(BGR) Sclerocona acutellus - Hodges#5298.1 (Sclerocona acutellus) 2016-6-18 Newark, DE

http://bugguide.net/node/view/1241218/bgimage
introduced
bg says:
-larvae feed on Phragmites australis - (that reed is in "my" "marsh")
-first seen in 2003 in Connecticut, Massachusetts, Maryland, and Rhode Island
bg currently list 7 states for this moth and Delaware makes #8

how to ID native from introduced Phragmites:
https://www.nps.gov/plants/alien/fact/phau1.htm