Crane fly


Crane fly is a common name referring to any member of the insect family Tipulidae, of the order Diptera, true flies in the superfamily Tipuloidea. Cylindrotominae, Limoniinae, and Pediciinae have been ranked as subfamilies of Tipulidae by most authors, though occasionally elevated to family rank. In the most recent classifications, only Pediciidae is now ranked as a separate family, due to considerations of paraphyly. In colloquial speech, crane flies are sometimes known as mosquito hawks or daddy longlegs, a term also used to describe opiliones or the family Pholcidae, both of which are arachnids. The larvae of crane flies are known commonly as leatherjackets.
Crane flies have existed since at least the Barremian stage of the Early Cretaceous and are found worldwide, though individual species usually have limited ranges. They are most diverse in the tropics but are also common in northern latitudes and high elevations.
The Tipulidae is one of the largest groups of flies, including over 15,000 species and subspecies in 525 genera and subgenera. Most crane flies were described by the entomologist Charles Paul Alexander, a fly specialist, in over 1000 research publications.

Description

Summary

An adult crane fly, resembling an oversized mosquito, typically has a slender body and stilt-like legs that are deciduous, easily coming off the body. The wingspan is generally about 1.0 to 6.5 cm, though some species of Holorusia can reach 11 cm. The antennae have up to 19 segments. It’s also characterized by a V-shaped suture or groove on the back of the thorax and by its wing venation. The rostrum is long and in some species as long as the head and thorax together.

Formal

Tipulidae are large to medium-sized flies with elongated legs, wings, and abdomen. Their colour is yellow, brown or grey. Ocelli are absent. The rostrum is short to very short with a beak-like point called the nasus. The apical segment of the maxillary palpi is flagelliform and much longer than the subapical segment. The antennae have 13 segments. These are whorled, serrate, or ctenidial. There is a distinct V-shaped suture between the mesonotal prescutum and scutum. The wings are monochromatic, longitudinally striped or marbled. In females the wings are sometimes rudimentary. The sub-costal vein joins through Sc2 with the radial vein, Sc1 is at most a short stump. There are four, rarely three branches of the radial vein merging into the alar margin. The discoidal wing cell is usually present. The wing has two anal veins. Sternite 9 of the male genitalia has, with few exceptions, two pairs of appendages. Sometimes appendages are also present on sternite 8. The female ovipositor has sclerotized valves and the cerci have a smooth or dentate lower margin. The valves are sometimes modified into thick bristles or short teeth.
The larva is elongated, usually cylindrical. The posterior two-thirds of the head capsule is enclosed or retracted within the prothoracic segment. The larva is metapneustic, but often with vestigial lateral spiracles. The head capsule is sclerotized anteriorly and deeply incised ventrally and often dorsolaterally. The mandibles are opposed and move in the horizontal or oblique plane. The abdominal segments have transverse creeping welts. The terminal segments of the abdomen are glabrous, often partially sclerotized and bearing posterior spiracles. The spiracular disc is usually surrounded by lobe-like projections and anal papillae or lobes.

Biology

The adult female usually contains mature eggs as she emerges from her pupa, and often mates immediately if a male is available. Males also search for females by walking or flying. Copulation takes a few minutes to hours and may be accomplished in flight. Adults have a lifespan of 10 to 15 days. The female immediately oviposits, usually in wet soil or mats of algae. Some lay eggs on the surface of a water body or in dry soils, and some reportedly simply drop them in flight. Most crane fly eggs are black in color. They often have a filament, which may help anchor the egg in wet or aquatic environments.
Crane fly larvae have been observed in many habitat types on dry land and in water, including marine, brackish, and fresh water. They are cylindrical in shape, but taper toward the front end, and the head capsule is often retracted into the thorax. The abdomen may be smooth, lined with hairs, or studded with projections or welt-like spots. Projections may occur around the spiracles. Larvae may eat algae, microflora, and living or decomposing plant matter, including wood. Some are predatory.

Ecology

Larval habitats include all kinds of freshwater, semiaquatic environments. Some Tipulinae, including Dolichopeza Curtis, are found in moist to wet cushions of mosses or liverworts. Ctenophora Meigen species are found in decaying wood or sodden logs. Nephrotoma Meigen and Tipula Linnaeus larvae are found in dry soils of pasturelands, lawns, and steppe. Tipulidae larvae are also found in rich organic earth and mud, in wet spots in woods where the humus is saturated, in leaf litter or mud, decaying plant materials, or fruits in various stages of putrefaction.
Larvae can be important in the soil ecosystem, because they process organic material and increase microbial activity. Larvae and adults are also valuable prey items for many animals, including insects, spiders, fish, amphibians, birds, and mammals.
The larvae of some species consume other living aquatic insects and invertebrates, which could potentially include mosquito larvae. Many adults, however, have such short lifespans that they do not eat at all, and, despite widely held beliefs that adult crane flies prey on mosquito populations, the adult crane fly is anatomically incapable of killing or consuming other insects.

Pest status

The common European crane fly, Tipula paludosa, and the marsh crane fly, T. oleracea, are agricultural pests in Europe. Crane fly larvae of economic importance live in the top layers of soil where they feed on the roots, root hairs, crown, and sometimes the leaves of crops, stunting their growth or killing the plants. They are pests on a variety of commodities. Since the late 1900s, T. paludosa and T. oleracea have become invasive in the United States. The larvae have been observed on many crops, including vegetables, fruits, cereals, pasture, lawn grasses, and ornamental plants.
In 1935, Lord's Cricket Ground in London was among venues affected by leatherjackets. Several thousand were collected by ground staff and burned, because they caused bald patches on the wicket and the pitch took unaccustomed spin for much of the season.

Genera

The phylogenetic position of the Tipulidae remains uncertain. The classical viewpoint that they are an early branch of Diptera—perhaps the sister group of all other Diptera—is giving way to modern views that they are more highly derived. This is thanks to evidence from molecular studies, which is consistent with the more derived larval characters similar to those of 'higher' Diptera. The Pediciidae and Tipulidae are sister groups and the Cylindrotominae appear to be a relict group that was much better represented in the Tertiary. Tipulidae probably evolved from ancestors in the Upper Jurassic, the Architipulidae.

Common names

Numerous other common names have been applied to the crane fly. Many of the names are more or less regional in the U.S., including mosquito hawk, mosquito eater, gallinipper, and gollywhopper. They are also known as daddy longlegs around the world, not to be confused with daddy-long-legs that refers to arachnids of the order Opiliones or the family Pholcidae. The larvae of crane flies are known commonly as leatherjackets.

Misconceptions

There is an enduring urban legend that crane flies are the most venomous insects in the world, but have no ability to administer the venom; this is not true. The myth likely arose due to their being confused with the cellar spider as they are also informally called "daddy longlegs", and although the spider does possess venom, this has also been debunked.
Crane flies are sometimes called "mosquito hawks", but they do not actually eat mosquitoes. Most crane fly larvae are scavengers or herbivores, while adults, if they feed at all, feed primarily on liquids such as nectar.

Species lists