Hellgrammites are the fearsome predatory larvae of the dobsonflies. Unlike mayflies, caddisflies, and stoneflies, their life cycle does not include specific points of vulnerability, but the larvae end up in the drift often enough to be important to trout. (Note: Some would say that technically only larvae of the Corydalus genus are hellgrammites, but anglers widely use the term for all larvae in the family.)
This common name refers to only one family. Click its scientific name to learn more.