Another fly in the garden, two really and they are pretending to be ichneumon wasps. The flies are syrphids (Family Syrphidae) but very different from the bee-fly species. It is named banded-wing hover-fly (Ocyptamus fascipennis). The species epithet “fascipennis” is from two Latin words, fascia (band) and penna (feather, wing) and means “banded feather” in reference to the dark band across the wings.
Range and Description
A Nearctic ecozone species, banded-wing hover-fly ranges from Manitoba to Quebec, south to Texas and Florida. There are 10 to 17 species of Ocyptamus in the US and Canada and many more in tropical regions from Mexico to South America.
The banded-winged hover-fly measures 9 to 13.5 mm long. Its wings are marked by a dark band across the middle. The long, thin abdominal section of the fly is dark brown to black with lighter brown and buff bands at each segment border. The fly looks like a small ichneumon wasp but can be told apart from them by its large compound eyes that nearly meet in the middle of the head and by its two full-sized wings and two stub-like wings (halteres) whereas wasps have compound eyes well separated on each side of the head, four full-sized wings, and no halteres.
A Friend in the Garden
Banded-wing hover-flies eat pollen as adults but the larva prey upon scale insects and aphids. The larvae of some tropical species of Ocyptamus have been discovered to prey upon flies that eat the honeydew secreted by white-fly nymphs, which are not true flies but aphid relatives. The Ocyptamus larvae live among the white-fly nymphs and trap the honeydew feeding flies with a sticky venomous liquid that they spray onto the fly. The larvae also eat white-fly nymphs but cannot grow to maturity on them alone so predation on flies is obligatory.
BugGuide Genus Ocyptamus
Davis, J. J. (1915). The Pea Aphis With Relation to Forage Crops. United States Department of Agriculture Bulletin No. 276.
Miranda, G. F. G., Young, A. D, Locke, M. M., Marshall, S. A., Skevington, J. H., Thompson, F. C. (2013). Key to the Genera of Nearctic Syrphidae. Canadian Journal of Arthropod Identification No. 23.
Udvardi, M. D. F. (1975). A Classification of the Biological Provinces of the World. International Union for the Conservation of Nature and Natural Resources Occasional Paper No. 18. Prepared for UNESCO Man and Biosphere Programme Project No. 8.
Ureña, O., Hanson P. (2010). A fly larva (Syrphidae: Ocyptamus) that preys on adult flies. Revista de Biologico Tropical. 58(4):1157-63.