164 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, 
Fig. t119.—The Emperor Moth (Saturnia carpin?) 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 antennz 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 Lnsects, thetr Structure and Life):— 
“Some male Mayflies are provided with peculiar large frontal 
eyes, carried on columnar outgrowths of the head, in addition 
