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Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

True Fly Family Simuliidae (Black Flies)

Black flies are not usually regarded as important trout fare, but scientific studies of some rivers have shown them to make up the majority of the trout's diet. Such places are few and far between, but anglers should be aware of the possibility and keep a lookout for high concentrations of the larvae.

The adults are nasty, annoying, biting flies.

Larva & pupa biology

Diet: Plankton

Environmental tolerance: Requires clean, cool, pure water

Black fly larvae live together in colonies, sticking to rocks in riffles and filtering plankton from the waters. Several of them are shown in my underwater photos. These colonies may be found in very very fast water.

Specimens of Black Flies:

5 Larvae

4 Underwater Pictures of Black Flies:

Recent Discussions of Simuliidae

Thank you for the nice quality pictures.
1 replies
Posted by Mushroom on Sep 22, 2014
Last reply on Sep 23, 2014 by Troutnut
Thank you for the nice quality pictures. I want to use your picture in my personal presentation in my science class. Would you mind this? I will wait your answer. thank you.
Black flies--bane and boon
37 replies
Posted by GONZO on Apr 4, 2007
Last reply on Jul 13, 2011 by Jmd123
Although many anglers have been driven from the stream by these nasty little flies, the fish love them. I remember a crazy day on a tiny Pike County brook trout creek. The black flies were legion, but so were the brookies. As long as I could stand it (I was prepared with a headnet, but it was only a partial defense) the little trout hammered a Griffith's Gnat on almost every cast.

Even if you can't tolerate the adult flies, an imitation of the larvae is very good. In fact, Don Holbrook (the author of Midge Magic) recently told me that his imitation of these larvae was the single most reliable and productive pattern of all of his "midge" imitations. He complained (only partly in jest) that the widespread spraying for black flies could ruin his fishing!

-Gonzo
tiny flies in my tank filter are reproducing like mad
16 replies
Posted by Wendy on Jun 28, 2007
Last reply on Dec 24, 2007 by Wendy
I've been looking around the web to find out what they are and I saw a site that said they were drain flies? It makes sense to call them that but what are their true name? It can't be drain flies can it? Anyway they are taking over my tank. They start out like 1cm long white inch worms that have a black tip on the face and tail, they then form a brownish-black shell, like a cocoon and then they turn into tiny flies the size of a gnat or fruit fly and they don't die under water they are water proof. I hate to say it if you guys are bug lovers but they have to move out, possibly to the swampy stream out back. Does anyone know their name and if they are harmful to goldfish at an epidemic rate? They breed like crazy and I can't keep up.
West Branch Flies
Posted by Jpsully on Sep 15, 2006
Last reply on Sep 15, 2006 by Jpsully
Jason:

Very nice site, indeed!

Just wanted to acknowledge your assistance and say thanks for your help in identifying a bug I happened to seine out of the Upper Delaware this week - on a drizzly afternoon, there were tiny BWO's coming off in small numbers; but also present (in greater numbers) was a size 24/26 down-winged light-olive insect, with black mottling, that I had not seen before. They rode the current for quite a while, and the trout were quietly sipping them. After describing the fly (as best I could), you were able to provide photos, along with the suggestion that these were "blackflies" (Simulidae). I had no idea that these flies were present in the Delaware system, but will certainly carry a few imitations from now on (just in case).

JP

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Taxonomy
» Family Simuliidae (Black Flies)
12 genera (Cnephia, Ectemnia, Greniera, Gymnopais, Mayacnephia, Metacnephia, Parasimulium, Piezosimulium, Prosimulium, Simulium, Stegopterna, and Twinnia) aren't included.
Common Name
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