HALF-WINGED INSECTS. 291 
takes place. Sometimes the animal 
is not able to effect its exit, and dies 
in the struggle. These shells may 
often be found clinging to trees and 
fences in considerable numbers. It 
\ is supposed that the Seventeen-years 
Locusts really remain in their grub 
state under ground seventeen years, 
but Jaeger holds to the contrary. 
494. The Frog-hoppers are so call- 
; ed from their great power of leaping. 
Fig. 220.—Grub of Cicada. Those of this family most familiar to 
us are the Tree-hoppers, of which a specimen is given in 
Fig. 226. The thorax or chest of these insects 
is very large. They are commonly motionless 
for hours together; but if they are disturbed, 
/' they make a sudden leap of two or three hund- 
Fig. 26.The Ted times their own length, and, spreading out 
Tree-hopper. : : 
their wings, fly off to some other spot. The 
insects of this family are sometimes called Froth-hoppers, 
from a frothy fluid which exudes from them. In some 
species, in tropical countries, this exudation 1s very_abun- 
dant. 
495. The Aphid, or Plant Lice, have small, round, 
full bodies, presenting different colors on different plants. 
Some have wings and some have not. They live in 
great numbers on the stalks and leaves of plants, sucking 
the sap with their beaks. The postures which they 
sometimes assume is very amusing. I saw the past 
summer in my garden some stalks of the wild Aster 
lined with them from top to bottom, and every one had 
its head downward. The hind legs did not touch the 
stalk at all, but were raised up, and the insects rested 
on the fore legs and the beak. Thus standing out, and 
being of a reddish color, they gave the appearance of or- 
namental appendages, until the eye was brought near 
_ enough to see what they were. 
i, 
