Sulphur Dun

A dry fly, tied #14–18, a summer pattern. It is tied against 4 named insects in this book — May–September.

A pale yellow-orange dry fly tied to sit up on its hackle as a freshly emerged mayfly does, and it is the evening hatch fly through the early part of summer. The hook is a standard dry-fly wire in sizes 14 through 18, the thread yellow 8/0, the tail pale dun hackle fibres, the body pale yellow-orange sulphur dubbing, the wings pale dun hen tips set upright, and the hackle pale ginger or cream. It is tied against the sulphur, Ephemerella dorothea and invaria, which comes off from May through July in water between 52 and 68 degrees, and against the pale morning dun, Ephemerella excrucians, in June and July from 50 to 65 degrees. Its hour is the last one of light, late May through early July, and the fly is fished until it can no longer be seen and then fished a while longer after that. Carried through the summer, tied for trout.

#14–18Hook size
dry flyType
SummerSeason
4Hatches matched

What it looks like

A drawing, not a photograph, and not traced from one. Its proportions were read off 5 independent reference photographs of the pattern and written down as 5 measured characteristics — wing angle, tail length against the shank, how far a hackle fibre reaches — every one of which had to hold across more than one of them before it could be drawn. What survives across many photographs of a fly is the fly.

The May and June evening fly on limestone and freestone alike. Pale yellow body, upright pale wings — matched to the hatch rather than a searching pattern, and it shows when a Parachute Adams starts getting refused. Drawn at #16 — 7.0 mm of shank and 3.5 mm of gape on a Tiemco 100.

The bare hook at every size this pattern is tied in, all to the same scale. There is no industry standard behind a hook number, so these are Tiemco 100 measurements and another maker's 14 will differ a little.

What it imitates

Each of these is the same hatch record the app's own panel reads, so a pattern recommended on a river card in the app is recommended for one of the insects below.

Tying recipe

In tying order. This dressing is the standard one — these patterns have been in the publicrecord for decades — and materials substitute freely: the proportions and the silhouette are the pattern, not the brand of dubbing.

Hook	Standard dry-fly hook, sizes 14–18
Thread	Yellow 8/0
Tail	Pale dun hackle fibres
Body	Pale yellow-orange sulphur dubbing
Wings	Pale dun hen tips, upright
Hackle	Pale ginger or cream

When to fish it

The last hour of light, late May through early July. Fish it until you cannot see it, then keep fishing it.

A summer pattern. The insects it matches are active may–september, in water from 50°F to 70°F.

Target species

Trout

Rivers it fishes well

Rivers with a page here that sit in the regions where the insects this pattern imitates are recorded. It is a claim about coverage, not a report of a fish caught.

Related patterns

Same type of fly, or tied for the same insects.

Open the trout map →Every trout stream near you, coloured by today's water temperature.