Hank49
Contributor
The sandlies on Roatan can be problematic any time of day. Maybe a bit more at dawn and or dusk according to some but that has not been my experience. Never took the time to look at them under a magnifying glass to see the color of their wings
Here in Belize you don't need a microscope. You can tell by the appearance of the bite.
And the white wing is more aggressive in the daylight hours.
As RoatanMan stated, the dark one is extremely aggressive in the dawn hours. But as you say, they'll get you all day long if you sit in one area for a few minutes.