Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Home » Guide » Arthropods (Arthropoda) » Hexapods (Hexapoda) » Insects (Insecta) » Flies (Diptera) » Orthorrhapha » Empidoidea » Dance Flies (Empididae) » Empidinae » Rhamphomyia » Long-tailed Dance Fly (Rhamphomyia longicauda)
Photo#8949
Long-tailed Dance Fly - Rhamphomyia longicauda - female
Copyright © 2004 Robin McLeod

Long-tailed Dance Fly - Rhamphomyia longicauda - Female
near Ailsa Craig, Ontario, Canada
June 25, 2004
Similar photos taken in 2003 were IDed as Rhamphomyia longicauda (Empididae) by Dr. Jeff Cumming in Ottawa, so I assume this is the same species. They're common in May & June in wooded areas near water. Females congregate in a swarm, and inflate abdominal air sacs (not visible here) in an attempt to fool males into thinking the swollen abdomens are full of ripe eggs. The hairy legs supposedly accentuate abdominal size. More info and a photo of the bizarre air sacs is in a PDF doc (186kb) here.

Update 14 March 2006: image moved from genus page to species page, based on IDed images here.
Contributed by Robin McLeod on 7 December, 2004 - 9:27pm
Last updated 14 March, 2006 - 9:59am

Another reference on mating in this species
FEMALEMATING SWARMS INCREASE PREDATION RISK...

Looks like this species has a really interesting mating system, where females swarm and males come in to select the most attractive female--the reverse of the usual system in flies, birds, etc.

Patrick Coin
Durham, North Carolina
… Cotinis, 23 May, 2005 - 11:16am

 
Yes
I referenced that PDF doc under the image of a male here. It's the most bizarre insect story I've read: to male Rhamphomyia longicauda, the most attractive female is the one with the fattest abdomen and hairiest legs (slightly different than the situation in Homo sapiens).
… Robin McLeod, 23 May, 2005 - 3:42pm

Disclaimer: Dedicated naturalists volunteer their time and resources here to provide this service. We strive to provide accurate information, but we are mostly just amateurs attempting to make sense of a diverse natural world. If you need expert professional advice, contact your local extension office.

Contributors own the copyright to and are solely responsible for contributed content.
Click the contributor's name for licensing and usage information.
Everything else copyright © 2003-2023 Iowa State University, unless otherwise noted.

Bugguide is hosted by:

Plant Pathology, Entomology and Microbiology at Iowa State University logo