Needhami
Eagle Claw,
I was curious about your question so I did a little research with the help of my old friend Les. The E. needhami is as Dennis said known as the Chocolate Dun. In NJ, it begins to hatch around June 15th and ends by June 30th so it isn't particularly a long hatch here but it could assume greater importance elsewhere as it seems to. Les has the nymph listed as a Pheasant Tail #16-18, the emerger as a Dark Baetis or Mahogany Sprout #16-18, the dun is either a Red Quill #16 or a Brown Quill #16-18, the spinner should be a dark Rusty spinner #16-18. I would also think that a Pheasant Tail Parachute #16-18 would work well up there as it did for me down here. It prefers moderate currents as opposed to roaring rapids according to Les' notes. The effects of a tail water fishery on this insect are unknown to me but it may prolong hatching activity so there you go. I also agree with Dennis that any Iso colored fly of that size should work although I would add brown dubbing to any commercial claret, the usual base for a dubbed Iso pattern. I also checked Caucci and Nastasi's Hatches II and the information is basically similiar. Ephemerella nymphs are known as weak crawlers so they'll be on the bottom in moderate currents. They make an extended undulating approach to the surface. This makes fishing an emerger or unweighted nymph productive in the period usually an hour or two prior to actually seeing duns on the water. As for them getting significantly smaller, I'm not sure but there some dark colored Baetis that are smaller and that may be the point of confusion. Hope this helps. Dennis good job on the pictures as it helped confirm my print resources!-JH