ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



57 



LIFE HISTORY 



There is only one generation of the pear thrips annually. The 

 adults, which are small, less than one-twentieth of an inch long, slim 

 and dark brown, emerge when the fruit buds are swelling and beginning 

 to show green. After a feeding period of about 3 weeks the egg-laying 

 period begins, and this lasts another 3 weeks. The eggs are very small, 

 whitish, and kidney-shaped, and they hatch in less than 2 weeks. 

 The young are white and similar to the adults 

 in shape (fig. 64). They develop for about 3 

 weeks, then drop to the ground, burrow into 

 the soil, and construct small cells a few inches 

 to 3 feet from the surface. Here they remain 

 dormant, changing late in the fall to adults, 

 which emerge the following spring. The pear 

 thrips is thus active on the trees for only about 

 2 months in spring and is dormant in the 

 ground the rest of the year. 



CONTROL 



The pear thrips may be controlled by 

 thoroughly spraying the trees during the first 

 warm weather after the buds have begun to 

 show green. Later sprays may be needed 

 when the blossom buds begin to show white 

 and just after blooming. The trees should be 

 examined some days after the first spray has 

 been applied; if there is an average of one or 

 more thrips to each bud at this time, the later 

 sprays are advisable. For prune and plum 

 trees an oil emulsion or a miscible oil suitable 

 for dormant spraying (p. 73) should be used, 

 2 gallons to 100 gallons of water, to which is 

 added 1 pint of nicotine sulfate (40 percent 

 nicotine). Control by cultural means "has 



not been successful, because many of the young are too deep in the 

 ground to be reached by cultivation. 



Eye-Spotted Budmoth 



The eye-spotted budmoth (Spilonota ocellana (D. and S.)) does 

 damage mainly to prunes and plums in the Pacific Northwest, but 

 may be found on all of the orchard fruits, as well as on some other 

 plants. It is a cool-climate insect, occurring chiefly in Oregon and 

 Washington west of the Cascade Mountains, in northern Idaho, and 

 in British Columbia. It is also a pest in the Eastern States, in Can- 

 ada, and in Europe, which was its original home. As indicated by 

 its name, it causes the most injury to the expanding buds, which are 

 devoured by the partly grown, hungry caterpillars that have hiber- 

 nated on the trees. Crops are reduced by this bud-feeding habit, and 

 injury to the terminal shoots causes a bushy growth (fig. 65). Later 

 the insects eat the foliage, and a new generation feeds more or less on the 

 fruit, often attaching a leaf to it and feeding in the shelter thus formed. 







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Figure 64. — Larva of 



pear thrips. X 50. 



