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Mayfly Species Maccaffertium terminatum

Pictures Below
I have found no information about this species in angling literature, but one mediocre evening on the West Branch of the Delaware I found them to be a substantial part of the mixed bag of cahills and other mayflies causing a half-hearted rise of trout.  

Where & When

Regions: East, Midwest, West

Time Of Year (?): My collections were on June 7th in the Catskills

The Mayflies of the United States webpage shows this species distributed across the East and Midwest and West into the Rockies, although not quite to the Pacific slope.

Hatching Behavior

Time Of Day (?): Evening

Spinner Behavior

Time Of Day: Evening

I collected a male and female mating while flying downstream over the tail of a long flat, not in part of any concentrated swarm over a riffle. I saw many of the females flying over the water and dipping down to lay their eggs.

Pictures of 4 Mayfly Specimens in the Species Maccaffertium terminatum:

Specimen Page:12
Female Maccaffertium terminatum Mayfly SpinnerFemale Maccaffertium terminatum  Mayfly Spinner View 5 PicturesI was able to identify this female because I captured her while she was mating with an identifiable male.
Collected June 7, 2007 from the West Branch of the Delaware River in New York
Added to by Troutnut on June 8, 2007
Male Maccaffertium terminatum Mayfly SpinnerMale Maccaffertium terminatum  Mayfly Spinner View 11 PicturesI positively identified this specimen under a microscope with a good key. It was one of the more common species in a generally light mixed bag of mayflies over a big Catskill tailwater last night.

I swooped this one out of the air while it was mating with a female, so I can be certain about her ID as well.
Collected June 7, 2007 from the West Branch of the Delaware River in New York
Added to by Troutnut on June 8, 2007
Specimen Page:12

Recent Discussions of Maccaffertium terminatum

Anybody know more about Maccaffertium terminatum? 3 Replies »
Posted by Troutnut on Jun 8, 2007
Last reply on Jun 11, 2007 by Konchu
I just wrote up what I found on the page for this species. I was mildly surprised to see so many of a species I've never seen mentioned in an angling context -- at least a few dozen throughout the evening. They piqued my curiosity.

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