ORCHAED INSECTS OF THE PACIFIC NORTHWEST 



27 



the trees become older, cover crops may be planted, for the injury is 

 less severe on older trees. Many of the worst-scarred twigs can be 

 pruned off during the winter, and should be burned to destroy the eggs. 

 A thorough dormant spray con- 

 taining 4 percent of lubricating- 

 oil emulsion kills most of the 

 eggs in the twigs and may reduce 

 the infestation the following 

 year. 



TARNISHED PLANT BUG 



The tarnished plant bug 

 (Lygus pratensis K) (fig. 31) 

 appears in the trees early in 

 the spring and punctures the 

 swelling fruit and leaf buds 

 (fig. 32), sucking the sap from 

 them. Its presence is often 

 first made known by the brown- 

 ish drops of sap exuding from 

 these punctures. This loss of 

 sap causes the buds to dry, and 

 in the case of fruit buds the 

 blossoms may never open, or, 

 if they do, they may be de- 

 formed. When the bugs are 

 sufficiently numerous, the in- 

 jury is severe (fig. 33) and 

 may result in almost a total 

 failure of the crop. The degree 

 of injury is contingent not only 

 on the number of bugs, but on 

 weather conditions. Continued 

 periods of settled warm weather 

 in March or early April, coming 

 before alfalfa and other ground 

 crops have developed, cause the 

 bugs to feed in the trees; cold, 

 rainy, or windy weather at this 

 time prevents extensive feeding. 

 Pears and Delicious apples are 

 the most susceptible to this in- 

 jury. The bugs also sometimes 

 feed on the young (fig. 34) and 

 maturing fruit and cause dry or 

 corky and sunken spots. The 

 tarnished plant bug occurs 

 throughout the Northern Hemisphere; 



LIFE HISTORY 



The adult tarnished plant bugs are nearly one fourth inch long, 

 dirty grayish or greenish, with variable markings. They come out of 

 hibernation during the first warm, sunny days of early spring and feed 

 for a time on fruit-tree buds and the leguminous cover crops. They 



Figure 30.— Apple twig scarred by green clover tree 

 hoppers in laying eggs. Three times natural size. 



its origin is uncertain. 



