Exploring the Life Cycle of Rat-Tailed Maggots

Rat-tailed maggots are the larval stage of a fly species that closely resembles the honey bee. These unique larvae can be identified by their whitish, ¾ inch long bodies and distinctive ½ inch long “tail,” which functions as a breathing tube when they are submerged in water. As part of their life cycle, rat-tailed maggots inhabit shallow aquatic environments with high nutrient content, allowing them to thrive in stagnant water sources.

The life cycle of rat-tailed maggots involves a fascinating transformation from larvae to adult flies, known as drone flies. This metamorphosis process is not only essential for their survival but also showcases their ability to adapt to various environments. Throughout their development, rat-tailed maggots undergo several instar stages, shedding their skin and growing in size as they mature.

One interesting feature of rat-tailed maggots is that they have a siphon – a tube-like structure – which allows them to breathe while they are in water. This siphon can be several times the length of their body and serves as a vital adaptation for their preferred aquatic habitats.

Rat-Tailed Maggot Life Cycle

Egg Stage

  • Laid in stagnant water or organic matter
  • Small and initially white in color

The egg stage of rat-tailed maggots begins with the female drone fly laying her eggs in stagnant water or organic matter, such as decaying plants. The eggs are small and initially white in color.

Larval Stage

  • Whitish, 3/4-inch long larvae with a 1/2-inch tail
  • Known as rat-tailed maggots
  • Tail serves as a breathing tube

The larval stage features whitish, 3/4-inch long larvae that possess a distinctive 1/2-inch tail which is used as a breathing tube. This feature gives them the name rat-tailed maggots.

Pupal Stage

  • Enclosed in a protective cocoon
  • Transition from larva to adult drone fly

During the pupal stage, rat-tailed maggots develop inside a protective cocoon, where they undergo the transformation from larva to adult drone fly.

Adult Drone Fly Stage

  • Resembles a honey bee
  • Mimic of European honey bee

In the final stage of their life cycle, rat-tailed maggots become adult drone flies. These flies closely resemble honey bees, specifically mimicking the European honey bee, which serves as a form of protection from predators.

Overall, rat-tailed maggots have a fascinating life cycle consisting of four key stages: the egg stage, the larval stage, the pupal stage, and the adult drone fly stage. Each stage has its unique features and characteristics that showcase how these insects thrive in their environments.

Habitats and Behavior

Aquatic Environments

Rat-tailed maggots thrive in shallow aquatic environments with high organic content, like lagoons and stagnant water containing decaying organic matter. They have a unique adaptation: a long, thin “tail” called a siphon, through which they breathe. This siphon can be several times the length of their body, allowing them to survive in low-oxygen conditions. Examples of their habitats include:

  • Manure pits
  • Stagnant ponds
  • Sewage treatment plants

Decaying Organic Matter

Rat-tailed maggots are also found in decaying organic matter, such as animal carcasses and compost. They feed on the bacteria present in these materials, contributing to the decomposition process. Organic materials they can be found in include:

  • Soil rich in decomposing plant matter
  • Rotting fruits and vegetables
  • Animal carcasses

Interaction with Other Insects

As they mature and transform into hoverflies, they become important pollinators, visiting flowers and aiding in the reproduction of plants. Hoverflies resemble honey bees, providing them some protection against predators.

Key characteristics of hoverflies:

  • Mimic honey bees in appearance
  • Act as pollinators for various plants

A comparison table of their interactions:

Interaction Examples
Prey on insects Aphids (as hoverfly adults)
Serve as prey themselves Birds and predatory insects
Share habitats (as adults) Other pollinators like bees

In summary, rat-tailed maggots play critical roles in both their aquatic and terrestrial environments, contributing to decomposition and pollination.

Anatomy and Identification

Morphology of Larvae

Rat-tailed maggots are the larval stage of the Eristalis tenax fly, which belongs to the Syrphidae family. These larvae are unique due to their distinct rat-tail-like siphon used as a breathing tube. The siphon can extend up to 1/2 inch in length, enabling the maggot to breathe while submerged in water.

Some notable features of rat-tailed maggot larvae include:

  • Whitish color
  • Length of around 3/4 inch
  • Long, extendable rat-tail siphon

Larvae can be found in stagnant water and develop through several stages before becoming adult drone flies.

