Bugs, Cicadas, Aphids, and Scale-insects 169 
in the east. It is gregarious and is attended by ants which feed on a sweetish 
substance excreted by it. It lays its eggs in little white waxen frothy masses. 
A curiously humpbacked form is Senilia camelas (Fig. 240). The best known 
and most injurious tree-hoppers are those 
of the genus Cerasa, of which the species 
C. bubalus, or buffalo tree-hopper (see initial 
letter of this chapter), injures fruit-trees 
both by piercing and sucking sap from 
Fig. 239. Fig. 240. 
Fig. 238.—The black-backed tree-hopper, Arthasia galleata. • (After Lugger; natural 
length | inch.) 
Fig. 239.—A tree-hopper, Enchenopa gracilis. (Three times natural size.) 
Fig. 240.—A tree-hopper, Senilia camelas. (Three times natural size.) 
them, and by making slits in the twigs to lay eggs in. It is about J inch 
long, light grass-green with whitish dots and a pale yellowish streak on 
each side. On the front there are two small sharp processes jutting out one 
on each side from the prothorax, and suggesting a pair of horns, hence 
the name. It is common on apple and many other trees from the middle 
of summer until late in the autumn. The eggs are laid in pairs of nearly 
parallel and slightly curved slits. The young hatch in the spring following 
egg-laying. 
Walking over our lawns or through pastures and meadows we often 
startle from the grass hundreds of small, usually greenish, little insects that 
leap or fly for a short distance, but soon settle again in the herbage. Nearly 
all these smidl and active insects are sap-sucking leaf-hoppers, of the family 
Jassidae, one of the largest and most injurious of the Hemipterous families. 
It is stated by careful students of these grass-pests that from nearly one- 
fourth to one-half of all the grass .springing up annually is destroyed by 
leaf-hoppers. Professor Osborn estimates that over one million leaf-hoppers 
can and often do live on an acre of grass-covered ground. These insects 
are rarely more than ^ inch long, and most of them are nearer half of that. 
The body is more slender than in the tree-hoppers, and is usually widest 
across the prothorax or a little behind it, tapering back to the tip of the 
folded wings. The head is more or less triangular, as seen from above, 
and the face is oblique, sloping back to the base of the fore legs. The 
family is a large one, containing many species, of which several are well 
