Is that a giant mosquito??!!

It’s late spring in Tuscon and we’re about to transition into summer.  This means that a lot of insects have been making an appearance in the area recently.  In particular, we’ve been invaded by one type of insect that I get questions about all the time.  It’s one I can ID without even seeing it, based solely on the description of non-entomologists.  The question is always this:

“What is that big insect with the really long legs that looks like a giant mosquito?”

The follow up question is always this:

“Does it bite?”

In case an image isn’t jumping instantly to mind the way it does for me, this is the insect that people are asking about with this question:

crane fly top view

Crane fly, top view

crane fly side view

Crane fly, side view

This insect is a crane fly (Order: Diptera, Family: Tipulidae).  That means it is NOT a mosquito (Order: Diptera, Family: Culicidae)!  Crane flies are large, slender flies with long wings and very long legs.  In the Tucson area, they are often about 3/4 inches long and with legs over an inch long, but they can get even bigger in other locations in Arizona.  These are big flies!  They also have a V-shaped line on the thorax and large large compound eyes.

I’ll admit that they do look a lot like mosquitoes, but there are several key differences.  The size is a big consideration.  Crane flies are often really big flies while most mosquitoes are, at best, medium sized flies.  Even if you’re looking at one of the smaller crane flies, one that is in the mosquito size range, there are several key differences to look for.  The mouthparts are all wrong.  Look at this photo of the crane fly, zoomed in to focus on it’s mouthparts:

Crane fly mouthparts

Crane fly mouthparts

Notice how there’s no long, needle-like mouthpart?  Mosquitoes use their proboscis to pierce the skin of their victims to suck their blood.  Crane flies, on the other hand, eat nectar or don’t eat at all.  As a result, they have thicker, blunt mouthparts with all kinds of crazy looking doodads sticking off them or no mouthparts at all.  (In answer to question 2 above, no, they don’t bite!)  And if that isn’t enough to convince you they’re not mosquitoes, take a good look at the wings.  Crane flies have smooth, membranous wings with no scales while mosquitoes usually have scales along the wing veins.

Crane fly larvae have a special place in my heart because several species have aquatic larvae, though many species live in the soil.  They’re really pretty disgusting looking, but that just makes me more fascinated with them.  Take a look at the larva in the image below and see if you can figure out why they’ve earned the common name leatherback.

Crane fly larva

Crane fly larva

Crane fly larvae have distinct heads that are often nestled down into the thorax and are hard to see (case in point: the head is on the left side of this larva).  The back ends are particularly interesting.  They have a ring of fleshy projections, often looking like tentacles, that surround the pores they use to breathe, their spiracles.  These tentacles make these really huge, fleshy larvae look extra awesome!  Unfortunately, I have never figured out what the insects use those lobes for beyond their usefulness in species identification.

I wanted to finish by mentioning one other structure that is very visible on crane flies.  Like all flies, crane flies have only 2 wings.  But did you notice those little knobby things where the hind wings would be?  If not, take a look at a zoomed-in image of them here:

Crane fly halteres

Crane fly halteres. Notice also the v shape on the thorax!

Those structures are called halteres.  Halteres are the remnants of the hind pair of wings and have been modified into new structures.  They are thought to be very important during flight, acting like a gyroscope to tell the fly how it is oriented in the air.  Crane fly halteres are very large and often highly visible due to the way the flies hold their wings out at rest – they’re an excellent fly to  illustrate these structures.  The next time you see a fly, take a close look and see if you can find the halteres!  They may be very small, but almost all flies have them.  Those tiny little wing nubs are likely why flies are such amazing fliers and responsible for their mid-air acrobatics, so they’re very important structures.

Next up is a series of posts on building a pond to attract aquatic insects, so check back in to learn all about my experiences building my pond.  Perhaps you’ll even be inspired to build your own!


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42 thoughts on “Is that a giant mosquito??!!

  1. The mouthparts look quite complex for an insect that sips nectar. I’d like to observe (and photograph) one one these feeding someday.

    Looking forward to you bug pond posts. I am planning to leave the goldfish out of my pond this year to encourage more water life, but I am concerned that mosquitoes may develop as a result. I hope you will comment on how to prevent that possibility.

    • I intend to address the mosquito problems associated with ponds in the last post in the pond series. There are several different things you can do, ranging from very easy to a bit more difficult, but none of them are particularly onerous – and certainly nothing compared to keeping the water clean enough for fish!

  2. 3/8th of an inch?! Oh, how I wish that was true! Here in California these awful beasts can be as long as THREE INCHES long (body), which makes them about the size of a saucer when you consider the wings. They flutter straight into your face and you can’t swat them (how disgusting would that be?), so all you can do is run, duck, and cower in utter terror. I’d rather face a swarm of mosquitoes or killer bees.

