54 



THE STUDY OF INSECTS 



Mm 



these fiddlers calling his mate. By moving quietly in the direction from 

 which the sound comes, and stopping whenever the insect stops chirping, 

 but moving on again when he renews his song, one can get near enough 

 to see how he does it. This can be done even in the 

 night with the aid of a lantern, as the crickets do not 

 seem to mind lights. 



Figure 89 represents the musical apparatus of a 

 cricket. From this it will be seen that the large 

 veins divide the wing-covers into disk-like membra- 

 nous spaces. If the principal vein which extends 

 diagonally across the base of the wing-cover be ex- 

 amined with a microscope, it will be seen to be fur- 

 nished with ridges like those of a file (Fig. 89, C). On 

 the inner margin of the wing-cover, a short distance 

 toward the base from the end of the principal vein, 

 there is a hardened portion which may be called the 

 scraper. This is shown enlarged at s in the figure. 

 Each wing-cover is therefore provided with a file and 

 a scraper. When the cricket wishes to make his call, 

 he elevates his wing-covers at an angle of about 

 forty-five degrees with the body ; then holding them 

 in such a position that the scraper of one rests upon 

 the file of the other, he moves the 

 wing-covers back and forth sidewise 

 so that the file and the scraper rasp 

 upon each other. This throws the 

 wing-covers into vibration, and pro- 

 duces the call. 



The crickets do not constitute a 



Fig. 89. — Fore wing , -j ui 



of Gryiius; a, as seen large group yet there is considerable 

 S^^SH^t diversity of form among them. The 

 down on the side of the m ore common species may be placed 



abdomen is not shown; . , ,. L ... .. J ., 



s, scraper; /,/, tympana, in three rather distinct groups; the 

 beio'wT t SET/fiE tree-crickets, the field-crickets, and the 



C, file greatly enlarged. mole-cricketS. „££ ^~ ^^ 



THE TREE-CRICKETS 



The common name of this group was suggested by the fact that these 

 crickets are very apt to inhabit trees; but they occur also on shrubs, or 

 even on high herbs and tall grass. They are delicate insects, many of 

 which are of a light green color. Most of them belong to the genus 

 (Ecanthus and the one that often attracts attention is the snowy tree- 

 cricket, 0. mveus (Fig. 90). Although usually unseen the males arc evi- 

 dent in late summer and in the autumn by their songs. Their song is 

 begun early in the evening and is continued throughout the night; it 

 consists of a monotonous scries of high-pitched trills rhythmically re- 

 peated indefinitely. It is a remarkable fact that all of these crickets that 

 are chirping in any locality chirp in unison. Except where the true katy- 

 did is heard, this is the most conspicuous insect song heard in the night 

 in the regions where this species occurs. 



