BUTTERFLIES AND MOTHS. 51 
during - a single season they would kill all vegetation 
on the earth. The number of eggs deposited is 
enormous, and the few which reach the caterpillar 
stage make great havoc with our orchards, and often 
with our shade-trees. The gypsy-moth alone, in spite 
Fig. 52.—The Kallima, natural size. Drawn by 
A. E. Sanford. 
of great efforts, still does much damage. The number 
and activity of caterpillar and butterfly enemies in 
most cases holds them in check and allows only a 
small number to come to maturity. Both two-winged 
and four-winged flies deposit their eggs on the larvae 
or pupae of butterflies or moths. When these eggs 
hatch they produce larvae which feed on the fat and 
muscle of their involuntary host and finally destroy its 
life. A living, but nearly dead, caterpillar bearing on 
