Crane flies are fascinating creatures, often mistaken for giant mosquitoes due to their size and appearance. However, they’re quite harmless and play an essential role in the ecosystem. One intriguing aspect of their life cycle is their mating behavior, a subject that is worth exploring in more detail.
Adult crane flies have a remarkably short lifespan, usually living for just a few days. During this time, their primary goal is to mate and lay eggs to ensure the continuation of their species. To attract a mate, male crane flies use their elongated legs and unique wing patterns as they compete with other males. Once a female selects a partner, the couple engages in a delicate mating dance before copulation.
Crane Fly Overview
What Are Crane Flies
Crane flies are insects belonging to the family Tipulidae and are often mistaken for mosquitoes due to their similar appearance. However, these two-winged insects (order Diptera) are harmless and usually found near water sources.
Family and Species
Crane flies belong to the order Diptera and family Tipulidae. They can be further classified into three subfamilies: Cylindrotominae, Limoniinae, and Tipulinae. There are hundreds of species of crane flies found in North America.
Crane flies exhibit distinct physical features, including:
- Slender, mosquito-like body
- Extremely long legs
- Varying sizes, ranging from tiny to almost 1.2 inches long
- One pair of wings
Certain species, like the larvae of crane flies, have additional characteristics:
- Plump, segmented catepillar-like appearance
- Definite head
- Tiny, fleshy projections at the hind end
Misconceptions and Common Names
Despite their similarity to mosquitoes, crane flies are not dangerous:
- They have a weak and slow flight pattern
- They do not bite or transmit diseases
- Common names include: mosquito hawks, mosquito eaters, and daddy longlegs
|Weak, slow flying
|Adults feed on nectar (if they eat at all)
|Females feed on blood for egg production; males feed on nectar
|Harmfulness to Humans
|None (beneficial to ecosystems)
|Potential disease vectors (like malaria, dengue, and Zika)
By understanding their physical characteristics and differences from mosquitoes, people can better appreciate the role of crane flies in the ecosystem.
Life Cycle and Behavior
Egg to Pupa Stages
Crane flies lay around 300 eggs in their short life span. The eggs hatch into larvae, known as leatherjackets, which are tan, gray, or greenish grubs. The larvae then grow and feed in various larval habitats, such as:
- Aquatic environments
- Damp soil
- Decaying plant material
These factors impact the ecosystem, as they contribute to breaking down organic matter.
Adult Crane Flies
The larval stage is followed by the pupal stage, during which the leatherjackets develop into adult crane flies. They have a slender body, long legs, and often resemble large mosquitoes. They can be found around water sources.
- Slender body
- Long legs
- Mosquito-like appearance
Mating and Reproduction
Once adult crane flies emerge, they focus on mating and reproducing. Some crane flies can have multiple generations per year, while others only produce one generation annually. Mating occurs swiftly, with females laying eggs within the first 24 hours of their adult life.
Crane flies don’t live long as adults. They typically live for only a few days, which is why their main focus is on mating and reproduction. During this time, they don’t cause much damage to their surroundings, with larvae being the primary stage affecting the environment and lawns.
Crane Fly Diet and Natural Predators
Food Sources for Larvae and Adults
Larvae: Crane fly larvae, also known as leatherjackets, are primarily consumers of organic matter. They typically feed on:
- Roots of grasses and weeds
- Small fungi
- Decaying plant material
Adults: Adult crane flies have a short lifespan, and their primary focus is on mating. They may occasionally feed on:
- Flower nectar
- Nectar from other plants
Crane Fly Predators
Crane flies and their larvae have various natural predators:
- Birds: Many bird species, such as robins and starlings, consume crane fly larvae.
- Bats: Bats may prey on adult crane flies due to their weak and slow flight.
- Spiders: Spiders catch adult crane flies in their webs or hunt them on the ground.
|Roots, grasses, decaying plant
|Fungi, insects (rarely)
Pros for larvae diet:
- Abundant source of nutrition
- Helps in decomposition of organic matter
Cons for larvae diet:
- Can cause damage to lawns and grassy areas
Pros for adult diet:
- Minimal need for food due to short lifespan
- No major negative impact on environment
Cons for adult diet:
- Limited food sources
- Poor nourishment
Crane Flies in the Environment
Crane flies, often mistaken for mosquitos, play a vital role in the environment. They primarily function as decomposers and help break down organic matter. The larvae, sometimes called leather jackets, consume decaying plant material and roots in their surroundings. Some crane flies, depending on their genus, may even prey on other insects.
