185 



light greyish yellow pubescence which is much longer and more denser 

 than in the female. 



Wings as in the female. Squamae in the alar and thoracal pairs 

 whitish and with the almost white margins, but in the alar pair with 

 a somewhat brownish margin. Halteres pale yellow. 



Legs lighter than in the female and their pubescence longer and 

 much more abundant, on the hind tibiae there are conspicuous fringes 

 composed of black and pale hairs. 



Abdomen whitish yellow or greyish yellow, leaving a rather 

 narrow median greyish black stripe and two similar coloured apical 

 segments ; the median stripe has almost straight sidemargins, this 

 stripe having a row of pale grey middle triangles (but sometimes the 

 triangles are not seen although in fresh materials) ; pubescence pale 

 yellowish grey, dense, and sloping, intermixed with a few blackish 

 hairs at the sides of the median stripe and at the middle part of the 

 last segment (these black hairs sometimes do not appear). Belly 

 greyish yellow, with an irregular narrow median blackish stripe which 

 is sometimes wanting, in some specimens the sides of the belly slightly 

 darkened so that there are greyish brown lateral spots on the last four 

 segments ; pubescence greyish yellow, and with no black hairs inter- 

 mixed but on the last segment there are some erect black bristly hairs 

 which very rarely extend to the preceding segment. 



Length : 11-12.5 mm. 



This species apparently varies considerably in colour of the 

 abdomen both dorsally and ventrally as Japanese specimens are frequently 

 much more ferruginous, but I have seen but little variation in Formosan 

 materials I have examined. It is easily distinguished from ditaeniatus, 

 Macquart, by the absence of the lateral blackish stripes of the abdomen, 

 by the distinctly narrower frontal stripe and by the absence of the 

 black hairs on the thorax (especially on the praealar calli and near 

 them), but is closely allied to A. fufctis and special attention must be 

 given to the absence of the conspicuous golden or orange hue which 



