Plumed Midge

• Its larvae are the so-called bloodworms, deep red because they contain haemoglobin, a pigment exceedingly rare in insects, which lets them breathe in mud that is almost devoid of oxygen.
• The swarms of males dancing over the water at dusk can form columns visible from a distance and set off smoke alarms in riverside towns.
• Its abundance is an indicator of water rich in organic matter: where only chironomids are left, the bed of the lake is badly degraded.
• Its larvae, the well-known bloodworms, are red because they carry haemoglobin dissolved in their haemolymph: that lets them live on the bottom with almost no oxygen and gives them a reserve of about nine minutes at rest.
• Larvae from deep, poorly oxygenated water have more haemoglobin than those from the shore.
• The shape of the tube determines how they feed: in U-shaped tubes they filter the water, in J-shaped tubes they feed on the sediment, and in horizontal ones they do both.
• By pumping water through their tubes they alter the oxygen balance of an entire lake: in Lake Erie much of the drop in bottom oxygen is attributed to them.
• The adult does not bite, and forms huge mating swarms in spring and summer.
• It forms a complex of cryptic species with C. muratensis and C. nudiventris, impossible to separate by adult morphology.

Habitat & environment

Muddy bottoms of lakes, reservoirs and slow rivers

Sources consulted: Walshe (1947, 1951); Soster et al. (2015), Journal of Great Lakes Research; Animal Diversity Web

Best time: Spring and summer, in swarms at dusk over lakes and rivers