Trans-

* For fuller details on the wing-characters in the Hymenoptera
generally see Foerster, Ueber den systematischen Werth des Fliigel-
geaders bei den Hymenopteren, 1877, and Andre, Species, i, Ixii,

et seq.



CELLULES. 11

verso-discoidalis, Andre ; Vena media, Foerster; = 1st
and 2nd inner apical or submarginal nervures of
Norton.

13. RECURRENT (PL X, fig. 1 w, n)= Vena transverso-
discoidales, Foerster; Ruwlaufendadern, Hartig.

14. TRANSVERSE RADIAL (PI. X, fig. 1 g dotted line >
absent in Hylotoma) =marginal nervures.

15. TRANSVERSE CUBITAL (PL X, fig. 1 i, j, fc)= sub-
marginal nervures ; cvlitnl scheidnerve, Zaddach.



Cellules.

1. RADIAL (PL X, fig. 1)= marginal, cellula rnargi-
nalis, Thomson.

2. APPENDICULAR (PL X, fig. 2).

3. CUBITAL (PL X, fig. 3, 4, 5, 6) = subniarginal,
Thomson.

4. COSTAL (PL X, fig. 16)= Area submarginalis,
T?oersteT=branchial i Andre.

5. HUMERAL (PL X, fig. 7) = Area humeralis antica,
Foerster ; costal, Andre.

6. DISCOIDAL. 1st (PL X, fig. 8) =C.furcata, Thomson;
Areola discoidalis prima, Foerster ; 2nd (PL X, fig. 9)
=CeUula disconlah's, Thomson ; 3rd (PL X, fig. 12) =
Areola humeralis media, Foerster ; C. secunda branchi-

Thomson.

7. POSTERIOR. 1st (PL X, fig. 10) = Areola discoidalis

Foerster; Erste Hinterzelle, Zaddach. 2nd (PL
X, fig. 13)= Aussere Hinterzelle, Zaddach =apical cells
of English authors.

8. MEDIAN (PL X, fig. 11) = Area humeralis media,
interna, Foerster.

9. LANCEOLATE (PL X, figs. 14 and 15).

14. ANAL. The anal cellule, Areola humeralis postica,
Htg., is situated between the lower edge of the wing
and the lanceolate cellule.

The number of radial cells is never more than two,



12 CELLULES.

and of the cubital four ; but sometimes at the apex
of the outer radial cellule there may be a small cellule
called the appendicular (Hi/lotoma), but it has never
any nervures. When two cells are present, their
relative length depends upon the place in which
the dividing nervure is received according as it is
received nearer the apex or the base of the cellule.



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