This document contains information about the biology and management of flies that breed in organic waste such as manure, garbage, and animal carcasses. A wide range of management options is listed. From this list, the IPM Practitioner can choose options to develop a unique management plan for each particular customer site.
Management Objectives for the Pest at the Particular Site
What do you want/need to accomplish at the site in regard to the pest flies?
The answer to this question will vary, depending on the site and the customer. Some examples are
- Reduce fly complaints in the building and work with occupants to prevent future complaints
- Keep flies out of food handling and food processing areas
- Help customer comply with Health Department regulations
All flies have only 2 wings. The larvae (maggots) of house, flesh, and blow flies are very similar: legless, round in cross-section, tapered at the front end and blunt at the hind end, cream to yellowish in color.
Important Garbage- and Manure-Breeding Flies
||Preferred Host Material
||(Drawing are not to scale)
|House fly (Musca domestica)
||¼” long; dull gray with 4 dark stripes on thorax; 4th wing vein sharply angled
||Animal waste, garbage, piles of lawn clippings, and other decaying organic matter
|| House Fly
|Flesh flies (Sarcophaga spp.)
||2 to 3 times larger than house fly; 3 dark stripes on thorax, gray and black checkerboard pattern on the abdomen
||Garbage, pet droppings, animal manure, and animal carcasses
|Blow flies or Bottle flies (Family Calliphoridae)
||About twice as large as house fly; no stripes on thorax; metallic blue, green, or bronze in color
||Animal carcasses, animal wounds, garbage, pet droppings, and animal manure
|| Blow Fly
Adapted from M.C. Wilson, G.W. Bennett, and A. V. Provonsha, Practical Insect Pest Management: Insects of Man’s Household and Health (Prospect Heights, IL: Waveland Press, 1977);
Why Flies are Considered Pests
- Flies contaminate food, eating utensils, food preparation surfaces.
- Flies are associated with many disease-causing organisms and their habits make them efficient mechanical vectors of these organisms.
- Their constant presence can be extremely annoying.
Special Regulatory Conditions
California Health and Safety Code Sections that relate to flies and cleanliness in food establishments:
114010. “All food shall be prepared, stored, displayed, dispensed, placed, transported, sold, and served as to be protected from dirt, vermin, unnecessary handling, droplet contamination, overhead leakage, or other contamination.”
114030. “A food facility shall at all times be so constructed, equipped, maintained, and operated as to prevent the entrance and harborage of animals, birds, and vermin, including, but not limited to, rodents and insects.”
114040. “The premises of each food facility shall be kept clean and free of litter, rubbish, and vermin.”
114050. “All food facilities and all equipment, utensils, and facilities shall be kept clean, fully operative, and in good repair”
Biology and Behavior
To be successful, management strategies must take into consideration the biology and behavior of the pest. Understanding the biology of a pest can reveal weaknesses and vulnerabilities that can be exploited when trying to manage the pest.
General Biology of the House Fly (Musca domestica)
- All flies have 4 distinct life stages: egg, larva (commonly called maggot), pupa, and adult.
- An adult female house fly lays batches of 75 to 100 tiny, white, oval eggs in organic material suitable for larvae to feed on (see below).
- In warm weather, the eggs can hatch in one day
- When the maggots are ready to pupate, they move to the drier portions of the material they have been living in, or they may crawl quite a distance to pupate in loose material, under boards, stones, etc.
- In warm weather, the house fly can grow from egg to adult in as little as 8 days.
- House flies can fly as far as 20 miles, but in general they do not move more than 1 or 2 miles.
Feeding Behavior of the House Fly (Musca domestica)
- Adult house flies have sponging mouthparts that only allow them to eat liquids. Some solid foods can be liquefied with regurgitated saliva and then sponged up through the mouthparts.
- While feeding, flies also defecate on their food.
- Adults are attracted to a wide variety of food materials.
