OF WASHINGTON, VOLUME XIII, 1911. 141 



STUDYING THE STRIDULATIONS OF ORTHOPTERA. 



BY H. A. ALLARD. 



Among the Orthoptera of the families Acridiidce, Locustidae, 

 aud Gryllidae, stridulatory powers have been very highly de- 

 veloped. The simplest and least musical sounds are char- 

 acteristic of the Acridiidae. Among the Gryllidse, however, 

 highly specialized sound-organs have been developed capable 

 of producing veritable musical tones. 



The strident sounds produced by insects are always of an 

 instrumental sort and are, for that reason, entirely unlike the 

 true vocal sounds characteristic of birds. Insect stridulations, 

 in the true sense, do not constitute real music, since, in most 

 instances, musical tones are entirely absent. Even when 

 musical tones are present, as in the trillings of the Gryllidae 

 (crickets), these trillings are almost wholly continued in a sin- 

 gle monotonous tone. 



With the exception of some of the Acridiidse, which stridu- 

 late by movements of the hind legs, the stridulations of the 

 musical Orthoptera are produced by definitely controlled 

 movements of the tegmina, which have been more or less com- 

 pletely modified for sound-producing purposes. Among the 

 Acridiidae which stridulate during flight, the inner wings are 

 brought in contact with the tegmina at will, so that a noisy 

 clack may accompany flight. These harsh sounds, however, 

 represent musical tendencies just as much as the calls of the 

 katydids, since they are more or less within the control of the 

 possessor, and not merely accidental noises attending every 

 flight movement of the wings. The tegmina of these grass- 

 hoppers have been least modified for sound producing pur- 

 poses. Among the more highly specialized Locustidae, how- 

 ever, a portion of the base of the tegmina has undergone con- 

 siderable modification to produce delicate, sound-producing 

 surfaces, which, among the different species, are used to fur- 

 nish a variety of sounds. The wings of the Gryllidae show 

 most complete modification for sound-producing purposes, and, 

 consequently, these insects produce the most varied and most 

 musical sounds of all the Orthoptera. 



"Entomologists, generally, have somewhat neglected the 

 musical habits of the Orthoptera. Consequently, the stridu- 

 lations of only the more common forms are definitely known. 

 From some of the early descriptions it appears that the notes 

 of different species have been somewhat confused. In some 

 instances a portion of the characteristic stridulation of a 

 species has been entirely overlooked, so that the description is 

 noticeably incomplete. In other instances the descriptions 

 are so vague that they have little or no meaning. 



