ORCHARD INSECTS OF THE PACIFIC NORTHWEST 



13 



Often there are nearly 100 eggs beneath a single scale. These eggs 

 hatch shortly after the apple trees bloom, and the minute, whitish 

 young crawl out and settle in a few hours on some 

 living part of the plant. They develop slowly, in- 

 creasing the size of the scale coverings as they grow, 

 until, in the case of the females, the scales are 

 about one-eighth of an inch long when completed, 

 dark brownish gray, and shaped somewhat like 

 oyster shells. The male scales are smaller and 

 oval, and the mature males emerge from the scales 

 with fully developed wings. The female insects, on 

 the other hand, remain beneath the scale coverings 

 throughout their lives, depositing eggs under the FlG ^" RE l }- — Invert- 

 shells in the fall before they die, There is apparently egra^f tL^ter? 

 only 1 generation a year in the Pacific Northwest. shell scale, x 9. 



CONTROL 



The dormant-season application of lime-sulfur solution is not so 

 effective against the oystershell scale as against the San Jose scale. 



However, the regular 

 annual use of the solu- 

 tion keeps the insects 

 fairly well in check. Oil 

 emulsions, at the dilu- 

 t i o n s recommended 

 for dormant spraying 

 (p. 73), are more 

 effective and should 

 be used for severe 

 infestations. Summer- 

 oil emulsion, contain- 

 ing 2 percent of oil, 

 applied just after 

 the eggs have hatched 

 is effective in killing 

 the young scales, 

 but this cannot be 

 used safely if lime- 

 sulfur solution has 

 been applied within 2 

 months. 



Cottony Maple 



Scale 



The cottony maple 

 scale (Pulvinaria vitis 

 (L.)) sometimes be- 

 comes quite common 

 on Winter Nelis and 

 Anjou pear trees, but 

 does not seem to thrive 

 Figure 12.— Cottony maple scale on maple twig. X 2. on the Bartlett va- 



