Late season cahills

A cream or yellowish Cahill mayfly (size #14 or #16) has been appearing on several Massachusetts streams this fall. Most likely a Maccaffertium of some sort, this fly has been seen on the Swift River as early as mid July this year, and as late as December 3 last year.

They never appear in great numbers (not to my knowledge, anyway), and spinners are seen more often than duns. The females seem to lay eggs by bouncing onto the water surface several times.

Here's a spinner from the Swift River, October 11:
http://www.inaturalist.org/observations/429910

A dun from the Deerfield River on September 26:
http://www.inaturalist.org/observations/410373

And a dun from the Millers River September 20: http://www.inaturalist.org/observations/416743

Posted on October 15, 2013 08:09 PM by jerry2000