Philonicus fuscatus
Very similar to Machimus. Note that the male genitalia form a ring when viewed dorsally, and the female has a swollen ovipositor. Also note the long arista, and reduced anterior dorsocentrals. Long, white mystax, orange and black legs. The femora are dark in this species.
Size: 10-16 mm
FL Season: May
Season: May-August throughout range
Range: Eastern U.S.
FL Range: Panhandle
Habitat: Along streams and rivers.
References
Hine, J. S. (1907). Robber flies of the genus Philonicus.
Hine, J. S. (1909). Robberflies of the genus Asilus. Annals of the Entomological Society of America, 2(2), 136-170.
Robber Flies of Florida 