Do Fly Pupae Move? Unraveling the Mystery of Insect Movement

Fly pupae are an intriguing aspect of insect development, often raising questions about their behavior and mobility. Understanding their movement, or lack thereof, can provide insights into the life cycle of flies and their impact on the environment.

Fly larvae, or maggots, undergo a process called pupation in which they transform into pupae before emerging as adult flies. During the pupal stage, movement is limited as the insect undergoes significant internal changes. In some species, pupae may exhibit small movements or wriggling, but generally, they remain stationary and vulnerable.

Different fly species have varying pupal behaviors, with some requiring specific conditions for successful development. For example, drain fly larvae typically stay within the top 2.5 cm of soil to breathe, while phorid flies can complete their development in just a few days. Exploring the varying characteristics of fly pupae highlights the unique adaptability of these insects across different environments.

Fly Pupae and Their Life Cycle

Egg Stage

Flies begin their life cycle as eggs, laid by adult females on suitable environments, such as decomposing organic material or near food sources for the larvae.

Larvae Stage

After a short period (approximately 24 hours), eggs hatch into larvae. These small, worm-like creatures, also known as maggots, feed on the same organic material as the eggs. As they consume and grow, larvae pass through several stages called instars.

Pupae Stage

Following the larval stage, the fly enters its pupal stage. During this phase, the larvae become encapsulated within a protective casing called a puparium. Inside, they undergo metamorphosis and develop into adult flies. Pupae are usually immobile, as their primary purpose is to protect and facilitate metamorphosis. However, in some cases, pupae may exhibit limited movement by using their wing pads or spines.

Stage Movement
Larvae Active, crawling movement
Pupae Limited or no movement
Adult Active, flying movement

Adult Stage

After a varying duration in the pupal stage, depending on the species and environmental conditions, the adult fly emerges from the pupal case, ready to reproduce and continue its life cycle. Adult flies have wings, allowing them to fly and search for food, mates, and appropriate locations to lay their eggs.

Habitats and Development

Temperature and Warm Weather

House flies thrive in warm temperatures and can complete their life cycle quite quickly. In optimal conditions, this can be done in as little as 7-10 days. However, under less favorable circumstances, this process might take up to two months.

Examples of warm habitats include:

  • Manure piles
  • Compost heaps
  • Garbage bins

Decomposing Organic Material

Fly pupae are often found in areas with decomposing organic materials. House flies lay their eggs in these nutrient-rich environments, providing maggots with the food they need to grow and develop.

Examples of decomposing matter include:

  • Rotting fruit or vegetables
  • Meat scraps
  • Dead animals

Manure and Garbage Exposure

Manure and garbage are ideal breeding grounds for flies due to their warm, moist nature and abundance of organic matter. House flies are commonly found in manure piles and garbage, where they lay their eggs and where maggots feed on the decomposing materials.

Fly infestations can be more prevalent in the spring, when temperatures rise and more decomposing matter becomes available.

A comparison of fly development characteristics:

Factor Favorable Conditions Unfavorable Conditions
Temperature Warm (~30°C) Cold (<15°C)
Organic Material Abundant Scarce
Moisture Moderate Dry

Pros of manure and garbage as fly habitats:

  • Plenty of food for maggots
  • Warm and moist conditions

Cons of manure and garbage as fly habitats:

  • Unsanitary conditions
  • Can lead to fly infestations
  • Potential spread of disease

In conclusion, fly pupae are more likely to be found in environments with warm temperatures, decomposing organic materials, and exposure to manure and garbage. These factors create the ideal conditions for house flies to thrive and reproduce.

Physical Characteristics

Size and Appearance

Fly pupae are generally small in size, typically ranging from 4.5-6 mm in length. Their appearance varies depending on the species, but they are often reddish-brown or dark in color.

Cocoon Structure

Fly pupae form inside a protective shell called a puparium. This cocoon-like structure is made from the hardened skin of the last larval stage, providing a safe environment for the fly to undergo metamorphosis.

Legs and Hooks

During the pupal stage, the legs and hooks of a fly are not yet fully developed. The fly’s legs and hooks begin to form as it transitions from a larva to a pupa, and will continue to develop internally until the adult fly emerges from the puparium.

