Mosquito Hawk? Skeeter Eater? Giant Mosquito? No, No, and No

By Leslie Mertz

That inch-long, gangly-legged insect that sneaks into your house and bounces around the walls and ceiling is a crane fly, and despite rumors to the contrary, it is neither a predator of mosquitoes nor a colossal mosquito. And it’s harmless.

Although the Internet abounds with reports of adult crane flies biting or stinging, they do neither.

Leslie Mertz

Leslie Mertz

“There has yet to be found a predatory adult crane fly,” said Matthew Bertone, PhD, a crane fly specialist and extension associate with the North Carolina State University Department of Entomology. “They just don’t have the mouthparts for it. So no, none are blood-feeding, and none of them attack people.”

In fact, many of the adult crane flies eat very little, if at all, according to Jon Gelhaus, PhD, a fellow crane fly specialist and curator in the Department of Entomology at the Academy of Natural Sciences of Drexel University.

“Some can sponge up liquids, such as dew and honey water, but we don’t see them do that much,” he said. “A number of them have independently evolved long mouthparts, and they’ll visit flowers to take up nectar.”

The slight diet is fine because adult crane flies typically live just a matter of days. Crane flies spend most of their time as larvae living underwater in streams, the edges of ponds, within wet logs, or in other damp places, and then they emerge as adults for a quick mating spree before dying.

The 15,000 or so known true crane flies in the family Tipulidae also share a somewhat similar appearance to mosquitoes. They have a narrow body with two long and slender wings, as well as six stilt-like legs that can be twice as long as the body. Crane flies are diverse in wing pattern, color, and size.

“The smallest crane fly in the world could probably stand on the head of the biggest crane fly in the world,” Bertone said. The tiniest ones have bodies that are mere millimeters in length, while the largest can be more than two inches long with leg spans topping 10 inches. The big differences between species, however, are found among the larvae.

“There are lots of crazy morphologies there,” said Bertone. “Some of them have inflatable rear ends that they use to move through soil more easily, some have fringed setae on the end to break the water tension, and some have these weird creeping structures, sort of like caterpillar prolegs with hooks on them, so it’s extremely variable. We don’t know much about the larvae. In fact, for many species, we have never seen the larvae.”

Although scientists have a greater understanding of adults — thanks in great part to the work of U.S. entomologist Charles Paul Alexander (1889- 1981), who described a whopping 11,000 crane fly species during his illustrious career — a multitude of questions remain. For example, according to Bertone, “Most of the crane flies have big eyes, but we don’t know how good their vision is and how much that’s used to sense where they’re going. The males in some of the groups have antennae with really elongate segments compared to females, but we don’t know what the purpose of that is.”

Scientists are also uncertain about courtship and communication. Some crane fly species engage in all-male swarms that apparently attract females, Gelhaus said. The males of other species will simply flit around their habitat with their forelegs outstretched, presumably using a contact pheromone to seek out females.

Other behaviors are also ripe for study. For instance, Gelhaus has seen both males and females of several tropical species aggregate together in dark areas.

“Whole groups of individuals will all be flying around together, sometimes bouncing at a constant level,” he said. “If you disturb them, they will fly away, but then in a little while they will re-aggregate back into those areas. We really don’t know what they’re doing in those situations.”

Gelhaus has also seen members of another tropical species in Peru that sandwich themselves between the surface of a stream and a suspended spider web.

“They seem to be hanging upside-down from the spider web, holding onto the threads of the web without being caught in it,” he said. “Behaviorally, I’d say crane flies aren’t super complex in comparison to even some other fly families, but there are a lot of these adaptations — including mimicry of ichneumonid wasps and other things — that really need study and will take somebody spending some time in the field and observing to figure out.”

Scientists are also still sorting out the evolutionary tree, particularly whether the large Tipulidae family should be split into several different families. Bertone was part of a research group that used morphology and genetics to try to sort it out. They concluded that the bulk of the species had more in common than not and should remain in the Tipulidae family, while just one smaller family of hairy-eyed crane flies (Pediciidae) should be separated out as a sister group.

Gelhaus appreciates their assiduous tone.

“Instead of splitting up Tipulidae all kinds of ways, which later evidence might not have supported, they said that the weight of the evidence conservatively supports two basic lineages, and I thought this was a pretty good way of approaching it,” he said. “I expect there’ll be some changes as we move along, and as more and more data is put to it, but that’s just part of the nature of classification and the taxonomy. It has to evolve along with our knowledge.”

There are other crane flies that fall outside the Tipulidae and Pediciidae families, but they are not as closely related. These include the phantom crane flies, winter crane flies, and primitive crane flies (Ptychopteridae, Trichoceridae, and Tanyderidae, respectively). The best known of these is the phantom crane fly Bittacomorpha clavipes, a large insect that flies with its inflated tarsi (“feet”) helping to float its long, black-and-white legs in the air.

