NymphIso Iso Baby

The Iso Iso Baby is a detailed and realistic imitation of an Isonychia nymph, one of the larger and more prolific mayflies. Its dark body, large white rubber legs, and distinctive markings make it a highly visible and irresistible target for trout.

Season
Summer, Fall
Difficulty
Advanced
Target Species
Trout
Iso Iso Baby - Image source: Orvis
Image source: Orvis

Overview

A modern Isonychia nymph imitation tied Euro-style with dark dubbing, thin ribbing, a tungsten bead, and sometimes rubber legs. It rides hook-up and gets down fast—ideal for late summer and fall Iso hatches in fast water.

Pattern Characteristics

Advanced Difficulty
Trout
Moving Water
Summer
Fall
Imitates: Isonychia Nymph
Variant of: N/A

Materials

Hook: Dai-Riki 300, size #10-#12.
Thread: 8/0 or 70 Denier, black.
Tail and post: Deer hair, cleaned and stacked.
Dubbing: Isonychia dry-fly dubbing.
Hackle: Medium dun.
Legs: Barred round rubber legs.
Thorax: Isonychia dry-fly dubbing.

Fishing Tips

Season

Summer and Fall, during Isonychia hatches.

Presentation

Dead drift along the bottom or in the middle of the water column.

When to Use

This pattern is particularly productive during Isonychia hatches, but can also be effective whenever mayflies are present.

Water Type

This fly is best suited for moving water.

Rigging Suggestions

Try using it as the point fly in a multi-fly rig, with a smaller nymph or emerger pattern trailing behind.

Visibility & Floatation

The dark body and large white legs make this fly highly visible underwater. It is designed to sink and imitate a nymph.