**Mayfly Species Maccaffertium ithaca (Light Cahill)**

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Heptageniidae (March Browns, Cahills, Quill Gordons)

» Genus Maccaffertium (March Browns and Cahills)

» Species ithaca (Light Cahill)

Common Names

Match	Common Name
	Light Cahill
	Pale Sulphur Dun
	Light Cahill Spinner
	Dark Cahill
	Ginger Quill Spinner
	Cahill
	Cream Dun

Where & When

Regions: East, Midwest

Time Of Year (?): June through early September; peaks in late June

Preferred Waters: Medium to large streams

This is primarily an Eastern species, but a couple books report that it produces fishable action in the Midwest as well.

Hatching Behavior

Time Of Day (?): Often spread out all day long; compressed toward dusk in hot weather

This species emerges much more gracefully than Maccaffertium vicarium, so emerger patterns are not as important.

The duns are better to match, since they may drift for quite a while time to dry their wings and make a commotion getting off the water. Caucci and Nastasi report in Hatches II that their stomach samples verify this preference for the duns.

Spinner Behavior

Time Of Day: Late afternoon to dusk, depending on weather

Habitat: Riffles

The spinners fall spent (Spent: The wing position of many aquatic insects when they fall on the water after mating. The wings of both sides lay flat on the water. The word may be used to describe insects with their wings in that position, as well as the position itself.) to the water to lay their eggs.

Nymph Biology

Current Speed: Riffles and runs

Substrate: Gravel

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Jargon Defined:

Duns: Mayflies have two adult stages. They first emerge from the water as duns (scientifically known as the subimago stage). They then molt into the spinner (imago) stage, in which they mate and die. Sometimes the word "dun" is confusingly used to refer to a brownish gray color in fly tying materials.

Spent: The wing position of many aquatic insects when they fall on the water after mating. The wings of both sides lay flat on the water. The word may be used to describe insects with their wings in that position, as well as the position itself.

Useful References:

Caucci, Al and Nastasi, Bob. 2004. Hatches II. The Lyons Press.

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.

Schwiebert, Ernest G. 1955. Matching the Hatch. MacMillan Publishing Company.