“Phantom crane flies are one of my favorites,” Bertone said. “They’re really pretty and I just like the way they fly.”

Even the true crane flies alone, however, are deceptively diverse.

“They have weird behaviors and weird morphologies,” Bertone said. “I’m always seeing photos of new ones, and it just blows my mind how they look or how they have all these crazy modifications. There are strange, wingless, spider-like snow crane flies that are thought to live in animal burrows and crawl underneath the snow; there are small, hairy ones; there are larger ones; there are lots of them that suck nectar — it’s a really diverse and pretty amazing group.”

Gelhaus agrees. He took a rather serendipitous path to his study of crane flies, with an internship at the California Academy of Sciences that just so happened to involve these insects, and he has enjoyed every minute.

“I’ve never regretted it,” he said. “It’s a very interesting group for me, and it’s taken me all over the world. Crane flies were definitely the right choice.”

Read more at:

“Phylogenetic synthesis of morphological and molecular data reveals new insights into the higher-level classification of Tipuloidea (Diptera)” by Matthew J. Petersen, Matthew A. Bertone, Brian M. Wiegmann, and Gregory W. Courtney in Systematic Entomology, Volume 35, Issue 3, pages 526–545, July 2010.


Leslie Mertz, PhD, teaches summer field-biology courses, writes about science, and runs an educational insect-identification website, www.knowyourinsects.org. She resides in northern Michigan.

Comments

  1. Have noticed crane flies here in Humboldt Co., Ca. regularly seem to enjoy hanging from spider webs without being caught,for no discernible reason… also these local species have a strange extra pair of back pointing antenna near the back of the head that stick out BACKWARDS at an angle and have a “ball” on the END (!). Has anyone else seem these structures, know what they’re called or what they’re used for? These ones around here I have also observed drinking water droplets, and have even hand-fed a few friendly ones water-droplets, which is amusing as well as endearing.

    • the backwards pointing “antannae” are called halteres. They don’t come out of the head, but the thorax behind the wings. All flies have these in some form or another but they are most noticeable on crane flies. Instead of having two pairs of wings, the back pair evolved into halteres to help with flight stabilization and orientation.

    • Always taught and thought to my son that they were mosquito hawks so I have always let them be.. ok so they are useless for that… and I see they are harmless … do they pose any disease/bacteria/etc.. threat? its cool that Mr Thompson hand feeds them. Every living thing is awesome!

  2. They are, in fact , Halteres. They are “club-like” extensions derived from wings. They function as a sort of flight balance sensor/regulator. There are two groups which have Halteres. The Strepsiptera and the Diptera. The former have Halteres derived from their front pair of wings and the latter developed theirs from the hind pair of wings.

  3. Man Bear Pig says:

    They still creep me out…. but i wont smash them.

  4. We have SO MANY of them here during late March in Gridley! I try to scoop them up and let them outside, but they always want to come back in for some reason. If they only live for a few days, my house must be a haven for generations of these things…

    • Small word Rick, I too am from Gridley and they are everywhere in my yard.

      • Kristy Day says:

        I live in Sacramento and they start coming out in March and through April/May. We have masses of them that keep coming into our home as well. My son, just turned 8, is fascinated by insects including these guys. I wanted to bring some in for a preschool show and tell for my youngest and asked for his help. I was getting ready to put one in a jar and he told me with certainty I was getting a female. I asked how he knew and he said because he dissected some in the backyard and discovered that the ones with “pointy butts” are females and the ones with “squared off butts” are males. He went on to add that the females lay little black eggs around or on wood and that there are always more males than females. I opened the shutters in the bathroom and found several trapped in there. After doing a count, ten were male and two were female.

        We went on to put a male in the jar and after rushing to get out the door for school that day forgot the crane flies. When we arrived home we discovered that the female had laid some eggs. Later that day my oldest was building with his Legos on our wool rug when we noticed a crane fly with it’s “butt” stuck in the carpet. My oldest said that it’s a female laying eggs. I piked it out and sure enough, she had laid some little black eggs in the carpet!

        My son has opened a whole new world to me–one that I would otherwise be too busy to explore.

  5. Leticia Uribe says:

    Interesting article, but I was wondering what a bunch of those crane flies were doing in my back yard. They looked like they were digging up dirt, maybe dropping their eggs? I read that they lay their eggs in lawns but this was taking place between the fence and cemented yard, and there is very little grass. Have video.

