Chrysotoxum

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Chrysotoxum is a genus of large hoverflies that mimic wasps. Adults have very long antennae, an oval body with yellow stripes, and yellow markings on the sides of the thorax. They are found mainly in the Holarctic region (North America, Europe, and northern Asia). The species look very similar to one another, so they’re hard to tell apart. The larvae prey on root aphids that live in ant nests. Chrysotoxum is the only genus in the tribe Chrysotoxini.

Common features
- The head is a little wider than the thorax.
- The eyes are hairy and touch in males but are separated in females.
- A prominent, angular frons; long, erect antennae with the first two segments roughly equal, and the third (flagellum) much longer.
- The face is slightly concave.
- The abdomen is very convex on top and has a deep margin.
- Wing venation includes a median vein before the middle of the discal cell, and the R4+5 vein dips into cell r4+5.

Taxonomy notes
- There are few reliable features to distinguish species.
- Characters often used (leg color, overall size, and how abdominal stripes/spots connect) vary a lot within a species.
- In many Chrysotoxum species, differences in male genitalia do not help with identification.