Fly Fishing for Trout Home
User Password
or register.
Scientific name search:

Mayfly Genus Procloeon (Tiny Sulphur Duns)

Taxonomic Navigation -?-
» Genus Procloeon (Tiny Sulphur Duns)
Species in ProcloeonNumber of SpecimensNumber of Pictures
Procloeon ingensTiny Sulphur Dun00
Procloeon insignificansTiny Sulphur Dun00
Procloeon mendaxTiny Sulphur Dun00
Procloeon pennulatumTiny Sulphur Dun00
Procloeon rubropictumTiny Sulphur Dun00
Procloeon rufostrigatumTiny Sulphur Dun00
Procloeon simplexTiny Sulphur Dun00
Procloeon venosumTiny Sulphur Dun00

14 species aren't included.
Common Names
Pictures Below
This genus is not well-known to fly fishers because most of its species were, until very recently, classified as either Centroptilum or Cloeon.

These mayflies may be abundant enough to cause fishable hatches in spite of their tiny size.

It's difficult to discern from previous angling literature exactly which statements now apply to Procloeon, because its species come from other little-known genera and the accounts for them conflict. They were mentioned in combination with other genera, adding to the confusion. So the information below is highly tentative and, where accounts seem to conflict, both have been given.

Where & When

Time Of Year (?): Mostly summer

Preferred Waters: Best in alkaline (Alkaline: Having a pH higher than 7 (opposite of acidic). Moderately alkaline water is ideal for trout because it's better for the growth of phytoplankton, the usual base of the aquatic food chain, and that's good for the growth of everything higher up the chain, including trout.) streams

Hatching Behavior

Time Of Day (?): Different sources say mid-evening or early morning

Trout may feed well on the tiny nymphs during a hatch. Caucci and Nastasi discovered and noted in Hatches II that these nymphs, despite their excellent swimming ability most of the time, become nearly immobile shortly before hatching. They slowly crawl out of the water or dead-drift (Dead-drift: The manner in which a fly drifts on the water when not moving by itself or by the influence of a line. Trout often prefer dead-drifting prey and imitating the dead-drift in tricky currents is a major challenge of fly fishing.) float to the surface, buoyed by gases they release.

According to one source, the duns crawl out onto shore to emerge.

Spinner Behavior

Procloeon duns usually molt into spinners, mate, and die the very day they hatched. Dun and spinner activity may overlap.

Nymph Biology

Current Speed: Slow

Substrate: Many, but weeds are best

They either prefer fertile, weedy spring creeks, or slow, silty stretches of relatively warm trout rivers, depending on which books should be believed.

Pictures of 2 Mayfly Specimens in the Genus Procloeon:

Female Procloeon (Tiny Sulphur Duns) Mayfly DunFemale Procloeon (Tiny Sulphur Duns) Mayfly Dun View 8 PicturesThis dun of a fairly large Baetidae species was one of only a couple I saw all evening.
Collected August 24, 2006 from Enfield Creek in New York
Added to by Troutnut on August 27, 2006
Procloeon pennulatum (Tiny Sulphur Dun) Mayfly NymphProcloeon pennulatum (Tiny Sulphur Dun) Mayfly Nymph View 1 PicturesThis fragile nymph is easily damaged during sampling making identification more difficult.
Collected June 19, 2009 from Murphy Lake in Montana
Added to by Bnewell on June 26, 2011

Your Thoughts On Procloeon:

You must log in at the top of the page to post. If you haven't registered yet, it's this easy:

Username:          Email:

Password:    Confirm Password:

I am at least 13 years old and agree to the rules.
Top 10 Fly Hatches
Top Gift Shop Designs
Top Insect Specimens
Miscellaneous Sites