ORTHOPTERA. 
II 7 
cover be examined with a microscope, it will be seen to be 
furnished with ridges like those of a file (Fig. 133, b). 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 c in the figure. Each wing-cover is there¬ 
fore 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 hold¬ 
ing 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 produces the call. 
There are comparatively few species of crickets, but they 
represent three quite distinct groups. These can be dis¬ 
tinguished as the Mole Crickets, the True Crickets, and the 
Tree Crickets. 
I. The Mole Crickets . — These are 
called Mole Crickets because they burrow 
in the ground like moles. There are 
species belonging to the next group, the 
true crickets, which burrow in the ground ; 
but the mole-crickets are pre-eminently 
burrowers. The form of the body is 
suited to this mode of life. The front 
tibiae, especially, are fitted for digging; 
they are greatly broadened, and shaped 
somewhat like hands, or the feet of a 
mole. Figure 134 represents one of 
these insects. The mole-crickets feed 
upon the tender roots of various plants, 
and where they are common they are 
serious pests. 
II. The True Crickets .—To this group belong our com¬ 
mon, black acquaintances that peep at us from the cracks 
