Non-biting midges are everywhere, and Antarctica's largest land animal is one
They look like mosquitoes, go by names like chizzywinks and Canadian soldiers, and emerge in clouds thick enough to coat windshields. Yet chironomid midges cannot bite. With well over 10,000 species, they live from glacier-fed mountain streams to the deepest lakes, and a wingless one is the biggest land animal in Antarctica.
The family name comes from an Ancient Greek word for a pantomime performer. Males are easy to spot by their feathery antennae, and adults lack the wing scales and long piercing mouthparts of true mosquitoes. Their common names are a muddle: lake flies in parts of Canada, bay flies around Green Bay, blind mosquitoes in Florida. The oldest known fossil, Aenne triassica, dates to the Late Triassic.
For a century, reference books claimed adults never eat. That turns out to be wrong for many species, which sip nectar, honeydew and pollen, and even fresh fly droppings. In experiments, Chironomus midges that fed on sugar flew far longer than starved ones. Males seem to spend the extra energy on flight while females use it to live longer.
Larvae live almost anywhere wet: tree holes, bromeliads, sewage, tidal flats and oxygen-poor mud. Some are bright red bloodworms, coloured by a haemoglobin-like pigment that helps them grab scarce oxygen. Clunio midges time their whole life cycle to the tides, making them a model for studying biological clocks. The larvae also spin silk, which researchers have studied as a source that can be harvested without killing the insect.
Because they tolerate low oxygen and shifting salinity, the mix of species in a lake reveals pollution, and fossil midges help reconstruct past climates. They feed trout, sticklebacks, swallows, bats and newly hatched tufted ducklings. Identifying them is hard; many sibling species look identical and are told apart by rearing males or reading the banded giant chromosomes in larval salivary glands, first seen in these midges in 1881.
Source: Chironomidae
