TREE INSECTS AND THEIR CONTROL 193 
gear of a wagon, and the pump fastened to a small plat¬ 
form at the top of the tank or at the rear end of the wagon. 
Instead of the tank, a barrel, or a 100 gallon hogs¬ 
head, may be used, placed at one end of the wagon 
bed to leave room for pump and operator. A suction hose 
extends into the container which holds the spray material. 
The pump is double action with double cylinder, and gives 
pressure for two lines of hose and for double nozzles. 
For results in spraying mature street trees, power 
sprayers, operated by gasoline engines, must be used, as the 
other outfits mentioned are not effective for this purpose. 
It is important that communities and neighborhoods should 
act together in their purchase and use where no municipal 
outfit is at hand. The ideal plan, of course, is to have all 
spraying operations conducted by the local government, 
since this plan makes it feasible to have even more com¬ 
plete and efficient outfits than are to be expected in com¬ 
munity or neighborhood cooperation. The power sprayer 
gives steadier spray than the hand-pump, insuring a more 
even and more thorough distribution of the application 
and makes it possible to reach the tops of the trees. 
Power sprayers as small as one horsepower may be pur¬ 
chased, while there are larger sprayers of as much as 
12 horsepower, with capacity of 50 gallons or more to the 
minute under pressure of from 150 to 300 pounds. Where 
a pressure of less than 100 pounds per square inch is used, 
the material is delivered in the form of a mist within a 
short distance from the nozzle, which necessitates the 
nozzle being carried near to the foliage to be sprayed. 
This practically limits the use of hand pumps to trees not 
over 30 to 40 feet high and then only after climbing into 
the trees. The compressed air pumps are not practicable 
for trees over 10 feet high. For tall trees, a solid stream 
delivered from a nozzle at a pressure of 150 to 200 pounds 
13 
