March, 1896.] MORSE, NOTES ON LoCUST StRIDULATION. 17 



These locusts belong to a group, the QEdipodinee, usually given 

 subfamily rank, of which fifteen species are found in New England. One 

 of the best known and most widely distributed of these in eastern North 

 America is a species whose wings are black with a pale buff outer bor- 

 der and with a few spots at the tip ; this is the Carolina locust. It is 

 very common on dusty roadsides and waste places in the latter part of 

 summer and the early autumn. Owing to the prevailing tint of quiet 

 brown which clothes the majority of individuals they are known in some 

 localities as " Quakers." 



Just how the rattling sound is produced is a matter of some specu- 

 lation ; it is, however, entirely under the control of the insect, which 

 can produce it or not at will. So far as recorded, only the male stridu- 

 lates, though I suspect thaf the females of some species occasionally do 

 in a less degree. Owing to the noise being produced in flight it is dif- 

 ficult not only to observe the exact method of its production, but also 

 to determine with certainty that it is confined to one sex. It is usually 

 stated to be caused by the striking of the front edge of the wing against 

 the under side of the wing- cover. This might occur as the result of an 

 up-and-down blow or, as I venture to suggest, of a slight antero- poste- 

 rior movement bringing the prominent veins of the under side of the 

 wing- cover (humeral trunk and ulnar or anal veins) into collision with 

 the raised veins of the base of the wing. 



Certain species, however, produce not only rattling, but distinct 

 snapping sounds consisting of separate loud snaps or clacks, e. g., Cir- 

 coteitix verrucnlatus, which often dances up and down in the air while 

 doing so and not infrequently ends its powerful and erratic flight with 

 a rattle immediately before alighting. It has seemed to me that the 

 clacks may be produced in a diff"erent manner from the rattling sounds, 

 and the following is suggested as a possible explanation. 



If the wing-cover of any of our larger Gildipodinse be examined 

 there will be readily seen near its point of attachment, about in its mid- 

 line, between the bases of two of the conspicuous veins (humeral trunk 

 and anal) and pressing them apart, as it were, a distinct prominence. 

 From this spring the two ulnar veins. If the wing-cover be inverted a 

 depression will be found corresponding to the external prominence. 

 In this depression lies the elevated base of the median vein of the wing 

 when the wings and wing-covers are closed, and this arrangement holds 

 these organs in place in the position of rest without any direct effort of 

 the insect. If the wing-cover of a newly killed or relaxed O^dipodine 

 be properly manipulated it will leave its place with a distinct snap, due 