Eyes and Wings

In the pupal stage, eyes and wings are also in the process of development. The eyes and wings of a fly pupa are not visible externally, as these features are still forming and growing inside the protective puparium.


Fly pupae have respiratory structures called spiracles, which allow them to breathe while inside the puparium. These tiny openings are located along the sides of the pupal case, providing a crucial function in the development of the insect.

To summarize, fly pupae have various distinct physical characteristics including:

  • Small size, typically 4.5-6 mm in length
  • Reddish-brown or dark coloration
  • Protective puparium for metamorphosis
  • Developing legs, hooks, eyes, and wings
  • Respiratory spiracles for breathing

Reproduction and Mating

Egg Laying

Female flies begin the reproduction process by laying eggs. Houseflies (Musca domestica), for instance, lay their eggs in clusters, typically in decaying organic matter. The time it takes for pupae to develop varies depending on temperature, taking 2-6 days at 32-37°C and 17-27 days at about 14°C.

Examples of egg-laying sites:

  • Decaying fruit
  • Animal feces
  • Garbage

Lifespan of Flies

Flies have relatively short lifespans, with most adult flies living for just a few weeks. Their lifespan depends on species and environmental conditions, but typically it ranges from several days to a month.

Comparison of fly lifespans:

Fly Species Approximate Lifespan
House fly 15-25 days
Fruit fly 40-50 days

During their lives, adult flies focus on two main tasks: mating and laying eggs. Mating often involves a male inserting his intromittent organ into the female genital tract for sperm deposition, as observed in most insects. The reproduction behaviors and genes associated with mating evolve rapidly and vary among different fly species.

Interactions with Other Species

Parasitic Wasps

Parasitic wasps are a group of insects in the order Hymenoptera that have a unique relationship with fly pupae. Female wasps lay their eggs inside the pupae, and the wasp larvae consume the developing fly pupa as they grow. This interaction provides a form of natural biological control for filth flies, as these tiny wasps can reduce the number of adult flies, benefiting both humans and animals.

  • Benefits of parasitic wasps:
    • Natural pest control
    • Harmless to humans and animals

Butterflies and Moths

Butterflies and moths belong to the order Lepidoptera, including many species that undergo a metamorphosis process. The fly pupae’s interaction with Lepidoptera mainly occurs through predation, competition, and decomposers.

Interaction Example
Predation Some ants prey on Lepidoptera pupae
Competition Caterpillars and fly larvae may compete for resources
Decomposers Moths can decompose dead organic matter

Some ants prey on butterfly and moth pupae, such as cocoons and chrysalises, making them predators of these Lepidoptera. Additionally, fly larvae and caterpillars may compete for resources like food and shelter. Moths, particularly found in the family Tineidae, are decomposers, aiding in breaking down dead organic matter – making them indirectly linked to fly pupae through the broader ecological web.

Characteristics of Lepidoptera:

  • Undergo metamorphosis
  • Distinct larval and adult stages (caterpillar and butterfly/moth)

Imaginal Discs and Emergence

Imaginal discs are found within the pupae of both Hymenoptera and Lepidoptera, playing a vital role in the emergence of adult insects. Through metamorphosis, these discs develop into the wings, legs, and other body parts for the adult insect. The process of emergence, or eclosion, involves breaking free from the pupal case to transition into an adult insect.

  • Imaginal discs:
    • Present in both wasps and butterflies/moths
    • Develop into adult insect body parts
  • Emergence (eclosion):
    • Insect breaks free from pupal case
    • Final transition to adult form

Fly Management and Control

Fly Traps

Fly traps are an effective way to control fly infestations. There are various types of traps, such as adhesive traps and light traps. Some examples include:

  • Sticky fly paper, which captures flies that land on it
  • Fly light traps, which use UV light to attract flies to an electrified grid


  • Chemical-free
  • Easy to use


  • May not eliminate all flies
  • Need to be replaced regularly

Sanitary Measures

To prevent fly infestations, it is crucial to maintain proper sanitation in and around your home. Some measures include:

  • Remove any sources of food, water, and breeding sites
  • Clean up animal waste and garbage regularly
  • Store food in sealed containers

Implementing these measures helps in reducing fly eggs and fly pupae in the area substantially.

