ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



15 



occur within a few days, as there is danger of injury to the trees under 

 those conditions. Neither should it be delayed until the eggs have 

 started to hatch. Severe infestations that have not been sufficiently 

 controlled by this means may sometimes be lessened by the use of 

 lead arsenate in the proportion 

 of 4 pounds to 100 gallons of 

 spray just at the time the buds 

 begin to separate in the clusters. 



RED SPIDERS 



Red spiders or mites do great 

 damage to apple and pear trees, 

 much of it difficult to measure. 

 They feed by withdrawing the 

 contents of the leaf cells, includ- 

 ing the chlorophyll, thus caus- 

 ing a whitening or mottling of 

 the leaves. Apparently this 

 chlorophyll is not replaced. 

 Apple foliage usually becomes 

 browned or bronzed as a result 

 of mite attacks. In irrigated 

 orchards the leaves seldom 

 drop, but in nonirrigated 

 orchards complete or partial 

 defoliation frequently results, 

 same way as apple foliage. 



Figure 14.- 



•Fruit eaten by larvae of the fruit tree leaf 

 roller. 



Pear foliage is affected in somewhat the 

 The leaves, particularly on Anjou, Winter 

 Nelis, and Bosc, often brown and dry up during the first extremely hot 

 weather in the summer. While this condition is probably due chiefly 



Figure 15.— Egs mass of fruit tree leaf 

 roller. 



Figure 16.— Fruit tres leaf roller cocoon, 

 pupal skin, and moth. About 2\i times 

 natural size. 



to the inability of the tree to supply moisture fast enough during the 

 sudden onset of hot weather, it may be aggravated by a severe infes- 

 tation of mites, since they remove large quantities of moisture from 

 the leaves. As the trees manufacture their food supply largely in 



