DON’T PANIC! It’s just a crane fly.

“WOW!  That’s a GIGANTIC mosquito!!”

That is a common response to most people’s first sighting of a crane fly, a flying insect with a wingspan of 1-2 cm or more.  Although they do somewhat resemble very large mosquitoes, crane flies are completely harmless to humans.  Crane flies are one of many groups of insects that are widespread and diverse, but almost completely unknown to most of us.

A crane fly on indiangrass at Lincoln Creek Prairie - Aurora, Nebraska.
A crane fly on indiangrass at Lincoln Creek Prairie – Aurora, Nebraska.

There are apparently over 15,000 species and subspecies of crane flies worldwide.  Raise your hand if you’d heard of them before this post…   Exactly.  That’s not a knock on you, but an indication of the great complexity and diversity of the our world.

The photo above is – I think – of a female tiger crane fly (Nephrotoma ferruginea).  That identification isn’t based upon any particular knowledge of mine, but upon a search of the fantastic website    I know diddly poo about crane flies, but according to a short blurb I found at this link , the larvae of this species hang out in the soil and eat decaying plants and roots. Most adult crane flies only live a week or two – just time to find a mate and lay eggs before dying.

Crane flies are common in prairies, but also easy to find in many other habitats, including backyards, so there are plenty of opportunities to mistake them for huge mosquitoes.  If you start keeping your life list of crane fly species now, maybe you can get all 15,000 of them by sometime next century…

17 thoughts on “DON’T PANIC! It’s just a crane fly.

  1. Karen d. January 15, 2015 / 9:07 am

    Thanks, Chris! I am a big fan of It’s a tremendous resource for amateur bug enthusiasts like me.

  2. Ernest Ochsner January 15, 2015 / 9:18 am

    These guys are fun to see in the house desperately trying to get out the windows. I think they come into the house via plants that have been out all summer. I love to watch them as they are so delicate and seem to hover more than fly. Thanks for a mid winter treat.

  3. The Birding Bunch January 15, 2015 / 9:38 am

    No, I’ve never heard of this insect, but I am starting to learn. This summer I started my native bug list, but only have 31 identified species at this point. It’ll take a while to get this list to catch up to our life list for birds.

  4. Erin Ingram January 15, 2015 / 9:40 am

    Another interesting fact of note is that the majority of the crane fly species we know about came from the work of 1 man, C.P. Alexander, who described over 11,000 species of crane fly in his lifetime! Information on his works can be found here:

    • Chris Helzer January 15, 2015 / 10:12 am

      Thanks Erin – that’s fascinating!

  5. anastaciast January 15, 2015 / 9:49 am

    I’m raising my hand! :) They are so adorable. Sometimes they get in the house and I have to be very careful when capturing them to put them back outside.
    Also a huge fan of bugnet!!!

  6. Tim Siegmund January 15, 2015 / 9:49 am

    We get tons of them here in mid to late spring in Texas. Folks call them mosquito hawks and you’ll find their carcasses stuck in cobwebs on old barns, porches and unkempt houses all over the place. Usually one of the signs to me that a risk of a frost or freeze is probably over.

  7. elfinelvin January 15, 2015 / 9:54 am

    We called them mosquito hawks, also. I’ve stopped many folks from killing them by explaining that they eat mosquitoes. Anything that eats mosquitoes is a good guy. (I’m still working on bats.) I’ll have to get a new story for the crane fly.

  8. Chris Helzer January 15, 2015 / 10:13 am

    Yep, I’m pretty sure mosquito hawk is a fun but misleading name for a species that doesn’t actually eat anything as an adult.

  9. Stephanie Frischie January 15, 2015 / 11:01 am

    Not panicking- just enjoying the coincidence that while taking a break at work and reading this post, it reminded me of a few months ago when a crane fly fell victim to the fly paper in the office which was there to catch house and horse flies. At that point, my officemate and I wondered, “What do crane flies eat?” and found information that the larva are the eaters, not the adults. The crane fly succumbed to the fly paper. Back to my break today and I asked my officemate if he remembered the crane fly from the fly paper and pointed to Chris’s photo here. The coincidence is that while I was in the office reading The Prairie Ecologist, my coworker had just made the 2nd spotting of a crane fly at work in 3 months, this time in the greenhouse. Not sure which one or two of the 15,000 species. I’ve seen some online sources say that some crane fly larvae eat mosquito larvae, but as this was described as carnivorous behavior, the accuracy of the source becomes clouded by skepticism.

  10. chrisherickson January 15, 2015 / 2:17 pm

    What strange paranoias we develop. Growing up I was the default go-to for removing unwanted insects from indoors and releasing them unharmed outside whether I was at home, friend’s houses, or school. I happily caught wasps, giant spiders (I know, not actually insects), centipedes, stink bugs, and all sorts of other “terrifying bugs” but I absolutely drew the line at the inch-long mosquitoes! I’d see one and feel my skin crawl. It took me a long time to figure out they weren’t really mosquitoes, and a lot longer to stop being creeped out by them.

    I only recently started following your blog and I love it! It reminds me achingly of working on prairies up in Minnesota. Great pictures and observations.

  11. Patrick January 15, 2015 / 5:51 pm

    Robber flies are similar in size and are predatory, but they are darker, beefier up front, and have bigger eyes as you might expect for a predatory insect. Chris, I can’t remember whether you have posted a picture of one here, but it may be useful for a comparison between the two types of fly.

    • Patrick January 15, 2015 / 5:55 pm

      A search of your blog turned up a few posts with robber fly pictures. Most are head shots…maybe the best is Oct 3, 2013.

  12. Craig Hemsath January 15, 2015 / 11:34 pm

    Love crane flies. Phantom crane fly is my favorite. Seeing one ‘float’ in an eerily quiet black spruce swamp up in Minnesota is always a supernatural experience. They’ll follow you, almost like they know something you don’t.

  13. James C. Trager January 24, 2015 / 8:43 am

    Hard to get too much bug education in, Chris. It’s amazing how much unsubstantiated lore there is about these harmless flies. As with many insects, most of the life of these animals is spent as a larva, in this case living in moist soil or leaf litter, feeding on decaying vegetable material. The adults only live for a few days, long enough to reproduce, and then themselves become preyed on or become part of the “brown food chain”, i.e., that based on decomposing organic material when they very quickly die of old age.
    One little thing about classification: You wrote, “Although they do somewhat resemble very large mosquitoes, crane flies are dipterans (true flies)…”. Note that mosquitoes are also true, dipteran flies.

    • Chris Helzer January 25, 2015 / 8:11 am

      Mosquitoes are flies, huh? I did not know that. I will edit the post appropriately – thanks! Thanks for helping me with the bug education process!


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