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Grannom Emergers

Grannom (Brachycentrus subnubilis) are a member of the Caddis family (Trichoptera order) and are among the first of the UK’s major hatches in Spring. Hatches can be huge, and I mean massive, to the point where every Grannom seemingly tries to crawl up your waders, under your glasses, down your neck, or smack into you as they are blown up or downstream by the usually unstable Spring weather.

Trout can go crazy during these hatches; however, it never appears to be the adult Grannom they are interested in. Instead, trout will usually gravitate to the emerging Grannom or pupa (and even their empty shucks), which (should you be lucky enough to experience these hatches on your rivers) will be drifting downstream in their millions.

Grannom (Brachycentrus subnubilis)

I recently posted an article on Facebook that detailed a great Grannom hatch on the River Usk in Wales, and following a few requests for the makeup of the Grannom pattern I used, I thought I’d put a quick article together.

Like a host of other anglers, I’ve not had a huge amount of success targetting feeding fish with adult imitations. They seem interested in the pupa and emerging stages of the invertebrate but seem too full to bother with the adults.

For years, I used the wonderful and inspired emerger tied by the Gwent Angling Society’s Dr David Collins; however, I’m a simple guy with simpler fly pattern tastes. Being able to remove the need to prepare the wing buds, for example, whilst still retaining the key triggers, was what I was looking to achieve.

A freshly emerging Grannom, clawing its way from its pupa shuck.

The below pattern is a super-simple Grannom pupa emerger. It could, in fact, probably be made even simpler by removing the thorax cover (the imitation doesn’t really need this); however, the main triggers and key materials we’re trying to utilise are outlined below.

  1. A slightly bulbous body (remember, we aren’t tying an ephemera imitation)
  2. The use of a dirty or washed-out yellowy-olive-green body further intensified by utilising a black thread underbody
  3. A dark rib
  4. A thorax with a hint of black (to give an approximation of legs) and orange (which is prevalent on the naturally emerging invertebrates).

The Semperfli Sparkle Dubbing is a superb choice for the body and thorax. Not only does it offer the colours we require, but it also lends itself perfectly to the translucency of the emerging pupa and gives just enough seal’s-fur-esque properties, perfect for imitating legs.

Finally, an important note regarding hook choice. Trout can hit these emergers violently hard – and why wouldn’t they? They’ve waited all winter for such hatches to start. Having the pattern tied on an appropriately strong hook pattern is key for me. For this, I love the Partridge of Redditch Grub/Shrimp (K4A/S) hook, and, in fact, I dress most of my emerges on this hook. Its gauge allows the butt of any emerger to penetrate the surface film and boasts some serious grunt when hooking and playing larger fish. As such hatches will attract the attention of seemingly every fish in the river, it is realistic to expect big trout attention, so whichever hook pattern you use, make sure it’s appropriate to handle the big girls.

When you’re in the middle of a Grannom hatch (having waited a winter’s eternity for such a hatch), I wouldn’t be without this emerger imitation. As long as you have an appropriately sized pattern that gives you confidence (whether that be similar to the above CdC-style emerger, a Klinkhamer-style pattern, etc.), have some fun and enjoy one of the first truly spectacular hatches of the season!

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