30 USEFUL BIRDS. 
puted that the unrestricted increase of the gipsy moth would 
be so great that the progeny of one pair would be numerous 
enough in eight years to devour all the foliage in the United 
States. 
THE VORACITY OF INSECTS. 
Many insects are remarkably destructive because of the 
enormous amount of food which they must consume to grow 
rapidly to maturity. Many caterpillars daily eat twice their 
weight of leaves; which is as if an ox were to devour, every 
twenty-four hours, three-quarters of a ton of grass.1 
This voracity and rapid growth may be shown by the 
statement of a few facts. A certain flesh-feeding larva will 
consume in twenty-four hours two hundred times its original 
weight ; a parallel to which, in the human race, would be an 
infant consuming, in the first day of its existence, fifteen 
hundred pounds of food. There are vegetable feeders, 
caterpillars, which during their progress to maturity, within 
thirty days, increase in size ten thousand times. To equal 
this remarkable growth, a man at his maturity would have 
to weigh forty tons. In view of such statements, need we 
wonder that the insect world is so destructive and so potent 
a power for harm ?? 
Mr. Leopold Trouvelot, who introduced the gipsy moth 
into this country, was occupied for some time in raising 
silkworms in Medford, Mass. He made a special study of 
the American silkworm ( Telea polyphemus). Regarding its 
food and growth he says : — 
It is astonishing how rapidly the larva grows, and one who has had 
no experience in the matter could hardly believe what an amount of 
food is devoured by these little creatures. One experiment which I 
made can give some idea of it. When the young worm hatches out, it 
1 A probable cause for this voracity in the case of herbivorous larve is that the 
stomachs do not have the power of dissolving the vegetable matter received into 
them, but merely of extracting from it a juice. This is proved both by their 
excrement, which consists of coiled-up and hardened particles of leaf, which, 
when put into water, expand like tea, and by the great proportion which the 
excrement bears to the quantity of food consumed (Kirby and Spence’s Ento- 
mology, p. 259). 
* Our Insect Enemies, by J. A. Lintner. Sixteenth Annual Report, New 
Jersey State Board of Agriculture, 1888-89, p. 295. 
