The Grannom is one of the most important spring caddis hatches in the UK and often provides the first truly prolific surface sport of the trout season. Unlike the Mayfly, which arrives later and attracts most of the attention, the Grannom hatch can produce exceptional fishing during April, particularly on freestone rivers where trout have been waiting for a substantial food source after the long winter.
Grannom are caddis flies rather than upwing flies. The larvae live on the riverbed in protective cases before transforming into pupae. When ready to hatch, the pupae swim rapidly towards the surface where the adults emerge. This ascent is one of the most vulnerable stages of the insect's life cycle and trout often feed aggressively on the ascending pupae long before adult flies begin appearing on the surface.
Unlike many upwing fly hatches, Grannom adults are relatively short-lived on the water. Once they emerge they quickly dry their wings and fly away, meaning the pupa is often the most important stage for the angler to imitate. During heavy hatches, trout may feed with complete confidence, switching between ascending pupae, struggling emergers and freshly hatched adults within minutes.
The hatch is often concentrated around the middle of the day and can begin very suddenly. One moment the river appears lifeless, then within a few minutes the air is full of fluttering caddis and trout are rising confidently throughout the pool. Having the correct flies ready before the hatch starts is often the difference between success and frustration.
Although dry fly fishing during a Grannom hatch can be outstanding, many experienced anglers continue fishing pupae just beneath the surface film. Trout frequently intercept the insects before they emerge, making a naturally drifting pupa one of the most effective patterns of the day.
At Peaks Fly Fishing, we regard the Grannom as one of the highlights of the spring season. While many anglers are already looking ahead to the Mayfly, the Grannom regularly produces some of the year's most consistent dry fly fishing. Understanding that trout often prefer the pupa to the adult will put considerably more fish in the net.
## Recommended Fly Patterns
### Larvae / Pupa
* Grannom Caddis Pupae Tungsten
* Olive Czech Nymph
* Tungsten Olive Pupa
### Emerger
* Peaks Fly Fishing Grannom Emerger
* Olive Klinkhammer
### Adults
* Grannom
* Elk Hair Caddis
### Alternatives
* Klinkhammer Special
* CDC Sedge
* Hare's Ear Nymph
## Peaks Fly Fishing Tips
* Watch for the hatch around the middle of the day.
* Don't wait until fish are rising before changing your flies.
* Fish pupae just below the surface before switching to adults.
* Caddis often hatch in large numbers over a short period, so be prepared before the action starts.
* If trout seem to ignore your dry fly, they're often taking ascending pupae just beneath the surface instead.
