Evening insect pulses on the Itchen
River Itchen (Winchester–Alresford) July evenings: caddis spinners trigger the rise
On this spring-blank chalkstream the evening caddis spinner fall and PMD dusk emergence set the calendar. Caddis pupae twitch to the film then collapse as spinners; PMD and Grannom dusk spinners follow, and the clock for aggressive surface feeding runs roughly 18:30–20:30 when water sits around 14–16°C.
Brown trout, typically 30–40 cm with occasional 18+ inch residents, hold in deeper runs 18–24 inches deep by boulders and root-ups until the hatch draws them into 6–10 inch glides. They are highly selective: emergers take priority early in the hatch; as light dies they switch to spent spinners and drowned adults with brutal decisiveness.
Gear and flies that work
A 9ft 4wt or 5wt with delicate taper is the ticket. Long nylon leaders 12–14ft into a 5X–6X fluorocarbon tippet are standard; presentation must be feather-light. Patterns that match the pulse: Sparkle Pupa and X-Caddis in 14–16, PMD Emerger 14–16, and Elk Hair Caddis or Spent PMD for the collapse. Fine twitching of emergers through the film often wins where bulkier dries spook the fish.
Conservation-minded anglers note that healthy caddis runs reflect clean, spring-fed flows and rich margins. Weekend beats between Winchester and Alresford reward early arrival, stealthy wading and steady observation of the surface film, where a spent caddis drifting under lantern light is often answered by a single violent slash from a trout.
Recommended: classic dry fly pack