104 
As the young hatched, they spread in great numbers over the vege¬ 
tation in the vicinity of the trees where they had their origin, and 
attached themselves to a great variety of plants, both shrubby and 
herbaceous, besides those mentioned above. We found them upon 
the bass-wood, green ash, American elm, black locust, osage orange 
plum, and cherry, and in their second stage upon leaves of clover 
and smartweed, upon wild cucumber, and upon the gooseberry 
In fact, their young occurred, in the middle of July, upon nearly ali 
the herbaceous plants within one or two hundred feet of infected 
trees; clover, plantain, Polygonum, mustard, various grasses, and 
Biclena frondosa, being the species apparently preferred. The latter 
plant seemed to suffer considerably from their attacks, the leaves 
being paled, spotted with yellow, and slightly curled when worst in¬ 
fested. By the latter part of July the larvae in the second stage 
were common upon the under sides of the leaves of strawberries 
near infested trees, causing them to contract and curl. 
The ultimate fate of these individuals which fixed themselves upon 
herbaceous plants and throve there, for a time at least, we neglected 
to make out, but it is probable that the greater part of them per¬ 
ished in autumn, although some may have succeeded in migrating 
at this period (when the young upon the trees are passing from the 
leaves to the twigs) to woody plants on which they could maintain 
themselves until the following season. The fact that in nurseries we 
sometimes found the young very abundant upon the suckers at the 
bases of the trunks of trees which were themselves but little infested, 
tended to confirm this supposition. 
I noticed a marked difference in the stage of advancement of the 
brood upon different trees, some retaining still a considerable per¬ 
centage of the eggs unhatched in the cottony masses attached to the 
twigs, after others had practically yielded all their young, and the 
obsolete bodies of the females and the egg masses had fallen to the 
ground, or were hanging in ragged shreds from the branches of the 
trees. As late as July 13, on some trees in Bloomington, fully 
twenty-five per cent, of the eggs were still unhatched. By the 20th 
of the month the young had nearly all left the nests of the mother 
bark lice and were established on the leaves, although a few eggs 
could occasionally be found which were still unliatched. 
By the 16tli August the injury effected by this new brood was at 
its height, and many trees in the vicinity of Bloomington lost a 
considerable part of their leaves, and the others were blackened and 
dwarfed, giving the branches a bare and unthrifty look. 
By the 30th October all the living bark lice had deserted the 
leaves, except a few found occasionally upon the petioles, but 
thousands of them occurred upon the under sides of the twigs and 
branches of nearly every tree of the species worst infested, ( Acer 
dasycarpum), the twigs being often crowded to their very tips. 
The common insect enemies of the species were moderately abun¬ 
dant throughout the season, the small black Coccinellid beetle. 
Hyperaspis signata, whose larva is found embedded within the egg 
mass devouring the eggs, being the most destructive. 
