HOW TO KNOW THE IMMATURE INSECTS 



16a. Posterior spiracles approximated, situated within a terminal or 

 subterminal cleft or chamber, usually concealed; body entirely 

 shagreened or wholly or in part longitudinally striated 17 



16b. Posterior spiracles rather widely separated, visible, situated on 

 apical segment, which may be tnmcated, sclerotized, or armed 

 with apical processes; or upon penultimate or antepenultimate 

 segment; body not shagreened or visibly striated 18 



17a. Head not retractile; body flattened, surface finely shagreened, 

 sometimes with lateral abdominal spiracles, without vestigial 

 pseudopods; spiracular fissure transverse, sometimes rather small; 

 pupae enclosed in larval skin. 

 Fig. 547 Family STRATIOMYIDAE 



About 1,200 species of the soldier flies have been 

 described. Some larvae live in water and feed on 

 decaying matter and algae or prey on small aquatic 

 animals. Some possess a long breathing tube on the 

 caudal end. Some live in mud, in fruit, in dung or 

 rotting wood. 



Fig. 547. Geosor- 

 gus viridos Say. 



17b. Head retractile; body cylindrical, surface not shagreened, usually 

 longitudinally striated; abdomen with a girdle of pseudopods on 

 each segment; spiracular fissure vertical; pupae free. 

 Fig. 548 Family TABANIDAE 



Around 2,500 spedies of the horse flies have been 

 described. The larvae are spindle-shaped, living in 

 water or damp places. The flies ore blood-sucking 

 insects and biting on warm-blooded animals includ- 

 ing man. Some of them are disease carriers. 



F-ig. 548. Tabo- 

 mts otrotus Fab. 



195 



