The young of these insects are commonly called hellgrammites (hellgrammites sold as bait are usually dragonfly nymphs). Trout and other fish find them delicious. To avoid becoming trout food, the nymph hides under rocks and comes out mostly at night. Fishflies and dobsonflies have little hooks at the end of their tails that help them hang onto rocks and sticks in fast-moving water. Fishfly and alderfly nymphs are carnivores and sometimes cannibals, feeding on other smaller insects and each other! Don't worry about those strange spines on their side; those are gills. But do watch out for their strong jaws. Large alderflies and dobsonflies can give a painful bite. Ouch!
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