1. Wing usually broken off, leaving a short stub; if wing complete, crossvein dm-cu absent. Female with abdominal sternites 1-5 absent; membrane with numerous setiferous sclerotized spots.
- Wing complete; posterior crossvein dm-cu present. Female with all abdominal sternites present; membrane usually sparsely bristled.
2. Frons with 1 pair of frontal setae medioclinate and 3 pairs of orbital setae reclinate; antennae separated across midline by broad, flat, median facial carina. Scutellum with 2-3 pairs of setae, anepisternum bare.
- Frons with 2 pairs of frontal setae medioclinate and 2 pairs of orbital setae lateroclinate, antennae separated only by narrow carina. Scutellum with 2 pairs of setae, anepisternum with hairs and one or more setae.
3. Wing with cell dm long; crossveins r-m and dm-cu widely separated. C extending to M1; M1 distinct. Cell cup closed; A1 strong.
- Wing with cell dm short; crossveins r-m and dm-cu narrowly separated. C ending at R4+5. Cell cup open; A1 weak, streak-like.
4. Face with lower margin and vibrissal angle projected well in front of eye; eye oval, long axis inclined anteroventrally. R4+5 and M1 converging near apex, costal sector between R2+3 and R4+5 longer than sector between R4+5 and M1.
- Face with lower margin and vibrissal angle not projected in front of eye; eye roundish. R4+5 not converging, costal sector between R2+3 and R4+5 shorter than sector between R4+5 and M1.