ORDER IV. MOTHS AND BUTTERFLIES. 129 



terous insects in existence in this country, and as each fe 

 male lays on an average 300 eggs, half their number, 

 viz., GOOO females, will produce 1,800,000 caterpillars; in 

 the second generation, 180,000,000 ; and in the third, 

 27,000,000,000. 



If such an immense multiplication of so voracious an 

 animal were to be continued without any check, man and 

 beast would soon be destroyed by starvation ; but it is un 

 doubtedly one of the designs of Nature that these should 

 increase immensely for the very purpose of furnishing suffi 

 cient nourishment for the birds and other winged animals 

 which make them their principal food. It is ascertained 

 that a single robin or woodpecker, and many others of the 

 warblers, carry every day about fifty grubs or caterpillars 

 to their nests as food for themselves and their young. 



Now if there were only one million of these birds, of 

 which each one devours COOO caterpillars during the months 

 of April, May, June, and July, by no means a large com 

 putation, the number of caterpillars and grubs thus de 

 stroyed will amount to 6,000,000,000 annually. 



Caterpillars are, therefore, of great use to us in furnish 

 ing so abundant food and nourishment for the birds, which 

 enliven and embellish the country with their happy songs 

 and their beautiful plumage, and which themselves supply 

 us with a palatable and delicious article of food. 



Caterpillars are also destroyed by various kinds of vein- 

 winged insects, principally by different species of the Ich 

 neumon fly, which with her ovipositor thrusts one or sever 

 al eggs into the body of the caterpillar, upon the flesh of 

 which the maggots of these flics subsist, until they come out 

 as perfect flies, of course destroying the larvae upon which 

 they feed. We can often see this process carried on upon 

 the body of a potato- worm, when it is full grown, and just 

 ready to change into a cocoon. It will be completely cov 

 ered with many hundred minute white silk-like bodies, which 



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