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Species Urophora quadrifasciata - Four-barred Knapweed Gall Fly

Unwelcome Newcomer - Urophora quadrifasciata - male Tephritid fly, Urophora quadrifasciata - Urophora quadrifasciata UV Knapweed Seed Head Fly - Urophora quadrifasciata - male tiny  fly - Urophora quadrifasciata Four-barred Knapweed Gall Fly - Urophora quadrifasciata - female Salticid Mimic on Tansy - Urophora quadrifasciata Salticid Mimic on Tansy - Urophora quadrifasciata Unknown Fly - Urophora quadrifasciata - female
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon ("Acalyptratae")
Superfamily Tephritoidea
Family Tephritidae (Fruit Flies)
Subfamily Tephritinae
Tribe Myopitini
Genus Urophora
Species quadrifasciata (Four-barred Knapweed Gall Fly)
Explanation of Names
Urophora quadrifasciata (Meigen 1826)
quadrifasciata = 'four-banded' (refers to the wing pattern)
Size
2-3 mm
Range
Native to Europe, introduced in NA in 1988 to control knapweeds (now across most of the US)
Food
Introduced to control knapweed (Centaurea spp.)
Life Cycle
Two generations a year. Overwintering generation emerges as adults from galls in the mature seedheads in the spring when new flower buds are beginning to form. Female fly uses her ovipositor to penetrate half grown flower buds it lays eggs among the developing stamens. May lay more than one egg per seedhead. Eggs hatch in three to four days and larvae chew down in a floret into the ovary causing the plant to start forming a gall about eight days after larvae hatched.
See Also
U. affinis has less extensive wing markings
Internet References
Fact sheets: R.F. Lang(1)M.B. Sacry(2)