Where Do Fungus Gnats Come From: Uncovering Their Origins and Habitats

Fungus gnats are tiny, flying pests that can be a real nuisance in your home or garden. You might have noticed these little insects buzzing around your plants or windows and wondered where they come from. Understanding the origin of fungus gnats and their life cycle can help you take control of the situation and protect your plants.

These bothersome insects most commonly originate from containers or soil of houseplants, as they are attracted to the moisture and decaying organic material found in potting mixes. Overwatering your plants can create an ideal environment for fungus gnat larvae to thrive, ultimately leading to an increase in the adult gnat population.

Fungus gnats have a short life cycle, passing through four developmental stages: eggs, larvae, pupae, and adults. The female gnats lay their eggs on the surface of moist soil or host plants, where they hatch and begin feeding on root hairs, fungi, and other organic matter. When trying to manage fungus gnats, focusing on their breeding grounds in your plants’ soil is key to eliminating these pests.

Origins of Fungus Gnats

Fungus gnats are tiny insects found worldwide, causing annoyance and damage to plants. They thrive in damp environments and are often associated with overwatered houseplants or poorly drained soils.

These tiny pests have a four-stage life cycle: eggs, larvae, pupae, and adults. They lay their eggs on the surface of soil or host plants where moisture is present. In just a matter of days, the eggs hatch into larvae which feed on fungi, algae, and decaying plant matter found in the top layers of soil.

Fungus gnat larvae can also cause damage to plants by feeding on their roots and leaves resting on the soil surface. This is particularly troublesome for young or weak plants that cannot easily recover from their feeding.

In order to minimize their presence, it’s important to manage moisture levels in plant containers. One helpful method involves drying out the potting soil, which leads to the death of the larvae. Yellow sticky traps can also be used to monitor and control adult fungus gnats around your plants.

By understanding the origins of these pests and their life cycle, you can prevent and control their harmful impact on your plants. So, ensure proper soil drainage and maintain appropriate moisture levels to keep your plants fungus gnat-free and healthy.

Life Cycle of Fungus Gnats

Fungus gnats have a fascinating life cycle that consists of four developmental stages: eggs, larvae, pupae, and adults. Let’s explore each stage briefly.

Eggs: These tiny, oval, and semi-transparent eggs are difficult to spot and can be found either in small groups or singly on the surface soil or host plants. They typically take about four to six days to hatch.

Larvae: The larvae primarily feed on fungi, algae, and decaying plant matter. However, they can also feed on plant roots and leaves resting on the growing medium surface. They usually reside in the top 2-3 inches of moist soil, depending on the moisture level.

Pupae: After the larvae complete their growth, they develop into oblong pupae, which occur in damp organic media. At a temperature of 75ºF, the pupation process takes approximately 4 days.

Adults: The adult fungus gnats can be seen flying around lamps and windows in homes. Though they are annoying, these tiny black flies are harmless and do not damage indoor plants.

It’s important to note that the life cycle of fungus gnats is influenced by temperature. The optimal temperature for their development is around 70-75° F. As temperatures decrease, their development time increases.

In homes, overwatering plants can contribute to the growth of the fungi these gnats prefer, leading to overlapping generations of these pests. To maintain a healthy indoor environment for your plants, ensure proper watering and drainage, and prevent excessive moisture in the soil that can encourage the growth of fungus gnats.

Appearance and Identification

Fungus gnats are small insects that can become a nuisance when they infest indoor plants and greenhouses. Identifying these pests can help you protect your plants and maintain a healthy environment.

Fungus gnats measure about 1/10 to 1/8 of an inch long and have a somewhat mosquito-like appearance. Their bodies are slender, which makes them easily distinguishable from other insects. These gnats can vary in color, ranging from gray to black or even orange-to-yellowish shades.

One noticeable feature of fungus gnats is their dark-colored antennae. These antennae are segmented and long, which is characteristic of their species. Another distinctive trait is their shiny black head which adds to their unique appearance.

In addition, they possess delicate, slender legs that allow them to navigate easily through soil and plants. When examining their wings, you will notice a distinct vein pattern that helps with identification.

So, when you encounter tiny insects near your indoor plants or in greenhouses, pay attention to their size, color, antennae, and distinct shiny black head. By doing so, you will be able to quickly identify fungus gnats and take appropriate action to protect your plants.

