Insect Encyclopedia
Spring Stonefly
Nemouridae
Nemouridae
StoneflyHook #16-186-9 mm body
Peak activity
JanFebMarAprMayJunJulAugSepOctNovDec
Nymph
Flattened body with two tail cerci; found under rocks in riffles.
Adult
Four wings folded flat over the back; long antennae.
Habitat & hatch
Found in rivers and tailwaters, most commonly in riffles and bank. Nymphs under rocks; adults crawl out on banks and boulders. Often associated with cobble and boulder. Nymphs crawl to rocks and banks to emerge; adults often found on riparian vegetation.
Timing
Individual emergence windows typically last 7 to 21 days. Strongest surface activity occurs around the morning, and the afternoon.
Sources
- AB Fish Report synthesis from peer-reviewed Alberta and western North America literature.