PLANT LICE. 169 
of gall. If at all numerous they can greatly deform the ends 
of the twigs, where all the leaves are curled, forming a mass of 
sickly, yellowish leaves. All the lice are covered with a whitish 
powder, and exude an abundance of liquid, which is very at- 
tractive to ants; and these active insects are not slow to dis- 
cover and to utilize such a store of food. If we carefully ex- 
amine the cracks and crevices of an elm badly infested with such 
lice the previous summer, we shall very likely be able to detect 
the impregnated eggs of this species. The minute, dull-yellow- 
ish, ovoid eggs are more or less effectually covered with the 
AOR 
lat Lo, NN ep 
Pg eet TIE 
Fic. 148—Schizoneura americana Riley.—c, c, leaf showing curl, natural size; a, 
winter egg; b, stem-mother; d, winged female; i, her antenna; j, her tarsus; e, 
true female, ventral view, showing solitary egg; g, her tarsus from beneath; f 
annus and genital points of male; h,antenna of fourth generation, all enlarged. 
After Riley and Monell, U. S. Geol. and Geog. Survey. 
parent’s dry skin, which still faintly shows the rings of the living 
female. As soon as the young louse hatches in spring it crawls 
to the more terminal twigs, and settles upon the under side of 
the first tender leaflet it meets with. This stem mother very 
soon causes the leaf to swell and curl, by the irritations and 
punctures of its beak. Persons whose elm trees are thus affected 
year after year should watch for the first signs of such deformed 
leaves and should remove and burn them, thus effectively de- 
stroying the later numerous generations of such nasty visitors. 
This insect is shown in various stages in Fig. 148. 
