Carrion Flies Identification Guide
Calliphoridae (Family)
Carrion flies are metallic-colored flies attracted to dead animals and decaying organic matter. Also known as blow flies, they are often the first insects to arrive at carcasses and can indicate a dead animal in or near your home.
Taxonomy
Carrion Flies Coloration
Common color patterns to help identify carrion flies
Carrion Flies
Seasonal Activity
When carrion flies are most active throughout the year
Where Carrion Flies Are Found
Hover over states to see their names. Green regions indicate where carrion flies have been reported.
Carrion Fly Identification Guide
Physical Characteristics
Carrion flies belong to the family Calliphoridae. The name comes from their love of carrion, or dead animal flesh. These flies are 6 to 16 mm long. That makes them a bit larger than house flies. You can spot them by their shiny, metallic bodies. They may look bright green, blue, bronze, or black based on the species.
The metallic color comes from how their outer shell reflects light. This gives them a shiny, rainbow-like look. It also makes them easy to tell apart from dull gray house flies. Short, stiff bristles cover their bodies. The bristles are thicker on the upper back.
Carrion flies have large eyes that are reddish-brown. In males, the eyes touch at the top of the head. In females, there is a gap between them. Like all true flies, they have one pair of wings. Their back wings are tiny knobs that help with balance in flight.
These flies make a loud buzzing sound when they fly. They are strong fliers and can travel up to a mile to find food. They have a great sense of smell and can detect dead animals within minutes of death.
Common Species in North America
About 80 carrion fly species live in North America. The most common ones you might see include:
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Common Green Bottle Fly (Lucilia sericata): The most common carrion fly. It has a bright green body and red eyes. You can find it near homes, farms, and wild areas across the continent.
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Blue Bottle Fly (Calliphora vomitoria): A large fly with a blue belly and gray upper body. It has orange hairs on the back of its head. This fly likes cooler weather and is common in the north.
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Black Blow Fly (Phormia regina): A dark blue-black fly. It is often the first to show up at dead animals in spring. It is common across northern North America.
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Secondary Screwworm Fly (Cochliomyia macellaria): A greenish-blue fly found mainly in southern states. It only feeds on dead tissue, not living animals.
Carrion Fly Behavior and Biology
Carrion flies help break down dead animals in nature. They recycle nutrients back into the soil. Without them, dead animals would take much longer to decay.
Attracted to Decay
These flies have a great sense of smell. Studies show they can smell a dead animal from up to one mile away. Within minutes of an animal dying, carrion flies may show up. This skill makes them useful in crime science, where experts use fly growth stages to tell how long a body has been dead.
Carrion flies are drawn to more than just dead animals. They also seek out:
- Garbage containing meat scraps
- Pet waste and manure
- Open wounds on animals
- Spoiled food left outdoors
- Compost piles with animal products
Life Cycle Stages
The carrion fly life cycle has four stages: egg, larva, pupa, and adult.
Eggs: Females lay 150 to 200 eggs at a time. The eggs are tiny, white, and look like grains of rice. They place eggs in cracks or moist spots on the food source. One female can lay up to 2,000 eggs in her 10 to 25 day life.
Larvae (Maggots): Eggs hatch in as little as 24 hours when it is warm. The maggots are cream-colored and have no legs. They have pointed heads with hook-like mouths for feeding. Maggots go through three growth stages over 6 to 11 days.
Pupae: When ready to change, maggots leave the food and dig into nearby soil. They form dark brown cases. This stage lasts about 8 days in warm weather.
Adults: New adults start mating within a few days. Adult carrion flies eat nectar, plant sap, and fluids from decay. They do not bite people or pets.
Seasonal Activity
Carrion flies are most active during warm months. Activity picks up in late spring as temperatures rise. Peak populations occur from June through September when warm, humid conditions speed up breeding. Numbers decline in fall as temperatures drop.
During winter, carrion flies survive as pupae in the soil or as adults in sheltered spots. A few may be active on warm winter days, especially in southern regions.
Signs of Carrion Fly Activity
Seeing carrion flies indoors almost always means something nearby is rotting. Look for these signs:
- Adult flies near windows: These flies seek light and gather at windows trying to get outside
- Loud buzzing: They buzz louder than house flies
- Shiny colored flies: The green or blue bodies stand out from other fly types
- Flies coming from walls: This points to a dead animal inside the structure
- Bad odor: A rotting smell often comes with carrion fly activity
- Maggots: Finding larvae means a breeding site is very close
Treatment Methods for Carrion Flies
To control carrion flies, you must find and remove what draws them. Spraying for adult flies only helps for a short time. If the dead animal or rotting matter stays, more flies will keep coming.
