Over the past year I have been scrutinizing every checkered-skipper I see and at least here in the Rio Grande Valley, identification from the upper wing surface seems pretty straight forward. I know nothing about how to separate Common from White Checkered Skipper and go with the commonly held assumption that all in the RGV are White Checkered-Skippers and that Common Checkered-Skipper does not occur.
White Checkered-Skipper has a white fringe with smaller black checks on the forewing. The row of white subterminal spots are small and the subapical white spot present in Tropical and Desert Checkered Skipper is absent or extremely small.
This White Checkered-Skipper has a small subapical spot.
Tropical Checkered-Skipper is very different with an almost back fringe on the forewing towards the apex with black and white checked fringe posteriorly. The apex has a very short white fringe. There is a row of small subterminal white spots including a subapical spot. Here is male and female.
Desert Checkered-Skipper is in my eye the most attractive of the three RGV species. The black and white checking on the fringe of the forewing ocurs in equal widths or with wider black checks . There is a subterminal row of round white spots, larger than on the other two species, including an apical spot.
This one shows the characteristic pale underwing with sub-costal spots.
The fringe is worn off from this Desert Checkered-Skipper but the row of larger white subterminal spots remain.
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Certainly hybrids may cloud the issue.
