SeasonalityAdults emerge over a two-week period from late June to early July.IdentificationMales (length = 25 mm) have paraprocts that are flattened, triangular and sharply pointed at their anteriorly directed tips, but lack spinules on Tergites 9 and 10. Females (length = 37 mm) have the subgenital plate produced over half of Sternum 9; the hind margin of the subgenital plate is slightly angular and usually has a squarish shiny spot at its apex. The nymph has anal gills but lacks an occipital ridge. The nymphal head has a yellow mark extending from the labrum to the anterior ocellus and dark brown abdominal terga.
Scientific NameHesperoperla pacificaSeasonality
Adults emerge over a two-week period from late June to early July.
Identification
Males (length = 25 mm) have paraprocts that are flattened, triangular and sharply pointed at their anteriorly directed tips, but lack spinules on Tergites 9 and 10. Females (length = 37 mm) have the subgenital plate…
Males (length = 25 mm) have paraprocts that are flattened, triangular and sharply pointed at their anteriorly directed tips, but lack spinules on Tergites 9 and 10. Females (length = 37 mm) have the subgenital plate produced over half of Sternum 9; the hind margin of the subgenital plate is slightly angular and usually has a squarish shiny spot at its apex. The nymph has anal gills but lacks an occipital ridge. The nymphal head has a yellow mark extending from the labrum to the anterior ocellus and dark brown abdominal terga.
Life History
The life cycle is three years, and the nymphal habitat is under larger rocks in regions of the stream with the swiftest current.
Conservation
The species is not endangered, but as with all stoneflies, it is sensitive to organic pollution.
Diet Info
Nymphs are carnivorous, preying principally on mayfly nymphs and chironomid and caddis fly larvae.
Range
In Alberta, the species is known from the Cypress Hills and Bow River. In North America, it ranges from British Columbia to California and New Mexico and east to South Dakota and Saskatchewan.
Citation
Page Citation for Hesperoperla pacifica
Page Citation
"Species Details - Hesperoperla pacifica, Freshwater Invertebrate Collection." University of Alberta Museums Search Site, https://search.museums.ualberta.ca/g/5-2127/10-58812. Accessed 04 Jan. 2025.
Specimen Information
There are 7 specimens of this Species.
6 results plotted on map in 4 markers. Note: Only records with latitude and longitude coordinates are plotted on map.