This article explains how to identify manure flies (Scathophagidae and other dung-associated Diptera), where they are found in North America, how to prevent infestations, and how to eliminate or manage these pests in barns, gardens, and homes.
In North America, manure flies are also referred to as dung flies, scavenger flies, or stable manure flies depending on species and context.
What do manure flies look like?
Manure flies are a broad group of small to medium-sized flies, typically ranging from 3 to 8 mm in length. Most species have yellowish, grey, or dark brown bodies, often with bristly hair and robust legs. Some have a shiny or metallic appearance, while others are dull and compact. The most common types include Scathophaga stercoraria (the yellow dung fly) and various members of the Sphaeroceridae and Muscidae families.
Adult manure flies can resemble house flies, but they are more likely to be found directly on or around animal waste. The larvae (maggots) are white or pale and feed on decomposing organic material, primarily manure.
Where are manure flies found in North America?
Manure flies are widespread throughout North America and occur in both rural and urban areas. They are especially abundant in agricultural regions where livestock are raised, but they can also be found near compost piles and in gardens using manure-based fertiliser.
Common habitats include:
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Barns, stables, and livestock pens
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Piles of fresh or decomposing manure
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Compost heaps containing animal waste or straw bedding
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Gardens fertilised with fresh manure
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Areas with poorly managed pet waste
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Occasionally indoors, especially in buildings near manure sources
These flies are active from spring to autumn and are most prevalent in warm, humid conditions.
Where do manure flies live and breed?
Manure flies lay their eggs directly in fresh manure, compost, or other organic waste. The eggs hatch within a day or two, and larvae feed on the decaying material. After several days to weeks of feeding, the larvae pupate in the same substrate or nearby soil. Adults emerge and begin the cycle again, often completing multiple generations during a single season.
They thrive in:
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Moist, nutrient-rich waste
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Fresh manure from cows, horses, pigs, or chickens
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Wet straw and bedding
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Warm temperatures with high organic matter presence
Their life cycle can range from one to three weeks depending on environmental conditions.
How can you avoid manure fly infestations?
Preventing manure fly problems begins with proper sanitation and management of organic waste.
Clean animal enclosures frequently
Remove manure from stalls, coops, and pens on a daily basis. Frequent removal breaks the breeding cycle and limits egg-laying opportunities.
Store manure properly
Pile manure away from animal shelters and living areas. Cover it with a tarp or use enclosed storage systems to reduce fly access.
Compost manure correctly
Maintain high compost temperatures and turn the pile regularly to destroy fly eggs and larvae. Avoid letting the pile remain moist and anaerobic for long periods.
Use dry bedding
Keep animal bedding dry to prevent it from becoming a breeding ground. Replace soiled bedding frequently.
Remove pet waste
In domestic gardens, clean up dog or cat waste promptly. Leftover pet faeces can attract manure flies, especially in summer.
Avoid spreading fresh manure
Use only well-composted manure in gardens. Spreading fresh manure can introduce eggs and larvae to new areas.
How do you recognise a manure fly problem?
Manure fly activity is often easy to spot in affected areas, particularly during warm months.
Common signs include:
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Large numbers of flies clustering on manure or compost
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Flies hovering or landing on livestock or around their eyes
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Visible maggots in bedding or waste piles
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Flies entering homes through open doors or windows near barns
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Persistent fly presence despite clean surroundings
Manure flies are more aggressive than house flies in some cases and may swarm in large numbers when not controlled.
How do you get rid of manure flies?
Remove breeding sites
The most effective control is to eliminate their breeding grounds. Remove manure and wet bedding regularly and dispose of it far from animals and buildings.
Improve airflow
Increase ventilation in barns and sheds to create drier conditions that discourage fly development. Fans can also help deter adult flies.
Use biological controls
Predatory insects such as beetles (Carabidae) and parasitic wasps (Spalangia spp., Muscidifurax spp.) can help reduce manure fly populations by targeting larvae and pupae.
Apply insecticides if necessary
Use approved residual sprays or larvicides on manure piles and barn surfaces. Always follow local regulations and product guidelines when using chemical treatments.
Use fly traps
Sticky traps, baited traps, or UV light traps can help reduce adult fly numbers, especially in enclosed or high-traffic areas.
Compost at high temperatures
A properly maintained compost heap should reach temperatures that kill fly larvae and eggs. Ensure good aeration and balance between nitrogen and carbon.
What is the manure fly’s life cycle?
The manure fly life cycle is rapid and varies with environmental factors:
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Eggs: Laid directly on manure or other decaying organic material.
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Larvae: Maggots hatch within 24–48 hours and feed for several days.
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Pupae: Develop in the same material or nearby soil.
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Adults: Emerge within 7–14 days, mate, and begin laying eggs again.
In ideal conditions, manure flies can complete a full cycle in as little as 10 days, with multiple generations possible from spring through early autumn.
Can manure flies get into homes?
Yes, manure flies can enter buildings, especially those near barns, stables, or composting sites. They may be attracted to lights, food smells, or indoor moisture. While they do not usually breed indoors, their presence can be unpleasant.
To prevent indoor issues:
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Seal cracks around windows, doors, and vents
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Install fine-mesh insect screens
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Avoid leaving doors open near compost or manure
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Keep kitchens and rubbish bins clean and covered
Are manure flies harmful?
Manure flies are not typically dangerous, but they can be a health concern due to their association with faecal material. They may carry bacteria or parasites from waste to animal feed, food surfaces, or open wounds. Their presence around livestock can also cause irritation or stress.
While most species do not bite, some can cause discomfort simply through their numbers or persistence. Proper hygiene and manure management remain the most effective defences against manure fly infestations.