The flies of the genus Brachyopa are small, unusually-shaped flies that are also unusually colored—pale-yellow, orange, or gray-brown. The lower part of the face protrudes forward and the eyes are large and shaped rather like goggles. The third antenna segment has a pit with sensory cells. The arista is bare for some species and slightly plumose for other species. The wings are relatively long, extending well beyond the end of the abdomen.
A number of factors combine to make these flies difficult to find: short flight period for adults, associated with sap-runs of wounded trees (instead of routinely visiting flowers), adults are small, inconspicuous, swift fliers that resemble, because of their color and shape, flies of families other than Syrphidae, such as Scathophagidae and Dryomyzidea for example. The majority of observations are made at sap runs where the adult flies hover in front of the wound, perch on the dry bark adjacent the sap run, or oviposit directly in the flowing sap.
The larvae live in sap runs of living trees and collections of sap under the bark of fallen trees. The larvae are somewhat flattened and have a relatively long posterior breathing tube. The final few segments are fringed with lappets.
Count yourself lucky if you encounter one of these rare and stealthy flies!
- Brachyopa (Brachyopa) flavescens Shannon 1915 – Yellow Sapeater
- Brachyopa (Brachyopa) notata Osten Sacken 1875 * – Black-banded Sapeater
- Brachyopa (Brachyopa) vacua Osten Sacken 1875 – Yellow-spotted Sapeater