HOW TO KNOW THE IMMATURE INSECTS 



73 



72a. Spiracles biforous. Fig. 261 



The spiracles, openings along the sides of 

 the thorax and abdomen of both immature and 

 adult insects which function in respiration take 

 various forms and numbers in different spe- 

 cies. 





.. ^qpsA/ifiis 



Fig. 261. A bi- 

 forus spiracle. 



72b. Spiracles annular. Fig. 262 77 



Fig. 262. An an- 

 nular spiracle. 



73a. Spiracles at least some borne on tubes; cerci terminating abrupt- 

 ly with 2 or 3 conical processes. (See Fig. 263) 74 



73b. Spiracles not at oil on tubes; cerci terminally pointed and simple, 

 or cerci absent. (See Fig. 265) 75 



74a. Labial palpus 1-segmented. Fig. 

 263. ..Family MONOTOMIDAE 



Fig. 263. Hesperobaenus sp. 



74b. Labial palpus 2-segmented. 

 Fig. 264 



Fig. 264. Rhizophagus grondis Gyli. 



Famly RHIZOPHAGIDAE 



Very little is known regard- 

 ing the habits of the family. 

 The larvae of i?hizophagus are 

 predacious upon xylophagous 

 insects. Less than 20 species 

 are known for North America. 



75 a. Body cylindrical; mandible with 3 apical teeth. 



Fig. 265 Subfamily Languriinae, EROTYLIDAE 



This subfamily does not 

 contain many American spe- 

 cies, but a few of them are 

 rather important as plant 

 pests. The larvae are slim 

 whitish "worms" which bore 

 in the stems of clover and 

 other plants. 



(^m?333^333& 



Fig. 265. Langurki angustata Beauv. 



103 



