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Month: October 2021

Pteronarcys dorsata – Giant Stonefly

Pteronarcys dorsata – Giant Stonefly

Pteronarcys (pronounced tear-a-nar-sis) dorsata is the largest stonefly found in the Upper Midwest trout streams. Its common name is the Giant Stonefly and out West it is called the American Salmonfly. The nymphs take 2-4 years to fully develop. So, these large morsels are trout food 24/7, all season long. In the cold-water trout streams of northern Wisconsin, you can find these big nymphs underneath decaying logs and branches in the shallows. Pteronarcys stonefly nymphs feed on detritus and diatoms….

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Hatch Guide for Upper Midwest Streams

Hatch Guide for Upper Midwest Streams

Ann Miller’s book, Hatch Guide for Upper Midwest Streams is an excellent reference guide to the upper Midwest aquatic insects. There is a wealth of useful information in this book without getting too deep into aquatic entomology and insect anatomy. The paperback book measures only 6″ x 4″ x 3/4″. So, it is easy to carry with you and covers all the commonly found aquatic insects in the Upper Midwest trout streams. Ann Miller, the author is an aquatic biologist…

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Mayfly & Stonefly Nymph Instar

Mayfly & Stonefly Nymph Instar

For mayfly nymphs and stonefly nymphs to develop from an egg to a mature nymph they go through several instars. Each instar period ends when the nymph sheds their existing exoskeleton. Then over 2-3 days a new exoskeleton hardens, which marks the beginning of the next instar period. Depending on the mayfly nymph species they go through 11-13 instars as they develop from an egg to a mature nymph. Most mayfly nymphs in our trout streams develop over a 1-year…

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