Are Crane Flies Harmful? Debunking Myths and Revealing Facts

Crane flies, often mistaken for giant mosquitoes, are actually members of the fly family Tipulidae.

These insects have slender mosquito-like bodies and extremely long legs, and they are usually found around water sources.

Though they may look intimidating, their presence in your surroundings is generally harmless.

Are Crane Flies Harmful
Crane Fly

In terms of lifecycle, adult crane flies have a rather short lifespan, living for only two weeks.

Crane fly larvae usually cause minimal damage as they feed on decaying plant matter. They can sometimes chew through patches of lawn, damaging roots and affecting grass growth.

However, this damage can be prevented through simple maintenance and irrigation practices.

It is essential to note that crane flies do not bite or transmit diseases like some of their mosquito counterparts.

They are simply a nuisance due to their large size and tendency to swarm around light sources.

What are Crane Flies?

Crane flies are insects belonging to the family Tipulidae within the order Diptera.

Although they resemble mosquitoes, they are not related to them. Crane flies are mostly found near water sources and are harmless creatures.

Physical Characteristics

Crane flies possess a slender body and extremely long legs. Their wingspan varies, and they have halteres, which are small knobbed structures used for balance.

Adult crane flies can range from tiny to almost 1.2 inches in length, with a wingspan around 2 inches.

Comparison between crane flies and mosquitoes

FeatureCrane FliesMosquitoes
SizeUp to 1.2 inches longSmaller
LegsExtremely longShorter
WingsTwo wings with halteresTwo wings
HarmfulNoYes (can transmit diseases)

Life Cycle

  • Crane fly eggs hatch into larvae, which are small and brown when young.
  • Mature larvae reach a length of 1-1.25 inches before transforming into pupae.
  • Adult crane flies emerge from the pupae and live for about two weeks.

Examples of other insects with similar life cycles include butterflies and mosquitoes.

Crane flies are an interesting species to observe, but they pose no harm or significant impact on humans or the environment.

Are Crane Flies Harmful?

Crane flies are often mistaken for mosquitoes due to their slender mosquito-like body and long legs.

However, adult crane flies are completely harmless to humans, as they have no stinger and their mouthparts are not designed for biting.

These slow-flying insects are usually found around water and grassy areas during the spring and fall seasons.

Larvae and Their Impact on Lawns

Crane fly larvae, also known as leatherjackets, can cause damage to lawns and grassy areas due to their feeding habits.

In the spring and fall seasons, leatherjackets feed on the roots, stems, and leaves of grass, leading to lawn problems.

However, various control measures can be taken to mitigate the impact:

  • Lawn care: Proper lawn care practices and refraining from overwatering, can reduce the larval population.
  • Natural predators: Crane fly larvae have natural enemies, such as birds, fungi, and nematodes, which can help suppress larval populations when soils are moist.
  • Biological controls: The combination of cultural and biological controls, like using the entomopathogenic nematode Steinernema carpocapsae, can be an effective way to manage crane fly larvae.

Table comparing crane fly larvae and adult crane flies

AspectCrane Fly AdultCrane Fly Larvae
Harmful to humansNoNo
Impact on lawnsNoYes
Control methodsN/ALawn care, natural predators, and biological controls

Crane Flies and Ecosystem

Crane flies play a significant role in the food chain, acting as a vital food source for various predators in the ecosystem.

Examples of animals that prey on crane flies include:

  • Birds
  • Frogs
  • Swallows
  • Lizards

Although adult crane flies have short lives, their larvae, known as “leatherjackets,” serve as a key ingredient in the diets of insectivorous birds and other predators.

Crane Fly

Adult crane flies also contribute to the ecosystem by providing nectar for pollinators such as bees, butterflies, and other insects.

Importance of crane flies for a Healthy Ecosystem

Crane flies are beneficial to maintaining a healthy ecosystem. Their presence indicates good water quality, as they are usually found around clean water sources.

