Stonefly nymph (likely)

Freshwater streams and cool, well-oxygenated rivers; adults may rest on nearby walls, vegetation, or buildings. The pictured insect’s slender body and long antennae suggest a recently emerged adult.

Nymphs feed on algae, leaf litter, and aquatic microorganisms; some are predatory. Adults usually eat little or nothing and may consume algae or nectar.

Nymphs crawl among streambed stones for months to several years, then emerge as winged adults. Adults are generally nocturnal or weak fliers and often remain near water.

Harmless to people and pets; they do not bite or sting. Stoneflies are valuable decomposers and important fish prey, and their presence commonly indicates clean, well-oxygenated water.