IOWA ACADEMY OP SCIENCES. 
87 
with corni, with the probability of a dimorphic form that 
remained on grass roots, or in the ground during winter. The 
observations of the past two seasons, however, seem to indicate 
a more distinct separation even than this. The fact that the 
panicola form has a fairly constant difference in color of the 
apterous individuals, is found quite constantly on annual grasses 
only, and its pseudogynes failed to colonize on Cornus, or the 
spring migrants from Cornus to colonize artificially on roots of 
annual grasses, favor the conclusion that it has become estab- 
lished as a variety at least, if hot a distinct species. On the 
other hand the identity of almost all structural details and the 
fact that undoubted corni has been bred from Setaria and colon- 
ized on Cornus, also that one specimen of corni was taken on 
Setaria the fall of 1893, along with the extreme variability of 
the wing venation in the form found on grass roots seem to 
indicate a close relationship between the two. 
There seems to be excellent reason for believing that the 
panicola form, if not a dimorphic one, is a variety which has 
arisen from corni as its antecedent and which, by the fostering 
care of ants, or possibly by selection of food plants, or some 
other condition, has become established as a permanently sub- 
terranean form. 
The variability of the structural characters, especially the 
venation; the number of its food plants; its dependency upon 
ants and the occurrence of winged forms without migration, all 
seem to point to comparatively recent origin for this form^ 
Whether a variety or a dimorphic form, from the observa- 
tion of Prof. Forbes, the facts gathered in 1889, and from those 
gathered the past season, it seems that their life cycle is as 
follows : 
The eggs are probably deposited in the soil, though they 
have not been found on the roots of annual grasses, and stored 
by ants in their chambers. In the spring the eggs, or newly 
hatched lice, are gathered and carried by ants to the roots of 
young Panicums and Setarias, possibly to the roots of Spartina 
cynosuroides CEnothera biennis, where they feed till the middle 
of May, or till the first of July, at which time they are trans- 
ferred to roots of Foxtail and corn. As the Foxtail dies early 
in the autumn they are again transferred to the Panicums, in 
8 One fact which is very strongly in favor of its being a distinct species is its habit 
of producing winged forms, principally in the spring. This habit has been noted in 
Melonoxcinthus flocculosus, ChcMophorus spinosci' and in a sedge infesting form. 
F. A. S. 
