| Crane fly | |
|---|---|
 | |
| Nephrotoma appendiculata (spotted crane fly) | |
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| Crane fly larva | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Diptera |
| Infraorder: | Tipulomorpha |
| Superfamily: | Tipuloidea Latreille, 1802 |
| Families | |
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Acrane fly is any member of thedipteransuperfamilyTipuloidea, which contains the living familiesCylindrotomidae,Limoniidae,Pediciidae andTipulidae, as well as several extinct families.[1] "Winter crane flies", members of the familyTrichoceridae, are sufficiently different from the typical crane flies of Tipuloidea to be excluded from the superfamily Tipuloidea, and are placed as their sister group withinTipulomorpha.[2] Two other families of flies, the phantom crane flies (Ptychopteridae) and primitive crane flies (Tanyderidae), have similar common names due to their similar appearance, but they are not closely related to true crane flies.[3]
The classification of crane flies has been varied in the past, with some or all of these families treated as subfamilies,[4] but the following classification is currently accepted.[5][6][1][7][8] Species counts are approximate, and vary over time.[1]
In colloquial speech, crane flies are known asmosquito hawks or "skeeter-eaters", though they do not actually prey on adultmosquitos or other insects.[9][10] They are also sometimes called "daddy longlegs", a name which is also used for arachnids of the familyPholcidae and the orderOpiliones. Thelarvae of crane flies are known commonly as leatherjackets.[9]
Crane flies first appeared during theMiddle Triassic, around 245 million years ago, making them one of the oldest known groups of flies,[11] andare found worldwide, though individual species usually have limited ranges. They are most diverse in thetropics but are also common in northern latitudes and high elevations.[12]
More than 15,500 species and over 500 genera of crane flies have been described, the majority byC.P. Alexander, who published descriptions of 10,890 new species and subspecies, and 256 new genera and subgenera over a period of 71 years from 1910–1981.[1][13]
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An adult crane fly, resembling an oversized malemosquito, typically has a slender body and long,stilt-like legs that are deciduous, easily coming off the body.[14][5] Like other insects, their wings are marked with wing interference patterns which vary among species, thus are useful for species identification.[15] They occur in moist, temperate environments such as vegetation near lakes and streams.[5] They generally do not feed, but some species consume nectar, pollen, or water.[16]
Thewingspan is generally about 1.0 to 6.5 cm (1⁄2 to2+1⁄2 in), though some species ofHolorusia can reach11 cm (4+1⁄4 in).[17] Theantennae have up to 19 segments.[9] It is also characterized by a 'V'‑shaped suture or groove on the back of thethorax (mesonotum) and by its wing venation.[12] Therostrum is long and in some species as long as the head and thorax together.[18]
Larvae occur in various habitats including marshes, springs, decaying wood, moist soil, leaf litter, fungi, vertebrate nests and vegetation. They usually feed on decaying plant matter and microbes associated with this, but some species instead feed on living plants, fungi, or other invertebrates.[14]
Tipuloidea are medium to large-sized flies (7–35 mm,1⁄4–1+1⁄2 in) with elongated legs, wings, and abdomen. Their colour is yellow, brown, or grey.Ocelli are absent. Therostrum (a snout) is short with a beak-like point called thenasus (rarely absent). The apical segment of the maxillary palpi is flagelliform (whip-like) and much longer than the subapical segment. The antennae have 13 segments (exceptionally 14–19). These are whorled, serrate, or ctenidial (comb-like). There is a distinct 'V'‑shaped suture between the mesonotalprescutum andscutum (near the level of the wing bases). The wings are monochromatic, longitudinally striped or marbled. In females the wings are sometimes rudimentary. The sub-costal vein (Sc) joins through Sc2 with the radial vein, Sc1 is at most a short stump. There are four, rarely (when R2 is reduced) 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 larvae are elongated, usually cylindrical. The posterior two-thirds of the head capsule is enclosed or retracted within the prothoracic segment. The larva is metapneustic (with only one pair ofspiracles, these on the anal segment of the abdomen), but often with vestigial lateral spiracles (rarely apneustic). 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 areglabrous, often partially sclerotized and bearing posterior spiracles. The spiracular disc is usually surrounded by lobe-like projections and anal papillae or lobes.
