Stichopogon can be fierce predators in open sandy habitats. S. abdominalis prefers areas of open white sand. S. trifasciatus are often found on the shores of lakes and rivers, though they can occur in the same sandy blowouts as S. abdominalis. Both are fairly small, but S. trifasciatus are larger. I have seen runt S. trifasciatus that approached the size of S. abdominalis. The abdominal patterns are distinctive.
Stichopogon trifasciatus
The name derives from the alternating pattern of silver and dark tergites (abdominal segments). It’s sometimes known as the three-banded robberfly.
Size: 9.5-14 mm
Range: Throughout U.S.
FL Range: Throughout
FL Season: April – October
Stichopogon abdominalis
Very small robbers, with dark or reddish bands on most abdominal segments. I often find these in the same white sand habitats as Moustached Tiger Beetle (Ellipsoptera hirtilabris).
Size: 6-8 mm
Range: Georgia and Florida
FL Range: Panhandle, north, and central Florida south to Highlands County.
FL Season: March – October
References:
Barnes, J. K. (2013). The genus Stichopogon Loew (Diptera: Asilidae) in America North of Mexico. Proceedings of the Entomological Society of Washington, 115(1), 9-36.
Robber Flies of Florida 