Adult crane flies, despite their large size, do not feed on blood like mosquitos. In fact, they are harmless and only consume liquids like nectar or water. Their presence in an ecosystem can indicate healthy soil and a balanced environment.
People often encounter crane flies after a rain event, as their emergence is triggered by such conditions. They are sometimes referred to as “daddy long legs” due to their long, slender legs, but it’s important to note that they are distinct from the true daddy long legs in the arachnid family.
Crane flies are attracted to lights at night, which can lead to increased human interactions in communities. While they can be a nuisance when they enter homes, it is important to remember that they are harmless and do not bite or transmit diseases like some mosquito species.
Crane Flies vs. Mosquitoes:
|Larger (up to 1.2 inches)
|Diet (adult life)
|Liquids (nectar or water)
|Blood (female mosquitoes)
|Harm to humans
|Can transmit diseases
Crane Fly Characteristics:
- Slender, mosquito-like body
- Very long legs
- One pair of wings
- Harmless to humans
In conclusion, crane flies play a vital role in maintaining the ecological balance by decomposing organic matter. Understanding their presence and behaviors can help promote a healthier environment and lessen negative interactions with humans.
Crane Fly Research and Resources
Crane flies, often confused with giant mosquitoes, are actually harmless insects with distinctive long legs. Experts have identified two species of interest – the European crane fly and the marsh crane fly. The European crane fly has one annual generation, while the marsh crane fly has multiple generations per year.
Some key features of crane flies include:
- Slender body
- Long legs
- Short lifespan
- Harmless to humans
According to Entomology Today and other publications, evidence points at T. paludosa (European crane fly) dating back to the early Cretaceous period, particularly the Barremian stage. Here’s a comparison of the European crane fly and the marsh crane fly:
|European Crane Fly
|Marsh Crane Fly
|Generations per year
|Damage to lawns
Despite their resemblance to mosquitoes, as previously mentioned, crane flies are relatively harmless and can be found near water sources. By understanding the differences between these two species, scientists and researchers can better manage and control their populations as well as the damage they may cause to lawns and agricultural fields.
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Mating Giant Crane Flies
large, mating bugs – Georgia
Location: Atlanta, Georgia
October 8, 2011 9:11 am
We saw these 2 insects (appear to be mating) on a sunny, warm day in early October 2011 in Atlanta, GA. They are quite large – perhaps wingspans of 6 inches and leg spans of 12 inches with almost iridescent wings. We’ve lived here almost 10 years and had never seen these, although we may be seeing more next year if mating was successful. Anyone know what they are? Thanks!
Signature: Dan and Ade
Dear Dan and Ade,
Most people who encounter Crane Flies mistake them for very large mosquitoes, but unlike Mosquitoes, Crane Flies do not feed on blood. A common name we have encountered for Crane Flies is Mosquito Hawks, however, Crane Flies do not prey on Mosquitoes. It is generally believed that adult Crane Flies do not feed, or that they subsist on a liquid diet. Your individuals are Giant Crane Flies, Tipula abdominalis, and according to BugGuide: “large size coupled with black velvety patches on thorax is diagnostic feature.” The God of Insects website has a nice synopsis of the life cycle of the Giant Crane Fly that is copyright 2003 by Barbara Strnadova that states: “This striking crane fly is found wherever there are freshwater streams in central and eastern North America. The large, plump larvae, often called “leather jackets”, are aquatic. They can be found under rocks, in debris and in mud along the bottoms of streams in many different habitats. The larvae are detritivores and are abundant wherever there is sufficient rotten leaf litter. Two generations of adults emerge each year; one May-July and another beginning in August or September. While Tipula abdominalis is one of the largest crane flies, many crane flies in the genus Tipula are also quite big. These large flies are often mistaken for giant mosquitoes, while in some parts of their range these giant flies are called “Mosquito Hawks”, a name that really refers to the famous Green Darner Dragonfly. Crane flies are called “Mosquito Hawks” or “Mosquito Eaters” under the mistaken assumption that they are some kind of predatory fly. The reality of the situation is quite different, for they take sustenance only from flower nectar – if they eat at all. They cannot bite so although they are huge, you have no need to fear them. Tipula abdominalis is often attracted to lights at night.” Since the larvae are aquatic, you would need a freshwater stream nearby for this mating to result in procreation, however, since Crane Flies are feeble fliers, we can presume that there is a nearby stream. Here is a photo of an aquatic larva of the Giant Crane Fly from BugGuide.