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Adults have a lifespan of 10–15 days.[19] The adult female usually contains mature eggs as she emerges from herpupa, 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. The female immediatelyoviposits, usually in wet soil or mats ofalgae. 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.[13]
Crane fly larvae (leatherjackets) have been observed in many habitat types on dry land and in water,[13] includingmarine,brackish, andfresh water.[18] 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.[18] Larvae may eat algae, microflora, and living or decomposing plant matter, including wood. Some are predatory.[12][13]
Larval habitats include all kinds of freshwater, semiaquatic environments. Some Tipuloidea, includingDolichopeza, are found in moist to wet cushions of mosses or liverworts.Ctenophora species are found in decaying wood or sodden logs.Nephrotoma andTipula larvae are found in dry soils of pasturelands, lawns, and steppe. Tipuloidea larvae are also found in rich organic earth and mud, in wet spots in woods where the humus is saturated, inleaf 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.[13] Larvae and adults are also valuable prey items for many animals, including insects,spiders,fish,amphibians,birds, andmammals.[18]
Adult crane flies may be used for transport by aquatic species of themite familyAscidae. This is known asphoresis.[20]
Some members of the tipulid genusTipula, such as the European crane fly,Tipula paludosa and the marsh crane flyT. oleracea are agricultural pests in Europe. The larvae of these species live in the top layers of soil where they feed on theroots,root hairs, crown, and sometimes the leaves of crops, stunting their growth or killing the plants. They are pests on a wide variety of plants. Since the late 1900s,T. paludosa andT. oleracea have becomeinvasive in the United States.[21][22][23] The larvae have been observed on many crops, including vegetables, fruits, cereals, pasture, lawn grasses, andornamental plants. Starlings and members of the crow family will predate leatherjackets by probing for them beneath the soil, and the grubs have been successfully controlled by pathogenic nematodes watered on to the ground.[24]
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 thepitch and the pitch took unaccustomed spin for much of the season.[25]
The phylogenetic position of the Tipuloidea remains uncertain. The classical viewpoint that they are an early branch of Diptera[26][27]—perhaps (with theTrichoceridae) thesister group of all other Diptera—is giving way to modern views that they are more highly derived.[28] This is thanks to evidence from molecular studies, which is consistent with the morederived larval characters similar to those of 'higher' Diptera.[29] ThePediciidae and Tipulidae are sister groups (the "limoniids" are a paraphyleticclade).[14] Specifically,Limoniidae has recently been treated by numerous authors at the rank of family, but subsequentphylogenetic analyses revealed that the remaining groups of tipulids render the groupparaphyletic.[14] TheCylindrotomidae appear to be a relict group that was much better represented in theTertiary.[30] Tipulidae probably evolved from ancestors in the UpperJurassic, the Architipulidae, and representatives of theLimoniidae are known from theUpper Triassic.
Numerous 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.[31] They are also known as "daddy longlegs" in English-speaking countries outside the U.S.,[9] not to be confused with the U.S. usages of "daddy long legs" that refer to eitherarachnids of the orderOpiliones or the familyPholcidae. Thelarvae of crane flies are known commonly as leatherjackets.[9]
They are also known as "Jenny long legs" in Scotland.[32] In Ireland, they are generally called "daddy long legs" in English, whereas inIrish they are commonly known asPilib an Gheataire, which means Skinny Philip.[32][33]
There is an enduringurban legend that crane flies are the most venomous insects in the world; however, they have neither venom nor the ability to bite.[34] The myth probably arose due to their being confused with thecellar spider as they are also informally called "daddy longlegs", and although the arachniddoes possess venom, it is not especially potent.[35]
Despite widely held beliefs that adult crane flies (or "mosquito hawks") prey on mosquito populations, the adult crane fly is anatomically incapable of killing or consuming other insects.[36] Although the adults of some species may feed on nectar, the adults of many species have such short lifespans that they do not eat at all.[37]