Crane fly larvae also play a role in breaking down decaying plant material, helping recycle nutrients within the ecosystem.

The short lifespans of adult crane flies might limit their overall impact on ecosystems, but their presence as a food source for birds, amphibians, reptiles, and insects contributes to the overall balance of the ecosystem.

Not only do they provide food for predators, but their larvae also recycle nutrients in the environment, making crane flies an essential component in supporting healthy ecosystems.

BustingMyths About Crane Flies

Crane Flies vs Mosquitoes

Crane flies and mosquitoes are often mistaken for each other due to their similar appearance. However, there are some key differences between the two insects:

  • Size: Crane flies are usually larger than mosquitoes, with some species reaching up to 1.2 inches in length1.
  • Leg length: Crane flies have longer, more slender legs compared to mosquitoes1.
  • Feeding habits: Mosquitoes feed on blood, while adult crane flies do not bite and usually feed on nectar2.

Here’s a comparison table to help differentiate between crane flies and mosquitoes:

FeatureCrane FlyMosquito
SizeUp to 1.2 inchesSmaller
Leg lengthLongerShorter
Feeding habitsNectarBlood

Mosquito Hawk Misconception

Many people mistakenly believe that crane flies are mosquito hawks or “skeeter eaters” that prey on mosquitoes.

However, this is a myth. Adult crane flies are mostly harmless and generally feed on nectar2. They do not eat mosquitoes or any other insects.

Therefore, it’s important to note that crane flies are not harmful and should not be mistaken for large mosquitoes or mosquito predators.

They are simply a different species of insect with their own unique characteristics and feeding habits.

Managing Crane Flies

Prevention Tips

  • Maintain healthy turf: Crane fly larvae can damage turf grass roots. Keep your lawn healthy to minimize their impact.
  • Monitor watering: Overwatering attracts crane flies. Adjust your irrigation practices to prevent damage to your grass.

Natural Control Methods

  • Encourage predators: Birds, spiders, and other insects feed on crane flies. Attract these natural predators to reduce their population.
  • Manual removal: Use a fly swatter or similar tool to swat adult crane flies when they are visible.

When to Use Insecticides?

Consider using insecticides when:

  • Crane fly larvae cause significant damage to your lawn.
  • Your neighbors complain about a nuisance due to large numbers of crane flies.
  • Natural control methods aren’t effective.

Crane fly control methods

MethodProsCons
Prevention TipsNon-toxic, cost-effectiveMay not deter all infestations
Natural Control MethodsEco-friendly, no chemicalsMay require patience, not always effective
InsecticidesEffective at controlling infestationsCan harm beneficial insects and plants, not always environmentally friendly

Conclusion

Despite the mosquito-like appearance and tendency to gather around lights, crane flies are harmless to humans and do not transmit diseases.

Their short lifespan and minimal impact on ecosystems make them an integral part of the food chain.

Understanding their differences from mosquitoes and deploying preventive measures when necessary can help us coexist with these fascinating creatures and maintain healthy lawns.

Footnotes

  1. University of Arizona – Crane Flies 2 3
  2. Smithsonian Institution – True Flies (Diptera) 2 3
  3. https://insectsinthecity.blogspot.com/2015/03/the-real-truth-about-crane-flies.html

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about crane flies. Scroll down to have a look at some of them.

Letter 1 – Crane Fly from Serbia

Mosquito
May 4, 2010
Hi there,
I know this is some kind of a mosquito, but I was shocked with the size of it… Can you tell me is it a rare specimen, or I can let it go =)
Uros
Serbia, Belgrade

Crane Fly

Hi Uros,
Many people believe Crane Flies to be giant mosquitoes, but they are actually quite harmless.  In some circles, they are known as Mosquito Hawks because people are under the misconception that Crane Flies prey upon mosquitoes.  Most Crane Flies do not feed as adults, though it is believed that some species feed on nectar.

Letter 2 – Crane Fly from Australia

Subject: What is this?
Location: South Sydney area
November 9, 2012 5:12 pm
Hi,
I live in Sydney, and spotted this when it followed me into the house today (10 November). Kind of reminds me of a large mosquito.

