Flies (order Diptera) can be divided into two large groups, the Brachycera and the Nematocera. The latter group includes mosquitoes (family Culicidae) and many other flies that resemble mosquitoes. Among these mosquito-like flies are the common midges (family Chironomidae).
There are a few obvious (and many more not-so-obvious) differences between adult midges and mosquitoes. First, midges lack the long proboscis of mosquitoes and they don’t bite (they may not even eat). Second, midges have long front legs, and many often rest with their front legs in the air. Mosquitoes normally rest with their hind legs in the air. Finally, midges lack scales along their wing veins, a trait that is indicative of mosquitoes.
Like mosquitoes, midges have worm-like aquatic larvae. Some midge larvae contain hemoglobin and appear red, and are commonly known as bloodworms. The larvae of many species are highly tolerant to polluted water with low dissolved oxygen, and their abundance can indicate poor water conditions. They’re quite common along the lower River Raisin in southeast Michigan, which is subjected to significant agricultural runoff and combined sewer overflows.