PROTECTIVE DEVICES IN IJASILARCIIIA. 261 



Tiiko first tlie c<i;;2;-sttige. Every one who lias attempted to rear butter- 

 flies knows what iinniense destruction falls to the lot of any species at this 

 stage of its life. Ants and spiders look on them as delicacies made for 

 their delectation, and there is a whole grouj) of tiny Ilymenoptera, almost 

 too small to l)rcathe, one would think, mere specks, which live s<jlely 

 upon insects' eggs, piercing them with their egg-daits, their })rogeny 

 living imprisoned and feeding on the contents until they have run the 

 cycle of their changes. Some attack whole batches of eggs, laying one 

 egg in each, so that one pai'asite 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 belono- which stino- the eggs of Basilarchia. How does Basilar- 

 chia 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 first that, — to judge from the latest researches — these parasitic 

 flies must be guided less by vision than by touch ; and second, that most 

 insect eggs are laid on the broader parts of the leaf on which the young 

 Avill feed ; it is here that the parasite will range in quest of prey ; but the 

 eggs of Basilarchia are rarely found except at the extreme tips of leaves, 

 and in addition the leaves of the food-plants concerned are all acuminate, 

 some to an excessive extent, as in some of the poplars and birches. When 

 the parasite has, however, found an egg, it may well be inquired whether 

 she would not be deceived by it. It differs from the eggs of all our other 

 butterflies. In that it is besprinkled with little flexible filaments, for all the 

 wtn'ld like the hairs of some leaves. Or if the clothinjy of the egorg did 

 not deceive, she might even then find it diflicult of attack, for minute as 

 these parasites are, less than half a millimetre long, their bodies Avould 

 extend across at least three of the polygonal cells which regularly stud 

 the surface of the egg, and which send forth these little filaments at every 

 angle, so that poor bewildered madame must struggle through a weary 

 chapparal before she can attain the barren grounds at the summit and find 

 a spot to readily insert her sting. Yet that she succeeds is only too evi- 

 dent to the collector ; the larger part of the eggs obtained in the open field 

 which have fallen into my hands have been parasitized. 



This is its but too partial defence against its special enemies. But how 

 about those wandering buccaneers, the ants, mites, and spiders? These 

 labor under the same visual defects as the direct parasites, or sometimes 

 greater ones ; and the position of the egg, remote from their usual hunting 

 ground, must serve as no inconsiderable protection ; how great, there are 

 hardly means of measurement. Their greatest protection from these 

 savages, which cannot fly but must wander ceaselessly about on foot in 

 search of prey with satanic energy, is undoubtedly in the fewness of their 