    • I find it interesting (and I’ll admit somewhat amusing) to hear that these insects bother you so much! It’s fascinating to me how people can be so scared of things that present absolutely no risk to them. My best friend is terrified of moths. She’ll run shrieking from the room with arms flailing protectively if she comes across one. She has this strong and completely irrational fear of them based solely on the worry that they might flutter around her face. Many people, including many entomologists I know, are scared of roaches because of the way they move. Things that move very fast are often scarier than things that are slow. I myself am terrified of many spiders and centipedes, based solely on movement – the way they move gives me the willies like nothing else. I’m completely fine with spiders that don’t run fast. Hmmm… Maybe I should do a post on fear of insects… Thanks for the idea!

      • I am posting this long after the page has been put up, but I wanted to say that I have an actual irrational fear of these crane flies merely due to the way they move, it makes them look like they have more legs than they really do, and they tend to fly straight for my face (from what I’ve seen it’s because lights nearby are magnified when reflecting off my glasses, and I figure they are highly attracted to lights just from watch the dozens that fly into my room at night.) and it’s frightening to think an innocent insect would just fly at me like that and ram itself into my face; though, this is also the same reason that multiple other flying insects bother me. Sorry I am posting this years after you have made this page, but I just wanted to add me two-cents :)

        • Thanks for the comment! And it’s completely fine to be scared of an insect – you’re not alone. Lots of people I have talked to are very scared of crane flies, or scared of roaches or wolf spiders for how they run, other insects for weird jerking motions, etc. I myself am terrified of a completely harmless snake and I can’t seem to shake that fear. It happens! I figure that as long as you know they’re harmless, even if you can’t get over the fear, then you’re at least moving a step in the right direction.

          • Thanks! And I do understand they are harmless, I think my problem is when more than one is in a small area. Me and my dad (I’m 18) were building my new bed in the garage and had the big door open the whole time and around 30-40 of them flew in and it took an hour to get them all shooed out, there is maybe one left in my room but I haven’t felt the panicky fear that I normally would when seeing three or four :)

              • I hope your right, just finding out (thanks to your site) that they are completely harmless makes me feel a little more comfortable around them, not completely, but a little bit more :)

    • Lara,

      I completely agree! I am terrified of these things, especially after I had an encounter in the shower at the tender age of 17. Give me cockroaches, crickets, spiders, hornets — I can handle those, but crane flies are a nightmare for me. I frequently run from them screaming at the top of my lungs; and when running is not an option, I too duck and cower in utter terror shaking like a leaf, and ready to make a dash at the very first opportunity. I am an educated person, and reacted very rationally in really dangerous situations, but an encounter with crane flies turns me into an irrational horrified mess. I know they can’t hurt me, but the thinking part of my brain stops functioning when I am faced with my nemesis, and the flight instinct kicks in with a vengeance.

  3. The thing about crane flies is that if there is one, there are usually twenty! Our living room window screen is torn in one spot, and my husband opened the window the other day and about 100 of those huge dead crane flies blew into our freshly swept living room floor. They obviously came to our living room window at night when the lights were on inside. They’re totally attracted to the light, and I couldn’t believe how many of them were dead in our windowsill! That screen is getting fixed this week. I don’t like the way they fly at my face either. I took my dog for walk once and some other insect (mosquito or gnat maybe?) flew directly into my eye. I felt it crawling around on my eyeball under my eyelid & then a horrible sting when it stung my EYEBALL! I was so far from home trying to control my son & my 90 lb boxer and cover my eye at the same time to keep from blinking. Finally the insect disintegrated in my eye & it took me over an hour trying to rinse out all the body parts when I made it home. (Feeling the thing crawling under my eyelid was one of the worst feelings I have ever experienced.) So now, I have a completely “rational” fear of insects that swarm my face when I walk outside. And the crane flies get in the house & if I can’t get them out, I hear them buzzing & bumping into things throughout the night. I have never been a fan of crane flies. But I have heard all my life that crane flies eat mosquitoes which somewhat impressed me. Until I read this article. Now I feel I’ve been lied to ever since I was a child. I now feel crane flies are completely & utterly useless.

    • There are so many urban myths about these flies! Sorry to reduce them to useless animals for you, but many of them are actually pollinators if that helps. :) And I’ve had a bug in my eye like that! Got it while riding my bike one day and couldn’t get it back out. It hurt SO badly when it got crushed and leaked all its fluids into my eye (that’s likely what you experienced rather than a sting – it feels about the same). I don’t blame you for not liking swarms of insects if you have had that experience! I always wear sunglasses when I ride my bike – or some sort of safety glasses if it’s too dark – just so I don’t repeat that experience. Of course, that didn’t keep me from getting stung right below my eye by a flying ant that I smashed into on my bike a few years ago. That wasn’t so fun either. Never seems to deter me from riding though…

    • I had heard the same thing all my childhood. My family would give them the nickname “SkeetoEaters” and even my sister-in-law knows them by that name, and she was raised a whole state away!

