92 ENTOMOLOGY 



In many of these instances the sound serves to bring the two sexes 

 together and is not necessarily confined to one sex; thus in Passalus cor- 

 nutus both sexes stridulate, and the larva as well. 



A few moths (Sphingidae) and a few butterflies make sounds; the 

 South American butterfly Ageronia feronia emits a sharp crackling 

 noise as it flies. A rasp and a scraper have been found in several ants, 

 though ants very seldom make any sounds that can be distinguished 

 by the human ear; Mutilla, however, makes a distinct squeaking sound 

 by means of a stridulating organ similar to those of ants. 



Stridulating organs attain their best development in Orthoptera, in 

 which group the ability to stridulate is often restricted to the male, 

 though not so often as is commonly supposed. Among Locustidae, 

 Stenobothrus rubs the hind femora against the tegmina to make a 

 sound, the femur bearing a series of teeth, which scrape across the 

 elevated veins of the wing-cover; while the male of Dissosteira makes a 

 crackling sound during flight or while poising, by means of friction 

 between the front and hind wings, where the two overlap. 



Tettigoniidae and Gryllidae stridulate by rubbing the bases of the teg- 

 mina against each other. Thus in the male Microcentrum laurifolium 

 the left tegmen, which overlaps the right, bears a file-like organ of about 

 fifty-five teeth (Fig. 138), while the opposite tegmen bears a scraper, at 

 right angles to the file. The tegmina are first spread a little; then, as 

 they close gradually, the scraper clicks across the teeth, making from 

 twenty to thirty sharp "tic' 7 - like sounds in rapid succession. This 

 call guides the female to the male and when they are a few inches apart 

 she makes now and then a short, soft chirp, to which he responds with a 

 similar chirp, which is quite unlike the first call and, moreover, is 

 made by the opening of the tegmina. These and other details of the 

 courtship may readily be observed in twilight and even under artificial 

 light, as the latter, if not too strong, does not disturb the pair. Some- 

 thing similar may be observed in the daytime in Orchelimum, Xiphidium 

 and the tree crickets, (Ecanthus. The stridulating areas are usually 

 membranous and the rasping organs are modified veins. Frequently 

 the wing-covers bulge out to form a resonant chamber that reinforces 

 the sound, as in the katydid. 



The naturalist can recognize many a species of grasshopper by its 

 song; Scudder has expressed some of these songs in musical notation. 

 The usual song of the common meadow-grasshopper, Orchelimum vul- 

 gare, may be represented by a prolonged zr . . . sound, followed by 

 a staccato jip-jip-jip-jip. . . . 



