Entomology of tice lUinois River, 239 



T. stygius Say. [Fig. 47, 48.] 



The present species was the most abundant tabanid 

 larva in the vicinity of Havana last spring (1895). It first 

 -appeared in our collections Sept. 14, when a number were 

 noted swimming amidst vegetation n^ar the margin at 

 Station B. In the spring they were found at nearly all 

 of the stations, but more particularly in connection with 

 tipulid, muscid, and Eristaiis larvae in matted accumula- 

 tions of dead stems and leaves over mud. They were 

 especially abundant March 30 in Flag Lake, where large 

 plump larvae appeared at eNery turn. It was a surprise 

 to find a few of them upon the bottom in open shallow wa- 

 ter, far from shore, in the middle of Quiver Lake at Sta- 

 tion A. Young larvae have been common in connection 

 with larvae of Bittacomorpha and Limnophila at Station 

 I since March 17. At Stations B and G, they have been 

 common in moist drifts of fine rubbish washed up by 

 waves. Pupae were formed in the breeding-cages May 10 

 and 23. One emeiged May 27, and another tried to 

 emerge June 2, but died and was removed from its case. 



The larvae resemble those of the lineola group in their 

 striation and coloration, but differ in their short lateral 

 prothoracic areas and larger size. They are like atratvs 

 jn size, but may be readily separated from it by their 

 coarser lateral striation, straw-yellow tint, slender lateral 

 vittae, and usually projecting terminal stigmatal spine- 



Larva [Fig. 47, 48].— Length 45-55 mm., diameter 

 6-7 mm. Blight straw-yellow, varying in some young 

 larvae to nearlj' clear white; marked with light fuscous 

 •brown mieioscopic pubescence, usually paler at each 

 «tage than atratus. 



Lateral prothoracic striated areas not more than half 

 a;8 long as the dorsal, striation not finer than that of 

 the middle and lower lateral areas of the mesothorax, 

 striated portion shining; a small smooth spot adjoining 

 the impressed line below; remaining upper lateral thoracic 

 areas a little less closely striated, but not strongly 

 different from that of the prothorax; abdominal lateral 



