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Species Rhamphomyia longicauda - Long-tailed Dance Fly

Fly with fringed legs - Rhamphomyia longicauda - female Long-tailed Dance Fly - Rhamphomyia longicauda - male Fly - Rhamphomyia longicauda - male Fly - Rhamphomyia longicauda - female Assassin Bug? - Rhamphomyia longicauda - female hairy legged fly - Rhamphomyia longicauda - female fly060917 - Rhamphomyia longicauda - female Dance Fly? - Rhamphomyia longicauda - male
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon (Orthorrhapha)
Superfamily Empidoidea
Family Empididae (Dance Flies)
Subfamily Empidinae
Genus Rhamphomyia
Species longicauda (Long-tailed Dance Fly)
Synonyms and other taxonomic changes
Rhamphomyia longicauda Loew, 1861
Explanation of Names
from the Latin "longus" (long) + "cauda" (tail); refers to the female's abdomen, which is relatively long for a dance fly but does not exceed the wingtips when at rest
Size
body length about 8-10 mm (guide images)
Identification
Adult: all black except for red or orange eyes, light-colored underside and coxae, and orangish inflatable abdominal sacs in female; head relatively small with slender beak slightly longer than head; antennae slightly longer than head, diverging at base into a curving V shape; female midlegs and hindlegs with long stiff scale-like hairs forming a fringe; male legs bare; male eyes meet at midline, whereas female eyes do not meet
Range
northeastern North America: Quebec south to North Carolina, west to Missouri and Michigan
Habitat
understorey of wet deciduous woods and wooded riparian areas; adults are often seen resting on low vegetation during the day
larvae develop in the soil near water
Season
adults fly from May to July
Food
larvae and adult males prey on small insects; adult females do not hunt - they only eat prey items brought to them by males
Remarks
Adult females congregate in a swarm above vegetation near water around sunset, and inflate abdominal sacs in an attempt to fool males into thinking the swollen abdomens are full of ripe eggs. The hairy legs are held alongside the abdomen in flight, supposedly to accentuate abdominal size. Males hunt small insects and bring the dead prey as "nuptial gifts" to females in exchange for a chance to mate. Males prefer to mate with the fattest and hairiest females, but the cost of being hairy is an increased chance of being caught in spider webs. See Internet References below for more information on mating behavior.

Adults are very common in appropriate habitat in southern Ontario. If approached quickly, they fly a short distance to another leaf; if approached slowly, they often walk to the far edge of the leaf they're on, then onto its underside.

R. longicauda cannot be placed in any currently described subgenus of Rhamphomyia.
Print References
Funk, D.H. and D.W. Tallamy. 2000. Courtship role reversal and deceptive signals in the long-tailed dance fly, Rhamphomyia longicauda. in Animal Behavior 59: 411-421. (see Abstract of the above paper)
Marshall, color photograph--460.4 (female), 460.5 (male) (1)
Internet References
PDF paper on female's increased risk of predation due to structural and/or behavioral differences (D.T. Gwynne and L.F. Bussiere, U. of Toronto, Behaviour, 2002)
PDF article on mating behavior and photo by D.H. Funk of female's inflated abdomen (Amanda Tromans, Nature, 2000)
distribution (The Diptera Site, USDA) (link dead 2012)
presence in North Carolina; list (North Carolina State U.)(link dead 2012)
presence in Ontario; list from Ojibway Prairie, Windsor (U. of Guelph Insect Collection)