A FEW ORCHARD PLANT LICE- 
41 
and wild hops and upon plums. 
At Fort Collins we have followed it upon the plum in mod¬ 
erate numbers throughout the entire season, and Mr. W. T. Clark* 
has reported it remaining upon the hop vines in California until 
the males and egg-laying females have been produced. So it seems 
probable that this louse can exist from year to year upon either of 
these food plants in the absence of the other. 
For an excellent account of the life habits of this insect and 
colored figures of the different stages, see an article by C. V. 
Riley in Department of Agriculture Report for 1888, p. 93. 
While we have not observed the stem-mothers in Colorado, 
we find the louse appearing during May and the early part of June 
upon the leaves of plum trees. Most of the lice acquire wings and 
leave early in July in the vicinity of Fort Collins, though on July 
8, 1907, trees were seen badly infested with this louse and there 
were many wingless adult females still present. 
appearance op the lice 
The wingless lice are light green or greenish yellow without 
noticeable markings of other colors. The winged lice have the 
same general body color with head, plates of the meso-thorax 
above, and a few dashes upon the abdomen black. All the lice are 
specially marked by having upon the head, at the base of each 
antenna, a prominent tubercle or tooth, and a less prominent one 
projects from the inner side of the first joint of the antenna. 
About the middle of September at Fort Collins the winged 
return migrants begin to come from the hops and alight upon the 
leaves of the plum. A note made at that place October 3, ’07, 
reads: “The winged migrants are fairly common on plum leaves 
now and most of them have a small colony of young surrounding 
them.” These young develop into the wingless egg-laying females 
(and possibly winged males also) and a little later the eggs are 
deposited upon the twigs to live over winter. 
REMEDlEvS 
The same as for the green apple aphis. 
THE RUSTY BROWN PLUM LOUSE 
{Aphis setariae. Thos.) 
This plum louse is readily distinguished from any of the other 
species mentioned in this bulletin by its dark rusty brown color 
together with the conspicuous white base of the antennae, entire 
tibiae, and tail 01 cauda. 
This louse appears early in the season upon the bark and 
leaves of the tender new shoots of plum trees. We have found it 
* Bull. 106, Calif. Experiment Station, 1904. 
