|scientific name Acroneuria abnormis |
Large, warm streams and rivers.
Adults emerge in late June to mid July depending on water temperatures.
Males (length = 25 mm) have broad, triangular, and sharp paraprocts, and have spinules on Tergites 9 and 10. Females (length = 42 mm) have the subgenital plate lightly produced and broadly rounded. Adults are distinguished from Acroneuria lycorias by the absence of subanal gill remnants, and the absence of dark markings on the head within the ocellar triangle. Nymphs lack anal gills and have a light M-pattern in front of the median ocellus.
The life cycle is three years in Saskatchewan, and the nymphal habitat is under larger rocks in water about one meter deep. Nymphs occur in streams where they are exposed to the strongest current. Eggs hatch soon after they are laid, and males emerge earlier than females.
The species is not endangered, but as with all stoneflies, it is sensitive to organic pollution.
Nymphs are carnivorous on other smaller aquatic insect nymphs.
In Alberta, the species is known from the Saskatchewan River System. In North America, it ranges from northern Quebec and the Maritimes to New England and south to Florida. It occurs west to Manitoba, Saskatchewan, Alberta, Illinois, and Minnesota.
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