HEMIPTERA. 



349 



bugs. They all have sucking mouth-parts, the mandibles 

 and first maxillae being bristle-like, and ensheathed by the 

 labium or second maxillae. Their metamor- 

 phoses are incomplete, the larva being like 

 the adult, except that the wings are absent 

 Many bugs secrete a disagreeable fluid from 

 glands seated in the metathorax. The lice 

 are low, wingless parasitic Hemiptera. The 

 squash-bug (Fig. 326, Coreus tristis) and 

 chinch-bug (Blissus leucopterus Uhler) are 

 types of the order.* 



While most insects live but a year or two, 

 or three at the most, the seventeen-year locust (Cicada sep~ 

 temdecim Linn., Fig. 327) lives over sixteen years as a larva, 



Fig. 326. Coreus 

 tristis, squash-bug. 



Fig. 327. Seventeen-year Locust, a, b, pupa; d, incisions for eggs. After Riley. 



finishing its transformations on the seventeenth; there is 

 also, according to Riley, a thirteen-year variety of this 

 species. 



The froth insect (Ptyelus lineatus) abounds on grass in 



early summer. The cochineal insect (Coccus cacti) belongs 



to the Coccidce, or bark-lice; the dried female is used as 



a dyestuff, and abounds in Central America. 



* See works by Amyot et Serville, Say, Uhler, Riley, Comstock, etc. 