Physical Features of Adult Drone Flies

Adult drone flies, or Eristalis tenax, are known for their resemblance to honeybees. They are actually hover flies, which are expert mimics of bees and wasps. This mimicry offers protection from predators as they assume drone flies are equipped with stingers.

Key features of adult drone flies are:

  • Wings with distinctive patterns of veins
  • Robust abdomen with alternating dark and light bands
  • Large eyes, typical of hover flies

A comparison table of hover flies (Eristalis tenax) and honeybees:

Characteristics Hover Flies Honeybees
Wings Single pair Two pairs
Vein patterns in wings Distinctive patterns Uniform vein patterns
Abdominal appearance Mimics honeybees True appearance
Eyes Large and prominent Smaller and less prominent

Thus, the rat-tailed maggot is an intriguing species with remarkable features in both its larval and adult stages. Identification can be made by observing the unique rat-tail siphon in the larvae and the distinct hover fly characteristics in the adult drone flies.

Role in Pollination and Mimicry

Pollination Importance

Rat-tailed maggots, or the larval stage of drone flies (Eristalis tenax), are known for their interesting life cycle and unique appearance. As they transition into adult hoverflies, they become important pollinators for various flowers. As adult drone flies, they have a few key features which contribute to their pollination ability:

  • Like bees, hoverflies can effectively transfer pollen from one flower to another during feeding, assisting with plant reproduction
  • They are less aggressive than bees, leading to minimal disturbance to gardeners and natural predators

Batesian Mimicry

The drone fly’s resemblance to the European honey bee (Apis mellifera) can be attributed to Batesian mimicry, where a harmless species imitates a harmful or unpalatable one for protection. This mimicry is beneficial for drone flies in multiple ways:

Natural Predators

  • By mimicking the appearance of bees and wasps, drone flies deter predators which may avoid attacking due to potential stings or toxins

Crop Pollinators

  • Many flowers and crops rely on a variety of pollinators, including honey bees, hummingbirds, and hoverflies. Drone flies’ mimicry allows them to blend in and become an effective pollinator without being targeted by predators

Comparison Table

Pollinator Mimicry Predators Deterred Role in Crop Pollination
Drone Fly Batesian mimicry (resembles honey bee) Many Significant
European Honey Bee None Fewer Crucial
Hummingbird Not Applicable Different set Varies

In summary, rat-tailed maggots’ life cycle contributes to their critical role in pollination, while the adult drone flies utilize clever Batesian mimicry to deter predators and successfully blend in with other recognized pollinators.

Health Risks and Prevention

Accidental Myiasis

Rat-tailed maggots, part of the Diptera family and specific to flower flies, can cause accidental myiasis in humans. This condition occurs when maggots unknowingly invade a living host typically through ingestion or contamination of food or water. The larval development in the host’s tissues may lead to symptoms such as abdominal pain, nausea, and vomiting.

Some cases of accidental myiasis are caused by contaminated water containing rat-tailed maggots. For example, if an individual unknowingly drinks water inhabited by these larvae, it could lead to the development of gastrointestinal myiasis. In more severe cases, this may progress to rectal myiasis, invoking considerable discomfort and risk of complications.

Hygiene and Sanitation

To prevent accidental myiasis caused by rat-tailed maggots, it is crucial to maintain proper hygiene and sanitation practices. Some key tips include:

  • Regularly clean and sanitize food preparation areas
  • Store food in well-sealed containers
  • Dispose of waste appropriately and ensure trash cans are covered
  • Avoid consuming water from untrusted sources

By following these simple measures, the risk of myiasis and other related diseases can be significantly minimized.

Species Distribution and Ecology

Geographical Range

Rat-tailed maggots, also known as the larvae of the adult drone fly (Eristalis tenax), have a cosmopolitan distribution. They can be found in various regions across the globe, from North America to Europe and parts of Asia. In the United States, they are more common in states like Alaska, California, and Florida.


  • Aquatic larvae: Rat-tailed maggots have a flexible breathing tube, or “snorkel,” that allows them to inhabit stagnant water or decaying organic matter.
  • False vein: Their wings feature a unique false vein, which is absent in other fly species.
  • Telescopic breathing tube: The larvae also possess a telescopic breathing tube, allowing them to extend their tail and reach the water’s surface.

