FOOD OF INSECTS. 219 
for ours, being to us useful only, but to it indispensable. The larvae of 
Scava Pyrastri, according to De Geer, eat no other Aphis but that of the 
rose Most Zchnewmons and Sphecina prey each upon a single species 
of insect only, which therefore they would seem to have been formed for 
the express purpose of keeping within due limits. Reaumur mentions 
having once found in.a parcel of decaying wood the nests of six different 
kinds of the latter tribe, each of which was filled with flies of a distinct 
species.2 Cerceris auritus and Philanthus ketus in the larva state feed solely 
on the weevil tribe of Coleoptera, the latter being restricted even to the 
short-rostrumed family, as Otiorhynchus raucus, &c.3; while Bembex 
rostrata, another hymenopterous insect, selects flies, as Musca Cesar, 
&e.4 
A very large proportion of species, however, are able to subsist on seve- 
ral kinds of food. Amongst the carnivorous tribes, it is indifferent to most 
of those which prey upon putrid substances from what source they have 
been derived: and the predaceous insects, such as the Libellulina, Tele- 
phorus, Empis, the Araneide, &c., will attack most smaller insects inferior 
to them in strength, not excepting in many instances their own species, 
The wax-moth larva (Galleria Cereana) will for want of wax eat paper, 
wafers, wool, &c.5; another Tinea described by Reaumur, and before ad- 
yerted to, attacks chocolate®, which cannot have been its natural food, 
even selecting that most highly perfumed; and the Tinee which devour 
dressed wool, but happily for the farmer and wool-stapler refuse it when 
unwashed, must have existed when no manufactured wool was accessible. 
The vegetable feeders are under great restrictions, yet probably the majo- 
rity can subsist on different kinds of food. This is certainly true of most 
lepidopterous larvae, several of which, as well as many Coleoptera (Haltica 
oleracea, &¢.) are polyphagous, eating almost every plant. It is worthy of 
remark, however, that when some of these have fed for a time on one 
plant they will die rather than eat another, which would have been per- 
fectly acceptable to them if accustomed to it from the first.? Here too it 
must be borne in mind, that by far the greater part of insects feed upon 
different substances in their different states of existence, eating one kind 
of food in the larva and another in the imago state. This isthe case with 
the whole order Lepidoptera, which in the former eat plants chiefly, in 
the latter nothing but honey or the sweet juices of fruit, which they have 
often been observed to imbibe ; and the same rule obtains also in regard to 
most dipterous and hymenopterous insects. Those which eat one kind of 
food in both states are chiefly of the remaining orders. 
I have said that insects, like other animals, draw their subsistence from 
the vegetable or animal kingdoms. But I ought not to omit noticing that 
some authors haye conceived that several species feed upon mineral sub- 
stances.6 Not to dwell upon Barchewitz’s idle tale of East Indian ants 
1 De Geer, vi. 112. 
2 Reaum. vi. 271.; and M. L. Dufour has recently described a species of sand- 
wasp (Cerceris) which selects various species of Buprestis as the food of its progeny, 
some of which are of the greatest rarity to collectors. 
5 Entomologische Bemerkungen (Braunschweig, 1799), p. 6. 
4 Latreille, Obs. sur les Hymenoptéres. Ann. de Mus. xiv. 412. 
5 Reaum, iii. 267. 6 Ibid. iii. 277. 7 Thid. ii, 334. 
wt For an instance in which an insect, usually subsisting upon animal food, 
derived nutriment from a mineral substance, see Philos. Mag. &c. for January 
