Soldier Flies 



the aquatic and subaquatic species have been studied by Hart in 

 his interesting investigations of the entomology of the Illinois 

 River. He finds that Stratiomyia seems to prefer the shore and 

 Odontomyia the water. The larvae are large, opaque, greenish 

 brown or gray, obscurely striped, and when in the water are 

 found upon vegetation near the surface or floating about, and 

 when on shore crawling about over the mud and in the green 

 scum so often found on wet banks. The pupa is formed within 

 the larval skin, but occupies only the head-end, the remainder of 

 the skin being filled with air which causes the pupa to float at 

 the surface of the water. When the fly is ready to emerge the 

 larval skin splits transversally on the fourth segment and the fly 

 emerges while the case is floating on the water or resting on the 

 shore. Hibernating larvae and pupae are found in large numbers 

 on loose drift on the shore, emerging, in Illinois, in early sum- 

 mer. Hart thinks there are two generations annually. He 

 watched the egg-laying of Odontomyia cincta and O. vertebrata. 

 They chose dead branches in the water, reeds and the stems of 

 various plants. The female generally stood with the head down- 

 wards, and the long and narrow eggs were placed in an irregular 

 oval mass to the number of several hundred closely laid with 

 their tapering ends inserted between the ends of those next to 

 them. 



The larvae and pupae are frequently parasitized by certain 

 Chalcis flies (Smicra rufofemorala and 5. microgaster.) Hart 

 made an extremely interesting observation when he found the 

 latter parasite mutilating with its jaws an egg mass of one of these 

 flies. I know of no observation parallel to this. The eggs above 

 referred to were laid June ist, and hatched in ten days. The 

 stomachs of the larvae were found to contain mud for the most 

 part, with a little vegetable matter, and here and there a diatom. 



About one thousand species of Stratiomyiidae have been 

 described, of which about two hundred are found in North 

 America. 



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