Relationship with Vertebrate Animals

Rat-tailed maggots are generally considered harmless, as they primarily feed on decaying organic matter. However, some species are known to cause myiasis in livestock and other vertebrate animals, such as the human bot fly, horse bot fly, and screwworms. Myiasis is a condition where fly larvae infest living tissue and feed on it.

Pros and Cons of Rat-Tailed Maggots:

  • Pro: They play a role in breaking down organic matter, contributing to the overall ecological process.
  • Con: Some species can infest vertebrate animals, leading to infections and discomfort.

Comparison Table: Rat-tailed Maggot vs. Other Fly Larvae

Characteristic Rat-tailed Maggot Other Fly Larvae
Feeding Habits Decaying organic matter Various
Nuisance Level Low (mostly harmless) Variable
Aquatic Adaptation Aquatic larvae with breathing tube Mostly non-aquatic

In summary, the rat-tailed maggot has a unique ecological role and life cycle compared to other fly species. Its cylindrical shape, flexible hairs, and breathing tube adaptations enable it to thrive in aquatic habitats and contribute to breaking down decaying organic matter. While they are generally not a concern as pests and have a relatively low impact on vertebrate animals, some species within the Eristalini tribe can cause myiasis in livestock and other vertebrates.

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 – Rat Tailed Maggots found in wood!!!

Wood Boring Larvae
January 12, 2010
Recently, while removing a mimosa tree
(beneath power lines), I discovered some wood boring larvae. The main body is about 3/4″ long, with a tail a bit longer than the body. One didn’t survive the chain saw.
Could this be a type of horntail wasp larva?
Larry Taylor
Central Oklahoma

Rat Tailed Maggots
Rat Tailed Maggots

Hi Larry,
We believe these are the larva of a Drone Fly, Eristalis tenas, which are called Rat Tailed Maggots.  According to BugGuide:  “The adults feed on nectar from flowers and are often seen hovering in front of flower blooms in gardens in both urban and rural areas. The larvae feed on rotting organic material in stagnant water in a variety of locations.  Life Cycle  The larva of the Drone-Fly feeds on decaying organic material in stagnant water in small ponds, ditches and drains. Such water usually contains little or no oxygen and the larva breathes through the long thin tube that extends from its rear end to the surface of the water and that gives it its common name of ‘rat-tailed maggot’.
We have not heard of them boring in wood, though BugGuide has an image of one that was ” found in a trash can filled with water and old logs. Most seemed embedded in the log surface. Your letter did not indicate if the tree was decaying.  We have not heard of Rat Tailed Maggots living other than an aquatic environment, but according to a University of Kentucky report, The maggots can be a nuisance when they crawl away from their breeding site to find a dry place where they can transform to the adult stage.”  Your letter did not indicate if they were found deep inside the wood, or in the bark.  We wish we had that information.  We are going to check with Eric Eaton to get his opinion on this.

Confirmation from Eric Eaton
Hi, Daniel:
You are correct about the rat-tailed maggots.  I wonder if there was a hole in the tree that had collected water and/or decaying leaves and other organic matter.  That would explain things right there.

Thanks so much for identifing this unusual maggot.  It makes sense, as the tree had a hollow. (But no water in the hollow at the time of cutting)  They fell out when the tree was felled.  There were burrows in the wood that hadn’t rotted and just assumed thats where they came from.
I’ve observed the drone flies but had no idea of their larval stage.
Thanks again! Larry
P.S. I would like to submit a query on the identification of a peculiar grasshopper that likes water.  It will take some time to find the photo.

Letter 2 – Rat-Tailed Maggot

We found this little creature in a water oak in Blountstown, FL (North FL). I’ve searched the internet with out any luck. It’s more of a greyish white with a long tail, then a spike sort of tail.

Hi Miranda,
The larva of the Drone Fly, Eristalis tenax, is known as the Rat-Tailed Maggot. The tail is actually a breathing aparatus as the Rat-Tailed Maggot is found in sluggish streams and stagnant ponds that are fouled with organic matter.

