Anglers Fishing Guide to Montana Insects: Beetles

An Introduction to Beetles

Beetles are particularly important to Montana fly fishing during the late summer in high elevation streams and lakes.

The Fins and Feathers team of Bozeman fly fishing guides relies on beetle imitations during September and August when working wary trout on the upper Yellowstone River and Depuy's Spring Creek.

Characteristics of Beetles

• Beetles feature tough, solid bodies, powerful jaws, and modified wings.
• Their first pair of wings is small and very hard acting as a protective covering for the 2^nd pair of wings, which can allow flight in some species.
• Most adults are black or brown, but there are some species that are brightly colored.
• They vary in size from hook size #12 through #18.

Overview of the Beetle Lifecycle

• Female beetles lay fertilized eggs in rotting wood, decaying leaves, or even in rotting animals.
• Once hatched, the larvae feeds until its skin becomes too small and it splits so it can crawl out and a new skin form and hardens in the molting process. This is usually repeated 3-5 times until it is fully mature.
• During the pupal stage, beetles’ morphology is similar to an adults’ except with a soft exoskeleton.
• Once the pupa skin is shed, the adult emerges where the wings are full sized, and the exoskeleton hardens.
• This process happens anywhere from 1-4 years and adults typically emerge in summer.

Top 5 Beetle Dry Fly Patterns for Fly Fishing in Montana

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