A vocabulary of landscape — a landscape of words
1469 entries
stonefly
A stonefly is an insect whose nymph lives under stones in fast clean cold water, gripping the rock with hooked claws and breathing through gill tufts. It needs high oxygen and will not tolerate silt or pollution, which makes it the most demanding of the standard river indicator groups. The adult is a poor flier with two pairs of wings folded flat along the back, and many emerge in winter.
Etymology
The English name is for where the nymph lives. The scientific order name is Greek and means twisted-wing, from the way the wings lie. Fly fishers have their own names for the large species and their imitations, including the salmonfly of western American rivers, whose emergence is one of the fixed events of the fishing calendar.
Notes
The presence or absence of stoneflies is one of the fastest reads available on a river. Kick a sample from the gravel and count the mayfly, stonefly, and caddis species. Stoneflies are the most demanding of the three, so a good stonefly list means water that is clean, cold, and well oxygenated. Some species emerge and mate on snow in midwinter.