OF EPPING FOREST. 281
These gall-makers are usually small insignificant looking
insects, their colour varying as a rule from black to brown.
This, however, is not always the case, as in some species, such as
Biorhiza terminalis, the general colour is a light yellowish red,
while the abdomens of the Trigonaspis crustalis gall-flies are a
bright red. As a rule the abdomen is glabrous and shining, but
in the genus Cynips it is pubescent.
The colour in males and females scarcely differs at all.
They are very sluggish insects and when disturbed feign death,
tucking their legs and wings close to the body and falling to the
ground.2 Many parasitic species frequent flowers, but gall-
makers are only known to take water. It is often difficult to
distinguish between the species and sometimes it is impossible
except from the galls.
Genera of the Sub-Family Cynipina, which occur as Inquilines in
Oak Galls:—
Genus Synergus. (The chief characteristics and habits have already been
given). The third and fourth true abdominal segments are amalgamated, the
suture being rarely visible. The antennae of the male are 15 jointed and in
the female 14 joints are present: the male also has the third antennal joint
curved and sometimes enlarged. The parapsidal furrows are complete.
There are two parallel keels on the medium segment. Claws cleft. One of
the chief differences between these insects and the oak gall-makers is the
closure of the radial cellule in the former.
They may be separated into two divisions (1) Those ovi-
positing in autumnal galls, leaving them early in the spring and
(2) those depositing eggs in spring galls, leaving them in July.
The former include the following species:—Synergus melanopus,
rheinhardi, tscheki, tristis, vulgaris, incrassatus, nervosus, pallicornis
and thaumacera. The latter division contains Synergus albipes,
faciates, and, according to Mayr, thaumacera, which latter he says
has been bred from the galls of Biorhiza renum.
2 "Feigning death" is an expression commonly applied to this habit in insects and
other creatures, but surely it is an incorrect one. Does an insect, when it dies, fold up its
limbs in this way, and why should a living one feign death at all ?—the fresh morsel whether
alive or apparently dead would probably be equally welcomed by a Tit or Creeper in search
of breakfast. Is not the habit rather a very effective form of concealment (as we think Prof.
Poulton has somewhere hinted) enabling the insect to escape notice by its close resemblance
in this attitude fo the soil or to some inanimate object ? Anyone who has collected by beating
branches of trees over an open umbrella or tray well knows bow difficult it is to see insects
when they are in this folded-up attitude, amid the mass of green and dried buds, leaves and
twigs, which are shaken down. And who could detect such an insect as the common beetle,
Byrrhus pilula lying in this concealment attitude on the rough and rutty soil of a footpath, or
many weevils when they fall from bushes or low plants on to the surface of a field or bank.
The habit seems to be well worthy of detailed study, and should be taken up by some
entomologist in search of a subject of research.—Ed.