108 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



very carefully on several occasions to see if there was any appreciable 

 difference in the number of eggs being deposited in them and in adja- 

 cent orchards where lights were not employed. It must be stated 

 emphatically that these traps caught vast numbers of the moths, 

 but so far as could be determined there was little difference in the 

 number of egg masses laid on the trees in these orchards than else- 

 where in the same immediate region. Some growers, before the 

 moths ceased flying, gave up the use of the light traps after they were 

 convinced that there was little hope of receiving much benefit in that 

 way. Light traps have never proven a success in control ling an 

 injurious insect. Although some benefit may be derived, it is so 

 slight that other means must be adopted in fighting the pest. 



Orchardists have told the writer of their endeavors to get rid of the 

 leaf-roller by crushing all egg masses that could be found on the 

 trees. Cases are known where growers have actually hired men to 

 go over their trees during the winter for the purpose of destroying 

 the eggs, thinking that it was possible to control the pest by such 

 operations. In the spring they found, much to their surprise, that 

 the steps taken during the winter season were of little use, as the 

 "worms" appeared, as usual, in enormous numbers on all trees. 

 Under orchard conditions it should be distinctly understood that 

 there is no hope of practically controlling the leaf-roller by destroy- 

 ing the egg masses by hand, because the masses are deposited on all 

 parts of the trees and their small size and close resemblance to the 

 color of the bark make their discovery difficult. 



CONCLUSIONS. 



The fruit-tree leaf -roller in the larval stage has been found difficult 

 of control because of the manner in which the larvae feed on the f oliage 

 and fruit, and also on account of the fact that they are very resistant 

 to poison sprays. Applications of arsenicals alone and in combina- 

 nation with 40 per cent nicotine solution have greatly reduced the 

 amount of injury to the fruit and foliage, but these sprays have not 

 been so effective as is desirable. 



A series of experiments for the destruction of the egg masses, con- 

 ducted during the dormant season, have shown the value of mineral 

 oils. Kerosene emulsion, crude-petroleum emulsion, and miscible 

 oils have been tested. The last mentioned, when used at the strength 

 commonly employed against the San Jose scale — that is, 1 gallon to 15 

 gallons of water — will prevent most of the eggs from hatching. 

 From 93.23 to 96.21 per cent of the egg masses were destroyed by 

 this material on the experimental plats. Good results also were 

 obtained by the use of kerosene and crude-petroleum emulsions, 

 although these substances were, on the whole, not quite equal to the 



