The plant lice of the first generation, that hatching from the 
epo’s, are wingless, viviparous females the form commonly 
known as the stem-mother, because from it all succeeding gen¬ 
erations of the season proceed without sexual reproduction, 
no males appearing in fact, in any of these generations until 
the last of the season, when both sexes are evolved and eggs 
are laid for the winter. This spring generation is readily distin- 
o-uished by characters of form and color from all that follow. 
Hatching usually before the corn appears, it is dependent at 
first in our region almost wholly upon young plants of smait- 
weed (Polygonum). The roots of these are laid bare bj the 
burrows of the ants, and upon these roots, within their narrow 
tunnels, the lice will usually be found thickly clustered Later, 
if the field be not planted to corn, our common species of pigeon 
o-rass (Setaria) divides the attention of the lice, offering m fact, 
For a little time, a more succulent herbage than the rapidly 
growing smartweed. 
Fhe second generation begins to appear about the 10th of 
May and, by the 20th of that month, may be itself mature. 
Many of this generation are winged, and others are certainly 
wingless, as careful breeding experiments upon isolated individ¬ 
uals have proven again and again. Our earliest observation of 
the winged form of the root louse was dated May 16. 1ms 
veneration mav live at first, like the other, upon smartweed and 
pigeon grass, but is most commonly transferred to corn, either 
m the same field or by flying to a distance. It is beyond all 
possible question a fact that the ants burrow the hills of corn 
industriously in advance of the appearance of these lice, and 
when they themselves have none in their possession with which 
to stock their burrows. That they will eagerly seize and convev 
to their corn-field habitations root lice exposed to them we have 
repeatedly demonstrated by experiment. They seem, however, 
to be not wholly dependent upon this louse for food, since in 
the earlv spring, before the root lice make their start, the ant 
often captures small larvae and various soft-bodied insects, which 
it kills ami carries to its nest. 
The third generation may appear from May 15 to 20 It is 
more generally winged than the second, so far as is indicated 
bv our & rather scanty observations. 
The fourth and fifth generations were brought out late in May 
and earlv in June in the single experiment which we carried to 
that length, but the subsequent history of the louse lias not 
been followed through the season in detail. It is only certain 
that successive broods appear throughout the summer, until 
fall, breeding continuously upon the roots, and that both winged 
ami windless viviparous females occur in variably proportions, 
seemingly determined in part by the condition of the plant upon 
which thev feed, the winged lice being rapidly evolved as the 
corn plant suffers from the attack. The midsummer generations 
become, consequently, widely scattered, and the lice may almost 
disappear in fields where earlier in the season they were ex- 
