134 



ELEMENTARY ENTOMOLOGY 



that they are rarely seen unless reared from the scales. Among the 

 most common of the armored scales are the oyster-shell bark-louse (so 

 called on account of the resemblance of the brown scale to an oyster 



FIG. 188. Peach twigs infested with San Jose scale. (Much enlarged) 



At left, large mature female and small young scales are clustered in a groove of the 

 twig. At right is shown a large female scale with the scale proper raised, showing the 



insect beneath. (After Britton) 



shell), which is common on apple and several shade trees ; the San 

 Jose scale, possibly the most serious pest of fruit trees ; the rose scale, 

 common on roses, raspberries, and blackberry canes ; and the various 

 flat scales found on palms and other greenhouse and house plants. 



