Nymphs
In the flats nymphs crawl around in moderate current.
Nymphs are 5/16,” dark winged with a mottled head and yellowish-olive mottled legs.
Widespread, debilis can produce memorable hatches in the East, Midwest,and West.
Hatches occur at midday from July through October; peaking in September and October in 50 to 55 degree water. Debilis are most important in the fall, when the hatch is at its greatest concentration and there are few competing insects on the water. It occurs across the continent and may be reinforced by Paraleptophlebia praepedita in the East or Paraleptophlebia bicornuta in the West.
Duns
Hatches begin in late morning and run through the afternoon. They occur in or just under the film.
Body sizes are 6-8mm, Size 16-22
Spinners.
Spinner falls are in the late afternoon. Body sizes 6-8mm. Size 16-22
Common Names:
Blue Quil, Paralep, Mahogany Dun, Slate Winged Mahogany Dun, Blue Dun, Blue Winged, Dun.
P debilis is the most reliable paralep Rocky Mountain hatch.
References