European Stonefly

• Stoneflies are the aquatic insects most demanding of oxygen and the first to disappear at the slightest pollution, so their presence is the best sign of a river in excellent condition.
• The adults fly poorly and barely stray from the watercourse; many do not even feed.
• They communicate by drumming the abdomen against the substrate, with rhythmic patterns particular to each species that work as a recognition code.
• It is one of the best bioindicators of water quality in existence. Stoneflies are extraordinarily demanding about dissolved oxygen and vanish at the first sign of organic pollution, so their presence certifies a clean river.
• European biological water-quality indices, such as the IBMWP used in Spain, assign them the highest score for precisely that reason.
• The nymph is predatory and hunts the larvae of other insects beneath the stones of the riverbed; it takes two or three years to develop.
• The adult lives for a few weeks, flies poorly and hardly strays from the river; many species in the group do not even feed.
• They communicate by drumming: males and females tap their abdomens against the substrate, producing rhythmic sequences specific to each species, a vibratory language that takes the place of song.
• They are an ancient lineage, with fossils from the Permian, and they retain traits regarded as primitive among winged insects.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat & environment

Fast, cold, highly oxygenated stretches of mountain streams and rivers

Sources consulted: https://es.wikipedia.org/wiki/Perla_marginata