function of the phagocytes is to act as scavengers by devouring what has
become effete and useless.




CHAPTER VI

LARVAE AND THEIR ADAPTATIONS


Among the insects that undergo a complete transformation, there is, as
we have seen in the preceding chapter, an amount of inward change, of
dissolution and rebuilding of tissues, that varies in its completeness
in members of different orders. It is now advisable to consider the
various outward forms assumed by the larvae of these insects, or rather
by a few examples chosen from a vast array of well-nigh 'infinite
variety.'

In comparing the transformations of endopterygote insects of different
orders, it is worthy of notice that in some cases all the members of an
order have larvae remarkably constant in their main structural features,
while in others there is great variety of larval form within the order.
For example, the caterpillars of all Lepidoptera are fundamentally much
alike, while the grubs of beetles of different families diverge widely
from one another. A review of a selected series of beetle-larvae will
therefore serve well to introduce this branch of the subject.

[Illustration: Fig. 12. _a_, Carrion-beetle (_Silpha_) with its larva,
_b_. Magnified, _a_ 3 times, and _b_ 4 times.]