Letter 2 – Mating Crane Flies from India and Mating relatives from Taiwan
Insect to be identified
Location: Mumbai, India
September 30, 2010 1:43 am
I just caught these insects mating (I guess) I am unable to identify these insects. I have uploaded couple of pictures which would help.
Thank you and Reagrds
Signature: Mahesh F. Pardesi
Your photos of mating Crane Flies in the family Tipulidae are stunning. This is a beautiful pair of insects. The male has the feathery antennae. We don’t know how much species information we would be able to find for Asian species, so we are going to contact an expert in the family for assistance. We generally search the Crane Flies of Pennsylvania for North American species, and Dr. Chen Young of Carnegie Museum of Natural History assists us when we have problems. Hopefully he will be able to provide a species name for us.
Thank you for taking out time and replying my mail.
Atleast I know now that these are Crane Fly.
Would be eager to know the Species.
Thank You again.
Mahesh F. Pardesi
Karl Unearths the Answer
Hi Daniel and Mahesh
These crane flies are so lovely that I couldn’t resist looking for more information. The species appears to be Pselliophora laeta (Tipulidae: Ctenophorinae). I could find only the one photo online but I did also find a matching illustration in a very old paper titled “Dipteres Exotiques Nouveaux” by M.J. Macquart (1837). It was presented under an older synonym, Ctenophora laeta. The wing pattern is very distinctive. According to Oosterbroek et al. (2006) the Ctenophorinae are all more or less spectacular and many resemble ichneumons or wasps. The comb-like antennae of the males are also distinctive. Ctenophorinae larvae all develop in decaying wood of deciduous trees and usually require old forest or orchard habitat. The genus Pselliophora is predominantly oriental in distribution and includes nearly a hundred species (so it is possible that these belong to a related and similar species). Regards. Karl
Dr. Chen Young responds
October 6, 2010
I sent the following message on 30 of September but was rejected due to your mailbox was full. I am forwarding it again and hope you will get it this time.
September 30, 2010
Thanks for the image and I am so glad to see the mating pair. As you may know by now that I am out of the museum and doing field research in Asia and your image really made my day since I have just seen one species of crane fly in the same group as the iamge you sent.
The crane fly of your image belong to Ctenophora (Pselliophora) group. I dont know the species for sure but I will look into it after I return to the museum where I will have references that I can check into. I am attaching one image of the one from Taiwan for your reference and you can also see the similarity they share. I schedule to return on the 22 of October and I will contact you soon after.
Thanks so much Chen,
We really appreciate you taking the time to resend this email while you are in the field. We are pleased to include your image of a mating related pair from Taiwan with the original posting.
Thank you for the wonderful explanations forwarded by you Daniel. Still curious to know the species name.
Mahesh F. Pardesi
Letter 3 – Mating Crane Flies
These are everywhere right now. I’m really tired of them. What are they? What can be done to keep them away?
These are Crane Flies, and though they resemble large mosquitos, they are not closely related (other than being flies) and they do not bite. Crane Flies are sometimes called Mosquito Hawks. Judging by the mating activity in your photo, you are apt to remain tired for a bit longer. Crane Fly adults are benign and do not feed. They are often seasonal in appearance and are attracted to lights at night. We don’t really have any suggestions on how to keep them away.
Letter 4 – Mating Crane Flies
These seem to be Mosquito Hawks in love
Over the years, we have received numerous images of mating Crane Flies, sometimes called Mosquito Hawks even though they do not eat mosquitos. Your photo stands out from the crowd since the shallow depth of field and subtle backlighting nicely isolate the pair from their surroundings.
Letter 5 – Mating Crane Flies
Another bug picture
I have been enjoying my 15 minutes of fame since sending you the cylindrical hardwood borer picture a few weeks ago. Now, it seems everywhere I look I see randy bugs doing it, thinking about doing it, or basking in the afterglow of having just done it. Here’s another picture of goodness knows what doing you know what.
We will extend your fame time allottment by posting your photo of mating Crane Flies, sometimes called Mosquito Hawks.
Letter 6 – Craneflies: Mating and Solo
2 Cranefly Pics
Love your site. Thought I’d send you these two pictures I took of craneflies in my backyard. One on its own and the other of a mating pair. I wouldn’t have known they were craneflies until identifying them on your site.