The body measures 5mm wide by 30mm long (was very patient with me while I photographed and measured it). I can’t find it in any other online source, but surely something this large is not a mystery. Would love to know what it is.
Signature: Thanks for your help

Crane Fly from Australia

This is a Crane Fly in the family Tipulidae.  We found a photo on FlickR that is identified as Ischnotoma eburnea.  We then verified that identification on the Encyclopedia of Life.  Crane Flies are harmless.

Letter 3 – Crane Fly from Serbia

Subject: Unindentified Flying Insect
Location: Belgrade, Serbia, Europe
May 9, 2013 2:28 pm
Hello,
I caught this insect a this evening, and can not find it on Google, so I’m wondering if you could help me. I never saw an insect like this, not even remotely similar.
Insect was caught on May 9th, weather has been unseasonably warm for 3 weeks, I live less than a mile from the river. Insect is little over 1 inch long (from head to the end of the body, without antenna).
I hope you can help me find out what species is this,
thank you in advance,
Janja
Signature: Janja Bobic

Crane Fly
Crane Fly

Hi Janja,
This is a Crane Fly in the family Tipulidae, and judging by those beautiful plumose antennae, this is a male.  Crane Flies are true flies with a single pair of wings.  We will contact Dr. Chen Young of the Carnegie Museum of Natural History to see if he can identify the species.  It looks similar to the
Ctenophora species on Diptera Info.

Thank you so much for your answer, I really appreciate it. This beautiful insect sparked a huge interest in my class today.
sincerely,
Janja Bobic

Hi Janja,
We got an “out of office” reply from Dr Chen Young, but we might get an update from him in a few weeks.

Letter 4 – Crane Fly: Ctenophora dorsalis

Subject: Never seen a bug like this!!
Location: Westchester NY
May 30, 2014 7:50 am
My boyfriend is an electrician, and sent me this picture of a strange looking bug he came across in this early summer season. I tried looking it up to see what it may be, but I haven’t been able to get an exact match. I’d really appreciate any input you can provide. Thanks!
Signature: Tiffany

Crane Fly
Crane Fly

Hi Tiffany,
This is a very distinctive species of Crane Fly,
Ctenophora dorsalis, and the presence of an ovipositor indicates she is a female.

Letter 5 – Crane Fly from England

Subject: Identifying wasp-like insect
Location: North East England
August 15, 2014 4:39 am
Hello there, I spotted a strange bug in my kitchen earlier today and took some pictures of it before I let it go out into my back garden.

I was wondering if you could help me on the front of identifying it, as I’ve not seen anything like it before and I’m intrigued (I’m a biology student, so it has really got me wondering!). I live in the North East of England. Thank you in advance for any help!
Signature: Ryan Simmons

Crane Fly
Crane Fly

Dear Ryan,
If you look closely, you will see that this insect has only one pair of wings, indicating that it is a fly and not a wasp.  It is a Crane Fly in the family Tipulidae.  It looks very similar to this
Ctenophora pectinicornis that is posted on this Dutch website.  Some Crane Flies are attracted to lights, which might explain why it was in your kitchen.

Letter 6 – Crane Fly from Japan

Subject:  Japanese Crane Fly?
Geographic location of the bug:  Wakayama, Japan
Date: 07/28/2021
Time: 05:46 PM EDT
Your letter to the bugman:  Looked like a wasp at first but then Google took me to your site and I think it’s very close to a crane fly you posted. It was sitting on my car at 35 degrees on July 27, 2021
How you want your letter signed:  Dirk

Crane Fly

Dear Dirk,
Your Crane Fly looks like an old posting from our archives that was identified as
Ctenophora ishiharai, and we located this FlickR posting that is identified as Ctenophora nohirae.  We believe the latter is a closer match.

Wow, thanks a lot!
Much appreciated.
Dirk

Authors

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  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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