A FEW ORCHARD PLANT LICE 39 
this lou^e present upon the roots of nursery stock that lias been 
shipped into the state. Undoutbedly the lice present in Colorado 
today, have descended from those brought to the state in this man¬ 
ner, and not in the egg stage. 
It is a matter of much importance then, to treat all nursery 
stock coming to Colorado in such a way as to prevent any possi¬ 
bility of introducing this louse into the peach orchards upon 
nursery trees. 
This may be done either by a thorough fumigation of the 
stock with hydrocyanic acid gas; or by thoroughly and forcefully 
spraying it with kerosene emulsion, a good quality of whale oil 
soap, or a tobacco decoction, before planting. 
If the louse has been introduced into the orchards and is found 
to be present upon peach trees it is highly important that the owner 
keep a very close watch over his trees especially in the early spring 
time for the purpose of detecting the first appearance of these lice, 
which would probably be during the latter part of February or 
sometime in March in the warmer sections of the state. In the 
colder sections where peaches are grown to some extent, the earliest 
date of their appearance would probably be the latter part of March 
or very early in April. As indicated above, the louse may become 
very abundant before the buds open at all, and that is when 
treatment of orchards trees can be made most effective and with 
least expense. So far as our observations have gone, the lime- 
sulfur preparations have not been satisfactory for the control of 
this louse, but it is very readily killed by the ordinary application 
of soaps, tobacco preparations or oil emulsions. We would espec¬ 
ially recommend kerosene emulsion that is 1-15 oil; ‘‘Black Leaf,” 
1 gallon in 65 gallons water; or home made tobacco decoction. 
If the treatment is made one week before the buds begin to open, 
the green peach aphis will also be killed by the same application. 
Thorough treatment should always be made before the winged 
forms begin to appear, which may be as early as the middle of 
-qii'ik 
This louse is very gregarious in habit so that it will often be 
the case that one or two trees, or even one side, or a few limbs 
upon a tree, may be quite badly attacked when no other infested 
trees are found in the orchard. 
PLUM LICE 
Besides being attacked somewhat by the green peach louse 
(M. persicae) plum and prune trees have three other species of 
plant lice of considerable importance in Colorado. 
THE MEALY PLUM LOUSE 
Hyalopterus arundinis (Fab.) 
This is a light green louse that colonizes the underside of the 