- Larvae feed on decaying organic matter such as
- Animal manure or droppings
- Wet garbage
- Piles of lawn clippings
- Decaying vegetables or fruits
- Soil contaminated with any of the above
General Behavior of the House Fly (Musca domestica)
- Wherever house flies rest, they leave “fly specks”, light brown/cream-colors specks of saliva and excrement that are a strong attractant for other house flies.
- For resting places during the day or night, house flies prefer corners, edges, and thin objects such as wires and strings, but can be found surfaces such as walls, ceilings, floors, the ground, plants, garbage cans, and fences.
General Biology and Behavior of the Little House Fly (Fannia canicularis)
- Fannia is smaller and more slender than the house fly and the 4th wing vein continues directly to the edge of the wing rather than being sharply angled as it is in the house fly.
- Fannia breeds in manure from dogs, poultry, horses, cows, and humans as well as decaying vegetable matter.
- Males of this species are often found flying in circles in the middle of a room, on a porch, or in a shaded area outdoors.
- Females are rarely found indoors.
- Larvae are brown, flattened, and have fleshy spines on their backs and sides.
- Larvae can tolerate a wide range of moisture in their habitat.
- This fly appears earlier in the spring than the house fly and disappears in the summer in areas with high temperatures.
- Adults are attracted to honeydew and can be found swarming under plants infested with aphids.
- These flies take from 18 to 22 days to grow from egg to adult.
General Biology and Behavior of Flesh Flies (Sarcophaga spp.)
- These flies are associated with small dead animals—insects and snails as well as small vertebrates (animals with backbones).
- Only a few species breed in larger animal carcasses.
- At least one species (Sarcophaga destructor) can develop entirely on decomposing vegetable matter.
- Around the home, these flies are attracted to garbage and compost piles.
General Biology and Behavior of Blow Flies (Family Calliphoridae)
- Adults make a loud droning buzz.
- Adults are attracted to dead animals, animal wounds, bloody or feces-caked hair or wool on pets or farm animals, and wet garbage.Birds or rodents that die in walls or chimneys can produce large numbers of blow flies.
- Green bottle flies can be found on dog droppings
- These flies require 15 or more days to develop from egg to adult.
- Flight range is 3 to 10 miles
Factors that favor the House Fly, Little House Fly, Flesh Flies, and Blow Flies
- Improperly stored food waste
- Food residues in garbage cans and dumpsters produce many kinds of flies. Blow flies generally breed more abundantly in garbage cans than do house flies.
- Rodent and other animal carcasses in traps, on glue boards, in walls and other inaccessible places will produce many hundreds of flies if left long enough.
- Piles of warm, moist lawn clippings can be an important source of house flies in urban areas.
- Poorly cared-for compost piles or bins can produce many kinds of flies.
- Piles of manure can be a principle source of house flies in rural areas.
Monitoring and Record Keeping
The purpose of monitoring is to track pest activity in order to catch small problems before they become overwhelming. Monitoring also makes it possible to properly time pest management actions and to evaluate the effectiveness of those actions. Records are kept to document the methods and products used and to record information that can be used to fine-tune pest management methods and plan future actions.
Fly traps and visual inspection of likely breeding sites are the most useful monitoring techniques.
The “tolerance level” is the number of flies that triggers action to control the pest. The tolerance level is site-specific and differs depending on the customer, the location, and other factors. Determining the tolerance levels for a site helps prioritize work that must be done to control the pest.
To manage flies, it is most effective to concentrate on eliminating conditions that support the immature stages (maggots). This involves proper storage and disposal of food wastes as well as keeping waste receptacles clean. Many of these sanitation practices will prevent problems with other insects as well.
The next most important management strategy for flies is denying their access to a structure.
To limit availability of food
- Discuss the importance of sanitation with the appropriate people.
- Drain food wastes before placing in a plastic bag for disposal in a waste receptacle or dumpster.
- Use plastic liners in all waste receptacles that might collect food garbage; seal the plastic liners before placing in outside dumpsters or garbage cans.
- Remove garbage containing food wastes from the building before nightfall or tie a knot in the plastic liner.
- Store garbage in closed, rodent-proof dumpsters or garbage cans outside the building and away from doors.
