adorned bee fly

Adorned bee fly is a medium-sized, parasitic fly. It occurs in the United States in the Northeast, the Upper Midwest, and the Great Plains. It occurs across southern Canada, but it is uncommon outside of Nova Scotia, Quebec, and Ontario.

Adults are active from late June to August. They are found in meadows and at forest edges. They are usually seen on flowers or resting on the ground in open areas. The larvae are parasites of wasp larvae.

Adults are stout-bodied, hairy, and ⅜″ to ⅝″ (10 to 15 mm) in length.

The face is cone shaped. The antennae are shorter than the head, and they have four segments, a scape at the base, a connecting pedicel, and two flagellomeres. The first flagellomere is cone shaped. The second flagellomere is long and has a slender appendage (style) at the tip. It does not have a tuft of hairs at the tip. The rear margin of each compound eye is strongly indented. The tube-like mouthpart (proboscis) is short, extending less than the length of the antennae.

The abdomen is black. The upper side is covered with a variable amount of black hairs. The sides are densely covered with soft, woolly, black hairs. White hairs are restricted to a few small spots. There are no white or orange bands.

The wings are as long as the abdomen. They are mostly dark brown with clear spots. The leading edge (costal margin) is dark brown from the base to beyond the end of the subcosta (Sc) vein. The dilated portion of the marginal cell is entirely brown. The basal half of the anal cell is brown. There are three broad, dark brown, transverse bands: one at the base (basal), one before the middle (median), and one before the tip (subapical). The basal band is poorly defined. The wing tip is clear. The clear area is restricted to cell r4 and the rear (distal) part of cell r₂₊₃. Vein M₁ ends behind the wing tip. Vein R₂₊₃ arises from vein R₄₊₅ at a right angle near crossvein r-m. It has a single curve near the end, and it is connected by a crossvein to the R₄ vein. The discal cell is present.

Total length: ⅜″ to ⅝″ (10 to 15 mm)

Meadows and at forest edges

Late June to August

The wings are held stretched out when at rest.

Adults do not bite.

Wasp larvae

Sources

24, 29, 30, 82, 83.

Infraorder
Orthorrhapha was historically one of two infraorders of Brachycera, a suborder of Diptera. However, Orthorrhapha was paraphyletic, meaning that it did not contain all of the descendants of the last common ancestor. It was split into five extant (still existing) and one extinct infraorder. Orthorrhapha is now considered obsolete and has not been used in the last decade, but it persists in printed literature and on some online sources. A recent revision of the order Diptera (Pape, et al., 2011) revived the name Orthorrhapha, but this has not been widely accepted.

Gregory Gilman
7/25/2025

Location: Rochester MN