This moth was identified by Dr. Jean Francois Landry of the Canadian National Collection of Insects, Ottawa, Canada. He provided some interesting information:
"This is Acentria ephemerella, family Crambidae, subfamily Acentropinae. This is a very cool and unsual moth. It is widespread here and in Europe. Its larvae are subaquatic and feed on aquatic plants, mainly Canadian waterweed (Eleodea canadensis) and pondweed (Potamogeton) up to a depth of 2m in standing or slow-moving water. Females come in two forms, one fully winged, the other with rudimentary wings and flightless. Wingless females swin below the water surface. Mating takes place on the water surface. Winged adults swarm at night, in June in our area. Adults live only a couple of days and winged ones can fly a great distance from the water. "