HOW TO KNOW THE IMMATURE INSECTS 



20b. Apical abdominal segment not as above; paired abdominal 

 pseudopods usually absent; other appendages always absent.. .21 



21a. Apical abdominal segment ending in 4 short pointed processes or 

 2 fleshy lips; internal portion of head with a large, arched, sclero- 

 tized upper plate, the longitudinal rods and other cephalic parts 

 on a horizontal plane Family RHAGIONIDAE 



21b. Apical abdominal segment not as above, or the internal portion 

 of head without arched upper plate, and the longitudinal cephalic 

 rods and other cephalic parts meet at right angles 22 



22a. Apical abdominal segment without projecting processes, spiracles 

 very small; parasites of spiders. 

 Fig. 551 Fanuly CYRTIDAE 



Around 200 species of the humpbacked flies are 

 known. The first instar larvae are caraboid in form 

 with distinct segments and two long anal bristles. 

 They feed on spider eggs and spiders. They change 

 to eruciform larva which is not so active as the first 

 instar. 



Fig. 551. Ptero- 

 dontia flavipes 



Grog. ]st instar. 



22b. Apical abdominal segment frequently with projecting processes, 

 spiracles large; species live in water, mud, earth, or decaying 

 vegetable matter. 

 Fig. 552 FamUy EMPIDAE and family DOLICHOPIDAE 



Empidae: About 1,600 species of 

 the dance flies are known. The 

 larvae live in water or in decay- 

 ing vegetation, dead wood, soil 

 and mosses where they feed upon 

 small animals. 



Dolichopidae: About 2,000 spe- 

 cies of the long-legged flies have 

 been described. The larvae are 

 mostly aquatic and feed on other 

 insects. Some are found in plant 

 stems or under tree bark. 



Fig. 552. Dolichopus sp. 



197 



