FOOD OF INSECTS. 219 



for ours, being to us useful only, but to it indispensable. The larva? of 

 Scceva Pyrastri, according to De Geer, eat no other Aphis but that of the 

 rose. 1 Most Ichneumons 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 Itetus 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 Ccesar, 

 &c. 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 Araneidce, &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- 

 verted to, attacks chocolate 6 , which cannot have been its natural food, 

 even selecting that most highly perfumed ; and the Tinece 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 larvas, several of which, as well as many Coleoptera (Haltica 

 oleracea, &c.) 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. 7 Here too it 

 must be borne in mind, that by far the greater part of insects feed upon 

 different substances in their dffferent states of existence, eating one kind 

 of food in the larva and another in the imago state. This is the 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 have conceived that several species feed upon mineral sub- 

 stances. 8 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 raritv to collectors. 



3 Entomoiogische Bemerkungen (Braunschweig, 1799), p. 6. 



4 Latreille, Obs. sur les Hymenopteres. Ann. de Mus. xiv. 412. 



5 Reaum. iii. 257. 6 ibid. iii. 277. 7 Ibid. ii. 334. 



8 For an instance in which an insect, usually subsisting upon animal food, 

 derived nutriment from a mineral substance, see PMos. Mag. &c. for January 

 1823. 



