496 BULLETIN 333 



High-power spraying machines 1 



In the crusade in New England against the gipsy and brown-tail moths, 

 great improvements have been made in spraying outfits for forest and 

 shade trees. The machines have been made much heavier and the engines 

 are of high horsepower, so that solid streams are thrown to the tops of the 

 highest trees from a nozzle held by a man on the ground (Fig. 168). This 

 has greatly simplified the work of spraying forest and shade trees. Lines 

 of hose 200 or 300 feet in length are laid along the ground, leading from 

 the machine. In this manner trees on either side of the road, for a con- 

 siderable distance back from the fences, may be sprayed without the 

 machine's leaving the highway. Such machines cost about $1,000 and 

 are rather expensive for most of the work with shade trees. However, 

 they furnish almost an ideal method of spraying trees. With a high- 

 power machine of this type it is not necessary to have a tower or to climb 

 trees. 



The large machines used in the work with gipsy moths have triplex 

 pumps and 8- or lo-horsepower engines. The two- and four-cycle engines 

 have been used, the latter apparently having given the better satisfaction. 

 Lately the two-cylinder marine-motor type of engine has been tried and 

 has proved very satisfactory. With these machines either ij-inch or 

 i -inch hose is used, the latter being preferable. The nozzle is of much 

 the same type as that used on fire hose. 



SPRAYING OPERATIONS 



In 1911 the first spraying was begun on May 16. This application 

 was made just as soon as the trees were in good leaf, although not in 

 full leaf. The adult, over-wintering beetles became active at least as 

 early as May 2. They had been observed on the windowpanes of houses 

 for some time previous to this date, therefore they must have left their 

 hibernating- places several days before. On May 1 1 the elms were rapidly 

 coming into leaf. The beetles were on the trees and were eating ravenously 

 on those trees that were well in leaf. The work was delayed, however, 

 until the following Monday, May 16, in order that more of the trees might 

 come into fuller leaf. 



In 1912 the season was considerably later and spraying for the beetles 

 was not begun until June 13. The trees were well in leaf by May 27, 

 however, for on May 27 and 28 spraying for the elm leaf -miner was done. 

 There was a difference of about ten days between the two seasons. In 

 1912 the beetles were first noted on the trees on May 17. By May 2 1 they 

 were abundant and were eating ravenously. 



Bulletin 87, Bureau of Entomology, United States Department of Agriculture, pp. 64-67. 



