PHYLUM ARTHROPODA 



347 



oats, and other grains. A host of other plants are also 

 infested. 



The scale insects (Family COCCID.E) are of the greatest im- 

 portance to fruit growers. They are small but numerous. The 

 San Jose scale, Aspidiotus perniciosm (Fig. 277), was imported 

 from its native home in Japan or China to California. It has 

 increased and spread over a large part of this country and has 

 been the cause of 

 considerable legis- 

 lation in an effort 

 to control its dep- 

 redations. The 

 cottony cushion 

 scale, Icerya pur- 

 chasi, which came 

 near ruining the 

 orange groves of 



California, was 

 successfully con- 

 trolled by a lady 

 beetle, Nomus car- 

 dinalis (Fig. 302), 



FIG. 278. Order HEMIPTERA. Seventeen-year 

 locust, Cicada septendecim. A, larva. B, nymph. 

 C, nymph skin after emergence of adult. D, adult. 

 E, section of tree showing how eggs are laid. F, two 

 eggs enlarged. (From Sedgwick's Zoology, after 



introduced from Riiey.) 



Australia. This 



beetle is the natural enemy of the cottony cushion scale, which 



is also a native of Australia. In two or three years these 



beetles checked the inroads of this species of scale insect. 



The cicadas (Family CICADID.E, Fig. 278) are especially inter- 

 esting, since one of them, the seventeen-year cicada or "locust" 

 (Cicada septendecim, Fig. 278), lives underground as a nymph 

 for over sixteen years. The eggs (F) are laid in slits made by 

 the female in living twigs (E). The young (A) hatch in about 

 six weeks, drop to the ground, and burrow r beneath the surface 

 (B). Here they feed on juices from roots and on humus until 

 the summer of the seventeenth year, when they emerge from 



