566 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 19 2 8 



ing almost stationary in the air, like the queer Carolina grasshopper, 

 Dissoteira Carolina^ or while at rest. The majority sing while at rest 

 by sawing their hind legs simultaneously upon the edges of their 

 wing covers. Teeth — in some instances upon the legs, in others upon 

 the vein of the wing covers — are made to scrape several times upon 

 a ridge of the other member to produce the characteristic lisping 

 sounds of the species. This action is in reality a true fiddling, even 

 though the sounds may not be particularly musical to the human ear. 



Flight stridulation is perhaps the commonest method of producing 

 sound among the grasshoppers {Acrididae). Nature has recognized 

 other potentialities here, however, and has even turned to casual 

 ambulant stridulation, as in the case of the wingless western katydid, 

 Stenopelmatus longispina. In this instance the rule that katydids 

 sing with their wing covers is broken. Sfenopelmutus lacks wings 

 but not the musical impulse, and so the hind legs developed a rasp 

 on the inner surface of the hind femur to play against short teeth 

 or tubercles upon the adjacent sclerites and connectiva of the ab- 

 domen. This queer katydid can make its joints squeak out unique 

 music, so to speak, while it walks, wasting no more time from the 

 ordinary duties of life than does the whistling human workman. 



In all of our common eastern katydids and crickets the base of the 

 wing covers is the seat of the musical organs. A file vein with teeth 

 on one wing cover and a scraper upon the other drawn over this 

 constitute the musical apparatus. In the many green and brown 

 katydids, the wing covers are opened a little, set somewhat at an 

 angle, and rasped upon each other. Many species of crickets, in- 

 cluding our pearly winged tree crickets {Oecanthus)^ raise the wings 

 nearly at right angles to the back during stridulation — that is, when 

 they make their sounds. 



WHY DO INSECTS SING? 



Insects probably make their sounds for the same reason that birds 

 and humans sing, because they love sound, and find it a means of self- 

 expression ; it is a part of their lives. It may in some instances have 

 a sexual significance, but the theory ascribing sound to sex in insects 

 has probably been much overdone. The females appear to have 

 definite sex calls which will bring the males quickly to them; but 

 in general the males alone are musical, although there are exceptions. 

 One acquainted with these musical creatures can no more regard 

 every sound they make as simply of sexual utility than he can so 

 regard the musical impulses of men. 



It seems to be in the makeup of many creatures, such as our 

 musical insects, to utilize the ubiquitous sound waves, just as certain 

 organisms have seized upon light and analyzed it to wear it in 

 marvelous patterns upon the integuments of their backs. Even to 



