120 Annuls Entomological Society of America [Vol. IX, 



of sound. During flight a dry crackling sound is made by the 

 wings and there is a brilliant display of color. It seems reason- 

 able that organs for making and receiving sounds which play 

 so important part in the sexual activities of the Locustidse and 

 •of the Gryllidae should not be without a similar function here. 

 The usual movements of the male of the Acrididas consist of a 

 few convulsive jerks of the body as he sights the female, followed 

 by a creeping toward her until he is within springing distance. 

 Some investigators have stated that the male will spring upon 

 the female from a distance of three or four feet. In the 

 Tettigidae (grouse locusts) this process is modified somewhat. 

 The male does not spring but, creeping toward the female, he 

 makes a rush and mounts from the side. It is not uncommon 

 for males of one species to spring upon other males or for males 

 to mate with the females of an entirely different species. Species 

 differing as widely as Hippiscus rugosum and Melanoplus 

 femur-rubrum have been found in copulation. These facts sug- 

 gest that sex discrimination and even species discrimination is of 

 a low order in this group. Sight and possibly sound furnish the 

 stimulus for the beginning of the preliminary movements, but 

 an actual body contact seems to be necessary for a final 

 discrimination of sex. 



The Locustidse with their great variety of habits and 

 structure furnish some of the most interesting variations in 

 their preliminary movements. Some are nocturnal; some are 

 diurnal ; some are winged ; some are not ; some have very com- 

 plex movements attending their copulation, some mate very 

 simply. Some forms like the katy-did have membraneous 

 organs in the wings for producing sounds. The shrilling of the 

 male as he attempts to call the female to him is one of the most 

 common sounds of the late summer nights. When a female has 

 been induced to approach the male stops shrilling and the two 

 indulge in a preliminary fencing with the antennae. Here we 

 may assume that the sense of hearing was the first factor used 

 in bringing the two sexes together. The sense of sight evidently 

 does not play an important part here. In the Mormon Cricket 

 (Anabrus simplex), however, sight is apparently the most 

 important factor while hearing plays a secondary part. Anabrus 

 is diurnal and congregates in great numbers on the prairie during 

 the breeding season. The preliminary movements have not 

 been observed but since the only sound uttered is a faint 



