20 The Colorado Experiment Station. 
black peach aphis (Aphis persicae niger) 
This enemy of the peach has never been of much economic 
importance in Colorado. It has been found from time to time, in 
'the peach growing sections of the Western Slope, but apparently 
has not been able to continue for any length of time in orchards 
where it has been introduced. Notwithstanding the fact that up to 
the present time it has never made any headway in the orchards, it 
is well for the peach growers not to take any chances in orchards 
where it does appear, but to be prompt in making a very thoro ap¬ 
plication of Black Leaf, or some other good contact spray to in¬ 
fested trees. 
The fact that this pest has the habit of feeding upon the roots 
as well as the twigs of peach trees, makes it one that is dreaded. 
Because of its ability to live below as well as above ground, it might 
become a serious pest if conditions should happen, at any time, to be 
favorable to its development. 
Very often peach nursery stock coming from an infested 
nursery, is found to be badly infested with this aphis. When such 
trees are found they should be either carefully fumigated witn 
hydrocyanic acid gas, or sprayed with a good contact insecticide 
such as Black Leaf, kerosene emulsion, or whale-oil soap. Plate I, 
Fig. 2 shows a section of a peach twig on which is a large number of 
these aphids. This twig was cut from a tree which had just been re¬ 
moved from a box shipped into the state from an outside nursery. 
There were so many aphids in the box that they found their way 
through the cracks and could actually be seen crawling on the out¬ 
side in considerable numbers. The box bore a fumigation tag and 
‘the inspector, whose duty it was to look over all shipments of 
nursery trees into the county, rightly condemned all the trees in 
(the box. The dark color of the adult lice and their habit of feeding 
on the tender bark rather than the leaves enables us to separate this 
louse readily from the foregoing species. 
