160 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
Distillate-oil emulsions at 6 per cent strength and crude-oil emul- 
sion at 12 per cent strength, measured by their efficiency against 
scales and lichens, convenience of preparation and application, and 
cost, are the sprays best adapted for the European fruit Lecanium 
and the European pear scale. 
The 6 per cent distillate-oil emulsion will cost about 23 cents for 
each prune tree and 34 cents for each apricot tree. 
The 12 per cent crude-oil emulsion will cost about 2 cents for each 
prune tree and 24 cents for each apricot tree. 
All sprays, to insure the best results, should be applied with a 
power outfit at a high pressure (180 to 200 pounds). A coarse, 
drenching spray applied with crook nozzles is preferable, and Feb- 
ruary is the best month in which to spray. 
O 