Dealing with Infestations

In case of a severe infestation, a combination of methods is recommended to achieve better results. Some approaches include:

  • Use of insecticides to target adult flies and their larvae
  • Introduction of biological control agents, like stingless parasitic wasps1

Table 1: Comparing Insecticides and Biological Control

Method Pros Cons
Insecticides Effective in killing adult flies May negatively impact non-target species
Biological Control Target-specific and eco-friendly May take time to establish

By combining various methods, such as fly traps, sanitary measures, and dealing with infestations, an effective fly management and control program can be established, reducing the presence of different fly species and their life stages in the surrounding environment.

Health Risks and Threats

Diseases Transmission

Fly pupae can be a source of disease transmission. They can carry pathogens, which are then spread by adult flies. For example:

  • Salmonella: This bacteria can cause severe food poisoning and even death in some cases.
  • E. coli: It leads to gastrointestinal illnesses and can be fatal for young children and elderly people.

Dangers of an Infestation

An infestation of fly pupae and adult flies pose various dangers, such as:

  • Contamination of food: Flies can contaminate food, leading to illness or spoilage.
  • Allergic reactions: Some people may have allergic reactions to flies, resulting in skin irritation or respiratory issues.
Fly pupae Potential Threats
Pathogens carriers Spread of diseases
Contamination of food Food poisoning or spoilage
Allergic reactions Skin irritation or respiratory issues

In conclusion, it is crucial to control fly infestations to minimize the health risks and threats associated with fly pupae and adult flies. Proper sanitation and preventive measures can help drastically reduce fly populations in and around your home or workplace.


  1. Fly control around horses – Extension at the University of Minnesota

Reader Emails

Over the years, our website, 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 – Fly Puparium


Subject: Little black pods?
Location: Mid Atlantic, Maryland, USA
July 10, 2014 7:28 am
I’m finding these pods around my house lately. I’ve squished them because I wanted to check and see if they were mouse droppings. They’re not. They are insect egg pods but I have no idea what I’m dealing with here. They look like grains of wild rice. Can you help me figure this out? Want to make sure we don’t have some kind of an infestation!
Signature: Nervous about pods

Fly Puparium
Fly Puparium

Dear Nervous about pods,
This is the Puparium of a Fly and if you are finding them in your home, we are guessing that somewhere in the home maggots were feeding on something.  When they are ready to pupate, the Maggots travel some distance from the food source and there they molt and transform into a Puparium.  Once back in the 1980s, our editorial staff discovered that Flesh Flies had discovered a bag with some rotting potatoes under the kitchen sink, and our first awareness was the Fly Puparia that appeared along the baseboard in the kitchen.  If you don’t find undiscarded garbage somewhere in the home, we would speculate on the possibility of a dead mouse or other creature between the walls.  Forensics for Fiction has a nice image of Fly Puparia.

Letter 2 – Fly Puparia


Subject: Pods
Location: Southern CA (Murrieta CA)
October 9, 2016 7:47 am
Hello, I need help identifying what these little pods are. At first glance they seem to be mouse poop but when you get close you can see that they are medium/light brown in color and have segmenting lines. I’m wondering if they are some sort of larva or droppings from some kind of animal
Signature: ?

Fly Puparia
Fly Puparia

Thank you for resubmitting your request using our standard submission form.  We now know where this sighting occurred, but you still did not provide much clarification on where in Murrieta, California you found them.  Were they in the house?  Were they in the garbage can?  These are the puparia of a Fly.  We suspect they were probably found in association with decaying plant or animal matter.  Many Flies are attracted to putrefaction, and lay their eggs on decaying organic matter found in garbage.  The eggs hatch into maggots that eventually transform into puparia.  Adult Flies will emerge.

Fly Puparia
Fly Puparia

Sorry I was not clear! So I actually found them all over my carpet along the baseboards in various rooms. They room that i found the most of them in has no food, plants, or animals in it. They are spread throughout the whole first floor of my house which the first floor alone is about 2200 sq ft. How can these be all throughout my carpet If there is not decaying plant or animal matter? What is the best way to get rid of these and prevent future ones from forming? My house is pretty clean. I do have a dog that goes outside but lives mostly inside. I vacuumed up all that I could see

We don’t want to make you paranoid, but if they did not come from a garbage can that was not emptied in a timely manner, they might have come from a dead animal inside your walls.

