Mayfly Overview

Overview: Mayflies are an iconic group of aquatic insects that play a vital role in freshwater ecosystems and fly fishing. Found in rivers, lakes, and streams, these delicate insects are known for their synchronized, seasonal hatches that bring trout to the surface in feeding frenzies. Mayflies have three main life stages—nymph, dun (sub-adult), and spinner (adult)—each offering unique opportunities for anglers to imitate and target.

Nymph Stage: Mayfly nymphs vary in size but are typically between 1/4 to 1 inch long. They range in color from olive and brown to tan and yellow, often with darker or mottled patterns. Hook sizes 12–18 are most common for imitations. These nymphs are excellent swimmers or clingers, depending on the species, and are often active during non-hatch periods. Fishing nymphs dead-drifted near the bottom is a reliable tactic.

Adult or Dry Stage: Mayfly adults (duns) are delicate and vary in size from 1/4 to 3/4 inch. They display a variety of colors, including olive, yellow, tan, or light gray, often with translucent or veined wings. Hook sizes 10–20 are typically used for adult imitations. Mayfly hatches often occur in the evening, with duns emerging on the surface, making dry flies incredibly effective. Spinner falls, where spent adults return to the water, are prime opportunities for targeting rising trout.