172 



FRUIT INSECTS 



United States for a century. By 1850 it was abundant through- 

 out the northern states east of the Mississippi. Spreading 



rather slowly, it has now reached 

 most of the orchard sections in the 

 far West, the South and all through 

 Canada, but it is most injurious 

 throughout its northern range from 

 Nova Scotia southward to the lati- 

 tude of Washington and westward to 

 Montana. In the North the scales 

 often develop on the fruit itself, caus- 

 ing red spots similar to those pro- 

 duced by the San Jose scale (Fig. 

 174). 



The oyster-shell scale is readily 

 distinguished from all other scale-in- 

 sects injuriously infesting deciduous 

 fruit-trees in America by its peculiar 

 shape and color, resembling a minia- 

 ture elongate, curved oyster shell of 

 a dark brownish bark-like color. The 

 convex scale covering the body of the 

 female is about I of an inch long and 

 consists of two minute cast skins at 

 the smaller end and a large scaly por- 

 tion gradually secreted from the body 

 of the insect underneath. The male 

 scale is much smaller and rarely seen 

 on fruit-trees ; they are often abun- 

 dant on ash. Old lifeless scales often 

 adhere to the bark for several years. 

 If at any time from September to May the female scales 

 formed during the preceding summer be overturned, they will be 

 found to cover from 30 to 100 minute, white eggs and the much 



Fig. 170. — Apple branch 

 badly infested with the oyster- 

 shell scale. 



