[7][8] They are also sometimes called "daddy longlegs",[7] a name which is also used for arachnids of the family Pholcidae and the order Opiliones.

[7] It is also characterized by a V-shaped suture or groove on the back of the thorax (mesonotum) and by its wing venation.

[16] Larvae occur in various habitats including marshes, springs, decaying wood, moist soil, leaf litter, fungi, vertebrate nests and vegetation.

[12] Tipuloidea are medium to large-sized flies (7–35 mm, 1⁄4–1+1⁄2 in) with elongated legs, wings, and abdomen.

There is a distinct V-shaped suture between the mesonotal prescutum and scutum (near the level of the wing bases).

The female ovipositor has sclerotized valves and the cerci have a smooth or dentate lower margin.

[17] The adult female usually contains mature eggs as she emerges from her pupa, and often mates immediately if a male is available.

Some lay eggs on the surface of a water body or in dry soils, and some reportedly simply drop them in flight.

[16] They are cylindrical in shape, but taper toward the front end, and the head capsule is often retracted into the thorax.

[16] Larvae may eat algae, microflora, and living or decomposing plant matter, including wood.

Larvae can be important in the soil ecosystem, because they process organic material and increase microbial activity.

[11] Larvae and adults are also valuable prey items for many animals, including insects, spiders, fish, amphibians, birds, and mammals.

[16] Adult crane flies may be used for transport by aquatic species of the mite family Ascidae.

[19][20][21] The larvae have been observed on many crops, including vegetables, fruits, cereals, pasture, lawn grasses, and ornamental plants.

The classical viewpoint that they are an early branch of Diptera[23][24]—perhaps (with the Trichoceridae) the sister group of all other Diptera—is giving way to modern views that they are more highly derived.

[25] This is thanks to evidence from molecular studies, which is consistent with the more derived larval characters similar to those of 'higher' Diptera.

[29] In Ireland, they are generally called 'daddy long legs' in English, whereas in Irish they are commonly known as Pilib an Gheataire, which means Skinny Philip.

[31] The myth probably arose due to their being confused with the cellar spider as they are also informally called "daddy longlegs", and although the arachnid does possess venom, it is not especially potent.