Synonyms and other taxonomic changes
formerly Acentria nivea, Acentropus niveus, Phryganea nivea
Numbers
the only species in this genus in North America
Identification
Adult females are wingless and stay on the water surface; adult males have a bare grayish thorax and satiny white or pale gray wings with slightly darkened veins and outer margin.
Range
Occurs throughout Eurasia; introduced in eastern North America, spreading westward at least to Alberta
Habitat
Larvae and adult females are aquatic; adult males are found near standing or slow-moving water containing the larval food plants, but may be attracted to light at distances far from water
Season
Adult males fly from June to August
Food
Larvae feed on Eurasian watermilfoil, pondweeds (Potomogeton spp.) and Canadian waterweed (Elodea canadensis).
Life Cycle
Larvae are aquatic and overwinter underwater in cases attached to milfoil leaves; females are wingless and stay on the water surface where they breed with winged males in midsummer; univoltine (one generation per year)
Remarks
Native to Eurasia; introduced to North America in the 1920s. Attempts to use the larvae as biological control agents in the control of watermilfoil in North America have had mixed results.
Dr. Jean Francois Landry of the Canadian National Collection of Insects, Ottawa, Canada provides 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 (Elodea 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."
