any of numerous dull-colored primitive aquatic insects of the order Plecoptera, having a distinctive flattened body shape: a major food source for game fish, esp. bass and trout, which makes them popular as models for fishing flies.
Origin: 1400–50; late ME ston flie.See stone, fly2
primitive winged insect with a flattened body; used as bait by fishermen; aquatic gilled larvae are carnivorous and live beneath stones [syn: stonefly]