6 
COLORADO EXPERIMENT STATION 
To prevent the spread of the woolly aphis from tree to tree and orchard 
to orchard, the lice should be well cleaned out of the orchard before the first 
week of September as it is about this time when the winged lice begin to 
fly about to spread the species. 
re:me:die:s above: ground 
Wherever this louse can be reached by sprays it may be destroyed like 
other plant lice, but one precaution is necessary, the spray must be ap¬ 
plied with sufficient force to remove or penetrate the wooly covering. There 
are several spray materials that we have found entirely successful when tho¬ 
roughly applied to this insect. 
Kerosene Emulsion —According to our experience, a good kerosene 
emulsion has no superior for the destruction of this insect. It seems 
to penetrate the woolly covering rather better than most other in¬ 
secticides. When used in the ordinary strength (1/15 oil) we have always 
found it efficient. In the proportion of one-twentieth oil (5%), we have 
usually found it sufficiently strong if applied with a good deal of force and 
thoroughness. 
Directions for preparing kerosene emulsion are given on a later page. 
To be most successful, apply as a moderately coarse spray and with 
a pressure, if possible, of one hundred forty to one hundred eighty pounds. 
Scalecide and Other Miscible Oils —There are upon the market a 
number of so-called miscible oils which, when put into water, break up 
at once into very fine particles forming a milky white emulsion. These 
oils we have found fairly successful. Two to three gallons are used in each 
one hundred gallons of water. After being prepared, if these oils separate 
out so as to form an oily film upon the surface of the water, they should 
not be used. 
Soaps —We have found the standard whale-oil soaps such as “Good’s 
Whale Oil Soap” and “Bowker’s Tree Soap” quite effectual for the des¬ 
truction of this louse when used in the proportion of one pound of soap 
to each six or eight gallons of water. 
Black Leaf —The Kentucky Tobacco Product Co., of Louisville, 
Kentucky, manufacture a tobacco extract which they sell under the above 
trade name and which has become very popular among the orchardists of 
Delta County, Colorado, as a spray for orchard plant lice. We have tested 
it quite thoroughly and have found it very efficient for the woolly aphis if 
used in the proportion of one gallon of the Black Leaf in sixty-five to 
seventy gallons of water. In fact, we have usually been successful when 
using Black Leaf as weak as one gallon to one hundred gallons of water. 
This strength, however, requires very thorough application. It would be a 
good plan for any one to treat a few trees with varying strengths of this 
or any other insecticide for the destruction of lice a day or two before 
taking up his general spraying work, for the purpose of determining whether 
or not the strength that he contemplates using is sufficient to kill the lice. 
In. this way he may save many dollars, from using the insecticides in a 
strength that will not do the work or in a proportion unnecessarily strong. 
Tobacco Decoction —If any prefer to make their own tobacco 
decoctions, they may use tobacco stems or tobacco dust or whole-leaf to- 
