224 FOOD OF INSECTS. 
in that of larve. The voracious caterpillar, when transformed into a 
butterfly, needs only a small quantity of honey ; and the gluttonous maggot, 
when become a fly, contents itself with an occasional drop or two of any 
sweet liquid. 
While in the state of larvee the quantity of food consumed by insects is 
vastly greater in proportion to their bulk than that required by larger 
animals. Many caterpillars eat daily twice their weight of leaves, which is 
as if an ox, weighing sixty stone, were to devour every twenty-four hours 
three quarters of a ton of grass—a power of stomach which our graziers 
may thank their stars that their oxen are not endowed with. A probable 
proximate cause for this voracity in the case of herbivorous larvae has been 
assigned by John Hunter, who attributes it to the circumstance of their 
stomach not haying the power of dissolving the vegetable matters received 
into it, but merely of extracting from them a juice.t This is proved both 
by their excrement, which consists of coiled-up and hardened particles of 
leaf, that being put into water expand like tea: and by the great propor- 
tion which the excrement bears to the quantity of food consumed. From 
experiments, with a detail of which he has favoured me, made by Colonel 
Machell of Beverley on the caterpillars of Huprepia Caja, he ascertained 
that, though a larva weighing thirty-six grains voided every twelve hours 
from fifteen to eighteen grains’ weight of excrement, it did not increase in 
weight in the same period more than one or two grains. On the other hand, 
many carnivorous larvae increase in weight in full proportion to the food 
consumed, and that in an astonishing degree. Redi found that the maggots 
of flesh-flies, of which, one day, twenty-five or thirty did not weigh above 
a grain, the next weighed seven grains each ; having thus in twenty-four 
hours become about two hundred times heavier than before.” 
Some insects have the faculty of sustaining a lony avstinence 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 fast- 
ing, 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. 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 micro- 
scopical discoveries, states that he kept a darkling beetle ( Blaps mortisaga) 
alive for three years without food of any kind.* Some insects, not of a 
peace description, are gifted with a similar power of abstinence. 
eeuwenhoek 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 
1 Obs. on the Animal GEconomy, p. 221. Compare Reaum, ii. 167. 
2 Redi de Insectis, 39. 
5 New Travels, i. xxxix, 
4 Phil. Trans. 1740, p. 441. I confess, notwithstanding Mr. Baker’s general accu- 
racy, that I suspect some mistake here. ‘ 
5 Leeuw. Op, ii. 363. 
