Dec.,i9i6 Bulletin of the Brooklyn Entomological Society 109 



normal ; thorax with 4 pairs of post-sutural dorso-central bristles ; 

 squamae unequal in size ; sternopleura with 2 bristles (1:1) ; sixth 

 vein of wing incomplete ; fore femora with i or 2 stout f orwardly 

 directed thorns near apices on ventral surface. 



Key to Imagines, Males. 



1. Hind femora with either a single stout downwardly directed spine or 



a closely approximated pair of such spines on ventral surface 2 



Hind femora without such spine or spines 6 



2. Hind femoral spine near base 3 



Hind femoral spine or spines near middle. 4 



3. Hind tibia with a conspicuous tuft of long hairs about one third from 



apex on ventral surface occulta Meigen. 



Hind tibia without such tuft of hairs ; mid metatarsus with about 4 

 long hairs on each side acuta Stein. 



4. Eyes bare ; fore femora with a few long bristles on basal half, the 



apices of which are slightly knobbed; hind femora with i spine. 



armipes Fallen. 

 Eyes distinctly pubescent; fore femora with the bristles acute apically. .5 



5. Mid femora with a number of long curled apical bristles; hind femora 



with I ventral spine ciliata Fabricius. 



Mid femora without long curled apical bristles ; hind femora with a 

 closely approximated pair of ventral spines cressoni Malloch. 



6. Wing with a conspicuous patch of upright microscopic hairs at apex 



of discal cell militaris Meigen. 



Wing without such patch of hairs 7 



7. Mid metatarsus with abnormal armature, either furnished on the entire 



ventral surface with stiff spinules that are at right angles to the 



surface of the joint, or with a number of long hairs 8 



Mid metatarsus with the normal armature, consisting of more or less 

 closely placed regular spinules which are directed slightly toward the 

 apex of the joint 9 



8. Mid metatarsus armed on its entire ventral surface with short stiff 



spinules which give it the appearance of being slightly thickened. 



irritans Fallen. 



Mid metatarsus with a slight depression near apex on ventral surface 



the posterior margin of which is fringed with a comb of from 4 to 6 



short, stiff, downwardly directed bristles metatarsata Stein. 



9. Hind tibia about one third from apex on the inner surface armed with 



a stout downwardly and apically directed spine which ends in 3 hairs. 



unispinosa Stein. 



Hind tibia without such spines 10 



.10. Mid tibia with 1-2 bristles on anterior surface. . . .bispinosa Zetterstedt. 

 Mid tibia without bristles on anterior surface 11 



