ORTHOPTERA. 293 
object to call the females, is nothing but a sort of stridulation or 
screeching, produced by the rubbing together of the wing cases, or 
elytra. But the mechanism by which this is produced varies a 
little in all the three kinds. With the Crickets the whole surface 
of the wing cases is covered with thick nervures, very prominent 
and very hard, which cause the noise the insect produces in rub- 
bing the elytra one against the other. With the Locusts, there 
exists only at the base of the elytra a transparent membrane called 
the mirror, which is furnished with prominent nervures, and 
produces the screeching noise. And, lastly, in the Crickets the 
thighs and elytra are provided with very hard ridges. The 
thighs, being passed rapidly and with force over the nervures of 
the elytra, produce the sound, in the same way as a fiddle-bow 
when drawn across the strings of a violin. With all these insects 
the male alone is endowed with the faculty of producing sound. 
The Crickets and Grasshoppers have very long thin antenne, 
whilst the Locusts have short antenne, and either flattened 
or filiform, or swelling out at one extremity like a club. The 
female of the first two is provided with an ovipositor in the shape 
of an auger. 
We will study successively the three types of these families, 
that is to say, the Crickets, the Locusts, and the Grasshoppers. 

S S 2 ~, S Nv 
Fig. 304.—Field Cricket ( Gryllus campestris). 
The Field Cricket (Gryllus campestris, Fig. 304) lives alone in a 
hole which it digs in the ground, and in which it remains during 
the day. It only quits its retreat at night, when it goes in 
