386 



organ as in Figure 1 1, Plate XXIV; abdominal segments covered with 

 short broad spinules, which become stronger posteriorly on each seg- 

 ment; apical abdominal appendages obtusely rounded, their margins 

 externally fringed with short, broad, scalelike hairs, two long lance- 

 olate hairs near the base of each. 



Imago; Male and Female. — Yellowish brown, appearing almost 

 black sometimes. Head blackish brown, antennae, antennal plumes, and 

 palpi grayish black. Mesonotum with the vittae very broad, so that 

 the whole disc appears blackish, the surface light gray pollinose; 

 pleurae with a large yellowish membranous area at center above, the 

 remainder brown, subshining ; scutellum obscurely yellow ; postnotum 

 brown. Abdomen almost entirely obscured with blackish brown, only 

 the posterior margins of segments yellowish. Legs varying from yel- 

 low to brown, with apices of tibiae, metatarsi, and secondjoints, and re- 

 maining tarsal joints brown, or almost entirely fuscous, with the 

 apices black. Wings as stated in key. Female with the light and dark 

 portions more sharply defined than in the male. 



Male. — Basal joint of antenna large, globular; last joint cleft, 

 about twice as long as remaining joints of flagellum combined, plumes 

 dense and long. Mesonotum with sparse short pale hairs on spaces 

 between vittae, and more noticeable hairs of same color in front of 

 wing-base. Hairs on abdomen dark, rather numerous but not very 

 long; hypopygium as in Figure 5, Plate XXVHI. Legs long and 

 slender, fore metatarsus two thirds as long as fore tibia and as long 

 as the next three joints together; the surface hairs short but distinct; 

 fourth tarsal joint on all legs longer than fifth. Petiole of cubitus 

 subequal in length to the posterior branch of cubitus; costal vein 

 reaching well beyond end of radius and round curved apex of wing. 



Female. — Antenna very much shorter than thorax, basal joint 

 much smaller than in male, last joint slightly swollen, surface hairs 

 short. Hairs in front of wing-base more numerous, stronger, and 

 darker than in male. Abdomen moderately stout, surface hairs pale 

 and weak. Legs stouter than in male ; basal joint of fore tarsus two 

 thirds as long as fore tarsi ; surface hairs very short. In other respects 

 as male. 



Length, 3.5-4 mm. 



Illinois localities: Algonquin, Dubois, St. Joseph, Urbana, Carmi, 

 Havana. Months of occurrence, April, May, and October. Speci- 

 mens taken by Mr. Hart at South Haven, Mich., bear the date July 

 14, 1914. The species occurs commonly at light. 



Dates affixed to specimens in the collection of the U. S. Bureau of 

 Biological Survey range from April to July 30, which seems to indi- 



