Grannom
Brachycentrus subnubilis — Green Tail Caddis, Green Flag Caddis
The first major caddis of the year — appearing in huge April swarms, the Grannom kick-starts the surface fly fishing season on chalk streams.
Caddisflies — Trichoptera
Brachycentridae
Body 7–10 mm / Hook size 14–16
Midday
Chalk streams and moderate-paced gravel rivers
Lifecycle
The Grannom larva builds distinctive square-sectioned cases from fine sand grains and plant material. The pupal stage lasts approximately two weeks. When ready to hatch, the pupa cuts free from its case and ascends to the surface in mid-water, then hatches rapidly through the film.
Peak months
The Grannom hatch in April is one of the great spectacles of the chalk stream season. On a warm April morning, the surface suddenly fills with dozens, then hundreds of small brown caddis with distinctive bright green egg sacs at their tails.
Fishing tips
The Emerging Pupa
Start with a Grannom Pupa or Cased Caddis Nymph in the hour before surface activity begins. Ascending pupae are easy targets for trout; fish the nymph on a dead-drift just below the surface film, then skate it upward to mimic a pupa breaking through.
Fly patterns
Other hatches
TerrestrialsBlack Gnat
Bibio johannisA ubiquitous summer terrestrial — the Black Gnat is available to fish on virtually every European river when other hatches are quiet.
MayfliesBlue Winged Olive
Serratella ignitaThe most important small olive on British and European chalk streams — reliable, widespread, and technically demanding.
Midges & DipteraBuzzer / Midge
Chironomidae sp.The most important insect of all on stillwaters — year-round, in every month, on every productive lake and reservoir in Europe.
MayfliesCaenis
Caenis horariaThe infuriatingly tiny mayfly that hatches in such vast numbers that fish refuse to look at anything larger — the tying and presentation challenge of a lifetime.
CaddisfliesCinnamon Sedge
Limnephilus lunatusA common summer evening caddis found across Europe — its reliable evening hatches from June to August provide consistent dry fly fishing.
