CAREFUL MOTHERS 



vegetarians, but when the egg-laying season approaches they become 

 ferocious beasts of prey. It is, of course, only for the sake of their 

 young that they turn to a predatory way of life, since their offspring 

 live on animal food alone, while their parents cannot share their 

 gory meals. 



In this respect again we may perceive, in the insect kingdom, 

 a series of evolutionary stages. There are small insects called Mantis- 

 flies which trap their prey; they look like little Mantises, and like 

 the latter they catch small insects in the gins formed by their folded 

 forelegs. In these species both adults and larvae are flesh-eaters. 

 For the tiny larvae which emerge from the eggs try to get into the 

 egg-sac of a Wolf-spider : which entails long effort and a protracted 

 fast. The female Wolf-spider, of course, always carries the sac about 

 with her. At last, however, the larva is successful; it bores its way 

 through the wall of the sac, and feeds on the yolky eggs, while the 

 spider notices nothing. The unsuspecting mother now guards and 

 protects the murderers of her offspring as though she were still 

 carrying her own eggs. In Brazil there are species of Mantisidae in 

 which the female, provided with an ovipositor, lays her eggs in 

 the cells of a wasps' nest ; in this case the larvae feed on the eggs 

 and the stores of their involuntary hosts. 



The history of the Ant-wasps (Mutillae) resembles that of the 

 insects which I have been describing. The males are not unlike 

 other wasps; one finds them on flowers, whose nectar they suck. 

 The females, however, have quite a different appearance; they are 

 like ants, and are wingless, and crawl about on the ground. The 

 body is hirsute, and has a satiny gloss ; it is often finely marked with 

 black and red or yellow. The females too are vegetarian, but when 

 they wish to lay their eggs they creep underground in pursuit of 

 living insects. It is to fit themselves for this underground adventure 

 that they have lost their wings; and their likeness to the ants may 

 serve as a protection. Some species lay their eggs on the brood-cells 

 of Bumble-bees, and the emerging larvae feed upon the rightful 

 occupants of the cells. 



The female Ant-wasps chirp like crickets, thanks to the special 

 formation of the edges of the abdominal segments, which they rub 

 together. Perhaps they are able by this means to attract the attention 

 of the flying males. In the case of the Thynnus, which has a similar 

 appearance, the union of the sexes has been observed. To the 

 observer, the procedure had the appearance of an abduction. The 

 male fell upon the female, embraced her with tender passion, and 



281 



