66 



SCHOOL ENTOMOLOGY 



of the worst pests of the fruit-growing industry are to 

 be found in this family. In the armored group we have 



the San Jose Scale, the Oyster- 

 shell Scale, the Rose Scale and a 

 host of others. (See page 287, Part 

 II.) Among the unarmored forms 

 are the Cottony-cushion Scale, the 

 Terrapin Scale or Peach Lecanium 

 and others. There is scarcely a 

 woody plant that is not subject 

 to the attacks of one or more 

 species of scale insects. Fortu- 

 nately, fairly effective means 

 have been devised for the con- 

 trol of these insects. 



Plant-lice are small in size, 

 oval or egg-shaped, winged or 



wingless. They live in colonies and are often found in 

 enormous numbers on plants. They often kill the leaves 



FIG. 42. Cottony Maple- 

 scale on Leaves of Soft 

 Maple. 



FIG. 43. A Winged Plant-louse (Aphididce) . Greatly enlarged. 



and may do great damage. Some species live on the 

 roots of plants for at least a part of their life-cycle. They 



