DESTRUCTIVE INSECTS. 



165 



sickly trees ; they inhabit both the trunk and limbs of a tree, 

 and, besides apple, pear, peach, and apricot trees, they also 

 attack a variety of forest trees. They are chiefly injurious to 

 young trees. 



The eggs are laid in crevices of the bark, and the larvae (Fig. 

 217) get their growth in one year, living mostly just beneath 

 the bark. The pupal 

 stage (Fig. 220), lasting 

 about three weeks, is 

 passed in a cell made in 

 'the solid wood. The 

 beetles emerge in May 

 and June through ellip- 

 tical-shaped holes. 



Trees badly infested 

 with this borer should 

 be burned at once. The 

 remedial measures ad- 

 vised for the round- 

 leaded borer may also 

 je applied against the 

 flat-headed species. 



SCALE-INSECTS are minute sucking insects, which now rank 

 among the most destructive fruit pests in many parts of the 

 country. We can here discuss only a few of the more com- 

 mon ones. 



The Oyster-shell Bark-louse {Mytilaspis pomoruni). This scale 

 (Fig. 222) is very common on apple-trees all over the country; 

 it also attacks many forest trees, and it is found all over the 

 world. It is shaped somewhat like an oyster-shell, and is 

 nearly the color of the apple bark. In northern latitudes there 

 is but a single annual generation of the insect ; in the South 

 there are two. It usually confines its attacks to the bark of 

 younger branches, but sometimes occurs on the fruit in the 

 North. 



If the scale be tipped over during the winter, it will present 

 the appearance seen at a in Fig. 221 ; that is, the shrivelled 

 body of the female is tucked away at one end, and from 30 to 

 90 white eggs occupy the rest of the scale. The winter is 

 passed in the egg, and the young lice usually hatch in the 



FIG. 217. FIG. 218. FIG. 219. FIG. am. 



The Flat-headed Apple-tree Borer. 

 FIG. 217. Larva or grub. FIG. 218. Beetle. 

 FIG. 220. Pupa. All twice natural size. (U.S. 

 Div. of Entomology.) 



