Systematic Course. 37 
in the tissues of a caterpillar. The larva isa little white legless grub 
which feeds upon the fatty tissues of its host, while the latter even- 
tually dies of exhaustion, though it may have strength before this 
happens to transform into a chrysalis, When full fed, the Ichneumonid 
larva spins itself up irito a cocoon, which is often attached to the body 
of the dead caterpillar. 
Very many caterpillars in India, including numerous wild silk- 
worms, are liable to be parasitised by Ichnenumonida, and the 
group must be looked upon as of some importance to the forester, as 
tending to keep down defoliating caterpillars in the forest. It should 
be noticed, however, that the Ichneumonide are very much less 
numerous in India, and consequently less effective than such insects as 
the Tachinw, which attack caterpillars in a very similar manner, 
The School Museum contains numerous specimens for examin- 
ation, 
Chalcidida.—In size and build these small insects are superficially not 
unlike house-flies, which belong to the totally different order of 
Diptera. As their name implies, the Chalcidide are generally more or 
less metallic incoloration. The wings are usually somewhat deficient 
in veins. The antennae have from six to fourteen joints. In some of 
the species the posterior femora are very much expanded. The 
Chalcidide are mostly parasitie on caterpillars, and in habits they 
resemble the Ichneumonidz. They have been reared from more than 
one forest-defoliating caterpillar in India, and no doubt have some 
effect. in keeping insects of this kind in check, So far as has been 
observed, however, they are very much less effective than such insects 
as the Tachina, 
The Museum contains a few specimens. 
Formicide (Ants).—Ants are excessively common in India. They may be 
recognised by the basal segment of the abdomen, which is constricted 
off so as to form as it were a knot in the stalk by which the posterior 
portion of the body is attached to the thorax. Care should be taken 
not to confuse the ants with the totally distinct insects which are 
known as white-ants (Zermitede), and which belong to the Orthoptera 
(vide pages 12 and 16). 
Ants live together in communities, which contain winged males 
and females and wingless neuters. The neuters are supposed (like 
worker bees) to be aborted females. They are usually of two kinds, 
which are distinguished as the worker major and worker minor. They 
possess poison glands and are said to be either armed with stings or 
to inject the poison fluid into wounds made with their mandibles. 
Ants form nests, which consist of passages and chambers dug out 
in earth or rotten wood, or built in leaves fastened together for the 
purpose, The larve are little legless grubs which are carefully looked 