Letter 3 – Rat Tailed Maggots in Comfrey Tea

cocoons in comfrey tea
January 23, 2010
I just found clear, wriggling cocoons in my comfrey compost tea. you can see the bug inside the cocoon, a long black object with wings wrapped around. they have long stringy tails and are all bundled in a mass together. they do not look like maggots and they are roughly 1 cm in length. can you help me? i could not really get good shots as my camera is not much of a close up one.
New zealand, north island

Rat Tailed Maggots in Comfrey Tea

Dear shayni,
Our first thought on this is that we need to research exactly what the pupa of the Rat Tailed Maggot looks like, and then we need to see if comfrey tea is the name for the liquid fertilizer that is made by brewing manure in water.  You are right about your photo being blurry, but it does give a general idea of this mass of insects, but alas, the details must remain in our imagination, though that has been known to be rather vivid at times.  We see we were wrong about the comfrey tea, which is made from the plant comfrey, Symphytum officinale, and is applied externally to a number of conditions including bruises, cuts and acne, and that it might be used as an organic fertilizer.  It appears you have brewed it outdoors in a large bucket, which is why you have what we suspect your insects are Rat Tailed Maggots.  Rat Tailed Maggots are the larvae of Drone Flies, Eristalis tenax,  According to Charles Hogue in Insects of the Los Angeles Basin:  “the larvae live in water, usually in sluggish streams or small stagnant ponds that are foul with organic matter; they may also breed in fresh liquid cow manure.  Because of their extremely long, extendable posterior breathing tube, the larvae are called ‘Rat-Tailed Maggots.'”  We then found an online article entitled Eristalis tenax and Musca vomitoria in New Zealand by G.V. Hudson, F.E.S. that was read before the Wellington Philosophical Society on the 2nd October 1889.  Suddenly, your simple letter opened up an entirely new can of worms since the Drone Fly was reported in New Zealand prior to 1889:  Is the Drone Fly a truly cosmopolitan species because its range expanded naturally?  Or was it spread by man?  Mmmmmmm.  BugGuide has some excellent images of Drone Flies mating and BugGuide indicates the Drone Fly was introduced to North America prior to 1874.  We can’t help but wonder why and how Drone Flies were introduced to North America.  This could be a graduate thesis topic, but alas, at some point, we need to stop and respond that you have Rat Tailed Maggots in your Comfrey Tea.  According to Wikipedia:  “When fully grown, the larva creeps out into drier habitats and seeks a suitable place to pupate. In doing so it sometimes enters buildings, especially barns and basements on farms. The pupa is 10-12 mm long, grey-brown, oval, and retains the long tail; it looks like a tiny mouse.
”  We should also mention that the adult Drone Fly is a perfect mimic to the adult Honey Bee, and this mimicry is in itself interesting in that both the Honey Bee and the Drone Fly are connected to human agriculture and animal husbandry. Mmmmmm.

Letter 4 – Rat Tailed Maggots eaten by Trout

These were coughed up out of a rainbow trout I recently caught
March 8, 2010
A friend of mine recently caught a rainbow trout that coughed these up when he landed the fish. Any idea what they are. They are it a shot glass for sizing scale.
Vancouver Island, British Columbia

Rat Tailed Maggots

Dear anonymous,
These Rat Tailed Maggots are the aquatic larvae of the Drone Fly.

Letter 5 – Rat-Tailed Maggot

Back Alley Bug
Found about 15 of these bugs in about 100 sq ft of alley, no where else, near my house in south western Canada. The peice of alley is located near some gardens and compost piles. These little guys (body: 1″, tail(?): 1 1/2″) were walking all over the place. They have little legs at the front and rear ends of the body.Two different camera setting acount for the variance in color in the two photos. Can you tell me what it is.

Hi D,
This appears to be a Drone Fly Larva, Eristalis temax, also known as a Rat-Tailed Maggot. Drone Flies are large flies that are often mistaken for bees. Adults are common in flower fields where they feed on nectar and pollen. The Rat-Tailed Maggots are found in stagnant water filled with organic matter and are sometimes found in liquid cow manure, hence their appearance in an alley with compost piles. Here is some interesting information from our Audubon Guide: “Larvae, called Rat-Tailed Maggots, are usually found on wet carrion and in open latrines. They are responsible for numerous cases of intestinal myiasis in people. Adult flies sometimes emerge from carrion, a phenomenon that was probably the basis for the myth that Honey Bees develop in dead mammals, as told in the Biblical story of Samson and the lion, and in writings of Ovid, Vergil and Solomon. the adults so closely resemble Honey Bees that people and insectivorous animals avoid them.”

