Where & When
» Genus Ameletus (Brown Duns)
25 species aren't included.
Preferred Waters: Streams of all sizesThere 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 BehaviorThese mayflies emerge sporadically by crawling out of the water as nymphs.Nymph BiologyAmeletus 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.
Altitude: Up to 11,000 feet
Recent Discussions of Ameletus
Brown Dun hatch/swarm time? 10 Replies »
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?Reply
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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