Habitat and Breeding Sites

Fungus gnats thrive in places with an abundance of soil, organic matter, and moisture. They are often found in areas with damp soil or near plants that prefer moist conditions.

Since these pests primarily feed on fungi, algae, and decaying plant matter, you may find them in compost or indoor mulch piles. In addition to soil, some common breeding sites include standing water, poor drainage areas, and even household drains.

To prevent fungus gnat infestations, ensure proper drainage for your plants and avoid overwatering. Let the soil dry out between watering, as moist soil provides the perfect environment for fungus gnat larvae to grow.

Keep in mind:

  • Fungus gnats can be found near plants that prefer moist soil.
  • Breeding sites include moist soil, poor drainage areas, and compost piles.
  • Adequate drainage and proper watering can help prevent infestations.

When dealing with fungus gnats, always remember that maintaining a clean and well-draining environment can significantly reduce their presence in your home or garden. By understanding their habitat and breeding sites, you can work towards creating a more fungus gnat-free space.

Diet and Feeding Habits

Fungus gnats are small insects that can be a nuisance for gardeners and plant lovers. Their larvae, eggs, and adult forms are closely associated with damp or moist areas around plants, where they can find fungi, decaying organic matter, and plant root hairs to feed on.

  • Larvae: At the larval stage, these tiny insects are especially fond of munching on fungi that grow in damp soil. As they feed, they may also consume plant root hairs, leading to stunted growth or even death for your beloved plants.
  • Eggs: Fungus gnat eggs typically hatch within four to six days after being laid by the adult females. The eggs can be found on the soil surface or even on the host plants. Moisture management is essential to controlling their population, as they thrive in overly damp conditions.
  • Fungi: It’s worth noting that fungus gnats are attracted to fungi in the soil, which is a primary food source for them. By keeping your plant soil less damp and improving air circulation, you can significantly reduce the fungi and, in turn, the fungus gnats population.
Habitat Fungus Gnats Presence Suitable Food Source Impact on Plants
Damp Soil High Fungi, Root Hairs Stunted growth
Dryer Soil Low Limited Healthy growth

To keep fungus gnats at bay, it’s important to be aware of the conditions that contribute to their growth and feeding habits. By maintaining proper moisture levels and reducing fungi in the soil, you can limit their impact on your plants and enjoy a healthy garden.

Common Places of Infestation

Indoor Infestation

When it comes to indoor infestations, houseplants are the most common source of fungus gnats. Overwatering can lead to the growth of fungi in the potting mix, which attracts the gnats. Keeping the soil moisture in check is key to avoiding this issue.

Here are some common indoor sites for fungus gnat infestations:

  • Indoor plants, especially those with high organic matter in the soil
  • Potted plants with damp potting soil
  • Areas with stagnant water, such as near sink drains or vases with flower arrangements
  • Raw potatoes stored in damp conditions, as these can attract fungus gnats and drain flies

Outdoor Infestation

Fungus gnats can breed in various outdoor settings, particularly in moist soil and decomposing organic matter such as:

  • Mulch or compost piles
  • Garden beds with high organic matter
  • Greenhouses with damp soil and plant debris
  • Areas around doors or windows, where gnats can fly in from outside

In the United States, certain fungal diseases like Blastomycosis and Histoplasmosis are associated with moist soil, which can attract fungus gnats. These diseases are common in moist environments and can be carried by fungus gnats, so tackling an infestation early is important for your health.

To prevent outdoor infestations, follow these tips:

  • Ensure proper drainage in your garden beds and potted plants
  • Regularly clean greenhouses and remove plant debris
  • Keep doors and windows sealed or use screens to prevent gnats from entering your space
  • Practice good sanitation in and around your home environment

Differences Between Fungus Gnats and Similar Pests

When dealing with small flying insects, it can be challenging to identify the exact type you’re encountering. Fungus gnats, fruit flies, and mosquitoes are among the most common pests people come across, and each has distinct features. In this section, we’ll compare these pests, as well as other lesser-known families like Diadocidiidae, Ditomyiidae, Keroplatidae, Bolitophilidae, and Mycetophilidae, to help you better understand their differences.

