FOOD OF INSECTS. 399 



liionly requires a frequent supply. If, on the contrary, 

 it is an insect of prey, and exposed to the danger of 

 being long deprived of its food- it is often endowed with 

 a power of fasting, wliich would be incredible but for 

 the numerous facts by which it is authenticated. The 

 ant-lion will exist without the smallest supply of food, 

 apparently uninjured, for six months; though, when it 

 can get it, it will devour daily an insect of its own size. 

 Vaillant, whose authority may be here taken, assures 

 us that he kept a spider without food under a sealed 

 glass for ten months, at the end of which time, though 

 shrunk in size, it was as vigorous as ever^ And Mr. 

 Baker, so well known for his microscopical discoveries, 

 states that he kept a beetle {Blaps mortisaga) alive for 

 three years without food of any kind^. Some insects, 

 not of a predacious description, are gifted with a simi- 

 lar power of abstinence. Leeuwenhoek tells us that a 

 mite, which he had gummed alive to the point of a 

 needle and placed before his microscope^ lived in that 

 situation eleven weeks''. 



In some cases the very want of food, however para- 

 doxical the proposition, seems actually to be a mean of 

 prolonging the life of insects. At least one such in- 

 stance has fallen under my own observation. The 

 aphidivorous flies, such as Sj/rphus Pz/rastri, &c. live 

 in the larva state ten or twelve days, in the pupa state 

 about a fortnight, and as perfect insects sometimes pos- 

 sibly as long — the whole term of their existence in 



■ New Travels, i. xxxix. 



" Phil. Trans. 5T40, p. 441. I confess, notwithstanding Mr. Baker's 

 general accuracy, that I suspect some mistake here. 

 • Leeuw. Op. ii. 363. 



