|scientific name Oemopteryx fosketti |
Larger, warmer rivers.
Adults emerge from March to April.
Males (length = 7.5 mm) are brachypterous, with forewings reduced (about 2.5 mm long), and upturned near the tips; hindwings are narrowed and of less than normal length. Females (length = 10.5 mm) have wings of normal length. Male genitalia have the supra-anal process divided into four parts: 1) the brown basal bulb is smoothly rounded with a low, dark, flat, conical apex next to a groove separating it from the anterior erect member; 2) the anterior erect member is slender and curved forward with low swellings laterally near the tip; 3) the posterior erect member is near the anterior erect member but broader and terminates in two hemispherical membranous bulges separated by an angular groove; 4) the hind surface of the posterior erect member is opened to a membranous sleeve or posterior portion of the epiproct. Females have a subgenital plate with its hind margin anterior to the hind margin of the eighth sternite. The subgenital plate is rounded and shallowly excavated medially.
Males emerge a few days earlier than females, in late March to mid-April. The time of ice break-up in rivers it inhabits is critical in determining the timing of adult emergence. When a water channel opens through the ice, adult emergence occurs soon thereafter. Mating occurs immediately after emergence, with males actively walking about on the snow searching for females. Eggs appear to hatch soon after oviposition, but in summer early-instar nymphs undergo diapause and are absent from the benthos. Nymphs resume development in September.
Species habitat is threatened by hydroelectric dams, untreated organic waste, and other disturbances
No specific information is available on diet, but nymphs are detrivorous.
This species is known only from the Saskatchewan River system in Canada, and from Colorado, Montana, and Utah, U.S.A.
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