Mating Banana Stalk Flies from Hawaii

Special Mosquitos?
Location: Palolo Valley, Honolulu, HI
December 16, 2010 5:39 pm
Found these two getting busy on the shoe rack this morning… I hope they don’t recognize and remember faces for an attack later on when they’re done… Are these special mosquitoes or something? They sure don’t look like a regular Mosquito!
Signature: TH

Mating Banana Stalk Flies

Dear TH,
Wow, what an awesome photo you have sent to us.  We have no idea where to begin researching the identity of these unusual looking mating Flies, but we can assure you that they are not mosquitoes.  Like so many other creatures in Hawaii, we suspect these might be an introduced species, possibly from Asia.

Immediate Update
We quickly found a match for your mating Flies.  They are identified on BugGuide as Banana Stalk Flies, Telostylinus lineolatus, in the family Neriidae, the Stilt Legged FliesThe Cook Islands Biodiversity website has a page devoted to the Banana Stalk Fly, and they list the other common names Banana Fly, Push-me-Pull-me Fly and Push-pull Fly.  The range is listed as “Sri Lanka – Indonesia / Australia – Marquesas, Hawai‘i” and it is considered a pest species, but the site does not indicate why.  The Rainforest Revelations website has this information:  “With enormous eyes, this tiny, tropical, stilt-legged fly maintains a confident distance from human approach, by swiftly running around the blind-side of whatever surface it is on.  … Telostylinus lineolatus inhabits tropical north Queensland, where it aggregates on flowers and rotting fruit.  They are members of Neriidae, which is a relatively small family of true flies (Diptera) with long, stilt-like legs.”  The Evolutionary Biology Lab Research website has this information on the family:  “Neriidae is a relatively small family of true flies (Diptera) with long, stilt-like legs. Most species are found in the tropics. Neriids have very interesting behaviours, and many species are strikingly sexually dimorphic, with males having much longer legs, heads and/or antennae than females. Like piophilid flies, neriid larvae have the ability to leap during the stage just before pupation when they migrate from the larval feeding substrate to the pupation site. Very little research has been done on this interesting group of flies.

Correction January 2, 2017
Though we correctly identified the species, we now know that Banana Stalk Flies are in the Cactus Fly family Neriidae.

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