FOOD OF INSECTS. 399 



i 



twenty-four hours become about two hundred times 

 heavier than before 1 . 



Some insects have the faculty of sustaining a long abs- 

 tinence from all kinds of food. This seems to depend 

 upon the nature of their habits. If the insect feeds on 

 a substance of a deficiency of which there is not much 

 probability, as on vegetables, &c. it commonly 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, 

 which would be incredible but for the numerous facts by 

 which it is authenticated. The ant-lion will exist with- 

 out 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 autho- 

 rity 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 vi- 

 gorous as ever b . 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 c . Some insects, not of a predaceous de- 

 scription, are gifted with a similar power of abstinence. 

 Leeuwenhoek tells us that a mite, which he had gum- 

 med alive to the point of a needle and-^laced before his 

 microscope, lived in that situation eleven weeks d . 



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



a Redi de Insecfu, 39. b New Travels, i. xxxix. 



c Phil. Trans. 1740, p. 441. I confess, notwithstanding Mr. Ba- 

 ker's general accuracy, that I suspect some mistake here. 

 d Leeuw. Op. ii. 363. 



