SOLID-STREAM SPRAYING IN NEW ENGLAND. 7 



pressure for spraying, it is necessary to have an engine transmission 

 of extra strength, and many other parts are oversize from what 

 would be necessary for an ordinary 3-ton truck. The chassis is of 

 1-inch beam construction, with platform springs and chain drive. 

 The engine is 45-60 horsepower and has an internal governor. It 

 has three speeds forward and one reverse, with special transfer 

 arrangement to the pump which makes it possible to spray while 

 traveling or standing. The controls for operating either the truck 

 or spraying attachment are easily reached from the driver's seat. 

 The pump is practically the same as those on horse-drawn outfits, 

 with the exception that it is reinforced in many places to stand extra 

 high pressures. The tank is of the U-shaped type, with a 400-gallon 

 capacity. 



In doing street-tree or roadside spraying, the motor truck is espe- 

 cially adapted, as very little time is wasted in securing water. 



POISON. 



The amount of poison to be used varies with different insects, as 

 some species will withstand more than others. In the case of the 

 apple-tree tent caterpillar (Malacosoma americana Fab.) about one- 

 half the amount of poison is required that is necessary to kill the 

 gipsy-moth caterpillars. It is obviously wasteful to use an unneces- 

 sary amount of poison. In the case of the gipsy moth, 10 pounds 

 of arsenate of lead and 100 gallons of water is sufficient until the 

 caterpillars have passed the third stage; then the poison should be 

 increased to 12J pounds to 100 gallons of water. This increase is 

 necessary, as the caterpillars are more resistant to poison as they 

 grow older. 



Spraying against any leaf-eating larva at the time when it is 

 about to change to the pupal stage is not as a rule satsifactory, as 

 very little feeding is done for a few days previous to transforming. 



In purchasing arsenate of lead paste, the following specifications 

 have been found satisfactory : 



Fifty per cent actual dry arsenate of lead, not less than 15 per cent 

 arsenic oxid (As 2 5 ), not more than three-fourths of 1 per cent of 

 soluble arsenates, no free acids, no adulterant or inert substances. 

 Arsenate of lead should be in a good mechanical and physical condi- 

 tion and should be subjected to analysis. 



These specifications carry 3 per cent more arsenic oxide (As 2 5 ) 

 than is required by Federal law, but much better work is done than 

 by the weaker percentage and with more economy. 



Poison carried over from one season to another in wooden con- 

 tainers should be tested before it is used to ascertain if it contains 