  6. Suzanne says:

    What a great article!, not only beautifully written, but also extremely informative. For the last few years my daughter’s and I thought these were mosquitoes, they’d freak out and come get me or their dad to take care of it. He’d continually tell us they’re mosquito hawks and arnt dangerous, but the girls wouldn’t buy it. I believe him though. We get them flying around the kitchen and just staying on the wall. They’d be there for hours, anyway thank you for your explanation it was very helpful.

  7. We have noticed a lot more of these insects flying around in our yard in Concord, especially compared to previous years. They drive our cats nuts! I agree with another poster above, I tried to usher one out of my house today, and it wanted to stay in.

    • Small world! I too live in concord and I have been seeing so many of these flies at home and around town that I had to look up some info on them, I’m glad I’m not the only one that noticed how abundant they are suddenly. They bug my cat and dog too. I often see them doing something that looks like laying eggs in holes they dig in the dirt as well as hanging in spider webs. Good info/article

  8. My name is Barrett and I’m 10 years old. How do craneflies survive without eating as adults? Do craneflies have nests?

  9. Good question, Barrett. The answer is that they simply do not live very long.

  10. AGFD Administrator says:

    Well one flew in my shirt and I smashed it my shirt and it stung me/bite me and left red marks. So either the mosquito eaters here hate me or they have twins!

    • Bellamy Blake says:

      Are you an idiot? Or did you just not read the article? They cannot bite and they don’t eat mosquitoes.

  11. Raquel Hughes says:

    Thanks for the information. I use to think Crain Flies are just bigger male mosquitos and they kind of acted like the prey mantis. I have a fear of un-known bugs I’m not afraid of bugs but if I don’t know about them I get nervous. I actually have a Crane Fly right on the couch next to me sitting on a pillow. Thanks for the information again our place is filled with these little-big guys.

  12. we have them too, my wife and I found tubes of built up dirt in our front yard, 3/8″ wide 3″-4″ high, obviously made by an insect, ever seen this?

    • Randy, those sound like termite mud tubes. You can break one open with a screwdriver or stick and see if termites come running out. If so, you should might want to call a pest management professional.

  13. They are everywhere in the Stockton area as well. They drive my cat buggy because she wants to catch them and EAT them! Is it safe for her to eat these things? It is really hard to stop her from doing it but I will if they are not safe for her to eat. Thanks for the informative article!!

    • Holly Bilski says:

      Totally safe for her to eat them–so encourage her to do so, because if she doesn’t they’ll just get outside, lay eggs, and make more next year!

  14. mark alan says:

    how can we keep them out of the house, I think they come in through the doggie door?

  15. God, they terrify me though…

  16. Thanks a lot of the report but whoever doesn’t know that they are innocous is not only paranoid but also really ignorant lol they’re not a new thing they’ve been around for decades

  17. Nicholas Alexander says:

    Lol good to know. My mother is deathly afraid of them but its good to know theyre harmless…I hope that keeps my family from smushing them from now on

  18. Carolyn says:

    I have gotten what I thought are very large mosquito bites on my hand and around my ear and head the last two nights. Just now my daughter yelled that she had a very large bug flying in her room. When I went in to get it, it looked like what I just read in this article a crane fly or a mosquito hawk. I have not seen any other insects at all till this one. Could this be what left these large very itch bites on me?

    • keithuct says:

      My guess is the bite came from a nocturnal bug, not the crane flies, as they have no stinging or biting parts. If the bites continue, I would see about getting your room/house checked for mites/bed bugs.

  19. Nicholas says:

    I live in NW georgia and these insects are drawn to our porch livht. I actually just witnessed one subdue a small moth and while restraining the moth with its legs, the crane fly pulled the struggling moth to its mouthparts and commence to, what I can only describe as use its mouthparts to either kill the moth for some reason but it kept the moth at its mouth for several minutes like it was ingesting the moths inner fluids or something. I then touched the moth and the crane fly started flying around, obviously because of my close contact but it appeared as though it was making every effort to keep ahold of that moth as though it were its meal in some way. It then landed and again pulled the moth to its mouthparts and started doing once again, what i can only describe as feeding on the moth. Are you sure no types of craneflies are at all predatory on other insects?? What i witnessed tonight very strongly suggests otherwise. Would be interested in hearing back from you if you should have any insight or if you end up doing further research, what you may find out. Thank you. I also want to appologize if it seems like I am insulting your expertise. This is not my intent.

    • keithuct says:

      Sounds to me like you’ve spotted a Robber Fly, which is pretty thin like the crane fly, as well has having many variations, some looking long and thin, and others being short and stubby like a bumble bee. Also, Robber flies have a tendency to not let go of their prey.

  20. Looked this up only because I have a Skeeter Eater flying around the room. Flew in front of my face a couple times, just minding his own. I grew up knowing about them since they are common here, and I know they are not predatory and just assumed they hunted mosquitos. Turns out I was wrong, so I got what I came for. Nice article.