Letter 6 – Rat Tailed Maggot

Alien Grub Thingy
March 10, 2010
I was out at about 2am this morning and couldn’t sleep.As I was walking along the sidewalk I heard a pop and looked down to see that there were about 5-7 of these things squirming on the concrete, and I unknowingly stepped on one. I decided to get a closer look so I shined my flashlight on it and it was a very pale caterpillar looking life form, I did not see any visible eyes or mouth on it, but what I did see once I attempted to pick it up was what struck me as being very alien. No sooner than i grabbed one up from the sidewalk a long almost lizard like tail popped out of what I guess is the back of the grub, the tail would move around and it wrapped itself around my finger, sparking my curiosity even further.So I brought it inside and took pictures and a small video of it.What I want to know is, could this possibly be a cicada larvae, or a small scale alien invasion?
Josh Hamblin
Springfield, MO

Rat Tailed Maggot

Hi Josh,
This is the larva of a Drone Fly and it is commonly called a Rat Tailed Maggot.

Letter 7 – Rat-Tailed Maggot

Subject: I have never encountered this at work before
Location: Seattle, WA
September 19, 2014 7:27 pm
I work in Seattle, WA on commercial boilers. The location I took these photos (which are actually screenshots from much more informative HQ videos that I took) is on the ground near an outdoor steam boiler in September at the end of summer. It was 75°F that day and was the last day of an unusually long and hot summer. The water (and sludge) these things were living in was very warm, I did not measure the temperature of the water but because it was continually being fed by 212°F boiler water. Please let me know if you need more information, pictures or video. Oh and these things were about half an inch long.
Signature: Aaron in Seattle

Rat-Tailed Maggot
Rat-Tailed Maggot

Dear Aaron,
One of your images appears to depict a Rat-Tailed Maggot, the larva of a Drone Fly,
Eristalis tenax.  According to BugGuide:  “The larva of the Drone-Fly feeds on decaying organic material in stagnant water in small ponds, ditches and drains. Such water usually contains little or no oxygen and the larva breathes through the long thin tube that extends from its rear end to the surface of the water and that gives it its common name of ‘rat-tailed maggot’.”

Rat-Tailed Maggot
Rat-Tailed Maggot


  • 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.

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  • 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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10 thoughts on “Exploring the Life Cycle of Rat-Tailed Maggots”

  1. At my place of work, we have been finding these rat-tailed maggots in the toilets, the toiles are on the second floor of the building, could you possibly tell how how they are getting there + why,
    Mave from Bath, UK

    • Adults fly, though how the maggots are developing in the toilet bowls is a mystery to us. BugGuide indicates: “The larva of the Drone-Fly feeds on decaying organic material in stagnant water in small ponds, ditches and drains. Such water usually contains little or no oxygen and the larva breathes through the long thin tube that extends from its rear end to the surface of the water and that gives it its common name of ‘rat-tailed maggot’.” Perhaps your coworkers are forgetting to flush for days at a time.

  2. to my horror spotted one of these in the bathroom sink when brushing teeth. Recognised it as am Biology teacher but what was it doing in my clean sink?

  3. Found what looks very like a rat-tailed maggot in my toilet. The toilet bowl was clean i.e. unused and the bug was just sitting at the bottom in the water. Gave me the creeps. We are connected to a septic tank but this was the upstairs toilet! Any reassurance would be very welcome. I do so hope these guys cannot reside inside me. Help!

  4. Are these maggots pollutants when left in liquid to decompose. I have made my own fertiliser from seaweed cow and horse manure. Putrud smell, decided to revove lumps from tubs and noticed quite pklum looking maggots with a tan coloured tail appendage. Can you identify what they are and if they are poisoning my intended liquid fertilizer. Also should I add blood mnd bone, lime??? to assist decomposition process. Ta

    • The Rat Tailed Maggots are attracted to the decomposition in the concoction you have made. The Rat Tailed Maggots are not harmful and they will not have a negative effect on your fertilizer, but rather they are a sign that the fertilizer is fertile. If it was our garden, we would add the lime and blood meal if needed to the soil when mixing in your decomposing fertilizer, not during the manure seasoning process.

  5. Hi I have got a lot of cow manure for my garden, but notice there is a lot of this rattailed maggot in it. Is this safe to use in my garden, of will the bugs destroy my plants? Regards Jude


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