Fungus gnats are attracted to moist environments and lay their eggs in damp soil. They are very tiny, around 1/10 to 1/8 inches in length, and have a delicate, mosquito-like appearance with dark-colored antennae and long legs as mentioned here. In contrast, fruit flies are slightly larger and typically have a reddish-brown coloration. They often gather around ripe or decaying fruits and vegetables.

Mosquitoes are larger than both fungus gnats and fruit flies, and they’re also more of a health concern due to their potential to transmit diseases. While fungus gnats and fruit flies are mostly harmless, mosquitoes can cause itching and irritation from their bites.

Various families of fungus gnats like Diadocidiidae, Ditomyiidae, Keroplatidae, Bolitophilidae, and Mycetophilidae share some similarities with the above-mentioned pests. However, they differ in their feeding habits, breeding grounds, and wing patterns. Some of these families are extremely small and are not commonly encountered.

Here’s a comparison table of the discussed pests:

Pest Size Appearance Habitat Impact on Humans
Fungus Gnat 1/10 – 1/8 in Mosquito-like Damp Soil Mostly Harmless
Fruit Fly Larger than gnats Reddish-brown Fruits, Vegetables Mostly Harmless
Mosquito Larger than both Distinctive wings Standing Water Disease Carrier

To sum up, the differences lie in their size, appearance, and habitat preferences. Identifying the type of insect pest you’re dealing with can help you take appropriate prevention and control measures to maintain a healthy living environment.

Effects of Fungus Gnats on Plants

Fungus gnats might seem harmless at first glance, but they can cause problems for your plants. In this section, we’ll briefly discuss the effects these pesky insects can have on your beloved plants.

Impact on seedlings and young plants: Fungus gnat larvae can feed on plant roots, especially of seedlings and young plants with underdeveloped root systems. This can interfere with callus formation and root initiation, making it difficult for your plants to properly grow.

Yellowing and poor growth: As fungus gnat larvae damage the roots, you might notice your plants’ leaves yellowing and their overall growth becoming weak. This is a result of the plant’s inability to properly take up nutrients and water due to damaged roots.

Disease transmission: Fungus gnats can carry plant pathogens on their bodies and transmit them to your plants. This might exacerbate the damage they’re already causing, especially if the pathogens bring diseases to your plants.

However, not all fungus gnats are completely bad news for your plants. Some adult fungus gnats can act as pollinators, transferring pollen between flowers and playing a role in the reproduction of some plants.

To sum it up, while fungus gnats are often just an annoyance, you should be aware of the potential harm their larvae can cause to your plants. Keep an eye on yellowing leaves, stunted growth, and diseases, and take action to tackle any infestations if necessary.

Control and Management Methods

To effectively manage and control fungus gnats, there are several methods you can employ:

  • Use sticky traps: Place yellow sticky traps near your plants to capture adult gnats and monitor their population. Yellow is an attractive color to these pests, making it easier to catch them.

  • Bacillus thuringiensis: Apply Bacillus thuringiensis var. israelensis (Bti), a natural soil bacterium, to the soil to target and kill fungus gnat larvae. This helps prevent them from maturing and damaging your plants.

  • Insecticides: Apply insecticides such as pyrethrins to the soil surface or foliage, but keep in mind that these may not always be effective against larvae. Use with caution and follow label instructions to avoid harm to beneficial insects.

  • Mosquito dunk: You can use mosquito dunk, a product containing Bti, in your water source to control fungus gnat populations in both the larval and adult stages.

  • Hydrogen peroxide: Mix a 3% hydrogen peroxide solution with water and drench the soil to eliminate larvae and kill the fungi they feed on. This helps break the life cycle of the gnats.

  • Biological control: Introduce natural predators, such as nematodes or predatory mites, to your growing area to manage fungus gnats naturally.

  • Diatomaceous earth: Apply food-grade diatomaceous earth to the soil surface. The tiny sharp particles can damage the exoskeletons of the gnats, killing them.

  • Neem oil: Spray neem oil on the affected plants to deter adult gnats and inhibit their ability to lay eggs.

  • Repotting: If you suspect an infestation, consider repotting your plants in fresh, well-draining soil to minimize breeding sites for fungus gnats.