Letter 3 – Larva or Pupa of a Fly


Subject: Slug/worm-ish creepy crawler
Location: Southeast Louisiana
August 16, 2014 9:43 pm
Two separate times today, we saw one of these in our garage. Never seen anything like it before. Moved like a slug but didn’t have any visible antennae. It is flat shaped with a pointy “tail”. What exactly might it be? We are curious as every search we’ve made turns up only things we can rule out. 😉
Signature: Dana

Subject: Worm/slug/other!?!
Location: Southeast Louisiana
August 16, 2014 9:33 pm
Twice today, we found one of these in the garage. It moves like a slug, but has no visible antennae. It is flat with a pointed “tail”. Never seen anything like it before and just curious as to what it may be. Thanks!!
Signature: Dana

Fly Pupa
Fly Pupa

Dear Dana,
Twice yesterday, about ten minutes apart, we received similar identification requests from you with the same image attached.  This is the larva or pupa of a fly, but we are uncertain which family or species it belongs to, though it does bear a resemblance to this Horse Fly larva pictured on BugGuide or this possibly Soldier Fly Larva from our archives.

Sorry about the duplicate requests…we didn’t think the first one had gone through. 🙂
And thanks for your quick response! We didn’t even think of anything like that bc of it’s size…about 2.5 inches long. But that does look very similar.
Thanks again,

Letter 4 – Fly Puparia


Subject: larvae
Location: richardson, tx
May 12, 2015 9:46 pm
Does anyone know what this could be? Just found about 2 dozen in my son’s room. They were primarily found under some laundry sheets that had been cleaned 2 days prior. Also some found around the baseboard in the room. Please help. . also have an unidentified smell coming from the same room around the same time these were found.
Signature: Jesse

Fly Puparia
Fly Puparia

Dear Jesse,
These look like the Puparia of Flies.  Perhaps something crawled into your son’s room and died, or perhaps some food was left to rot.  It is also possible there might be a dead animal in the walls that could have attracted the flies that laid the eggs that hatched into maggots that fed on the rotting organic material and that eventually metamorphosed into these Puparia.
  The likeliest candidates are Flesh Flies.

Letter 5 – Hairy Maggot Blow Fly


Subject: Fly with Really Large Eyes
Location: Northeast Florida
June 24, 2012 7:23 pm
Here’s another fly I saw the other day in my yard in northeast Florida. It wasn’t very big, about 10mm, but it had enormous eyes that almost took up its entire head. With its huge red eyes and bright blue-green body I thought it was colorful and interesting. I went looking for it on BugGuide and found that it’s a Chrysomya megacephala, also known as a Hairy Maggot Blowfly–not a very appealing name! I couldn’t find any flies like this one on What’s That Bug so I’m sending you a photo.
Signature: Karen in FL

Hairy Maggot Blow Fly

Hi Karen,
This is the second time this week you have provided us with a wonderful new fly species photo for our site as well as doing the necessary research to determine the species.  BugGuide does not provide any information on the species page for
Chrysomya megacephala, but if our knowledge of ancient languages is not too rusty, we believe megacephala refers to the large head in Greek and supports that.  On the genus page on BugGuide, we learned that “Adults are robust flies metallic green in color with a distinct blue hue when viewed under bright sunlit conditions. The posterior margin of the abdominal tergites are a brilliant blue” and as an introduced species, “It is now established in Southern California, Arizona, Texas, Louisiana, and Florida. It is also found throughout Central America, Japan, India, and the remainder of the old world.”  Backing off to the family page on BugGuide for Blow Flies, the reader learns that they are “scavengers (larvae in carrion, excrement, etc.) or parasites” and that they are “very common in a wide variety of habitats, including heavily urbanized areas.”  Normally we do not link to Wikipedia, but that resource does have an extensive page on this species where it is called the even less appealing Oriental Latrine Fly.  Wikipedia also states:  “C. megacephala is considered one of the most important species of flies to forensic science. This is because it is one of the first species to show up on a corpse.”  

Hi Daniel,
I’m glad the fly photos are helpful! I learned about BugGuide from you and What’s That Bug?, and now I always try to identify the bugs I photograph by looking here and at BugGuide. Usually I can figure it out to my satisfaction. This was such a colorful fly and turned out to have such an unpleasant name! I’ve been seeing some very pretty Long-Legged Flies and I’ll try to send you some photos of those.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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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