BIONOMICS AND DEVELOPMENT OF LYGOCERUS SP. 107 
a kind of peristaltic movement of the body, but under normal 
conditions it probably does not need to move from where it 
was hatched, provided that the host be a larva. If the latter 
be a pupa, the hyperparasite is generally found feeding on the 
posterior part of the abdomen, where the integument is still 
soft. As the egg, as previously described, is always deposited 
on the third or fourth segment of the Aphidius, the hyper- 
parasite must needs seek the new situation for itself after 
hatching. 
TEXT-FIG. 3. 
The larva, newly hatched, showing tracheal and nervous systems. 
x 200. 
The internal anatomy, with the exception of the tracheal 
system, does not change essentially during development, so 
that an account of it is left to the description of the fourth 
instar. The mouth, which is very small and transversely oval, 
is furnished with two slerder mandibles, set behind the hood- 
hike labrum, and the labium (fig. 5). The head is furnished 
with two tactile papillae. The mid-gut, which at this stage, 
as with the other parasitic Hymenoptera, does not communi- 
cate with the proctodaeum, is large and globose, and_ its 
contents tinge the otherwise transparent larva pale yellow. 
The tracheal system consists of a pair of lateral trunks, united 
by an anterior commissure passing above the oesophagus in 