Source Identification
The first step is finding what draws the flies. Check these common spots:
- Walls, especially near where flies cluster
- Attics, particularly near vents and eaves
- Crawl spaces and basements
- Chimneys and fireplace areas
- Trash cans and dumpsters
- Compost bins
- Areas where pets spend time
Watch the flies closely. They often fly back and forth between the source and windows. A group of flies in one area points to the breeding site. Stains on walls or ceilings may mean fluids from a dead animal inside.
Source Removal
Once you find the source, remove it if possible. For dead animals:
- Wear disposable gloves
- Place the carcass in a sealed plastic bag
- Dispose of it in outdoor trash
- Clean the area thoroughly with disinfectant
Sometimes the dead animal is in a wall or space you cannot reach. In these cases, you may need to wait for decay to finish. This takes about two to three weeks for a small animal like a mouse. Open windows and use odor sprays to help with the smell during this time.
Reducing Fly Activity Indoors
While you address the source, these steps help cut down on flies inside your home:
- Check and repair window screens
- Install door sweeps on exterior doors
- Keep doors closed or use screen doors
- Set up fly traps near problem areas
- Cover all food and clean up spills immediately
- Empty indoor trash frequently
Prevention Strategies
To stop future carrion fly problems:
- Seal entry points where rodents could get inside walls and die
- Install chimney caps to keep birds from getting trapped
- Use trash cans with tight-fitting lids
- Pick up pet waste daily
- Move outdoor trash bins away from doors
- Clean up dead animals on your property promptly
- Maintain screens and weatherstripping
References
Other Flies
Explore other species in the flies family
Commonly Confused With
Carrion Flies are often mistaken for these similar pests
Where Carrion Flies Are Found
Hover over states to see their names. Green regions indicate where carrion flies have been reported.
Common Questions about Carrion Flies
What is the difference between carrion flies and blow flies?
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Carrion flies and blow flies are the same insects. Both names refer to flies in the family Calliphoridae. The term carrion fly highlights their attraction to dead animals, while blow fly comes from the old English term for bloated meat. They are also called bottle flies due to their metallic coloring.
Why do I have carrion flies in my house?
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Carrion flies indoors almost always mean a dead animal is nearby. A mouse, rat, bird, or squirrel may have died in a wall, attic, crawl space, or chimney. These flies can smell decay from up to a mile away and arrive quickly to feed and breed.
How long do carrion flies stay after an animal dies?
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Carrion flies typically remain active for two to three weeks while a carcass breaks down. The first wave of adult flies arrives within minutes of death. Fly activity peaks as maggots develop and declines as the food source is consumed.
Are carrion flies harmful to humans?
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Carrion flies do not bite or sting. However, they can spread bacteria by landing on food after feeding on decaying matter. They may carry pathogens including E. coli and Salmonella. Keep food covered when these flies are present.
How do I get rid of carrion flies?
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The only way to get rid of carrion flies is to find and remove the dead animal or decaying matter attracting them. Killing adult flies provides only temporary relief. Once the source is gone, the flies will leave within a few days.
What do carrion fly maggots look like?
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Carrion fly maggots are cream-colored, legless larvae that measure 9 to 22 mm when full grown. They are pointed at one end and have hook-shaped mouthparts. Maggots move by contracting their bodies and may cluster together while feeding.
How fast do carrion flies reproduce?
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Carrion flies reproduce rapidly. Females lay 150 to 200 eggs at a time, up to 2,000 in their lifetime. Eggs hatch within 24 hours into maggots that feed for about a week before pupating. The entire life cycle takes two to three weeks in warm weather.
Can carrion flies come from garbage?
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Yes. While carrion flies prefer dead animals, they will also breed in garbage containing meat scraps, spoiled food, or pet waste. Keep trash in sealed containers with tight-fitting lids to prevent attraction.
With five years of hands-on experience in the pest control industry, George Schulz is a registered technician with the Virginia Pest Management Association and a proud third-generation professional in a family business that's been protecting homes for over 57 years. He manages and trains a team of service pros while also leading internal research efforts—recently spearheading a deep-dive review of thousands of documents on pest control materials to hand-pick the most kid and pet friendly, most effective solutions tailored specifically for homes in the DC metro area.