FOOD OF INSECTS. 



335 



nature of their habits. If the insect feeds on a substance of a 

 deficiency of which there is not much probability, as on ve- 

 getables, &c., it commonly requires a frequent supply ; if, on 

 the contrary, it is an insect of prey, and exposed to the dan- 

 ger 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 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. Yaillant, whose au- 

 thority 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 darkling beetle {Blaps mor- 

 tisaga) alive for three years without food of any kind. ^ Some 

 insects, not of a predaceous description, are gifted with a 

 similar 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'^ ; and Mr. Stephens, having, in June, 1831, put 

 a specimen of Lepisma saccharina (the common " wood " or 

 sugar fish ") in a pill-box containing only a few grains of 

 magnesia, found it, to his great surprise, alive and active in 

 June, 1833, after this protracted confinement, without food, 

 of two years. * 



In some cases the very want of food, however paradoxical 

 the proposition, seems actually to be a mean of prolonging 

 the life of insects. At least one such instance has fallen 

 under my own observation. The aphidivorous flies, such as 

 SccBva Pyrastri, &c., live in the larva state ten or twelve 

 days, in the pupa state about a fortnight, and as perfect 

 insects possibly as long, the whole term of their existence in 

 summer not exceeding at the very utmost six weeks. But 



1 New Travels, i. xxxix. 



2 Phil. Trans. 1740, p, 441. I confess, notwithstanding Islr. Baker's general 

 accuracy, that I suspect some mistake here. 



3 Leeuw. Op. ii. 36S. 



4 Entom. Mag. i. 526. 



