As reading some forum posts by Niklas Dahlin (Sweden) has recently pointed out, the Baetis nymph is an important pattern to the river angler. If you have ever kick sampled and studied these insects, you will see they are deserving of their 'Agile Darter' name. They can move really fast.
Obviously at their most vulnerable when hatching, the nymph still is a Go-To pattern. Here is a trio of variations on the theme that are making their way to Hans for photographing and hopefully adding to Flytiers' page:
Baetis (sparse hair) soft-hackle: