Cumberland River Mayflies - Unraveling the Mystery
by Brett Billings - Brett@cumberlandtrout.com

Mayflies...
Appearing now at a stream near you!

Little Yellow Mayflies

Sulphurs...Pale morning/evening duns...hendricksons...what ARE these little yellow mayflies? Well, they may be any of those, because we have them all here.

Many refer to all mayflies that are yellowish as "sulphurs," and this causes some confusion. We have pale yellowish mayflies that range from size 18 to size 6. Here's the rundown on our two principle "little yellow mayflies."

Pale Evening Dun (also called "sulphur dun" Latin name: Ephemerella dorothea) Size 14-16 cream to pale yellow, often with darker thorax (See picture at left) that may have olive or orange cast. Dun's wings are pale gray. (Duns usually emerge later in the day in slow water areas.) Spinner's wings are transparent with cream-yellow abdomen and orangeish-yellow thorax. Flies: Light cahill and dark cahill sizes 14-16.

Eastern Sulphur Dun (Latin names Ephemerella invaria and Ephemerella rotunda) Size 10-12 (Duns usually emerge by early afternoon in fast water areas.) Duns have cream to beige bodies with light grey wings. Spinners slightly smaller sizes 12-16. Flies: Light cahills and Gray Fox in sizes 10-12.

Best Sulphur Dries

Dry fly afficionado, Ray Zavada, relies heavily on thorax flies and comparaduns for the sulphur hatches. I've seen Ray out on the water fishing and know how effective those sulphur flies can be! Here's a suggested dressing:

Light Cahill Thorax Dry Fly
Hook: Mustad 94840 or TMC 100
Size: 12-14
Thread: Cream
Tails: Cream hackle fibers, split
Body: Yellow-cream fur or quill
Hackle: Light dun to dark cream
Wing: Clump of white or gray CDC

Ray Zavada's killer comparadun!

March Brown mayfly admiring my rod

March Brown Mayflies

Guide Gerald McDaniel reports seeing some March browns (Latin name: Stenonema vicarium) floating down the river May 5th. These are really HUGE bugs (size 10) with mottled wings and 2 tails. Colors vary from light brown to almost pure white for the true light cahills (Stenonema pulchellum). All of the Stenonema mayflies are fast-water mayflies, so look for them near riffles.

BWO-time is on its Way!

Blue-winged Olives - the river's main mayflies - are just starting to emerge (or "hatch" as fishermen say, but "hatch" actually refers to breaking out of an egg, technically.) These include Drunella species early in the season in sizes 14-16. Be sure to check the duns riding the current for an indication of the right color. Those duns already sitting in the streamside vegetation may have darkened considerably compared to what the trout see drifting down the river.

Later in the season we also see various Baetis species that can also be called "Blue-winged olives." Starting in July, Timpanoga or "tiny BWO's" are seen which have an apple green body and nearly black wing. These guys range from 14-18 in size. Make sure to have a selection of Swisher-Richards "sidewinder" no-hackles or comparaduns on hand, as these mayflies ride particularly low and long in the current before fluttering off.

Blue-winged Olives
Most populous mayfly on the Cumberland River.