Other Common Names
Black Onion Fly (T. flexa)
Numbers
Nearctica.com lists 5 spp. in genus:
Tritoxa cuneata Loew, 1873
Tritoxa flexa (Wiedemann, 1830)
Tritoxa incurva Loew, 1873
Tritoxa pollinosa Cole, 1919
Tritoxa ra Harriot, 1942
Identification
Medium-sized flies found in meadows. Apparently the wing pattern is distinctive. T. flexa, "Black Onion Fly" is presumably dark to black. A brown species seen in the southeastern United States may be T. incurva.
Range
Much of North America. T. incurva is widespread in central and eastern North America. T. flexa is found in east, and reported from western US by Swan and Papp.
(1)
The range of T. flexa has been given as follows: Manitoba and North Dakota to Connecticut and south to Illinois and Georgia, (Stone, 1965). However, T. flexa has also been reported in California (Cole and Schlinger, 1969).
Season
May-October (T. incurva, North Carolina)
Food
Food of adults unknown. Perhaps take nectar, as are seen in meadows with flowers.
Life Cycle
Tritoxa flexa is known as the "Black Onion Fly" and is associated with cultivated garlic. (See also this
family account.) Other species have been observed to be associated with grasses--see photos.
Print References
Lutz, illustrates T. flexa, 1st ed., plate LXXI, 3rd. ed., plate 54, size bar indicates length circa 8 mm.
(2)
Swan and Papp, pg. 624, fig. 1339, illustrate T. flexa, give size as 0.25 inches, or 6.4 mm
(1)
Brimley, p. 381, lists T. incurva at Raleigh, North Carolina in May, September, October
(3)
This genus
not listed on pp. 890-891 under Otitidae, family #58 by Arnett, that I can find.
(4)Internet References
North Carolina State Entomology Collection lists two species, both occurring in that state, with number pinned: T. flexa (21), T. incurva (64).
