Primitive winged insect with a flattened body

• Aquatic insect
• Aquatic gilled larvae are carnivorous and live beneath stones
• Used as bait by fishermen

Wiktionary Word definitions in Wiktionary
n. any insect, of the order Plecoptera, having a flattened body; they are used by fishermen as bait

WordNet Word definitions in WordNet
n. primitive winged insect with a flattened body; used as bait by fishermen; aquatic gilled larvae are carnivorous and live beneath stones [syn: stone fly , plecopteran ]

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
mid-15c., from stone (n.) + fly (n.). So called because the larval forms abound under stones of steams.