322 THE CANADIAN ENTOMOLOGIST. 



a _ 



OVIPOSITION OF BIBIO FEMORATA, WIED., AND 

 OVIPOSITING FEMALES. 



BY ALECANDRE ARSENE GIRAULT, WASHINGTON, D. C. 



On the morning of March 24th, 1904, at 9 o'clock, in the town of 

 Paris, Texas, many dark-coloured flies were noticed crawling over the 

 trunks and lower limbs of two adjacent box-elder trees {Negwido species). 

 They proved to be the above species.* 



They were found in various positions. Some resting in crevices of 

 the bark, or crawling about on the trunk, while others were resting in 

 clumps of grass and weeds along the gutter and fences near the two trees. 

 The latter were situated on the edge of a sandy sidewalk, about six feet 

 apart, and about eighteen inches above the gutter, which was unstoned 

 and abounding in patches of grass and weeds. 



Both sexes were present, the females greatly predominating ; a few 

 pairs were in copula. They suddenly disappeared about forty-eight hours 

 afterwards, but again on March 29th others appeared in numbers on the 

 same trees. As formerly, these in turn remained several days, but gradu- 

 ally disappeared, many apparently killed by heavy rains which occurred 

 at that time. 



I. Adults and adult habits. 



The females are dark reddish, with garnet thighs and black wings ; 

 they varied in length, in six specimens measured from 9 to 11.5 mm. 

 Their abdomens are thick, cylindric and heavy, especially following 

 copulation. The males are smaller, from 8 to 10 mm., with slenderer, 

 tapering abdomens, more hairy bodies, and very much larger eyes. Their 

 wings are transparent. 



Copulation takes places about twelve hours after emergence from the 

 soil. It was observed on the 24th and 25th of March. As the larvae are 

 gregarious, the eggs being deposited in a single mass, the descendants from 

 a single female doubtless emerge simultaneously from the soil, as in this 

 case, and crawl up any convenient object near-by. Here the sexes inter- 

 mingle freely and mate. 



The flight of the gravid female is heavy and slow, and apparently 

 seldom resorted to. Crawling seems to be the natural mode of locomo- 

 tion, although the adults are able to fly considerable distances. They 



*Determined by Mr. Charles T. Brues. 



September, 1905. 