Remember to practice proper moisture management as fungus gnats thrive in overly moist environments. Allow your plants’ soil to dry out between watering, thus preventing conditions favorable for gnats to reproduce and spread. Regularly monitor and use multiple methods for the best results in controlling and managing fungus gnats.

Tips for Prevention

Keeping fungus gnats at bay is easier when you follow these simple prevention tips. By implementing these measures in your home or garden, you’ll reduce the chances of these pests making themselves at home in your space.

Instead of retaining excess moisture, add a layer of sand to the top of your plant’s soil. Sand allows for better drainage, creating a less hospitable environment for fungi.

Keep your space clean to avoid giving these gnats a reason to invade. Regularly remove any plant debris and minimize standing water. By doing so, you’ll reduce their food source and their preferred breeding ground.

An effective way to prevent Pythium, a common fungus often associated with gnats, is to let your plants have a proper rest time between waterings. By allowing the soil to partially dry out, you diminish the chances of fungus, and therefore fungus gnats, from thriving.

Keep in mind that fungus gnats could be confused with drain flies, another nuisance in a damp environment. Identifying the correct pest helps greatly in choosing the appropriate control measures.

Consider the following for controlling fungus gnats:

  • Use yellow sticky traps to monitor and catch adult gnats
  • Introduce natural predators like nematodes or predatory mites

In summary, remember these key points when preventing fungus gnats:

  • Add a sand layer to your soil for better drainage
  • Clean up plant debris and minimize standing water
  • Let plants rest between waterings
  • Properly identify the pest to choose the right control methods

By following these suggestions in a friendly tone, you’ll be on your way to a gnat-free environment.

When to Call a Professional

You might be wondering when it’s time to call an exterminator to deal with fungus gnats. If you’ve tried all the DIY methods and can’t seem to get rid of them, it could be time to bring in a professional.

Here are some scenarios in which you should consider calling an expert:

  • You have a significant infestation that impacts your indoor plants or your comfort in your living space.
  • You’ve tried the common remedies, such as drying out the soil and using yellow sticky traps, with no success.
  • The infestation is spreading to other areas of your home or multiple plants.
  • You are unable to identify the exact source, and it’s causing you stress.

A professional exterminator will have access to more advanced tools and methods for dealing with fungus gnats. They can help identify the source of the infestation and provide tailored solutions to get rid of them once and for all.

Remember to keep it friendly and always maintain a second person point of view while writing in English.

Conclusion

In summary, fungus gnats originate from moist, organic-rich environments where their larval stages can feed on decaying matter and fungi. For example, overwatered potted soil or decomposing plants provide ideal breeding grounds for these pesky insects 1.

To prevent their growth, try the following measures:

  • Avoid overwatering your plants
  • Allow the soil to dry out between waterings 2
  • Make use of yellow sticky traps to monitor and control their populations

Remember, fungus gnats may not cause severe damage to your plants, but their presence can be annoying and may indicate other underlying issues with plant care. By keeping a close eye on your plants and maintaining a friendly environment for plant growth, you can prevent fungus gnats from becoming a major problem in your space.

Reader Emails

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 – Mysterious Larvae in webbing possibly Fungus Gnat Larvae

 

Strange White Larvae In Webbing Under Rock
November 21, 2009
Hi,
I’ve been using your site to identify insects ever since I discovered it a year ago. The work you guys do here is really amazing, especially encouraging people not to kill the insect for identification!
Please note that the image here was taken in September under a rock on the bare ground. There were none of these larva on the ground under the rock, they seemed to be confined to their ‘webbing’. I only took one photo unfortunately, as I figured they’d be pretty characteristic and easy to identify. This has not been the case so far…
Christie
Muskoka, Ontario, Canada

Unidentified Mass of Larvae
Mass of Larvae: Fungus Gnats

Hi Christie,
Your image represents one of two letters with mystery larvae we just received.  We thought your example must be some species of fly, but our preliminary search drew a big blank.  We also entertained the possibility that they might be Flea larvae since they spin a silken cocoon, and though there is a resemblance, we cannot find any information indicating this degree of group habitation.  We will contact Eric Eaton in an attempt to give you an answer.  You might want to consider providing a comment to this posting online in the event that we get a response far in the future.

