putney] A GRASSHOPPER'S EARLY LIFE 131 



ing the heat of the day when they go down on the stem in the 

 shade of the plant " umbrella." The birds do not care for them 

 as that scent organ is enough to drive all desire to eat them away 

 on first acquaintance with it. But there is a reason why these 

 little creatures are not more pestiferous than they are. One 

 might naturally think that with the freedom that comes from 

 being let alone, the caterpillars would soon overun a place; that 

 would be the result if it were not for the ichneumon fly. This 

 latter creature seeks the caterpillars of the black swallow-tail 

 and in their bodies lay eggs. This is no inconvenience to the 

 caterpillar in its present stage for no harm is done to any of the 

 •vital organs and the caterpillar does not realize that it is carry- 

 ing around a parasite. But when the cocoon is made the eggs 

 hatch into minute grubs that feed upon the bodies of the cater- 

 pillars and instead of a beautiful butterfly coming from the co- 

 coon we find the ichneumon! Scientists speak of such a pro- 

 cess as "bewitching" of the caterpillar, for surely it does look 

 as if some old witch had transformed the beautiful swallow-tail 

 into a homely fly as a punishment for some misdeed. Out of 

 a hundred chrysalides it is doubtful if more than ten or fifteen 

 percent produce the butterflies. 



When, however, a swallow-tail does appear, what a beauty 

 he is! The wings are black and are crossed by two rows of yel- 

 low spots and with little marginal lines (or linules) of yellow. 



On the hind wings between the two rows of yellow spots there 

 are scattered blue scales which are very attractive in color. 



Then near the inner back angle of the hind wing is an orange 

 spot with a black center that adds much to the beauty of the 

 butterfly. This spot is supposed to be a scent spot, protecting 

 the butterfly from attack, just as the Y-shaped organ protects 

 the caterpillar. Authorities, however, differ on this, some claim- 

 ing that the scent is not at all noticeable and that the notion 

 that it was a scent spot originated from the idea of associating 

 the color, orange, with the color of the scent organ of the cater- 

 pillar. The female is much like the male except that the second 

 row of yellow wing spots is less conspicuous and the blue more 

 marked. 



