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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington
This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

True Bugs

This common name refers to only one order. Click its scientific name to learn more.

Insect Order Hemiptera

These are often called True Bugs.
The large, diverse family of "true bugs" contains several insects of importance to anglers, both aquatic and terrestrial.

Perhaps the best known are the water boatmen of Corixidae, which are a primary trout food source at times in many high lakes, spring ponds, and slow-moving rivers. They are generally aquatic, although they may come out of the water to mate. I have seen good numbers of them flying over a northwoods river in late March, a sight that had me baffled until I captured one of the odd insects that kept flying past me and plunging into the water.

Other aquatic true bugs have received very little attention in
fly fishing literature, but they probably deserve more, because they are among the largest insects native to the trout's environment. The giant water bugs of Belostoma are especially favored, but trout also feed on the water scorpions of Nepidae. I plan soon to spend more time researching and imitating these insects to confirm my hunches and early observations.

The most famous terrestrial members of Hemiptera are the cicadas, which make for good fishing on those rare years when a large brood appears. Late every summer some fly fishers turn to tiny related terrestrials they call Jassids, which are the leaf hoppers and tree hoppers of the families Membracidae and Cicadellidae.
Dorsal view of a Ranatra (Nepidae) Water Scorpion Adult from unknown in Wisconsin
Here's a big water scorpion (no relation to actual scorpions). These guys are just about the most sinister-looking creatures you could find, and what's especially creepy is that they can come up out of the water and fly around, as I learned when one left my aquarium and buzzed my head while I was peeking into the microscope at a mayfly nymph.

True Bugs

Scientific Name
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