Unidentified Mass of Larvae
Mass of Larvae: Fungus Gnats

Eric Eaton Responds
Daniel:
I have now found several images of fungus gnat larvae on the ‘net that show a distinct head capsule.  They are well-known to spin silk or mucus, too, so that part fits.  There may be a species up in Canada that is colonial as suggested by the image, but that is a group of flies I am barely familiar with (families Mycetophilidae and Sciaridae).
Eric

Letter 2 – Unidentified Sluglike Mystery Organism and Fungus Gnat Larvae or Keroplatid

 

slug-like creature
Mon, Dec 29, 2008 at 3:02 PM
Hi,
I found this little guy under a log at my aunt’s house in central Oklahoma this summer. I see these guys pretty often, but have no idea what they are. They leave a trail of slime like a slug, but don’t have any eye-stalks, and they make little “webs” out of their slime. Any help you can provide would be much appreciated. Thanks for the great site, and happy holidays.
Josh Kouri,
Oklahoma City , Ok.

Big Mystery
Keroplatid

Hi Josh,
We are not certain how to classify your mystery organism. We don’t believe it is a mollusc, so would rule out that it is a slug. We also don’t believe it is an insect, though some larval insects are very uninsectlike, including many larval flies, commonly called maggots. This might be a fly larva. It also doesn’t seem very wormlike or leechlike to us. For now, we would say perhaps this is some type of fly larva, but we are far from certain. Perhaps our readership will come to our rescue. Meanwhile, is it possible for you to tell us how large this organism is?

The ones I’ve seen range in size from about 1/4 inch to one inch. The one
pictured was about 3/4 of an inch. Hope this helps. I’ll see if I have any
other pics.

Identification: December 31, 2008
Daniel:
Well, the description of the behavior is more helpful than the image in this case. You are quite right about it being a fly larva, most likely that of a fungus gnat in the family Mycetophilidae. Some species are known to build mucous “webs,” most notably the bioluminescent ones in Waitomo Caves in New Zealand. This one sure ‘looks’ like a slug….
Eric Eaton

Update:
January 1, 2009
Hi,
I was looking at some of my older pictures today and realized that the slug-like creature is not what makes the “webs”, and the one pictured is the only one I have seen. The creatures that make the “webs” are more worm-like, and the lengths I gave you are for the worms, as I have only seen one of the slug-creatures. I still don’t know what either of the creatures is, and I hope you guys can help. Sorry for the mistakes. Thanks for the awesome site, and happy New Year.
Josh Kouri

Fungus Gnat Larvae
Fungus Gnat Larvae

Hi Josh,
Eric Eaton wrote in to say that based on your written description, your creature was a Fungus Gnat larva in the family Mycetophilidae. That would mean that your original image is still a mystery and the new photo which shows the webs would be the Fungus Gnat larva.

fungus gnat larvae update
Fri, Jan 2, 2009 at 11:31 AM
Hi,
When I saw that you guys identified the “worms” as fungus gnat larvae I decided to look for better pictures on the internet.
The pictures I found looked a lot different from what I have been seeing. Is it possible the “worms” are some other type of fly or gnat larvae, or even something completely different? Thanks again for all you do.
Josh Kouri

Update: January 5, 2009
Daniel:
Saw the update that the image is not what is making the mucous webs. Well, I would say that the image is that of a slug, then, and it shouldn’t be that hard to ID. It is probably an introduced European species that has spread via commerce, ship’s ballast, etc.
Eric

Update:  June 2, 2017
Thanks to a comment from Rafaela, we are able to identify this as a member of the family Keroplatidae, the Predatory Fungus Gnats.  According to BugGuide:  “Larvae are predaceous or mycophagous; they spin hygroscopic webs to collect spores or small invertebrate prey. Predaceous species kill their prey with an acid fluid (mostly oxalic acid) secreted by labial glands and deposited in the droplets of their web; mycophagous larvae also have acid webs and occasionally feed on pupae of their own species or on dead insects. Larva of a Tasmanian species lives endoparasitically in land planarians.”  

