370 



ZOOLOGY. 



Order 4. Hemiptera. Insects of this group are called 

 bugs. They all (except the bird-lice and Thrips} have 

 sucking mouth-parts, the mandi- 

 bles and first maxillae are bristle- 

 like, and ensheathed by the labium 

 or second maxillae. There are no 

 palpi except in Thrips and the 

 bird-lice. The metamorphoses are 

 incomplete, the larva being like the 

 adult, except that the wings are ab- 

 sent. Many bugs secrete a disa- 

 greeable fluid from glands seated in 

 the metathorax. The lice are low, 

 wingless parasitic Hemiptera. The 

 squash-bug (Fig. 334, Coreus tristis) and chinch-bug (Blis 

 sus leucopteriis Uhler) are types of the order. 



Fig. 331. Cor- 

 eus tristis, squash- 

 bug. 



Fig. 335. 

 Thrips. 



Fig. 336. Seventeen-year Locust, a, b, pupa ; d, incisions for eggs. After Riley. 



An aberrant form is Thrips (Fig. 335, Thrips cerealium), 



with long, slender white wings and free biting mouth-parts. 



While most insects live but a year or two, or three at the 



