24 THE STRUGGLE FOR EXISTENCE 



their wakeful, indefatigable, persistent enemies 

 among the insect tribes, — ichneumons, ants, wasps, 

 flies, mites, and spiders ? 



Take first the egg-stage. Every one who has 

 attempted to rear butterflies knows what immense 

 destruction falls to the lot of any species at this 

 stage of its life. Ants and spiders look on eggs 

 as delicacies made for their delectation, and there 

 is a whole group of tiny Hymenoptera, almost too 

 small to breathe, one would think, mere specks, 

 which live solely upon insects' eggs, piercing them 

 with their egg-darts, their progeny living imprisoned 

 and feeding on the contents until they have run the 

 cycle of their changes. Some attack whole batches 

 of eggs, laying one e^gg in each, so that one parasite 

 may destroy the entire brood of one butterfly ; 

 others lay their all in one or two eggs, and it is to 

 this class that those belong which sting the eggs 

 of Basilarchia. How does Basilarchia escape this 

 danger ? In the first place, the mother rarely lays 

 more than one egg in one spot or even on one bush, 

 though as many as a dozen or two may occasionally 

 be found, where the butterfly's numbers are great 

 and they are growing as it were imprudent. Then 

 it must be remembered that these parasitic flies 

 must be guided less by vision than by touch ; and 