Letter 3 – Fungus Gnat Larvae: Strange Formations

 

Unknown Larvae Formations
September 24, 2009
We live in central TN and found these larvae formations around our driveway after heavy rains. Mostly seen in circular and abstract formations but always in clusters, never single larva alone. They also seem to stay in one location for long periods of time after patterns are formed. Their exterior has a translucent appearance rather than solid color and has a black tip or end. Do you know what this is?
Thanks for your help – Shannon
Central TN

Fungus Gnat Larvae
Fungus Gnat Larvae

Hi Shannon,
We contacted Eric Eaton and here is what he had to say:  “Hi, Daniel:  Well, these must be the dumbest larvae in history to be going in a circle.  LOL!  They are the larvae of some kind of dark-winged fungus gnat, family Sciaridae.  The larvae of some species are well-known for their occasional, spectacular mass movements.
Eric

Fungus Gnat Larvae
Fungus Gnat Larvae

Letter 4 – Fungus Gnat Larvae in South Africa

 

Subject:  Bugs mimic snake
Geographic location of the bug:  KwaZuluNatal, South Africa
Date: 05/08/2019
Time: 08:57 AM EDT
Your letter to the bugman:  Looked like a snake moving across a porch. Closer inspection showed it was made up of many ‘bugs’ – ?caterpillar-like (not sure – photo sent to me).
How you want your letter signed:  bewilderbeast

Fungus Gnat Larvae

Dear bewilderbeast,
This is an aggregation of Fungus Gnat larvae in the family Sciaridae,
and we have gotten reports in the past from South Africa.  According to GrowVeg:  “The small translucent eggs are laid in batches of 20-50 into the compost surface. These hatch into small cream-coloured maggots that have shiny black heads. The larvae live within the soil and feed on plant roots, lower stems and on leaves that touch the compost surface. When mature, the larvae are around 6mm in length.

Fungus Gnat Larvae

Letter 5 – Fungus Gnat Larvae from South Africa

 

Subject: catepillars
Location: Mpumalanga south africa
February 20, 2017 12:32 am
Hi there
I know the precessionary caterpillars. These ones move like, and obviously mimics a snake. they are much smaller. is it maybe the early stage of precessionary catepillars?
thanks
Signature: wetie

Fungus Gnat Larvae

Dear wetie,
We believe these are Fungus Gnat larvae from the family Sciaridae.  According to iSpot, Fungus Gnats are found in South Africa.  According to BugGuide:  “Sometimes abundant enough to form a crawling mass of several inches across and several feet long, similar to armyworm migrations.”

Fungus Gnat Larvae

Letter 6 – Probably Dark Winged Fungus Gnats

 

Subject: Bug ID
Location: Bois Blanc Island, MI
February 9, 2017 1:07 pm
Last July, on an inland hike on Bois Blanc Island, MI we discovered swamp milkweed covered in these insects. I have zero idea what they were and had never seen them before. But curiosity has the best of me and I would like to know what they were if possible.
THANK YOU!
Signature: B. Dunn

Fungus Gnats, we believe

Dear B. Dunn,
At first we thought these might be March Flies, but they do not feed and most insects attracted to milkweed blossoms do so because of the rich nectar they provide.  We then entertained they might be Soft Winged Flower Beetles, but that did not look correct, so we contacted Eric Eaton for assistance.

Eric Eaton provides a possible identification.
Daniel:
These remind me of dark-winged fungus gnats, family Sciaridae, but I cannot tell for certain from this one image.
Eric

Ed. Note:  This BugGuide image supports Eric Eaton’s identification.  Though BugGuide does not provide any information on adult food preferences, BugGuide does contain some images of adult Dark Winged Fungus Gnats feeding from blossoms.

Fungus Gnats, we believe

Reader Emails

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 – Mysterious Larvae in webbing possibly Fungus Gnat Larvae

 

Strange White Larvae In Webbing Under Rock
November 21, 2009
Hi,
I’ve been using your site to identify insects ever since I discovered it a year ago. The work you guys do here is really amazing, especially encouraging people not to kill the insect for identification!
Please note that the image here was taken in September under a rock on the bare ground. There were none of these larva on the ground under the rock, they seemed to be confined to their ‘webbing’. I only took one photo unfortunately, as I figured they’d be pretty characteristic and easy to identify. This has not been the case so far…
Christie
Muskoka, Ontario, Canada

Unidentified Mass of Larvae
Mass of Larvae: Fungus Gnats

Hi Christie,
Your image represents one of two letters with mystery larvae we just received.  We thought your example must be some species of fly, but our preliminary search drew a big blank.  We also entertained the possibility that they might be Flea larvae since they spin a silken cocoon, and though there is a resemblance, we cannot find any information indicating this degree of group habitation.  We will contact Eric Eaton in an attempt to give you an answer.  You might want to consider providing a comment to this posting online in the event that we get a response far in the future.

