376 Royal Institution :—~ 
The lecturer then pointed out that, when the habits were alike, 
similar larvee might be met with in very different families of insects. 
Thus, among beetles, the Melolontha (cockchafer), Anobium 
(death-watch), and Chlamys are very similar in their larva state, 
although they belong to perfectly distinct families of beetles—namely, 
the Melolonthide, Ptinide, and Chrysomelide. 
The same fact holds good even in larve’ belonging to different 
orders of insects. Those larve which, in the words of Mr. Herbert 
Spencer, are ‘symmetrically related to the environment,” and 
which either are surrounded by their food, or have it brought to 
them, are fat, legless, fleshy grubs or maggots. Such are almost all 
the larvee of flies. So, again, the Hymenopterous larvee are generally 
of this character : whether they inhabit other insects, like those of 
the ichneumons, or live inside galls, like those of the Cynipide, or 
are enclosed in cells and fed by the perfect insects, like those of the 
bees, practically any great deviation from that which may be looked 
upon as the normal type is unnecessary. The larve of beetles, on 
the contrary, are generally of a very different character. But there 
is one group, that of the weevils, which are internal feeders. The 
grub of a nut-weevil feeding inside a nut is under very similar con- 
ditions to those of a Cynips-larva in a gall, or an Anthraz-larva 
living parasitically in a bees’ cell ; and we accordingly find that these 
larvee, though belonging to three different orders of insects, very 
closely resemble one another. 
To this type belong most Hymenopterous larvee ; but there are 
two exceptional groups, the Tenthredinida, or sawflies, and the 
Siricide. The larve of the Tenthredinide feed, like those of but- 
terflies, on leaves, and in the general form of the body, in the possession 
of three pairs of legs and several pairs of abdominal prolegs, they 
very closely resemble ordinary caterpillars, and differ extremely from 
the ordinary type of Hymenopterous larvee. In the same manner 
the larvee of the Scricide, which are wood-borers, possess thoracic 
legs, and closely resemble the larvee of some wood-boring beetles. 
From these facts it may be concluded that the form of a larva de- 
pends more on the conditions in which it lives than on the form which 
it will ultimately assume. But this is shown still more clearly in the 
case of Sitaris, a small beetle which is parasitic on a species of solitary 
bee (Anthophora), and the habits of which have been carefully ob- 
served and excellently described by a French naturalist, M. Fabre. - 
The female Sttaris, which comes to maturity in August, never 
wanders far away from the sandy banks in which the Anthophora loves 
to burrow. At that time no Anthophoras are abroad, their period of 
maturity is not in autumn, but in spring ; and consequently, though 
the bee is so necessary to the beetle, we are at once met with the re- 
markable fact that no perfect Sifaris ever saw one of the bees, and 
it is probable that no Anthophora has ever yet seen a Sitaris. The 
latter lays her eggs, which are about 2500 in number, in the burrow 
leading to the cell of the Anthophora. These eggs are arenes in 
September, and produce small, black, active larvee, about j-th of an 
inch in length, with four eyes, two Paiher long antennee, and six well- 
