I think it likely the brownish species seen here is T. incurva. T. flexa and T. incurva are apparently the widespread and common eastern species. T. flexa is very dark. This suggests the brownish species is something else, thus likely T. incurva. See guide page for genus Tritoxa for references.

Patrick Coin
Durham, North Carolina

I love those mouthparts, look like the hooked beak of a vulture.

We should be able to get species on these--with only five in the genus. (Perhaps with a quick trip to a museum.) Looks like 3/4 photos so far are likely of the same species, brownish, as opposed to the one much darker species, which might be T. flexa, I'm speculating.

Patrick Coin
Durham, North Carolina