Green Rock Worm / Free-living Caddis
Nymphs are in the water all year, long before and after the hatch window — the season and temperature figures on this card describe when the adults emerge, not when this stage is available. It very nearly always is.
No case and no net — this one roams the stones hunting other insects, and it's a predator rather than a shredder. Bright green, conspicuous, and genuinely active, especially as the light goes. That movement is the point: unlike almost every other caddis larva, a little life in the retrieve is right rather than wrong.
- New ZealandPresent
Hydrobiosis is a genus of free-living, predatory caddisflies (family Hydrobiosidae) endemic to the southwestern Pacific — New Zealand, the Chatham Islands, Tasmania, South Australia and Fiji. Mature larvae actively hunt other invertebrates rather than build a case or net; younger stages take organic detritus and algae. Known to NZ anglers as the green rock-worm, the ecological analogue of the Northern Hemisphere's Rhyacophila.