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.
This smaller Isonychia nymph was caught with a bunch of bicolor specimens, but it does not have the fluffy spine structure at the base of its gills. This might mean it's Isonychia sayi, or it might just be a bicolor nymph too young to have developed those structures.
This mayfly was collected from the Namekagon River in Wisconsin on January 13th, 2004 and added to Troutnut.com by Troutnut on January 25th, 2006.