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 Avhich 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 ? 2 



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 larvae 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) . 



2 Our Insect Enemies, by J. A. Lintner. Sixteenth Annual Keport, New 

 Jersey State Board of Agriculture, 1888-89, p. 295. 



