**Mayfly Genus Ameletus (Brown Duns)**

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Ameletidae (Brown Duns)

» Genus Ameletus (Brown Duns)

Species in Ameletus
Ameletus celerBrown Dun	1	2
Ameletus lineatusBrown Dun	0	0
Ameletus ludensBrown Dun	3	22
Ameletus oregonensisBrown Dun	2	4
Ameletus sparsatusBrown Dun	0	0
Ameletus subnotatusBrown Dun	1	1
Ameletus validusBrown Dun	0	0
Ameletus veloxBrown Dun	0	0
Ameletus vernalisBrown Dun	5	5

25 species aren't included.

Common Name

Match	Common Name
	Brown Duns

Where & When

Preferred Waters: Streams of all sizes

Altitude: Up to 11,000 feet

There are many Ameletus species in the United states, but only two are regarded as significant: Ameletus velox in the West and Ameletus ludens in the East. Neither one constitutes a widespread superhatch, but they can be very abundant locally.

Hatching Behavior

These mayflies emerge sporadically by crawling out of the water as nymphs.

Nymph Biology

Ameletus nymphs are very fast swimmers. They are occasionally mistaken (especially in early instars (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.)) for some species in the Baetidae family, having roughly similar body shape and coloration. They are easily separated under close inspection based on gill coloration and prominent mouth parts. As mature nymphs their large size and intense maculation (the scientific common name for this family in some circles is Painted Minnow nymph) make them much easier to differentiate from others.

Recent Discussions of Ameletus

Brown Dun hatch/swarm time? 10 Replies »

Posted by Konchu on Apr 25, 2009 in the species Ameletus ludens

Last reply on Apr 30, 2009 by Troutnut

Has anyone else watched a Brown Dun hatch or swarm? If so, what time of day did you see it, and how long did it last?

I came upon a woodland swarm late this evening. I thought I saw mating occurring higher above the stream. This would mean that parthenogenesis is not necessarily happening in "my" stream. I watched for awhile, but got distracted (venomous snake). I hope to catch it (the hatch, not the snake) again tomorrow night and note the egg-laying behavior and possibly nab some male adults for science. There's a range of nymph ages, so I should be OK, weather permitting.

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Jargon Defined:

Instars: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.

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).

Useful References:

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

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.