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Mayfly Family Isonychiidae (Slate Drakes)

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» Family Isonychiidae (Slate Drakes)
Genus in IsonychiidaeNumber of SpecimensNumber of Pictures
IsonychiaSlate Drakes20105
Common Name
MatchCommon Name
***Slate Drakes
Pictures Below ↓
See Isonychia for details. It is the only North American genus in this family.

Pictures of 20 Mayfly Specimens in the Family Isonychiidae:

Specimen Page:123
Female Isonychia bicolor (Mahogany Dun) Mayfly DunFemale Isonychia bicolor (Mahogany Dun) Mayfly Dun View 13 Pictures
Collected June 14, 2005 from the Namekagon River in Wisconsin
Added to Troutnut.com by Troutnut on May 26, 2006
Isonychia bicolor (Mahogany Dun) Mayfly NymphIsonychia bicolor (Mahogany Dun) Mayfly Nymph View 7 PicturesThis Isonychia bicolor nymph from the Catskills displays the prominent white stripe sometimes characteristic of its species. This is the first such specimen I've photographed, because members of the same species in the Upper Midwest have a more subdued stripe (and were once thought to be a different species, Isonychia sadleri). The striking coloration on this eastern nymph is more appealing.
Collected April 19, 2006 from the Beaverkill River in New York
Added to Troutnut.com by Troutnut on April 21, 2006
Male Isonychia bicolor (Mahogany Dun) Mayfly SpinnerMale Isonychia bicolor (Mahogany Dun) Mayfly Spinner View 15 PicturesI got several really nice pictures of this spinner. I also collected a female on the same trip.
Collected August 9, 2006 from the West Branch of Owego Creek in New York
Added to Troutnut.com by Troutnut on August 11, 2006
Specimen Page:123

5 Streamside Pictures of Isonychiidae Mayflies:

Streamside Photo Page:12
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Closeup of some recently emerged Isonychia bicolor nymphs from a small stream. In this picture: Mayfly Species Isonychia bicolor (Mahogany Dun). From the West Branch of Owego Creek in New York.
Closeup of some recently emerged Isonychia bicolor nymphs from a small stream.

In this picture: Mayfly Species Isonychia bicolor (Mahogany Dun).
StateNew York
LocationWest Branch of Owego Creek
Date TakenAug 9, 2006
Date AddedAug 10, 2006
AuthorTroutnut
CameraPENTAX Optio WPi
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In this picture: Mayfly Species Isonychia bicolor (Mahogany Dun). From Schoharie Creek in New York.


In this picture: Mayfly Species Isonychia bicolor (Mahogany Dun).
StateNew York
LocationSchoharie Creek
Date TakenSep 7, 2006
Date AddedOct 4, 2006
AuthorTroutnut
CameraPENTAX Optio WPi
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Several Isonychia bicolor nymphs had recently crawled out onto these rocks to emerge, leaving behind their telltale shucks. In this picture: Mayfly Species Isonychia bicolor (Mahogany Dun). From the West Branch of Owego Creek in New York.
Several Isonychia bicolor nymphs had recently crawled out onto these rocks to emerge, leaving behind their telltale shucks (
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Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.
Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.
Shuck: The shed exoskeleton left over when an insect molts into its next stage or instar. Most often it describes the last nymphal or pupal skin exited during emergence into a winged adult.).

In this picture: Mayfly Species Isonychia bicolor (Mahogany Dun).
StateNew York
LocationWest Branch of Owego Creek
Date TakenAug 9, 2006
Date AddedAug 10, 2006
AuthorTroutnut
CameraPENTAX Optio WPi
Streamside Photo Page:12

Recent Discussions of Isonychiidae

Are Isonychia mayflies technically multibrooded? 4 Replies »
Posted by Troutnut on Jul 22, 2006 in the genus Isonychia
Last reply on Apr 17, 2009 by GONZO
Here's what I've written in my article on Isonychia about their hatching:

Some Isonychia species are multibrooded, but not in the same way as most other multibrooded mayflies like the Baetidae. In those species, the flies emerging in midsummer or Fall are the offspring of the earlier hatch from the same year. In Isonychia, the Fall emergers are offspring from the previous Fall. They are present as half-grown nymphs when the first of their generation emerge. Although Isonychia broods have distinct peaks, some may be found on the water at any time in between.

I'm curious if they can really be called multibrooded or not, since they don't produce more than one generation per year (as far as I know). They simply have distinct populations within the same generation which emerge at different times during the year. Does that count?

All my books are packed up in boxes right now so I don't have a technical definition of the term handy.
ReplyPenns Creek Slate Draker's 4 Replies »
Posted by Jsell925 on Jul 17, 2007 in the genus Isonychia
Last reply on Sep 23, 2007 by Shawnny3
Penns is one of the few places where a #10 iso will nail em' all year long
ReplyIso 1 Reply »
Posted by JMV on Sep 21, 2006 in the species Isonychia bicolor
Last reply on Sep 21, 2006 by Troutnut
Great site, I'm an Iso. fanatic... JM
Reply
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