168 PLANT LICE. 
to the rank of a sub-family, and they may be correct, although 
the habits and development are similar in both sections. 
We have two genera in Minnesota. In Colepha the hind 
wings have only one discoidal vein; in Schizoneura they have 
two. 
Lice belonging to the genus Colepha are very common in 
some parts of the state, and seem to be spreading very rapidly, 
infesting the elms and causing considerable damage to these fine 
trees. According to Oestlund the oviparous female produces but 
one large egg in the fall. 
Colopha ulmicola Fitch. (The Elm-leaf Cockscomb Gall). 
This gall, looking very much like a cock’s comb, occurs most 
commonly on young elm trees, arising abruptly on the upper sur- 
face of the leaves. It is usually an inch long and a quarter of 
an inch high, compressed, with the sides wrinkled perpendicu- 
larly, and its summit irregularly gashed and toothed. It is of 
a paler green color than the leaf, but is more or less red on the 
side exposed to the sun. The gall opens on the under side of 
the leaf by a long slit-like orifice; inside.it is wrinkled perpen- 
dicularly into deep plates. The gall is always found between 
two of the branching parallel veins, and those between which it 
grows are usually drawn closer together than the rest. The galls 
are always crowded with lice and white flocculent material, and as 
they become old and are deserted by their inhabitants, they be- 
come darker and darker, thus greatly disfiguring the trees. 
The illustration, Fig. 135, shows the galls as well as the 
various stages of the insect. 
The genus Schizoneura is well represented in Minnesota, and 
contains some very destructive insects, most of which are cov- 
ered with woolly or flocculent matter. Some species infest leaves 
without curling them, others are found on twigs and leaves cov- 
ered with woolly material, and not a few lead a subterranean 
existence onthe roots of grasses or trees. 
Only a few of the more destructive species are given. 
Schizoneura americana Riley. (The White-elm Schizoneura). 
This louse is found on the under side of the leaves of the 
elm, (Ulmus americana), which it causes to curl, forming a sort 
