444 



not confined to the areas between vittse but covers the latter, giving 

 them an opaque appearance ; vittse deep black, the median vitta dis- 

 tinctly divided ; pleurse green, lower two-thirds of sternopleura and a 

 large patch below wing-base blackened ; scutellum yellow ; postnotum 

 black, vellowish at base. Abdomen black, segments w^ith very narrow 

 pale posterior margins ; basal half with the segments narrowly gray 

 pruinescent on posterior margins, apical half almost entirely covered 

 with pruinescence, only the bases narrowly bare. Legs yellow, coxae 

 and trochanters more or less suffused with brown ; apices of femora, 

 bases and apices of tibiae, and tarsi from near base of first joint suf- 

 fused with brown. Wings clear, veins of anterior half brown, of the 

 posterior half vitreous, cross vein infuscated. Halteres yellow. An- 

 tennal plumes deep yellow, body hairs wdiitish. 



Frontal tubercles distinct ; penultimate joint of palpi slightly 

 shorter than antepenultimate and ultimate joints. Pronotum of mod- 

 erate width, slightly concave in outline when viewed from the side, the 

 upper extremity slightly produced, median dorsal excision shallow and 

 narrow ; hairs on mesonotum short and weak, mostly confined to areas 

 between the vittse. Abdomen with slight indications of a dorso- 

 median raised line on each segment; hypopygium as in Figure i, Plate 

 XXXIII. Fore tarsus bare, basal joint less than one fifth longer than 

 tibia (5 : 4.25) ; mid and hind legs with soft hairs, the longest of which 

 are barely longer than diameter of the joints upon which they are situ- 

 ated. Third vein ends beyond beginning of curve at apex of wing, the 

 first at nearly two thirds the distance from cross vein to apex of third ; 

 cubitus forking distinctly beyond cross vein. 



Pemalc. — Similar to male in coloration except that the antennae are 

 yellow with the exception of the apical joint, and the mid and hind 

 tibiae have the bases either without any darkening or but slightly 

 browned. 



Length, 9-1 1 mm. 



Illinois localitv, Havana, April-May, 1914 (C. A. Hart and J. R. 

 Malloch). 



This species occurred in immense numbers on houses, fence posts, 

 and tree trunks along and near the banks of the Illinois River at and 

 near Havana on April 29, 1914, in company with fcrrugiucovittaUts. 

 Crassicaudatiis resembles tcnians in size and color, differing in having 

 long hairs on the fore tarsi and in the structure of the hypopygium. 



The larva of tenfans has been described by Weyenbergh,* from 

 whose description it is evident that it is very similar to larvae belonging 



*Ti,idschr. v. Entom., Vol. 17, 1874, p. 149. 



