Damsel
Olive marabou and a slim body on a long-shank hook, designed to undulate on the retrieve like a nymph swimming to the margins. Fish it on a slow figure-of-eight through weedy bays in June and July. When damsel migration is on, trout cruise predictable lanes to intercept them — put this in the path and the rest takes care of itself.
Summer on stillwaters and slow reaches when nymphs are migrating through vegetation. Fish it with jerky, darting strips.
Swimming action of the natural. Bright colours (olive, green, brown) are visible against weeds. Mimics rapid acceleration of hunting nymphs.
Starting points, not rules — depth, presentation and size usually matter more.
Olive is the natural default, especially when real damsel nymphs are present — try a darker olive in low light or over dark weed. Add blue flash, gold or an orange head in coloured water, early season, or for stocked fish. Use slimmer, duller olive versions in clear summer water.