354 



yond base of second ; costal setulse about equal to diameter of costal 

 vein; veins 4 and 5 very distinctly divergent at apices; greatest dis- 

 tance from vein 7 to margin of wing equal to greatest distance from 

 vein 4 to margin. 



Female. — Reddish yellow. Eyes black ; f rons with a slight pearl- 

 aceous iridescence, antennae and palpi concolorous with head. Thorax 

 similar in color to upper part of head. Abdomen dorsally darker than 

 thorax, becoming dark brown or fuscous at apex, the iridescence very 

 distinct, especially at base ; ventral surface opaque black except at ex- 

 treme base. Legs reddish yellow, the short setulose hairs on tibise and 

 tarsi giving them a slight fuscous color. 



Ocelli indistinguishable; width of frons less than twice its length 

 at center, anterior outline convex; eyes very small, each about one 

 tenth the width of frons seen from aboA^e ; surface of frons with sparse 

 microscopic hairs; antennae smaller than in the male, shape similar; 

 arista with very slight pale pubescence; palpi almost as large as third 

 antennal joint, with apical setulge as in male; cheek with 2 distinct 

 groups of setulae, one extending from middle to eye margin and con- 

 sisting of 3 strong setulse and several weak hairs, the other located on 

 mouth margin and consisting of 3 strong setulae. Mesothorax 

 slightly over 1.5 as broad as long; disc with very weak setulae, lateral 

 margins more strongly setulose ; posterior outline slightly emarginate ; 

 appearance of dorsum as in Figure 17, Plate LXXXIV. Abdomen 

 with 6 distinct segments, undifferentiated from thorax except by the 

 transverse suture, its dorsal level and lateral margins similar to those 

 of thorax; fourth segment slightly elongated, its posterior margin 

 broadly and slightly concave ; surfaces of all segments with weak set- 

 ulae. Legs rather short and stout ; fore tarsi short and distinctly dilat- 

 ed, basal joint as long as next two together and less than half as long 

 as tibia; armature of legs as in male except that the mid tibiae have a 

 long apical spur. Wings and halteres absent. 



Length: male, 1.7 mm.; female, i mm. 



Type locality, White Heath, 111.. August 22, 191 5 — a pair taken 

 in copula on a sandy bank along the Illinois Central Railroad between 

 White Heath and the Sangamon River by the writer. 



The male of this species bears a strong resemblance to coloradensis 

 Brues*, differing noticeablv however in wing venation, which in flavo- 

 femorata is similar to that of enrynota, which Brues described at the 

 same time. In separating the males of the three North American 

 species the following key will be found useful. 



*Psyehe, Vol. 21, 1914, p. 79. 



