HEMIPTERA. 



mandibles and maxilla have been converted into long hair-like organs, the 

 latter uniting to form a single lancet. All three are enclosed in the enlarged 

 labium. This generally consists of a number of telescopic joints (not exceed- 

 ing five), which close up as the lancets are thrust into the plant. 



Wa n c/i bles 



Figure 227. Ovipositor saws. 



Wax i//ae 



Fig-ure 225. Mouthparts of vine hopper. 



Economically the Hemiptera are of great importance, especially in an 

 arid climate, because they withdraw the moisture from the plant when it 

 can least afford to lose it. Plant lice and scale Insects are the most im- 

 portant families as plant pests. 



A number of groups have become predaceous on other insects. Among 

 these certain Reduviids commonly known as kissing bugs can produce a 

 painful bite. The bed bug is a case of one of these insects becoming a 

 human parasite and the lice are even more strictly parasitic. 



