200 THE COURTSHIP OF ANIMALS 



they are arranged to form a thick, glistening white felt, 

 which fills a folded-over portion of the edge of the hind- 

 wing, and in many cases " the perfume can be retained," 

 Weismann remarks, " and then, by a sudden turning out 

 of the wing-fold, be allowed to stream forth." In the 

 Ghost-moth {Hepialus humuli), the hind-legs of the male 

 have become pressed into service and have become trans- 

 formed into scent-bottles, since they are swollen and 

 filled with glands for the manufacture of odorous matter. 



The naturalist Fritz Miiller discovered the fact that 

 some of the Butterflies which haunted his Brazilian 

 garden exhaled a flower-like fragrance. Anyone can 

 test this curious trait for himself who will take the trouble 

 to brush his finger over the wing of a newly-caught male 

 Garden- White Butterfly (Pieris napi). The white powder 

 which will adhere to the finger will be found to be made 

 up of the wing-scales, which will exhale a delicate perfume 

 of lemon or balsam ! Among the Moths the strong 

 odour of musk is exhaled by the Convolvulus Hawk-moth 

 {Sphinx convolvuli). 



It is, however, only in the males that these odours 

 can be detected, and, though palpable enough to human 

 nostrils, their power of diffusion is apparently extremely 

 limited. They would seem to serve as aphrodisiacs for 

 the stimulation of the female, and, as a consequence, 

 there is no need that they should start into activity until 

 the male has arrived at the immediate neighbourhood 

 of his prospective mate. 



With the females of the Moths, however, matters are 

 otherwise. For the most part Moths are nocturnal, and 

 hence could not distinguish one another when on the 

 search for mates, and in many species the females 

 are wingless, and consequently are unable to move 