Unidentified Mass of Larvae
Mass of Larvae: Fungus Gnats

Eric Eaton Responds
Daniel:
I have now found several images of fungus gnat larvae on the ‘net that show a distinct head capsule.  They are well-known to spin silk or mucus, too, so that part fits.  There may be a species up in Canada that is colonial as suggested by the image, but that is a group of flies I am barely familiar with (families Mycetophilidae and Sciaridae).
Eric

Letter 2 – Unidentified Sluglike Mystery Organism and Fungus Gnat Larvae or Keroplatid

 

slug-like creature
Mon, Dec 29, 2008 at 3:02 PM
Hi,
I found this little guy under a log at my aunt’s house in central Oklahoma this summer. I see these guys pretty often, but have no idea what they are. They leave a trail of slime like a slug, but don’t have any eye-stalks, and they make little “webs” out of their slime. Any help you can provide would be much appreciated. Thanks for the great site, and happy holidays.
Josh Kouri,
Oklahoma City , Ok.

Big Mystery
Keroplatid

Hi Josh,
We are not certain how to classify your mystery organism. We don’t believe it is a mollusc, so would rule out that it is a slug. We also don’t believe it is an insect, though some larval insects are very uninsectlike, including many larval flies, commonly called maggots. This might be a fly larva. It also doesn’t seem very wormlike or leechlike to us. For now, we would say perhaps this is some type of fly larva, but we are far from certain. Perhaps our readership will come to our rescue. Meanwhile, is it possible for you to tell us how large this organism is?

The ones I’ve seen range in size from about 1/4 inch to one inch. The one
pictured was about 3/4 of an inch. Hope this helps. I’ll see if I have any
other pics.

Identification: December 31, 2008
Daniel:
Well, the description of the behavior is more helpful than the image in this case. You are quite right about it being a fly larva, most likely that of a fungus gnat in the family Mycetophilidae. Some species are known to build mucous “webs,” most notably the bioluminescent ones in Waitomo Caves in New Zealand. This one sure ‘looks’ like a slug….
Eric Eaton

Update:
January 1, 2009
Hi,
I was looking at some of my older pictures today and realized that the slug-like creature is not what makes the “webs”, and the one pictured is the only one I have seen. The creatures that make the “webs” are more worm-like, and the lengths I gave you are for the worms, as I have only seen one of the slug-creatures. I still don’t know what either of the creatures is, and I hope you guys can help. Sorry for the mistakes. Thanks for the awesome site, and happy New Year.
Josh Kouri

Fungus Gnat Larvae
Fungus Gnat Larvae

Hi Josh,
Eric Eaton wrote in to say that based on your written description, your creature was a Fungus Gnat larva in the family Mycetophilidae. That would mean that your original image is still a mystery and the new photo which shows the webs would be the Fungus Gnat larva.

fungus gnat larvae update
Fri, Jan 2, 2009 at 11:31 AM
Hi,
When I saw that you guys identified the “worms” as fungus gnat larvae I decided to look for better pictures on the internet.
The pictures I found looked a lot different from what I have been seeing. Is it possible the “worms” are some other type of fly or gnat larvae, or even something completely different? Thanks again for all you do.
Josh Kouri

Update: January 5, 2009
Daniel:
Saw the update that the image is not what is making the mucous webs. Well, I would say that the image is that of a slug, then, and it shouldn’t be that hard to ID. It is probably an introduced European species that has spread via commerce, ship’s ballast, etc.
Eric

Update:  June 2, 2017
Thanks to a comment from Rafaela, we are able to identify this as a member of the family Keroplatidae, the Predatory Fungus Gnats.  According to BugGuide:  “Larvae are predaceous or mycophagous; they spin hygroscopic webs to collect spores or small invertebrate prey. Predaceous species kill their prey with an acid fluid (mostly oxalic acid) secreted by labial glands and deposited in the droplets of their web; mycophagous larvae also have acid webs and occasionally feed on pupae of their own species or on dead insects. Larva of a Tasmanian species lives endoparasitically in land planarians.”  

