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What is a Crane Fly?

O. Wallace
O. Wallace

The crane fly is quite possibly one of the most misunderstood of the insect kingdom. Also known as Daddy Long Legs in England and mosquito hawks or mosquito eaters in the US, crane flies are not spiders, mosquitoes or eaters of mosquitoes. The scientific name of the crane fly is Tipula, and it belongs to the order Diptera. There are many different species of crane fly, but they are difficult to distinguish.

The crane fly is characterized by its six extremely long, skinny legs, which look like the legs of a Daddy Long Legs spider. Their legs can be nearly twice the length of their body and are very fragile. Even the most careful handling can result in the detachment of a leg. This is a beneficial characteristic, as crane flies frequently fall prey to many animals. Their long legs, wings and mouthpiece lead many causal observers to believe that they are giant mosquitoes.

Crane fly larvae can be found on the bank of a stream.
Crane fly larvae can be found on the bank of a stream.

The crane fly is tan to grayish brown, grows up to two and a half inches (6.35 centimeters), and has an approximate three inch (7.62 centimeters) wingspan. Its rather cumbersome body and legs make it a slow moving fly. While crane flies may be a nuisance inside a home, they are harmless.

Crane flies tend to live in wooded areas and open fields, but they can live nearly anywhere, including snowy northern climates and desert lands. In order for their eggs to hatch and larvae to grow into adults, they require either water or damp, decaying material in which to lay their eggs, depending on the species. Crane fly larvae and pupae can be found in damp sod or compost piles, or under the decomposing leaves on the banks of rivers, streams, ponds or lakes.

Crane flies can live nearly anywhere, even in arid desert environments.
Crane flies can live nearly anywhere, even in arid desert environments.

Crane fly larvae and pupae feed on decomposing material, grass and the roots of many plants. This makes them a beneficial insect, as they assist in the cycle of decomposition. Once they emerge in late winter or early spring as adults, after maturing over the winter, their primary purpose is to mate and lay eggs.

Crane flies only survive a couple of days after emerging from their aquatic or damp nursery. Adult crane flies do not eat, as far as researchers are aware. This dispels the myth that they bite or eat mosquitoes.

As larvae, crane flies fall prey to fish, as well as birds and small mammals. Adult crane flies are also a treat for birds and mammals. For the most part, the insects are completely beneficial. Occasionally, however, an overpopulation of larvae in a lawn or new sod can cause damage to the grass and root system by overfeeding. While the bird population in the area may love the smorgasbord of fat, juicy larvae, your exterminator or law care specialist may have some advice about how to keep crane fly larvae under control.

Frequently Asked Questions

What exactly is a crane fly?

A crane fly, often mistaken for a large mosquito, is actually a harmless insect belonging to the family Tipulidae. Despite their intimidating size, with wingspans reaching up to 2.5 inches, they do not bite or sting humans. Crane flies are found worldwide, with over 15,000 species, playing a role in the ecosystem as decomposers and food for predators.

How can you distinguish a crane fly from a mosquito?

Crane flies are much larger than mosquitoes, with a wingspan that can be several times that of a mosquito. They have long, slender legs that can easily break off, a feature that has earned them the nickname "daddy longlegs." Unlike mosquitoes, crane flies do not have piercing mouthparts and therefore cannot bite. Their flight is also more erratic and less directed than that of mosquitoes.

What do crane flies eat?

Adult crane flies typically do not feed at all; their primary purpose is reproduction. Some may sip on nectar, but many lack functional mouthparts altogether. In contrast, crane fly larvae, known as leatherjackets, consume organic matter in soil, helping to break down decaying plant material and enriching the soil as they feed.

Are crane flies beneficial or harmful to the environment?

Crane flies play a dual role in the environment. As larvae, they contribute to soil health by decomposing organic matter. However, in large numbers, they can damage root systems of turfgrass and crops, leading to agricultural challenges. Overall, they are an important food source for birds, fish, and other insects, thus contributing to the biodiversity of their habitats.

How long do crane flies live?

The lifespan of a crane fly is quite short. After spending time as an egg, larva, and pupa, the adult crane fly emerges with a sole purpose to mate. This adult stage typically lasts only 10 to 15 days. During this brief period, they do not eat and invest all their energy into reproduction before dying.

Can crane flies be considered pests?

While crane flies are generally not harmful to humans, they can be considered pests in certain contexts. Their larvae, when present in large numbers, can cause significant damage to lawns and agricultural fields by feeding on the roots of grasses and crops. However, they are not a pest in the traditional sense, as they do not pose a direct threat to human health or structures.

Discussion Comments

anon278090

How long does a baby fly take to turn into an adult fly?

anon258134

I have found a crane fly larva in my room and I took it outside, but I keep finding little baby crane flies or something like it. How do I get rid of all of them?

anon243014

I am freaked out and need to know what the heck was just outside on my french door! I live in Southern California, three miles east of the beach. It was dark outside so I could not see the color but it was large, about two to three inches, had wings, a long tail and crawled slowly.

I thought it was a baby lizard but it had wings and eew! It was crawling toward the door I had to open to get back inside and by the time I opened the door and freaked out long enough to recoil before I went inside, it was gone. It made an intermittent, one sort of screeching, ichk sound, until I saw it and backed away, then it stopped. What is that? I so hope it didn't go inside!

anon161953

We have crane flies around our area and i have just identified them through a google search. However, one thing i haven't read in any web site is how they like to swarm in sheltered cool spaces, thousands of them! we have an old out door toilet we don't use and they love to hang out in there and today they are in our chook shed, just hovering by the thousands in the corner. Just thought it interesting no one else had mentioned this.

anon114748

I took a macro photo of a crane fly today and I see two (comparatively) large protrusions from the center of its eyes. Can anyone tell me what they are please? Thanks in anticipation.

anon90191

The best way to handle a crane fly in your house is to smash it with a flyswatter. I have about 100,000 flying outside my house in Julian, CA at night and if I leave the door open for more than a few seconds, I get about 15-20 inside flying around all the lights and the TV. Very annoying.

anon32258

I was noticing that crane flies have these sensory finger-like structures that droop down from there "nose" area and saw a crane fly using these "feelers" to sniff or to read its surrounding. I was also thinking that maybe it was eating bacteria...not sure though. Just a thought.

anon21104

I have more than one crane fly in my house - about one every day or two, always in the basement. I brought some plants indoors. Could this be the source? Could there be pupa in the soil?

I know they're not harmful, our cats have caught & eaten a couple, but I don't really like them in the house. Any suggestions? Get more cats is not an option.

anon11359

Thank you for this valuable information. I have a crane fly as a guest in my house now. Should I just let it die indoors and then transfer the body outside so some lucky bird might eat it? Or should I try to transfer it so gingerly so that it can mate? It might be too late, but I'd like to do the right thing, so any advice is greatly appreciated!

anon5922

how many eyes does the crane fly have?

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    • Crane fly larvae can be found on the bank of a stream.
      By: Chianuri
      Crane fly larvae can be found on the bank of a stream.
    • Crane flies can live nearly anywhere, even in arid desert environments.
      By: george kuna
      Crane flies can live nearly anywhere, even in arid desert environments.