THE BIONOMICS OF AUSTRALIAN TABANIDAE. 



59 



is on the dorso-lateral margins, and midway between the base of the second pair of 

 projecting spurs and the posterior margin of the 7th abdominal segment, a well- 

 developed group of from five to seven very irregular bristles arising from a raised base. 

 In some specimens these bristles are reduced to three or four in number, and in one 

 they are absent on one side and on the other represented by two rudimentary bristles. 

 In the male the anal opening is bordered anteriorly by a semicircle of stout and very 

 irregular bristles, some of which are expanded and branched at the base, others short 

 and almost rudimentary, or all may be long and moderately slender. Posteriorly the 

 opening is bordered by a raised and deeply furrowed prominence. In the female 

 (fig. 18) the fringe of bristles in front of the anal opening is broadly interrupted in the 

 middle, each group being composed of from five to eight bristles of variable size. 



The Adult. In hfe the eyes of the male are dull yehow-green and coarsely facetted 

 above the point of junction of the eyes on the front ; below this and on the sides and 

 posterior margin the facets are smaller and bronze-coloured, with gold and green 

 iridescence. In the females the eyes are uniformly dull yellow-green. 



Fig. \S. T. vignlcnsis, ventral surface of last segment of female pupa. 



Seasonal Occurrence. Apart from the three flies reared in the laboratory only two 

 individuals (females) have come under my notice during the period 25th February 

 1919 to 30th September 1920. Both were captured whilst attacking horses during the 

 last week in February of this year. In the Northern Territory (1912-1917) this 

 species was regarded as the most numerous and most troublesome to stock during the 

 months of December-February. The egg-masses found there were small and 

 compact and were generally placed on the underside of pandanus leaves overhanging 

 water. 



Silvius notatus, Ric. 



5. notatus, Ricardo, Ann, Mag. Nat. Hist. (8) xvi, 1915, p. 264. 

 S. psarophanes, Taylor, Proc. Linn. Soc. N.S.W. xhi, 1917, p. 520. 

 S.fuliginosns, Taylor, op. cit. xl, 1915, p. 810. 



