328 



FOOD OF INSECTS. 



several species feed upon mineral substances.^ Not to dwell 

 upon Barchewitz's idle tale of East Indian ants which eat 

 iron^, or on the stone-eating caterpillars recorded in the 

 Memoirs of the French Academy^, which are now known to 

 erode the walls on which they are found solely for the purpose 

 of forming their cocoons, Keaumur and Swammerdam have 

 both stated the food of the larv« of Ephemerce to be earth, 

 that being the only substance ever found in the stomachs and 

 intestines, which are filled with it. This supposition, which 

 if correct renders invalid the definition by which Mirbel (and 

 my friend Dr. Alderson of Hull long before him) proposed to 

 distinguish the animal and vegetable kingdoms, is certainly 

 not inadmissible ; for, though we might not be inclined to give 

 much weight to Father Paulian's history of a flint-eater who 

 digested flints and stone the testimony of Humboldt seems 

 to prove that the human race is capable of drawing nutriment 

 from earth, which, if the odious Ottomaques can digest and 

 assimilate, may doubtless afford support to the larvae of Ephe- 

 merae. Yet, after all, it is perhaps more probable that these 

 insects feed on the decaying vegetable matter intermixed with 

 the earth in which they reside, from which after being swal- 

 lowed it is extracted by the action of the stomach : like the 

 sand that, from being found in a similar situation, Borelli er- 

 roneously supposed to be the food of many Testacea, though 

 in fact a mere extraneous substance. 



The majority of insects, either imbibing their food in a 

 liquid state, or feeding on succulent substances, require no 

 aqueous fluid for diluting it. Water, however, is essential to 

 bees, ants, and some other tribes, which drink it with avidity ; 

 as well as in warm climates to many Lepidoptera, which are 

 there chiefly taken in court-yards, near the margins of drains, 

 &c."^ Even some larvae which feed upon juicy leaves have 



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

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

 1823. 



2 Lesser, L. i. 259. 3 x. 458. Bictionnaire Physique. 



^ Mr. Doubleday has observed the habit which butterflies have of settling on 

 damp mud on road sides in the United States, where they congregate in groups, 

 sometimes literally consisting of hundreds of individuals clustered together on a 

 few yards of mud (Westwood, Arc. Ent. i. p. H4.). The same habit may oc- 

 casionally be noticed in this country. 



