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Species Physocephala tibialis

Thick-headed Fly - Physocephala tibialis Conopidea - Physocephala tibialis Thick-headed Fly - Physocephala tibialis Ceriini? Monoceromyia? - Physocephala tibialis Physocephala ? - Physocephala tibialis Id help needed - fly - Physocephala tibialis - male Wasp - Physocephala tibialis Fly (Bee Mimic) on Butterfly Weed - Physocephala tibialis
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon ("Acalyptratae")
Superfamily Sciomyzoidea
Family Conopidae (Thick-headed Flies)
Subfamily Conopinae
Genus Physocephala
Species tibialis (Physocephala tibialis)
Synonyms and other taxonomic changes
Conops tibialis Say 1829 (1823 sometimes given erroneously, see "Remarks" section below)
Conops nigricornis Wiede., 1830
Conops fulvipennis Macq., 1843
Conops lugubris Macq., 1843
Adult body mostly black, with thin white band between abdominal segments one and two; tibiae whitish at base.

Wings dark anteriorly, including entire discal cell (see "dm" here). Humeral corners of thorax typically dark/black, with little or no pollinose dusting.

Lateral edges of face and frons white. Facial grooves black (see "fg" here). Cheeks uniformly black.
Eastern US and southeastern Canada (in US, from WI south to TX, and east to MA and FL(1); in Canada s.e. ON)
Adults visit flowers of herbaceous plants during the day
Adults in June and July (in OH & WV)
Life Cycle
Reported to parasitize workers of the bumble bee Bombus bimaculatus
This eastern species is perhaps the most frequently encountered species of Physocephala in our area, with more BugGuide posts than any other.
Say's original 1829 description appeared in the Journal of the Academy of Natural Sciences of Philadelphia, vol 6, pg 171. It can be read here. Williston gave a more detailed description of P. tibialis in 1883.
For a discussion of what appear to be aberrant reddish forms of P. tibialis, see this forum article.
Note some references [e.g. Parsons (1948) and Camras (1957)] erroneously state the original description date as 1823 and give "Jour. Acad. Nat. Sci. Phil., v 4, pg 83" as the source...but that's the date and source for the original description of Conops sagittaria, not C. tibialis. (A.S. 1/20/13)
See Also
P. furcillata looks similar, but it can be distinguished by having (most of) the discal cell of the wing hyaline, and facial grooves pale (whitish to yellowish):

The discal cell is entirely dark in P. tibialis (ref. here), as illustrated below:

Print References
Parsons, C. T. (1948). "A Classification of North American Conopidae", Ann. Ent. Soc. Am., Vol. 41, No. 2, pp. 223-246 (Full Text)
Camras, S. (1957). "A review of the New World Physocephala (Diptera: Conopidae)". Ann. Ent. Soc. Am. 50:213-218.
Internet References
Presence in OH and WV and seasonality (W.B. Bond)
Presence in IL (Flower-visiting Insects of Prairie Coreopsis, John Hilty)
Works Cited
1.A Catalog of the Diptera of America North of Mexico
Alan Stone, et al. 1965. United States Department of Agriculture.