Bug of the Week: Crane Flies

With all the rain this winter we’ve had an emergence of large insects that look somewhat like a giant mosquitoes or what my neighbors called "long-legged wasps." Here is what they are seeing (the thumb is for scale).

crane fly

They have nothing to be concerned about. This big, fragile fly is called a crane fly.

Crane fly adults are often over an inch long with two flimsy wings that they hold straight out from their sides when at rest. Although their appearance is unusual, crane flies are truly gentle giants of the insect world. They don’t bite or sting. In fact, they do not even feed as adults. Their only interest is finding other crane flies.

The photo of the adult was from a few years ago. This afternoon my son found the larva while digging in some soil.

crane fly larva

The larval stages of crane flies are sometimes called leatherjackets because of the leathery-looking covering over their bodies. I was able to capture the end of its abdomen as it crawled away, so you can see the tubes it breathes with when it is under water. You can see the outline best in the shadow behind it.

The larvae munch on dead leaves piled up in wet areas, part of nature’s clean up crew. With all the rain storms we’ve had lately, the crane flies have had a lot to eat and so we have a lot of them.

crane fly larva

Interestingly, the larva emitted a brownish substance from the tip of its abdomen as it crawled away, almost like the “chewing tobacco” that grasshoppers make from their mouths if you pick them. I’ve never read anything about crane fly larvae having chemical defenses, but that’s what it looked like.

I'm afraid this larva was moving too fast for a good photo. For better views, you might want to check these truly spectacular photos of crane flies.

10 thoughts on “Bug of the Week: Crane Flies

  1. Jerry Shapins

    We have had these creatures living with us here in the Catalina Footbills for a few weeks. I killed one or two each evening, but always thought I was attacking Mosquitos. But we wondered why they never bit us, they were easy to find, and they did not seem to buzz like a mosquito. But tonite there were many landing on our kitchen floor and ceiling. We frantically researched this critter and realized finally that they are the crane flies. Yes they move slowly, and they are always losing their too long legs. But I relaxed upon learning about their identity tonite, we are more relaxed with their presence in our home. When will they leave? Can I find where they breed?? Thanks!

  2. Post author

    Crane fly season will be over very shortly, as things heat up and dry out. They usually breed in wet areas where there are dead leaves and other plant material lying around. Here in Arizona, they are most numerous in years when we have a lot of winter rains and thus a lot of winter weeds 🙂

    By the way, crane flies are food for wildlife. Birds and lizards love them.

  3. Hi, there is a species of crane fly (I think) which lives in the tropics and I have observed groups of them clinging on to strands of what seem to be spider web. They are not caught in it as they are able to fly away freely when disturbed. I've been wondering for a long time why they do this. Any helping in aiding me find out the answer will be greatly appreciated!

  4. Post author

    Sorry, it took me a while to get back to you. I couldn't find any information on these crane flies. Perhaps you might contact a biologist from a nearby university?

  5. Silvia Estévez

    We have them here in Paraguay too!! They called the attention of my students at San Ignacio de Loyola School here in Asunción. It has been raining a lot.

  6. Morris Thompson

    I live in Austin Texas, and with all the rain we have had in the past month, I have noticed there are Crane Fly's in my in ground pool - the seem to be breeding because there are some 'small' one as well are large. Never noticed this before not (had the pool for 25+ years) - and I keep the pool well balanced.
    Question: will the eventually go away? or do I need to 'treat' the pool with something (and what). With "summer' coming on, my granddaughters will be wanting to swim (4-8 yrs old) and they DON'T LIKE 'BUGS' OF ANY KIND 🙂
    Any input will be appreciated.

  7. Post author

    Hi,

    I understand that you have had a lot of rain.

    The crane flies are a temporary issue. The good news is that they are not breeding in your pool. The crane fly life cycle is that the adult flies lay their eggs in piles of old dead plants or leaf litter. Those eggs hatch into larvae. The larvae look like a worm, but are dark green to gray in color.

    It is likely what you are seeing are either two different species of crane flies or the males are smaller than the females. Also, really "small crane flies" might be another aquatic insect, such as midges.

    If you are interested in helping your granddaughters overcome their fear/dislike of insects, I suggest picking up some children's books that feature insects and helping them learn more. I would be happy to make some suggestions.

    Hopefully some sunshine is headed your way.

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