- Keep waste receptacles and dumpsters clean; use a high-pressure stream of water or a brush and soapy water. Rinsing with a mild solution of borax or baking soda and water will eliminate odors.
- Flies can breed in soil soaked with water used to clean garbage cans and dumpsters. Check these areas regularly and scrape up any maggots along with the soil, and dispose of the material in a sealed plastic bag.
- Promptly fix drains or electric garbage disposal units that leak or drains that allow food waste to accumulate under sinks or floors. This food waste will attract many different kinds of flies.
- If drains or garbage disposal units do leak food waste, remove all the food waste and clean the area thoroughly.
- Store food in the refrigerator, freezer, or cooler, or in insect-proof containers such as Tupperware or screw-top jars (screw-top jars are not insect-proof unless the lid has a rubber gasket).
- Limit areas where food can be eaten and make sure to clean those areas after holiday, birthday, or other kinds of parties.
- Remove and clean pet dishes after pets have eaten..
- Outdoors, pick up and remove fallen fruit as soon as possible.
- Maintain compost piles properly, otherwise they can produce large numbers of flies.
To limit attractive odors
Flies are strongly attracted to odors that come from materials that might provide them food or a place to lay eggs, and they can detect these odors over long distances. To limit attractive odors:
- Place dumpsters, garbage cans, and recycling containers away from outside doors to the building.
- Keep dumpsters and garbage cans clean to eliminate odors (see above)
- Empty dumpsters and garbage frequently, at least once a week; consider twice-weekly garbage pickup during warm weather if the fly problem is severe.
- Drain food garbage and store in sealed plastic bags. In schools, the smells of souring milk and yogurt in hundreds of containers thrown into dumpsters can attract thousands of flies from the surrounding neighborhood.
- Remove pet feces as soon as possible, place in a sealed plastic bag, and then into a waste receptacle or dumpster.
- The brown- to cream-colored fly specks found on walls and other surfaces where flies rest have a strong fly-attracting odor. They should be frequently cleaned off of surfaces with an odor-eliminating cleaner (a mild solution of borax or baking soda and water is effective).
Physical controls employ physical means to remove flies or prevent their entrance to a structure.
- To prevent fly entry:
- Tightly screen all windows and doors
- Weather-strip all windows and doors
- Seal gaps around windows and doors
- Screen air intake and exhaust vents
- Equip doors with self-closing devices to prevent their being left open inadvertently
- Install air curtains on doors that must remain open and cannot be screened. The air stream must have a velocity of 1,600 feet per second to be effective.
- Sticky fly tape and/or fly swatters can eliminate a small number of flies indoors; however, fly paper may be considered unsightly.
- Outside, cone-type fly traps with strong-smelling bait can be extremely effective in helping to control fly populations.
- Fly traps using ultraviolet light bulbs can be effective inside as a supplement to other measures. They must be used in areas where they are not competing with natural light. Follow the manufacturer's instructions carefully.
- Note that Fannia (the little house fly) is not attracted to the same baits or traps as the house fly.
- A fan directed at circling Fannia will make the area less attractive to them because strong air currents disperse them.
Chemical controls are not recommended for fly control.
The IPM Partnership
The PCO-Customer Partnership is Very Important
IPM works best when the customer and Pestec form a partnership to tackle the pest problem. Garbage- and manure-breeding cannot be managed satisfactorily without the cooperation of the customer, especially in the area of sanitation. Pestec will discuss the findings of the initial inspection and any subsequent monitoring sessions with the customer to determine which issues and tasks will be the responsibility of Pestec and which will be the responsibility of the customer.
Information is a powerful tool in IPM. Information can help change people’s behavior, particularly in how they store food and dispose of waste. Changing these behaviors is a necessary part of managing flies. Occupants of buildings and homeowners can also help in the early detection of pests so that Pestec can be alerted before the problem is severe.
Pestec’s highly trained and knowledgeable staff can provide pest management education or training sessions for facilities managers, risk managers, building occupants, homeowner associations, and others.