170 Eev. T. A. MarshalPs monograph of 



4. Blacus tripudians, Hal. 



Ganycliorus tripudians, Hal., Ent. Mag., iii., 41, $ ? . 

 Blacus rufescens, Eutlie, Berl. ent. Zeit., 1861, p. 141, 



? . Nigro-piceous, 2d abdominal segment paler ; legs pale 

 ochreous ; mouth and clypeiis rufescent. Antennae 19-jointed, 

 ferrnginous, scape and apex fusceseent. Thorax as in B. tuber- 

 culatus, but the hind angles of the metathorax are dentiform. 

 Wings hyaline, stigma, radix, and squamulae pale ochreous, most 

 of the nervures decolorous, the rest pale fuscous. Legs slender ; 

 last joint of tarsi (at least of the 4 anterior), and claws, fuscous. 

 Terebra hardly as long as -^ of the abdomen. ^ variable, fuscous, 

 or rufo-castaneous, with the head and posterior segments of the 

 abdomen fusceseent. Palpi pale, fuscous at the base. Antennae a 

 little longer than the body, 22-jointed, fuscous, ferruginous at the 

 base; 2 first joints of the flagellum almost equal in length. Pro- 

 thorax rufo-testaceous, punctato-rugulose ; mesothorax more or 

 less brown or rufous ; pectus often rufescent ; scutellmn not very 

 prominent, obtuse ; mesopleurae punctato-rugulose, with a shining 

 medial space ; metathorax not gibbous, almost straight fi'om the 

 base to the apex, punctate, almost reticulato-rugose, tricarinated, 

 ferruginous ; the 2 lateral carinse end in dentiform processes. 

 Wings broad, greyish hyaline, nervures and stigma brown, radix 

 and squamulae more rufous ; 1st and 2d abscissa of the radius 

 straight, forming a right angle ; 1st abscissa originating behind the 

 middle of the stigma, and longer than the intercubital nervure ; 

 anterior angle of the praediscoidal areolet not truncated by the 

 parastigma. Legs elongate ; hind tibiae and tarsi somewhat in- 

 fuscated, the latter hardly as long as the former. Abdomen not 

 quite so long as the head and thorax, fuscous ; the 1st segment 

 often rufous, impressed at the base, not much dilated posteriorly, 

 and there only striated. Length, 1| ; wings, 3^ lin. 



Not SO common as I'nficornis ; according to Haliday 

 gregarious, frequenting willows {Salix cap>rea) in large 

 numbers ; the males sport together in airy dances on 

 warm, sunny afternoons, like the gnats of the genus 

 Chironomus. I have observed a similar habit in another 

 species — probably ruficornis — but of tripudians I have 

 only taken a few isolated examples. Euthe conjectured 

 that his Blacus mamillanus might be the $ of this 

 species, but this is sufficiently disproved by the descrip- 

 tions. 



