CICADAS, PLANT LICE, AND SCALE INSECTS 35 



less, though winged females (Fig. 18) are produced which 

 start colonies in other places, sometimes on a different food 

 plant. Both winged and wingless females are able to pro- 

 duce young parthenogenetically within from ten to twenty 

 days. This kind of reproduction goes on till the approach 

 of cold weather or the failure of the food supply, when 

 males are produced. After pairing, the female lays eggs 

 which last through the winter and hatch into females in the 

 spring. These start 

 new colonies as al- 

 ready described. 



Scale Insects. In- 

 cluded among the 

 scale insects are 

 some of the great- 

 est enemies to the 

 horticulturist. Al- 

 most all kinds of 

 trees and shrubs are 

 subject to their at- 

 tack. Most of these 

 scale insects become so changed in form (Figs. 21, 22) that 

 they would scarcely be recognized as insects. Ordinarily 

 they become immovably attached to the surface of the 

 plant, from which they draw their nourishment by means 

 of a beak, or sucking tube, thrust permanently into the 

 bark. The back of the insect is covered by a crust-like 

 scale which completely conceals the body. Fixed here 

 permanently, the female produces her eggs or her young, 

 which are at first sheltered by the parent scale. Frequently 

 the male (Fig. 22, d) is distinguishable from the female by 

 its smaller size and because it develops in an entirely differ- 

 ent manner. In most instances the young wingless females 

 after hatching from the egg soon leave the parent scale. 



Fig. 20. An adult male scale insect. 

 (Much enlarged) 



From the Illinois State Natural History Survey 