Ajax, ON CANADA (just east of Toronto)
Sorry for the long delay. We are posting both of your images on our Cranefly page and our second Bug Love page. The images are both stunning.
Letter 7 – Disabled Craneflies Mating
Hi bugman love your job.
We have another example of Cranefly’s in the heat of the moment.
Rob from North Vancouver, British Columbia
Thanks for the image. It is nice to see that losing several legs, a common Cranefly disability, hasn’t hindered the process of procreation.
Letter 8 – Craneflies Mating
I just today discovered your website. Awesome! Creepy – but really neat. I have a different picture, once I find it, of an as of yet unidentified bug. Noone knows what it is. But until I find that one, I have another submission for your Bug Love section. I went through your website, and think I identified this two in the picture. I’ve always been a city girl – and now live in a rural area of Central Virginia. Since moving here a year ago, I’ve seen more creepy crawlies than I knew existed. Last year, I went out the front door, totally oblivious to what was sitting on the door frame. I only noticed it when I turned around to lock the door. They were too.. involved… to notice me coming in and out of the door, so I got my camera. Are they crane flies mating? Thanks
Your Craneflies are indeed mating, and this represents the intimate activity of a new species for our Love Among the Bugs page. Thanks for the contribution.
Letter 9 – Crane Flies: Mating Swarm Interrupted!!!
In a stump, flies, mates. What is it?
Mon, Apr 27, 2009 at 4:25 PM
My wife and I have a really decayed stump that we are planing on removing and planting a garden over. So I decided to kick it a bit to see how easy it would be to remove. It crumbled very easily (as does the ground around it where the roots have rotted) but a bunch of these bugs flew out. Well, they hovered because they were busy mating, ends stuck together and flew awkwardly around.
The bugs themselves are dark brown with light yellowish markings. The karings are kinda stripey down the abdomen and a blotch on either side of the thorax. The head looks tiny and curled under the round thorax. I caught a mating pair, one has what looks like a stinger, but I think I know what it really is *winks*. They are about an inch long, with thin long smoke colored wings.
What a wonderful account of the mating activity of these Crane Flies. We believe they are Ctenophora vittata – Ctenophora angustipennis as evidenced by the images posted to BugGuide. The “stinger” is actually the ovipositor, and it is the female that is in possession of it. We are going to contact Chen Young at the Crane Flies of Pennsylvania website to see if he can elaborate on the mating activity you witnessed. Our guess is that these adults are newly emerged. Adult Crane Flies don’t feed, so they don’t live long anyways. The larvae, sometimes called Leatherjackets, eat decaying organic material, and perhaps they were in the stump as larvae. We are also going to tag your images Bug Love despite the mating activity being observed and not documented.
Letter 10 – Mating Crane Flies
Mating Crane Flies
April 13, 2010
Congratulations on the progress of your book. Looking forward to it.
If you think that Crane Flies are ridiculously poor flyers at best, you should see them trying to aviate as a pair while locked in the embrace of bug love. Southern Arizona, attracted to a light in a community at the edge of the Sonoran Desert; about 2,900′. Mid-April.
In our opinion, you are being a tad harsh regarding the aerodynamic capabilities of Crane Flies. They are gangling and awkward, but they are not really seriously impacted by the fact that they will never win an air race. Your photo is lovely and your confidential comment about our hot button topic is appreciated.
Letter 11 – Crane Flies Mating
Location: Red Rock Canyon National Conservation Area, Las Vegas NV
January 30, 2012 1:27 pm
Here are ’tipulids’ mating. I think the view of the wing venation is good enough to put it in the Phantom Crane Fly family (Ptychopteridae) as opposed to the Crane Fly family (Tipulidae). Whaddaya think?
Sorry, only one image.
Signature: Bruce Lund
We are by no means experts on Crane Flies, but it is our opinion that these are not Phantom Crane Flies. We will check with Chen Young, an expert in Crane Flies, to see if he can provide a species identification.
Daniel – Thanks for the update AND for forwarding my query onwards. I
look forward to learning more.
Chen Young identifies Crane Fly genus
The most I can tell from the images is they are crane fly species in the genus Limnophila.
Letter 12 – Mating Crane Flies
Subject: what kind of bug is this
May 22, 2013 6:45 am
This was found at 9am in Connecticut. It had rained pretty hard with thunder and lightning the night before. I legt to bring the kids to school and daycare. Which took about 30 minutes and it was in the same position when I got back.
