brown swellings at bases of antennae, 9 mm excluding antennae
Limnia shannoni. Rock Creek Park, Washington, DC, USA.
I'm not very sure about Eutreta because the wings aren't separated like in most photos.
It looks like it has a tiny blue gem at the base of the antennae.
The swollen brown base of the antennae is apparently distinctive to this particular species of Limnia.
On plant stems in a planter that is kept flooded for growing rice; lots of wetland plants in planter, too (sedges, duckweed, frog’s bit, etc.).
Marsh Fly - Limnia species
Also posted at:
bugguide.net/node/view/2254781/
References
Edit. See comments--the swollen antennae is not a character for males--just a characteristic of this species, Limnia shannoni:
https://bugguide.net/node/view/481904