  4. ok, several years ago i found an insect on my screen door, and the best description i can give is it had a body that resembled a large wasp about the size of my thumb, it had 4 wings like a dragonfly, and the weirdest of all, what looked like a 3 inch long stinger. naturally i killed it, and inspected it, and to my surprise the stinger would separate into 3 pieces attached at the thorax. my question is what the heck was it?? i don’t think it was a crane fly and nobody i know has a clue…

    • Oh wow, I have no idea! I would say it sounds a lot like some of the long braconid or ichneumonid wasps, but they would definitely have their stingers coming off the back end and not the thorax. Very strange! Don’t suppose you could draw it so I could see what you remember?

  5. I’m doing this insect collection for class and I have a bug that looks exactly like a crane fly but with a reddish abdomen. What is it?

  6. Wow — I can’t believe my boyfriend & I found your page! I was so worried about what I now know are harmless crane flies! I thought they were giant mosquitos, but he said they were squito eaters. Anyways, he just caught one & put it outside. The mosquitos are awful here in Ohio already, but I am relieved to know those “squito eaters” are crane flies & not mosquitos. Do you by chance know why some people attract mosquitos? He gets bitten & I don’t.

    • There are a lot of ideas floating around about why specific people are more attractive to skeeters than others, but I’ve never read of a definitive answer to the question. I do know that I am an attractive person to mosquitoes, though I wish I wasn’t!

      Glad I could help dispel some misinformation!

  7. I’m happy to learn that the big mosquito looking insect is a fly. You don’t explaine their use in nature. They such nector. For what purpose ?
    What good at they?
    I live in upstate Nee York and have never seen so many of these Crane Flys.

      • I found one of these in my sink just “resting” in there. When I went to turn on the tap it flew out into a dim room and now I can’t find it. It will either die in my apartment or get eaten by my kitten unless he manages to escape, which brings me to my question…..I frequently go out on my porch to enjoy the weather, and I am super aware of the insects around the door, and make sure to get anything that dare try to cross my path into my home. Can these flies find their way into homes in the larvae state? I find them in ways described above but have never been aware of their presence outside, on my porch, or while quickly going in or outside. How do they magically appear in my home without seeming to gain access through the doorway? I am super diligent about keeping insects out. Thanks in advance, your blog posts and comment responses are super informative and kind towards the less educated.

        • Hello! Sorry for the delayed response. I was out of the country and have crazy busy since I got home.

          I’m not 100% sure how they get into your house without your noticing them, but I’m quite sure they’re coming in as adults. The larvae of many crane flies are aquatic and they’re going to be living in rivers or creeks (flowing water), not in your plumbing. Some of them have larvae that live in dirt, so again, probably not in your home (unless you have a dirt floor, which I’m going to bet is not the case). My theory, and this is because I never notice them coming in either, is that because they are so lightweight, any of them anywhere around your door (back behind light fixtures, on plants, etc) get sucked into the house by the little vacuum you create when you swing the door inward or slide a sliding door open. You never seem to see them flying in, and I too have far more in my house than I’ve ever noticed on the door, or even near the door, outside. They’re pretty fragile, so I doubt they’re squeezing into cracks and crevices or anything.

          So, this isn’t entirely helpful, but I hope it at least sets your mind at ease that they’re not coming from anywhere inside your house. Not sure how they get in, but I’m quite sure that they’re coming in as adults somehow and are not breeding in your home anywhere.

          • Thank you so much, your response was very greatfully received, I’m willing to bet you are right about how they got in, little bugger got past my radar. Thank you for you time!

  8. Oh wow! This is quite an old post but I HAD to figure out what the heck these creepy bugs were! They swarm around my door when I get home from work in the morning and they’re all over the windows at work trying to sneak in. I’m so glad to find out that they’re NOT gigantic mosquitoes. I’ve never seen so many of them like there is here on the east coast of Canada. Great article, thank you so much for helping me sleep better at night knowing I’m not going to get eaten alive by giant mosquitoes ;)

  9. I just put one of these outside. You can easily cup your hand around it and then let it out the door. Since I was a kid I knew they were good bugs but did not know what they were. Just looked at your website and it made me happy to learn something new.

  10. Does anyone know what type of crane fly this is? I’m doing a biology project and I caught something similar to this, but I just can’t figure what exactly it is. Any help would be appreciated.

    • If you send a photo of it to, you’re likely to get it IDed fairly quickly. You can also look through the images there and see which is most likely by browsing through the photos.

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