Signature: norm delaura
These are mating Crane Flies in the infraorder Tipulomorpha which can be browsed on BugGuide if you want to try to determine the species. Because of their long legs, Crane Flies were named after the long legged wading birds called cranes. Crane Flies are mistakenly called Mosquito Hunters in some parts of the country. Most Crane Flies do not eat as adults and they do not bite humans. We will contact Dr. Chen Young who runs the Crane Flies of Pennsylvania website to see if he is able to provide a species identification.
Dr. Chen Young responds:
A mating pair of Tipula trivittata.
Letter 13 – Mating Crane Flies in Canada
Subject: Looks like 2 insects connected
Location: Edmonton Canada
July 4, 2013 9:14 pm
Found this in my vegetable garden. At first i thought it was 2 insects really close to each other until it jumped away. Googled and googled and can not find. I am in edmonton , alberta. Canada Thanks
These are mating Crane Flies. Crane Flies do not bite nor sting.
Letter 14 – Mating Crane Flies
Subject: What is this?
July 29, 2015 8:41 am
This bug literally flew onto my patio door right as I was about to let my dog out. Noticing the weird thing, i had to stop and take pictures. It looks like it almost is a conjoined twin? I have no idea what it could be, either.
Signature: Hayley P
While this may look like conjoined twins, it is actually a pair of Crane Flies in flagrante delicto. Mating Crane Flies are not the only insects that are able to fly while in the act, but their gangly appearance with their long legs makes them an especially memorable sighting.
Letter 15 – Mating Crane Flies
Subject: What kind of bug is this
May 26, 2017 7:36 am
I would just like to know what kind of bug this is?!
These are mating Crane Flies, and in some locations they are called Mosquito Hawks or Skeeter Hawks because people mistakenly believe they eat Mosquitoes. Crane Flies are harmless. They neither sting nor bite. According to Texas A&M City Bugs: “Crane flies are among the gentlest of insects. Some are nectar feeders, sipping sweet sugars from plants and possibly helping out a little with pollination in the process. Other species lack mouth parts entirely. Instead, the adults live out their short lives relying on fat reserves built up during their underground larval stage.” The site also states: “Enjoy crane flies while they last. And keep in mind that as adults, these flies only have love on their tiny minds. The sole purpose of the adult crane fly is to mate and, for the females, to lay eggs for next spring’s crop of flies. Crane flies are harmless to handle, so the next time one makes its way indoors, simply cup it gently to release outdoors. Think of it as a romantic gesture.”
Letter 16 – Mating Crane Flies
Subject: Flying bug
Geographic location of the bug: South Louisiana
Time: 07:10 PM EDT
Your letter to the bugman: I have these insects that appeared suddenly around my home. Please help me identify them.
How you want your letter signed: Jackie Stelly
These are harmless mating Crane Flies. They neither sting nor bite. Crane Flies tend to be more common during wetter years.
Letter 17 – Mating Tiger Crane Flies
Subject: Crane Fly?
Geographic location of the bug: Plymouth Meeting Pa
Time: 01:39 PM EDT
Your letter to the bugman: Is this a crane fly? If so what kind of crane fly is this? Are they agricultural pests? They were found mating on my aronia.
How you want your letter signed: Concerned Gardener
Dear Concerned Gardener,
We believe these are mating Tiger Crane Flies in the genus Nephrotoma, which is pictured on BugGuide. According to the Crane Flies of Pennsylvania: “Although individual adults have a relatively short life span of 10 to 15 days, the flight period for each species can last from 25-30 days. The main functions of the adult stage are mating and egg-laying. Feeding is less important, and probably water is the most pressing need.” That said, adults are benign for the gardener, except that they provide food for insect eating birds and other predators that often benefit the garden. The larvae are probably a greater concern since they feed, but according to the Crane Flies of Pennsylvania: “The larvae are found in a wide variety of habitats, varying from strictly aquatic to terrestrial, even relatively dry soil. Their habitats include fresh water in fast-flowing streams, marshes, springs, meadows, seeps, tree holes, algal growth or mosses on rock faces near water, organic mud and decaying vegetable debris along the shores of streams and ponds, accumulated decomposed leaves and rotting wood on the forest floor, and occasionally soil in lawn and pastures. … Larvae are the growth stage and the majority of crane fly larvae are scavengers feeding on decomposing plant material and the associated microorganisms. Larvae of some aquatic species are predators on other small invertebrates, and several are herbivores on algae, moss or herbaceous plants.” There are also many nice images of Tiger Crane Flies on iNaturalist.