I tend to think of these as beach robbers, because that’s where you’ll find Laphystia litoralis and texensis. They generally only occur on beaches that have intact dune systems, and some of the western Laphystia are found on inland sand dunes. As you walk a beach, loose closely at what you may otherwise think is a shore fly or a tiger beetle flushing from your footsteps.
Focus on the pattern of black and silver on the abdomen as viewed dorsally. This can be difficult to see on robbers that rest with their wings covering their abdomen. L. texensis and L. litoralis may overlap on panhandle beaches, or L. litoralis may be restricted to the Atlantic coast. Considering how similar they are, it would not surprise me that museum specimens for L. litoralis on panhandle beaches are mislabeled.
Silver overall with white hairs. Some of the abdominal bands (3 to 5) are interrupted. It can be tough to see the black interrupting the abdominal bands.
Size: 10-12 mm
FL Season: March – November
FL Range: Atlantic beaches and possibly also panhandle beaches. There is one FSCA specimen labeled as Alachua County which is strange.
Silver overall with white hairs. All abdominal silver bands are intact and cover half of each abdominal segment.
Size: 9-12 mm
FL Season: June – November
FL Range: Panhandle beaches
Wilcox (1960) notes that L. texensis may be a variant of L. opaca, which also is known from the Louisiana and Texas coast. The abdomen of L. opaca has black reduced to triangles at the base of each segment.
Hairs on head and thorax can be white (on males) or golden (on females). Silver on the abdomen is highly reduced such that the dorsum is entirely black. Scutum (top of thorax) mostly black. Wings light brown.
Size: 9-11 mm
FL Season: May – August
FL Range: Panhandle rivers
Figures from Wilcox (1960)
Curran, C. H. (1931). New American Asilidae (Diptera). 2. American Museum novitates; no. 487.
Wilcox, J. (1960). Laphystia Loew in North America (Diptera: Asilidae). Annals of the Entomological Society of America, 53(3), 328-346.