HOW TO KNOW THE IMMATURE INSECTS 



5b. Head incomplete posteriorly, either with 3 deep wedge-shaped 

 slits (2 on dorsum and 1 on venter), or ventral suriace very poorly 

 sclerotized and the dorsal one posteriorly in the form of 4 slender 

 heavily sclerotized rods, with a weakly sclerotized divided plate on 

 anterior hali of the dorsum. Fig. 537. Family TIPULIDAE 



There are about 6,000 spe* 

 cies of crane flies describ- 

 ed. The larvae are common- 

 ly called leather jackets. 

 They are aquatic, semiaqua- 

 tic, and some are terrestrial. 

 They feed upon decaying 

 wood, decaying vegetations, 

 fungi, moss, and roots of 

 many plant:*. A few are leaf 

 miners. 



Fig. 537. Tipula eiuta Loew. 



Sa. Thoracic segments fused ond dilated, forming a complex mass. 

 Fig. 538 Family CUUCIDAE 



Around 2,000 species of mos- 

 quitoes hove been described. 

 The larvae are aquatic and 

 live in various types of fresh 

 water and even in brackish 

 and salt water. The cxilicine 

 larvae rest under water sur- 

 face with the body obliquely 

 placed while the anophelines 

 ore horizontally placed. Many 

 species of female mosquitoes 

 are the vectors of human di- 

 seases. Anopheles are respon- 

 sible for malaria and Aedes 

 cany the causative agent of 

 yellow fever and dengue. 



6b. Thoracic segments distinct. 7 



7a. Larvae peripneustic, or with at least rudimentary abdominal spir- 

 acles 8 



7b. Larvae amphipneustic or metopneustic 11 



191 



