328 Insects and their Surroundings 



sembling " of scores or hundreds of males eager to 

 pay their court. It is often found that such com- 

 plexity of antennal structure in the males is associated 

 with vestigial mouth-organs, and consequently short 

 imaginal life ; the male must find a mate quickly 

 if he is to pair at all. Some male Mayflies are pro- 

 vided with peculiar large frontal eyes, carried on 

 columnar outgrowths of the head, in addition to 

 normal lateral eyes like those of the females. The 

 reduction of pigment and the presence of a thick 

 layer of homogeneous fluid between the nuclear and 

 rhabdom layers has led to the conclusion that the 

 special function of these eyes is to discern moving 

 objects in the dusk, to enable the male to secure a 

 mate in the airy twilight dance of the short-lived 

 Mayflies (193). 



Family Life. — Among the vast majority of insects, 

 family life exists only in a very rudimentary form. 

 Pairing concluded, the female lays her eggs in such 

 a situation as to ensure food-supply for the young, 

 and maternal care as a rule goes no farther. The 

 mother Mole-cricket, however, watches carefully over 

 her eggs and feeds her brood until the first moult. 

 Often the eggs are laid singly and the larva lives alone, 

 or, if the eggs are laid together, the young scatter in 

 search of food as soon as hatched. In other cases, 

 however, there is an association among the members 

 of a brood. Many young caterpillars unite to spin 

 over their food-plant a web of silk (fig. 173) which 

 affords shelter and protection to the whole family ; 

 usually, however, when a certain stage of growth has 

 been reached, the limited food supply necessitates the 

 dispersal of the family, whose surviving members pass 

 the rest of their lives independently. Many adult 

 insects of various orders habitually live together in 

 flocks, but there is no mutual help among the in- 