Letter 3 – Fungus Gnat Larvae: Strange Formations

 

Unknown Larvae Formations
September 24, 2009
We live in central TN and found these larvae formations around our driveway after heavy rains. Mostly seen in circular and abstract formations but always in clusters, never single larva alone. They also seem to stay in one location for long periods of time after patterns are formed. Their exterior has a translucent appearance rather than solid color and has a black tip or end. Do you know what this is?
Thanks for your help – Shannon
Central TN

Fungus Gnat Larvae
Fungus Gnat Larvae

Hi Shannon,
We contacted Eric Eaton and here is what he had to say:  “Hi, Daniel:  Well, these must be the dumbest larvae in history to be going in a circle.  LOL!  They are the larvae of some kind of dark-winged fungus gnat, family Sciaridae.  The larvae of some species are well-known for their occasional, spectacular mass movements.
Eric

Fungus Gnat Larvae
Fungus Gnat Larvae

Letter 4 – Fungus Gnat Larvae in South Africa

 

Subject:  Bugs mimic snake
Geographic location of the bug:  KwaZuluNatal, South Africa
Date: 05/08/2019
Time: 08:57 AM EDT
Your letter to the bugman:  Looked like a snake moving across a porch. Closer inspection showed it was made up of many ‘bugs’ – ?caterpillar-like (not sure – photo sent to me).
How you want your letter signed:  bewilderbeast

Fungus Gnat Larvae

Dear bewilderbeast,
This is an aggregation of Fungus Gnat larvae in the family Sciaridae,
and we have gotten reports in the past from South Africa.  According to GrowVeg:  “The small translucent eggs are laid in batches of 20-50 into the compost surface. These hatch into small cream-coloured maggots that have shiny black heads. The larvae live within the soil and feed on plant roots, lower stems and on leaves that touch the compost surface. When mature, the larvae are around 6mm in length.

Fungus Gnat Larvae

Letter 5 – Fungus Gnat Larvae from South Africa

 

Subject: catepillars
Location: Mpumalanga south africa
February 20, 2017 12:32 am
Hi there
I know the precessionary caterpillars. These ones move like, and obviously mimics a snake. they are much smaller. is it maybe the early stage of precessionary catepillars?
thanks
Signature: wetie

Fungus Gnat Larvae

Dear wetie,
We believe these are Fungus Gnat larvae from the family Sciaridae.  According to iSpot, Fungus Gnats are found in South Africa.  According to BugGuide:  “Sometimes abundant enough to form a crawling mass of several inches across and several feet long, similar to armyworm migrations.”

Fungus Gnat Larvae

Letter 6 – Probably Dark Winged Fungus Gnats

 

Subject: Bug ID
Location: Bois Blanc Island, MI
February 9, 2017 1:07 pm
Last July, on an inland hike on Bois Blanc Island, MI we discovered swamp milkweed covered in these insects. I have zero idea what they were and had never seen them before. But curiosity has the best of me and I would like to know what they were if possible.
THANK YOU!
Signature: B. Dunn

Fungus Gnats, we believe

Dear B. Dunn,
At first we thought these might be March Flies, but they do not feed and most insects attracted to milkweed blossoms do so because of the rich nectar they provide.  We then entertained they might be Soft Winged Flower Beetles, but that did not look correct, so we contacted Eric Eaton for assistance.

Eric Eaton provides a possible identification.
Daniel:
These remind me of dark-winged fungus gnats, family Sciaridae, but I cannot tell for certain from this one image.
Eric

Ed. Note:  This BugGuide image supports Eric Eaton’s identification.  Though BugGuide does not provide any information on adult food preferences, BugGuide does contain some images of adult Dark Winged Fungus Gnats feeding from blossoms.

Fungus Gnats, we believe

Authors

    by
  • 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.

5 thoughts on “Where Do Fungus Gnats Come From: Uncovering Their Origins and Habitats”

  1. I don’t know what “webbing” means. I have hundreds or thousands of these worms which just showed up after a rain. They are primarily in the 1 inch area between concrete slabs where boards previously were used as dividers. These have rotted away years ago and now the area is covered with these worms – covered.

    Reply

Leave a Comment