**Mayfly Species Ephemerella tibialis (Small Western Dark Hendrickson)**

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Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

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

» Genus Ephemerella (Hendricksons, Sulphurs, PMDs)

» Species tibialis (Small Western Dark Hendrickson)

Common Names

Match	Common Name
	Small Western Dark Hendrickson
	Little Dark Hendrickson
	Western Small Dark Hendrickson
	White-Gloved Howdy
	Red Quill

Pictures Below ↓

Where & When

Region: West

Time Of Year (?): August to September

Altitude: Medium to high

This widespread Western species is especially adaptable to many habitats.

Hatching Behavior

Time Of Day (?): Midday

The hatches are brief, usually less than an hour in duration, but they may cause good fishing. They produce an exceptional number of cripples (Cripple: In fly fishing, a cripple is any insect which has been injured or deformed so that it cannot escape the water. This may include stillborn emergers or fully emerged adults which have been damaged, often by wind or waves, so that they can no longer fly. Trout often favor eating crippled insects.) and stillborns (

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This stillborn Ephemerella subvaria dun is trapped in its shuck.

Stillborn: In fly fishing, a stillborn insect is one which got stuck in its nymphal or pupal shuck during emergence and floats helplessly on the surface instead of flying away. It is a specific class of cripple, although it is sometimes used interchangeably with that term.).

Spinner Behavior

This is the only spinner (imago (Imago: The sexually mature adult stage of the mayfly is called the imago by scientists and the spinner by anglers.)) in the genus with dark blackish eggs. These spinner falls are rarely important.

Pictures of 1 Mayfly Specimen in the Species Ephemerella tibialis:

Female Ephemerella tibialis (Small Western Dark Hendrickson) Mayfly Dun

View 1 Pictures

Collected September 7, 2007 from Crazy Beaver Spring in Montana
Added to Troutnut.com by Bnewell on July 2, 2011

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Jargon Defined:

Cripples: In fly fishing, a cripple is any insect which has been injured or deformed so that it cannot escape the water. This may include stillborn emergers or fully emerged adults which have been damaged, often by wind or waves, so that they can no longer fly. Trout often favor eating crippled insects.

Imago: The sexually mature adult stage of the mayfly is called the imago by scientists and the spinner by anglers.

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.

View Full Size

This stillborn Ephemerella subvaria dun is trapped in its shuck.

Stillborns: In fly fishing, a stillborn insect is one which got stuck in its nymphal or pupal shuck during emergence and floats helplessly on the surface instead of flying away. It is a specific class of cripple, although it is sometimes used interchangeably with that term.

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.