5 
These two forms are very closely related, and the differences ex- 
~~ hibited do not seem to warrant more than varietal separation, although 
some authors treat them as distinet species. In typical niger the aver- 
age size is larger, the color of the female and worker is usually darker, 
and the antennal scape and the tibiz bear, among the usual pubescence, 
scattered, nearly erect, hairs, which are not usually apparent in alienus. 
THe Grass Root Louse. 
(Schizoneura panicola, Thos.) 
(Plate VIII.; Fig. 6; and Plate IX., Fig. 1.) 
This species was discovered on the roots of Panicum glabrum and 
other grasses by Mr. H. Pergande, at St. Louis, Mo., in November, 
1877, and first described by Dr. Thomas, in 1879, in the Eighth Re- 
port of the State Entomologist of Illinois. The first observations of 
its occurrence in this State on corn were made in 1883, and it has been 
seen by us more or less abundant on the roots of various plants every 
year during the past eleven years. Its economic importance is but 
small, owing to the usually trivial numbers in which it occurs on corn, 
and the evanescent character of its attack. It is often important, how- 
ever, that the corn farmer should be able to distinguish it from the far 
more dangerous corn root aphis—a matter of no difficulty to a fairly 
good observer. It may be told at once from that species by its white or 
yellowish color, and by the absence of the projecting cornicles or honey- 
tubes characteristic of Aphis, these being replaced in the present spe- 
cies by a pair of minute circular openings on the hinder part of the 
back, each delicately rimmed with brown, and surrounded by a small 
dark patch. 
This root louse has been identified by Prof. Osborn as an alternate 
-form, with a species of the same genus, S. corm, Fabr., from the leaves 
of the dogwood (U. 8. Department of Agriculture, Division of Ento- 
mology, Bulletin No. 22, p. 40); but from all available evidence I am 
not yet satisfied that the species here described as S. panicola ever 
leaves the ground except to fly from the roots of one food plant to those 
of another. It has been found by us in various underground situations 
from the early part of April until the latter part of November, as is 
shown by the following table, which gives also the plants on which it 
occurred. 
= Adult wingless j Winged 
Date. | Young. females. Pup. females. 
Apr. 5 In log, with ants. 
In breeding cage; 
Apr. 10-25 on grass roots 
with ants. 
Apr. 12 Born in breeding 
cage. 
