The emergent phase is a mess. The bugs are in constant change, and shuck, legs and wings are all over the place. The CdC Z Lon Stillborn Cripple tries to mimic those BWOs that don’t succeed and die while hatching – aka the stillborn.


Stillborn mayflies, or cripples, are not that rare to imitate. I have fished a variant of CdC Z Lon Stillborn Crippe for years, but have now tied a version to fit the idea of using Z Lon in the body – such as in with the CdZ-Lon flymf and the CdC-Lon emerger variant.

I really can’t make up my mind if I like the standard emerger hook, or the semidropped like the TMC 200R. If you look at how most of the BWOs emerge, I guess the 200R has the most correct angle. But still, these curved grub-hooks seem to work very well for most mayflies.

Therefore, I always carry these patterns, but make sure also to have as many straight/slightly curved versions in my box.

Please look at the two flies linked above for a more detailed description of the techniques and material choices.

The standard hook that I use for these kind of flies are either the TMC 2488 or the TMC 2487, depending on the size of the emerger I am tying. But I also like the Hends grubs – usually in the BL versions.

This  pattern can be adapted to any mayfly species, and if you don’t like the Z Lon approach, you might choose either standard dubbing, a biot or quill for the body. When tying the Ephemerella Aurivilli I usually choose golden olive and brown in the body.


Hook: TMC2488 Size 12-16
Thread: Sheer 14/0 Orange
Shuck: Mix of Golden Olive and Brown Z-Lon.
Abdomen:  Same as Shuck
Wing: Two fairly dense CdC feathers, natural brown
Thorax: Golden Olive and Brown dubbing mix – brushed out to suggest legs

Materials are listed in order of tying.

Read more about the TMC 2488 here

Fishing Tips

High and dry  – dead drift as most other dry duns. Apply floatant to thorax and wing.