Blister-beetles (Meloidae) as first described by J.H. Fabre (1857), and
later with more elaboration by H. Beaurégard (1890). From the egg of one
of these beetles is hatched a minute armoured larva, with long feelers,
legs, and cerci, whose task is, for example, to seize hold of a bee in
order that the latter may carry it, an uninvited guest, to her nest.
Safely within the nest, the little 'triungulin' beetle-grub moults; the
second instar has a soft cuticle and relatively shorter legs, which, as
the larva, now living as a cuckoo-parasite, proceeds to gorge itself
with honey, soon appear still further abbreviated. Later comes a stage
during which legs are entirely wanting, the larva then resting and
taking no food. The last larval instar again has short legs like the
grub of the second period. In connection with this life-history we
notice that the newly-hatched larva is not in the neighbourhood of its
appropriate food. Hence the preliminary armoured and active instar is
necessary in order to reach the feeding place; this journey
accomplished, the eruciform condition is at once assumed.

In all cases indeed we may say that the particular larval form is
adapted to the special conditions of life. A few examples from other
orders of endopterygote insects will illustrate this point. The
campodeiform type is relatively unusual, but most of the Neuroptera have
larvae of this kind, active, armoured creatures with long legs, though
devoid of the tail-processes often associated with similar larvae among
the Coleoptera. Such are the 'Ant-lions,' larvae of the exotic lacewing
flies, which hunt small insects, digging a sandy pit for their unwary
steps in the case of the best-known members of the group, some of which
are found as far north as Paris. In our own islands the 'Aphis-lions,'
larvae of Hemerobius and Chrysopa, prowl on plants infested with
'green-fly' which they impale on their sharp grooved mandibles, sucking
out the victims' juices, and then, in some cases, using the dried