A FEW ORCHARD PLANT LICE 23 
Ions to a tree, or, if the soil is quite open and porous, carbon bisul- 
fid* *. 
THE GREEN APPLE APHIS 
{Aphis pomi DeGeer.) 
Plate I, Figs. I to 8, and Plate III, Fig. 5. 
This insect was first described in Europe by DeGeer in 1773 
and two years later was described by Fabrecius as Aphis mali. 
It is not known when it first appeared in America, but Mr. Theodore 
Pergande has been quoted as saying that he first saw it here in 
1897. In 1900 Dr. J. B. Smith gave excellent descriptions of this 
louse in its different forms with an account of its habits in Bull. 
143 of the New Jersey Experiment Station. This seems to be the 
first published account of what we are calling the “green apple 
aphis” in this country. Now it is known to be very generally dis¬ 
tributed throughout the country, being readily carried upon nursery 
stock in the egg stage. 
The dry climate of Colorado seems favorable for the develop¬ 
ment of this louse and its natural enemies have not been sufficient 
in recent years to keep it in check without the aid of spray pumps 
and insecticides. 
Sanderson’s statement* that A. pomi. “is, however, by no means 
as common as A. htchii^ (really avenae), surely does not apply at 
all to Colorado, where the latter species, in all the apple growing 
sections, is a comparatively rare insect and one that we have never 
found occuring in abundance upon a single tree. A. pomi is one of 
our very worst orchard enemies, and is, also, the species most 
commonly brought into the state in the egg stage, upon nursery 
stock. 
FOOD PLANTS 
This louse spends its entire life cycle upon the apple and pear 
trees and does not, so far as we have been able to observe, leave 
these trees during a portion of the summer to feed upon other 
plants, as so often occurs with other species. So one need 
never fear that this insect will migrate from the apple and pear 
trees to other fruits or vegetables, and it is equally true that it will 
not migrate to the apple and pear trees from weeds or vegetables, 
as it does not infest them. 
Besides the apple and pear, this aphis also attacks the haw¬ 
thorn, the quince and. the flowering crab, but the cultivated apple 
seems to be its favorite food plant. Among the apple trees it has 
its preference. The Missouri Pippin seems to be its first choice 
* Carbon bisulfld may be procured tin quantity from Edward R. Taylor, 
Penn Yan, New York. 
* Thirteenth Ann. Rep. Del. Ex. Sta., p. 131, 1901. 
