Crane flies are found all around the world. These gangly insects look a lot like large mosquitoes, but they’re harmless. Crane flies don’t bite, and many of them don’t even have mouths! Though they can be irritating, crane flies are an important part of the ecosystem.
What Are Crane Flies?
Crane flies (Tipulidae family), sometimes called “mosquito hawks,” are a family of over 15,000 species. Crane flies look a lot like very large mosquitoes, which is no surprise as both belong to the order Diptera of true flies.
These insects have been on earth for a long time. Currently, the earliest evidence of crane flies is dated to be from the Late Barremian stage of the Early Cretaceous period, from about 129 million to 121 million years ago. Crane flies can be found all over the world, and there are three generally agreed-upon subfamilies:
- Cylindrotominae
- Limoniinae
- Tipulinae
Crane flies are easily mistaken for large mosquitoes. They have a wiry, gangly look with thin bodies and long, fragile legs. Mosquito hawk size, not including legs, is usually 0.5 to 0.8 inches long (13 to 20 millimeters), although the largest species, the giant western crane fly (Holorusia hespera), can grow to 1.4 inches (35 millimeters) long.
Most crane flies are found in dull colors, like brown, black, or pale yellow. They have narrow, membranous wings, and their wingspan can range from 1.25 to 2 inches (31 to 50 millimeters). Females may have a broader wingspan than males.
Though they may resemble mosquitoes, there’s no need to fear a crane fly bite. Most species of crane flies have no mouth parts, and the ones that do only drink nectar. Crane flies don’t bite. They don’t sting, either. Though they may show up in large numbers and can be obnoxious, crane flies are harmless.
Crane Fly Habitat
Various species of crane fly can be found all over the world, but they’re often found in similar habitats. The majority of crane fly species are found in moist habitats, usually along the shores of lakes and streams, although some species may be adapted to living in meadows, dry rangelands, and even deserts.
Adult crane flies live only on land, but in their juvenile stages, they're often aquatic or semi-aquatic. Larvae that are fully aquatic can live in:
- Fresh water, especially rapidly flowing rivers and streams
- Brackish water, areas where fresh water and salt water mix
- Intertidal zones, areas where the ocean meets the land between high and low tide
Fully aquatic larvae can live their entire lives underwater, or they may come to the surface for oxygen, depending on the species.
Species that are semi-aquatic often live in damp moss, leaves, or mud along the edges of bodies of water like rivers, lakes, and ponds. Some can live in decaying plants, fungi, and dead wood. They often go through the pupal stages in drier areas than they did in their larval stage.
Mosquito Hawk Diet
Many species of adult crane fly do not eat at all and don’t even have mouths. They’re alive for such a short time that they don’t need to. Those that do eat only drink nectar from flowers.
For crane flies, most of the eating is done during their larval stage. In this stage, they usually feed on decaying plants and vegetation. Some species are reported to eat the roots of forage crops, like grass or hay, and the seedlings of field crops, but this is rare.
Crane Fly Lifespan and Life Cycle
Like many other insect species, crane flies have four stages in their life cycle: egg, larva, pupa, and adult.
Eggs. Female crane flies lay their eggs in moist ground, usually along sources of water but sometimes in over-watered lawns. After six to 14 days, the larvae hatch from the eggs.
Larvae. The larvae of the crane fly look like worms. They have a tough skin, leading to the nickname “leatherjackets.” As the larvae get bigger, they start to outgrow their skin, so they’ll grow a new layer of skin and molt, or shed, the old one. Most species do this about four times. The amount of time the crane fly spends in the larval stage depends on the species and the environment.
After molting for the last time, the crane fly moves into the pupal stage. This stage usually lasts five to 12 days, but some species may stay in this stage for a few months. Pupas often have wing sheaths and prominent eyes and may be covered in spines. During the pupal stage, the body will change, or metamorphose, into the adult form.
Once the crane fly has completely undergone metamorphosis, it breaks from the pupal case. On average, crane flies only live in the adult stage for one to three days. During this stage, they’re focused on reproducing. This short lifespan is why many adults don’t even have mouth parts.
Overall, the lifespan from egg to death may be as short as six weeks. Some species, especially in arctic climates, may last up to five years, likely due to the short arctic summer.
How to Get Rid of Crane Flies
Once crane flies start to break from their pupal case, there isn’t much you can do to control them. You just have to live with them.
While crane flies don’t bite, they can be a nuisance if they get into your house, especially as they hover around the lights. The best thing you can do is keep your windows and doors closed to prevent them from getting inside. If a crane fly does end up in your house, you’ll probably be able to cup it in your hands to let it outside. Crane flies are harmless and focus on conserving energy for mating, so releasing one outside is often easy.
Though they might be a nuisance, crane flies are an important part of the ecosystem. Many different animals, including bats, birds, lizards, predatory insects, and spiders, feed on them, and the abundance of crane flies every year provides plenty of food so these species can thrive.