THE VAPOURER MOTH 79 



vestiges. Her feelers are smaller and simpler than those of 

 the male. She sits still for the short remnant of her days, 

 close to or actually resting upon the cocoon from which she 

 emerged, and gives no other sign of life than an in and out 

 movement of the end of the abdomen, such as everyone has 

 observed in bees and wasps. This is her way of filling and 

 emptying her air-tubes. 



The male is quick to detect the presence of a female. 

 He can find her out, not only in a sheltered corner, but in 

 the dark, or when she is imprisoned in a box. Since the 

 female utters no sound, we conclude that he is guided by J:iis 

 sense of smell, which, as in not a few other insects, is prob- 

 ably lodged in the large and elaborate feelers. The eggs are 

 laid upon or close to the cocoon, and the female dies soon 

 after laying, having never flown, nor crept more than the 

 length of her own body, nor taken a particle of food. Both 

 male and female are incapable of feeding, for the mouth is 

 closed up, and there is but a vestige of a proboscis. 



We must now put a question : Why has the female vapourer 

 no wings, or wings so minute that she cannot fly ? Before we 

 attempt an answer, let us consider why moths and other 

 insects fly at all. It is not merely that they may seek their 

 food, for they are full-grown when they get their wings, and 

 many of them never feed afterwards. The life of an insect 

 is often divided into two active stages, with. a resting-stage 

 between. There is a feeding-and-growing stage, when they 

 creep, burrow, or swim ; and afterwards a pairing-and-egg- 

 laying stage, in which they are often equipped for flying. 

 The power of flight enables the female to lay her eggs far 

 from the spot where she was herself reared, and if need be, 

 to lay some here and some there over a wide tract of land. 

 Then the larvae which issue from the eggs will not be too 

 crowded. Wings are to insects what spores are to ferns, 

 plumed seeds to dandelions, and hooked seeds to burrs — a 

 ready means of dispersal. 



Some insects, though wingless, can make up for their 

 inability to fly by running or leaping. Cockroaches, spring- 

 tails, and flightless beetles find no more difficulty in dispersing 

 their eggs than spiders or centipedes, which are equally 

 wingless. But the female vapourer can neither fly nor run. 

 All her eggs, perhaps a couple of hundred in number, are 



