Their foods include decaying vegetation, fungi, roots, the leaves of emergent plants, and some animal matter. Water larvae are often found among mats of algae or other water plants on the sandy bottom of ponds. The larvae grow to be 13 mm to 38 mm long and are greyish-brown to pale brown depending on the kind or species. When mating, males dance in swarms above bushes and wait to grab or seize females. The pair lands on leaves to mate.
Some flies even mate in mid-air.
Slender eggs are laid in or on moist soil, or at the water's edge. Fully grown larvae turn into pupae in soil or mud. Dark pupae usually live over the winter in the mud. The adult crane flies come out of the pupae in the spring ready to mate. Crane fly adults do not eat.