**Mayfly Species Dannella simplex (Blue-Winged Olive)**

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)

» Genus Dannella

» Species simplex (Blue-Winged Olive)

Common Names

Match	Common Name
	Blue-Winged Olive
	Small Blue-Winged Olive
	Dark Olive Brown Spinner
	Dark Olive Spinner

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.

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.

Your Thoughts On Dannella simplex:

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Jargon Defined:

Nymphs: The juvenile, underwater stages of mayflies, stoneflies, dragonflies, and damselflies and other aquatic insects whose juvenile stages are covered by hard exoskeletons. The word can also refer to the fishing flies which imitate these creatures, in which case it is used as a blanket term for flies imitating any underwater stage of an invertebrate (except for crayfish and leeches).

The operculate gills of a Caenis nymph.

Spinner: There are two winged stages of adult mayflies. They emerge from the water as duns, molt on land (usually) into their fully mature stage, spinners. As spinners, they mate, lay eggs, and die.

Useful References:

Arbona, Fred Jr. 1989. Mayflies, the Angler, and the Trout. Nick Lyons Books.

Knopp, Malcolm and Robert Cormier. 1997. Mayflies: An Angler's Study of Trout Water Ephemeroptera . The Lyons Press.

Leonard, Justin W. and Fannie A. Leonard. 1962. Mayflies of Michigan Trout Streams. Cranbrook Institute of Science.