Crane fly, any insect of the family Tipulidae (order Diptera). Crane flies have a slender mosquito-like body and extremely long legs. Ranging in size from tiny to almost 3 cm (1.2 inches) long, these harmless slow-flying insects are usually found around water or among abundant vegetation. The best-known species, the range crane fly (Tipula simplex), deposits its small black eggs in damp areas. Each egg hatches into a long slender larva, called a leatherjacket because of its tough brown skin. The larvae usually feed on decaying plant tissue; some species are carnivorous, and others damage the roots of cereal and grass crops. The larvae feed all winter, then enter a resting stage in the spring. The adult feeding habits are not yet known. In northern latitudes a species of slow-crawling wingless crane fly is found on snow.

Range crane fly (Tipula simplex) Stephen Dalton—NHPA/Encyclopædia Britannica, Inc.

diagram showing diversity among dipterans Diversity among the dipterans: (from left to right, top) crane fly, horse bot fly, big-headed fly, moth fly, robber fly, (bottom) louse fly, bee fly, horse fly, gall midge, mosquito. From Inverebrate Identification Manual by Richard A. Pimentel, © 1967 by Litton Educational Publishing, Inc. Reprinted by permission of Van Nostrand Reinhold Company

Britannica Quiz Know Your Bugs Quiz Which of these insects is an aerial predator as an adult and an aquatic predator as a larva?

Related to the Tipulidae are the primitive crane flies, Tanyderidae; the phantom crane flies, Ptychopteridae; and the winter gnats, or winter crane flies, Trichoceridae. These families closely resemble the Tipulidae, but the insects are smaller.