UEMIPTEEA. 



349 



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

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

 labium or second maxillES. 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. 337) lives over sixteen years as a larva. 



Fig. 326 — Coreus 

 tristis^ squash-bug. 



Fig. 337.— Seventeen-year Locust, u. b, pupa; d, incisions for eggs— After Eiley. 



finishing its transformations on the seventeenth; there is 

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

 species. 



The froth insect (Pit/elus lineatus) abounds on grass in 

 early summer. The cochineal insect {Coccus cacti) belongs 

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

 a dyestuff, and abounds in Central America. 



