20 FLASHLIGHTS ON NATURE 



males are budded out ; it is only when the cold 

 threatens to destroy the entire colony that little 

 husbands are born, so as to give rise to eggs which 

 may bridge over the gulf between summer and 

 summer. If you keep the insects warm, however, 

 and supply them with abundant food (as in a con- 

 servatory), they will go on producing imperfect 

 females and fatherless broods, without intermission, 

 for many years together. The egg-laying genera- 

 tion is thus shown to be merely a device for meeting 

 the adverse chances of winter ; the budding process 

 suffices well enough, as long as warmth and food 

 render the possibility of freezing or starvation un- 

 important. 



On the other hand, the eggs and the brood born 

 from them revert to the earlier habit of the race, 

 when it was still an active, free-flying type, before 

 it had been demoralised by acquiring its sedentary, 

 parasitic habits. They hatch out into active little six- 

 footed or six-legged larvae, which again, in some cases, 

 give rise to very similar chrysalis forms, and finally 

 develop into the " viviparous" or budding females. 

 Whenever a species earns its livelihood with too 

 little exertion, it invariably degenerates, and often 

 grows small, unintelligent, and vastly prolific ; for 

 superior races have relatively small families, while 

 inferior races reproduce by the million. The mites 

 which infest cheese and other food-stuffs are an 

 exactly analogous case to that of the aphides, for 

 they are degenerate spiders, grown small and prolific 

 through the excessive ease of life afforded them by 



