Wingspan: 5-11 mm
Traits of the Winter Crane Flies include hairy antennae with a 16-segmented flagellum (the segments become indistinct toward the distal end). The legs, while fragile, do not fall off as easily as in the Tipulid Crane flies. Also, Winter Crane Flies have three ocelli present, while Tipulids and Limoniids have none.
The family's common name alludes to the unusual life history, with adults flying in winter, as well as late autumn and early spring. Males are most commonly seen, typically in all-male swarms on cool, sunny days. Adults are also found in caves, deep mines, and in hollow trees. Larvae feed on decaying plants, including in some cases stored root crops or mushrooms.
There are three genera of Winter Crane Flies in America north of Mexico; Paracladura is found only in the West. The one species in genus Diazosma is found from California to Vermont and New York; Stone (1965) indicates no records of Diazosma spp. south of New York.
The third genus is Trichocera. To separate genus Diazosma from genus Trichocera, check that tibial spurs are present; these spurs are lacking in genus Diazosma. Also, Diazosma adults are active in summer, the only eastern Winter Crane Fly for which that is true. And finally, the only Winter Crane Flies with vein A2 short and curved is Trichocera. This trait is illustrated in the Trichocera wing detail below.
Writing about Winter Crane Flies, Pratt and Pratt (1984) told how in eastern north America, "swarms of males are seen dancing in the late afternoon sunlight, sometimes thousands of individuals in hundreds of swarms over many acres of lawns and open woodlands." Trichocera sp. are even seen walking on snow, or swarming above it, when temperatures are just above freezing.
Winter Crane Flies also show up at lights, as did the one pictured here in lateral view, and they have been collected at molasses traps.
Note that this is both the family page for Trichoceridae and the genus page for Trichocera