66 
root lice (generations two and three) sufficiently abundant in 
ground not previously in corn to be worthy of special atten¬ 
tion. 
The evolution of winged root lice is not confined to the second 
generation, above mentioned, but continues throughout the sea¬ 
son in numbers varying according to some law not yet ascer¬ 
tained. It is to be noticed, however, that we have taken the 
winged form in August but once, although our collections of 
wingless specimens were made on twenty-seven days within that 
month. In September also the winged louse is relatively rare, 
occurring but three times in twenty collections made on as many 
different dates. By November the viviparous generations are 
all dead, as a rule, and the species is thereafter represented only 
by the sexual generation and the egg. 
RELATION TO ANTS. 
Seven kinds of ants have been fouiid by us fulfilling the re¬ 
lation of host, guardian, and nurse to the corn root aphis; viz., 
Formica, fusca, Formica schaufussi, Lasius niger, Lasius niger 
alienus, Lasius interjectus, Myrmica, scabrinodis, and Lo/enopsis 
debilis. The occurrence in this relation of all but the third and 
fourth just mentioned* is, however, so rare that they need re¬ 
ceive here no more than this passing mention, especially as their 
services to the aphis are, so far as observed, the same in charac¬ 
ter and value as those of the much more abundant species. 
The fact lias already been mentioned in this paper that the 
sexual egg-laying generation of the corn root aphis—the last to 
appear in fall—is born in the galleries of the nests or homes of 
ants, and that here the sexes pair and the females drop their 
eggs. As one explores these nests in November, when the root 
louse eggs are being laid, he is struck with the relative inde¬ 
pendence of these oviparous adults, which are allowed to wander 
unattended through the burrows of their hosts as far as a foot 
or more from a corn root. We have found them, however, still 
feeding as late as November 5, and laying eggs November 21. 
These egg*s, which are yellow when first deposited, but soon be¬ 
come shining black, and turn green just before hatching, are at 
first scattered here and there, as it happens, but are finally 
gathered by the ants for the winter in little heaps and stored 
in their galleries, or sometimes in chambers made by widening 
the gallery as if for storage purposes. If a nest is disturbed, 
the ants will commonly seize the aphis eggs—often several at a 
grasp—and carry them away. In winter they are taken to the 
deepest parts of the nests (six or seven inches below the surface 
in some cases observed) as if for some partial protection against 
frost; but on bright days in spring they are brought up, some¬ 
times within half an inch or less of the surface, sometimes even 
scattered about in the sunshine, and carried back again at night 
* Typical Lasius niger and its barely distinguishable variety alienus are almost equally 
at home in the corn field, and do not differ noticeably in their relations to the corn root 
aphis. 
