Large Crane Flies, Family Tipulidae

Habits and Traits of Large Crane Flies

Crane fly.
To some, a crane fly looks like a giant mosquito. Pennsylvania Department of Conservation and Natural Resources - Forestry, Bugwood.org

Large crane flies (Family Tipulidae) are indeed large, so much so that most people think they're giant mosquitoes. There's no need to worry, because crane flies don't bite (or sting, for that matter).

Please note that members of several other fly families are also referred to as crane flies, but this article focuses only on the large crane flies classified in the Tipulidae.

Description:

The family name Tipulidae derives from the Latin tipula, meaning "water spider." Crane flies are not spiders, of course, but do appear somewhat spider-like with their extraordinarily long, slender legs.

They range in size from tiny to large. The biggest North American species, Holorusia hespera, has a wingspan of 70mm. The largest known tipulids  inhabit southeastern Asia, where two species of Holorusia measure a whopping 10 cm or more in wingspan.

You can identify crane flies by two key features (see this interactive labelled image of each ID feature) First, crane flies have a V-shaped suture running across the upper side of the thorax. And second, they have a pair of conspicuous halteres just behind the wings (they look similar to antennae, but extend from the sides of the body). Halteres work like gyroscopes during flight, helping the crane fly stay on course.

Adult crane flies have slender bodies and a single pair of membranous wings (all true flies have one pair of wings). They're typically unremarkable in color, though some bear spots or bands of brown or gray.

Crane fly larvae can withdraw their heads into their thoracic segments.

They're cylindrical in shape, and slightly tapered at the ends. They generally inhabit moist terrestrial environments or aquatic habitats, depending on the type.

Classification:

Kingdom - Animalia
Phylum - Arthropoda
Class – Insecta
Order – Diptera
Family - Tipulidae

Diet:

Most crane fly larvae feed on decomposing plant matter, including mosses, liverworts, fungi, and rotting wood.

Some terrestrial larvae feed on the roots of grasses and crop seedlings, and are considered pests of economic concern. Though most aquatic crane fly larvae are also detritivores, some species prey on other aquatic organisms. As adults, crane flies are not known to feed.

Life Cycle:

Like all true flies, crane flies undergo complete metamorphosis with four life stages: egg, larva, pupa, and adult. Adults are short-lived, surviving just long enough to mate and reproduce (usually less than a week). Mated females oviposit either in or near water, in most species. Larvae may live and feed in the water, underground, or in leaf litter, again, depending on the species. Aquatic crane flies usually pupate underwater, but emerge from the water to shed their pupal skins well before sunrise. By the time the sun rises, the new adults are ready to fly and begin searching for mates.

Special Behaviors and Defenses:

Crane flies will shed a leg if needed to escape the grasp of a predator. This ability is known as autotomy, and is common in long-legged arthropods like stick insects and harvestmen. They do so by means of a special fracture line between the femur and trochanter, so the leg separates cleanly.

Range and Distribution:

Large crane flies live throughout the world, with over 1,400 species described globally. Just over 750 species are known to inhabit the Nearctic region, which includes the U.S. and Canada.

 

Sources:

  • Borror and DeLong's Introduction to the Study of Insects, 7th Edition, by Charles A. Triplehorn and Norman F. Johnson.
  • Encyclopedia of Entomology, 2nd Edition, edited by John L. Capinera.
  • Catalogue of the Craneflies of the World, Pjotr Oosterbroek. Accessed online October 17, 2015.
  • Tipulidae – Crane Flies, Dr. John Meyer, Department of Entomology, North Carolina State University. Accessed online October 17, 2015.
  • Family Tipulidae – Large Crane Flies, Bugguide.net. Accessed online October 17, 2015.
  • Crane Flies, Missouri Department of Conservation website. Accessed online October 17, 2015.
  • Insect Defenses, Dr. John Meyer, Department of Entomology, North Carolina State University. Accessed online October 17, 2015.