Hatches are temperature- and photoperiod-driven, repeating in roughly the same window each year. Sulphur, blue-winged olive, green drake, hendrickson, and various caddisflies have predictable hatch windows. Hatch calendar pages cover specific rivers and species.
Freshwater Trout & Hatches
What is a hatch and why does it matter for fly fishing?
A hatch is the mass emergence of aquatic insects (mayflies, caddisflies, stoneflies) from their underwater larval stage to airborne adult form. Trout feed selectively on whatever's hatching, often ignoring other food entirely during peak emergence. "Matching the hatch" — using a fly that imitates the active insect — is the foundation of dry-fly fishing.
More from Freshwater Trout & Hatches
- When is the sulphur hatch on Eastern trout streams?
- What is the green drake hatch and why is it so famous?
- What is a Blue Winged Olive hatch?
- How do I match the hatch when trout are rising?
- What water temperature triggers mayfly hatches?
- What time of day do most hatches occur?
- What is a spinner fall and how do I fish it?
- What is the difference between a dry fly and a nymph?
Bield Fish earns its predictions.
14-day free trial. No credit card. Cancel anytime.