28 The Structure and Special Physiology of Insects 



various communities the members of their own community. Miss Fielde's 

 experiments show that the recognition of ants by each other depends on the 

 existence of a sense of smell of remarkable differentiative capacity. The 

 odors of the nest, of the species, of the female parent, and of the individ- 

 ual are all distinct and perceivable by the smelling-organs, situated on 

 distinct particular antennal segments. In the insectary at Cornell University 

 a few years ago a few females of the beautiful large promethea moth were 

 put into a covered box which was kept inside of the insectary building. 

 No males of this moth species had been seen about the insectary nor in 



its immediate vicin- 

 ity for several days, 

 although they had 

 been specially sought 

 for by collectors. 

 Yet in a few hours 

 after the female 

 moths were first con- 

 fined nearly fifty 

 male prometheas 

 were fluttering about 

 outside over the glass 

 roof of the insectary. 

 They could not see 

 the females, but un- 

 doubtedly discovered 

 them by the sense of 

 smell. These pro- 

 methea moths have 

 elaborately branched 

 or feathered anten- 

 nae, affording area 

 for very many smell- 

 ing-pits. 



Mayer's experiments with promethea also reveal the high specialization 

 of the sense of smell. This investigator carried 450 promethea cocoons 

 from Massachusetts to the Florida keys. Here on separated small 

 islands the moths issued from the cocoons, hundreds of miles south of their 

 natural habitat. This isolation insured that no other individuals than 

 those controlled by the experimenter could confuse the observations. 

 Female moths were confined in glass jars with the mouth closed by 

 netting. Other females were confined in smaller glass jars turned upside 

 down and the mouth buried in sand. Males being released at various 



FIG. 55. Auditory organ of a locust, Melanoplus sp. The 

 large clear part in the center of the figure is the thin tym- 

 panum with the auditory vesicle (small, black, pear-shaped 

 spot) and auditory ganglion (at left of vesicle and connected 

 with it by a nerve) on its inner surface. (Photomicrograph 

 by George O. Mitchell; greatly magnified.) 



