The only known species was collected from the Rocky Mountains where the larvae grow in torrential streams.

The larvae are similar to those of Athericidae and Tabanidae but with long crocheted false-legs (prolegs) arising from abdominal segments 2-7.

The adults were found very similar to Pelecorhynchidae when identifying using the key in McAlpine's 1981 Manual of Nearctic Diptera, but they stand apart due to the aedeagal tines and other male reproductive parts which indicate a clear similarity to the Athericidae and Tabanidae.

[1] The name is said to be derived from Greek oreos (mountain) and leptos (thin, delicate).

[2] This article related to members of the fly superfamily Tabanoidea is a stub.