14 
COLORADO EXPERIMENT STATION 
year upon the plum, though it is known to attack barn grass Echinochloa 
Crus-galli. 
The remedies for this louse are exactly the same as for the green 
peach aphis already mentioned, 
THE BLACK CHERRY LOUSE. {Myzus cerasi Fab.) ' 
This louse has long been known in Europe as a pest upon cherry trees. 
It is generally distributed throughout the cherry growing districts of the 
eastern slope in Colorado, but as yet only occurs in isolated orchards upon 
the western slope. 
Those having cherry trees should make a vigorous attempt to exter¬ 
minate this louse as soon as it is noticed in the cherry orchards. It could 
not be mistaken for any other insect upon the cherry tree as it is deep black 
in color and infests the under side of the leaves and the bark of the tender 
new growth. It is usually accompanied by ants in abundance. This insect 
remains upon the cherry, and so far as known, does not migrate to any other 
plant. On account of its numerous insect enemies it is likely to almost dis¬ 
appear for a time during the middle of the summer, but may continue quite 
abundant thoroughout the season. The last brood in the fall lay eggs which 
carry the species over winter to hatch in the spring. 
The remedies are exactly the same as for the foregoing species. 
THE HOP PLANT LOUSE. (^Phorodon humuli.) 
This is the green louse that has caused such severe losses in hop 
vineyards. The hop is the summer food-plant and in the fall winged hop 
lice migrate to the plum trees where the egg-laying females later deposite 
eggs upon the branches which hatch the following spring. These lice are 
very similar to the preceding in general appearance but lack the heavy 
covering of powder. While most of the lice leave the trees for the hop be¬ 
fore the middle of July, we have found some of the lice remaining through¬ 
out the summer on plum leaves. 
RKMEDli:s 
The same as for the green peach aphis. * 
PREPARATION OF A FEW IMPORTANT PLANT LOUSE 
INSECTICIDES 
Kerosene Emulsion —Prepare in the following proportions: 
Soap one half pound. 
Water one gallon. 
Kerosene two gallons. 
To prepare, dissolve one half pound of soap in one gallon of soft water 
by boiling; when well dissolved and still boiling hot, remove from the fire 
and add two gallons of kerosene, and agitate at once as briskly as possible. 
If large quantities are being made, a good way to emulsify is to u§e a 
force pump and spraying nozzel and pump the mixture as forcefully as 
possible back into the vessel containing it. If the emulsion is properly 
formed, the whole mass will appear much like whipped cream and will mix 
readilly in water without a film of oil rising to the top. Sometimes, when 
