Content Author Object Flagger Flag Created Reason Resolved by Resolution
Giant Western Crane Fly (Holorusia hespera) treegrow Thu, 03 Sep 2020 03:21:06 +0000

Tons of misidentifications due to incorrect iNat suggestions

Not Resolved


iNat suggestions for crane flies cannot be trusted. There are hundreds of species in the US alone, but the iNat algorithm only "knows" a handful of them and suggests Holorusia hespera, Tipula abdominalis, Tipula furca, Tipula paludosa or Nephrotoma ferruginea for any crane fly looking thing you upload.

Holorusia hespera is endemic to the Western US and Canada: Alaska, British Columbia, south to California and Arizona, east to Montana, Colorado, and New Mexico. Any records east of the Rockies or from outside the US/Canada are misidentifications.

Holorusia hespera is one of several huge crane flies with a wing span of up to 10 cm (4 inches). It has dark eyes, short antennae, and a plain, unmarked, reddish brown body. There are no stripes or spots on the abdomen or on the top of the thorax, and there is a broad white stripe on the side of the otherwise dark thorax. The wings are long (longer than the abdomen) and more or less opaque brown. Some individuals have weakly tinted wings, but the wings are never entirely clear. There's always a brownish cast, and the wing veins are nearly the same color as the wing membrane, never dark and strongly contrasting. Also, there are never any dark spots, stripes, or bands on the wings. There can sometimes be some tiny white spots in the distal part of the wing but they are never large enough to coalesce into a band.

So each one the following characteristics rules out Holorusia hespera:

Any distinct spots, stripes, or bands on the wings, the abdomen, or the top of the thorax
Lack of a white stripe on the side of the thorax
Long antennae
Bright green eyes
Wings are shorter than abdomen
Clear, untinted wing membrane
Dark wing veins contrasting with the color of the wing membrane
Small size: wing span less than 2 inches (5 cm)

Posted by treegrow over 2 years ago (Flag)

This is wonderfully helpful, thank you for taking the time to post this!

Posted by luck about 2 years ago (Flag)

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