22 
May 3, although the eggs of the preceding year were not yet all 
hatched. 
At this time an interesting and important comparison was made 
between the contents of ants' nests in fields of corn last year and 
those on which a single crop of oats had been raised. Every nest 
of the former contained numerous root-lice or their eggs, while thir- 
teen nests of Lasius alienus found in the oats field in corn for the 
three preceding years were carefully explored, but not an aphis 
could be found in the possession of the ants. Later, a single colony 
of thirty-six ants was found with no eggs but with seventy-eight 
root-lice in their possession. These had very likely been carried in 
from an adjacent part of the field. In the absence of root-lice the 
ants seemed to be maintaining themselves, in part at least, by cap- 
turing beetles and insect larvae, the remains of which were found in 
their nests. 
On the other hand, in the oats fields which had Ijeen in corn for 
some years before, ants were now less abundant than in the adjacent 
corn, and the eggs and young of root-lice were common in their 
nests. In fourteen nests explored May 3, eight hundred and eighty- 
six ants were found, an average of sixty-three per nest, togetlier 
with five hundred and sixty-five eggs and eight hundred and eight- 
;en young of root-lice. This was an average of ninety-eight to 
each nest, and is to be compared with the average of one hundred 
and ninety-six root-lice and root-louse eggs per nest in the adjacent 
fields of corn. 
By May 8 the second generation of the root-lice was abundant 
in the oats fields, but none of them had as yet acquired wings. Heavy 
rains fell on the loth and nth of May and at occasional intervals 
thereafter, and the muddy fields were not revisited until May 18. 
Then many ants were crawling about and making new burrows 
in the ground (each of which contained from two to ten ants, 
and no root-lice. Specimens of the latter, dropped near these 
new-made burrows, were promptly pounced upon by ants and 
carried under ground. The root-lice seemed to be less numerous 
than before, as if affected by the rains. On the 22d of May the 
fields continuously in corn were visited again, and fourteen nests 
of ants were dug out and the contents caught and counted. Five 
hundred and seventy-one ants were found in these nests, an aver- 
age of forty-one each, and six hundred and fifty-five ant larvae 
in eight of them. The aphis contents, on the other hand, had 
dwindled greatly, consisting of forty-six wingless adults, thirty- 
three pupse, and one hundred and seventy-three young, a total aver- 
age of thirty-seven to each ant's nest. 
