crane fly, true fly resembling a mosquito, often called daddy longlegs because of its six long, delicate legs. (The harvestman, also called daddy longlegs, belongs to an unrelated order.) Most species of crane flies have a single pair of wings and slender bodies. They feed upon plant substances and frequent damp places in pastures and meadows. Crane flies belong to the phylum Arthropoda, class Insecta, order Diptera, family Tipulidae.