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Mayfly Species Dannella simplex (Blue-Winged Olive)

Although by no means a superhatch, this species can be important. Authors who discuss it lament the general lack of credit it receives for the fine hatches it produces on some streams.  

Where & When

Regions: East, Midwest

Time Of Year (?): June through mid-September, but best in June and July

Hatching Behavior

Time Of Day (?): Morning

Spinner Behavior

Spinner falls are sparse and unimportant.

Nymph Biology

Current Speed: Slow

Substrate: Silt

These nymphs have operculate (
The operculate gills of a Caenis nymph.
The operculate gills of a Caenis nymph.
Operculate: Lidlike; usually used to describe the pair of enlarged elytroid gills (called the operculum) which some silt-dwelling mayfly nymphs like Caenis and Eurylophella have developed to shield their other gills from debris.
gills on segment four. This adaptation protects their other gills from the loose silt covering the bottom in the slow backwaters and pools they prefer.

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