1 64 ASSOCIATION OF ORGANISMS THE WEB OF LIFE 



graphs, an insect may be guided to a suitable mate in several ways. 

 One of the most remarkable is found in the possession of an 

 exceedingly delicate sense of smell by male insects, especially 

 in cases where sight would often be useless. The moths which 

 " assemble " are no doubt a case in point. When an adult female 

 makes her appearance in the world she is quickly attended by 

 a large number of admirers, although immediately before none 

 were to be seen in the immediate vicinity. This fact is well 

 known to collectors, who by the simple device of putting a female 

 that has just left the chrysalis into a little box, with gauze sides, 



p^ 



Fig. 1119. The Emperor Moth (Sat-urnia carpini}. Male left; female right 



and carrying the same into a suitable locality, are often able to 

 capture large numbers of the corresponding male. In such cases 

 the antennae of the latter are large and complicated (fig. 1119), 

 no doubt ministering to an unusually acute sense of smell. The 

 mouth-parts of an insect of the kind are often much reduced, his 

 last meal having been taken when he was still a voracious larva. 

 Courtship and mating fill up the brief span of his adult life, and 

 unless a partner be quickly found he is doomed to speedy death 

 in a celibate condition. Hence the extraordinary development of 

 the olfactory organs, to aid him in his quest. 



In other cases the visual organs are unusually large, appa- 

 rently with the same purpose. An instance of the kind is thus 

 described by Carpenter (in Insects, their Structure and Life] : 

 " Some male Mayflies are provided with peculiar large frontal 

 eyes, carried on columnar outgrowths of the head, in addition 