  21. I was a little worried about them moving in with me recently. There were so many of them I just started referring to them as my room mates. Bug repellent didn’t seem to bother them. I agree that they are cool just because they are alive but now that I know they are harmless and that there are so many kinds I am facinated. I can’t wait to learn more about them. I would like to know what eats them.

    • Skeeterfighter says:

      Yeah those darn Skeeter are er where this yer Skeeter bug here Skeeter bug there I just don’t know what to do then bomb diggety I just moved out of the house and went to Alaska and we’ll let me tell you that I have not yet to seen even one of em nasty skeeter bugs God bless. Although them moose and bear git up in my house and they destroy erthing I might move to this underwater community or something cause I can’t do no skeeter bug no bears no moose no nothing

  22. Typically around this time of year, we have the insanely large swarms all around our home. We live near the bay in southern NJ and always thought the water had something to do with it. This was a very informative article! Last night, just after sunset, we noticed hundreds of funnel shaped swarms over the wildlife refuge behind our home. They were very high in the air and appeared to extend to the ground. It was the most bizarre thing we have seen. Any information explaining this phenom?

  23. Are you kidding? Yes – they can sting. I was in a workout room and saw one bouncing around a light so I cupped it in my hand to bring it outside. It expertly curled it body around the finger of my glove and jammed it’s stinger right through and into my finger. The same species in the first picture @ beginning of article. You can see the stinger in the pic…lul. Tons around my house too, I went out and grabbed one as I typed this and sure enough – stung again. Go grab one, I dare you c;

    • I can’t wait for a response on this one. Either this article is incorrect, or there is a similar bug. Until I know for certain, my same rule applies: outside, safe; inside, not so much.

      • keithuct says:

        Ignore the troll. Either one, he knows it can’t sting and is having his fun, or two, he has mistakenly picked up a wasp that looks similar. Flies cannot sting, and only certain flies bite (i.e. horseflies and robber flies.)

  24. BigSeksy says:

    Wow, i feel the calculations might be off a bit. I have about 15,000 in my house alone. They hide an die in the most unusual places. Though im in the southeast.

  25. Why are all the articles saying these pests don’t bite? THEY DO!!!

    • keithuct says:

      Because crane flies don’t bite. Same with Harvestmen (daddy long legs) not being deadly spiders because they are in fact mites. There are many wasps and other insects that appear similar.

  26. Janet Darvas says:

    This is interesting. I thought that this website was run by a scientist and that it was she who said they didn’t bite. Wow, if they bite, it’s almost impossible that I wouldn’t have noticed that. They were everywhere here but I was never bitten. This site also says that they don’t eat anything when they are in adult form. That seems to be being contradicted here also. I’m surprised that we haven’t heard from the person who runs this site. Maybe I’m wrong….maybe this is not a professional site?

  27. Janet Darvas says:

    Yes, I’m sure that these things don’t bite. I always am touching them by accident. So, that guy is probably a troll or just mistaken. Thanks. LOL….who trolls a insect site? too funny

  28. Jessica says:

    I don’t know where you are getting that they don’t sting or bite.. They do SOMETHING because I have been stung three different times by three different ones and it feels like a wasp sting and leaves the appearance of a wasp sting. They most certainly sting. Now, they won’t land on you and sting you, but one got caught between my fingers and stung me pretty good.

  29. Janet Darvas says:

    I guess we’re getting the idea that they don’t bite from the woman professional who writes this column, plus personal experience. I’m disappointed that Leslie Mertz hasn’t restated her information or added clarification.

  30. They do bite.. I caught one in my fist and it felt like a wasp stung me…

  31. I just had one fly into a glass I had used earlier for sweet tea, and I could see it’s little moth thinger tapping the side to suck up the sugar.

  32. futuremike27 . says:

    So the thing I thought was a small crane fly and loosely cupped in my hand to get it outside and instantly felt a needle-like stab on my hand was not really a crane fly. Great. It’s still in the house.

  33. I have just noticed one flying in my room, and it freaked me the hell out. I was trying to catch this “mosquito” for around an hour until I completely lost him, so I freaked out even more – I was just about to go to sleep in a room with an enormous blood-hungry insect. Leslie, thank you so goddamn much for this article, you saved both my consciousnesses and my sleep.

  34. Tina Kelsey says:

    I live in Southern California and have caught literally hundreds of Crane Flies bare-handed and never been stung! I think those folks that have been stung should do more research on stinging insects in their locale to avoid obvious cases of mistaken identification. Learn your bugs, spiders, and reptiles in your area. You will feel more prepared to deal with your creature encounters!

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