The Xyelidae are a small family of sawflies known from fewer than 50 extant species in five genera, but with an extensive fossil record; they are the oldest fossil Hymenoptera, dating back to the Triassic, between 245 and 208 million years ago. Most species occur in the Northern Hemisphere, especially in boreal regions, though there are a few neotropical species. Most are associated with conifers (esp. Pinus and Abies), where the larvae feed on pollen or within buds, though larvae of a few species feed on the leaves of deciduous trees.
The family is characterized by the appendages of the head, which are remarkable in that the antennae and palpi are nearly leg-like in structure, with a long basal segment followed by a series of tiny segments, as in the tibia-tarsus.