Many species of flies can become a problem in schools. Each fly species has a distinct breeding site inside or outside the school building. In order to control flies, it is necessary to know which species is causing the problem and where it is breeding. Drain flies, fruit flies and fungus gnats are addressed in the next section.
Flies such as house flies, little house flies, dump flies, blow flies, and blue and green bottle flies which breed in food wastes (garbage) and/or animal feces, are generally referred to as "filth flies." Other flies such as stable flies breed in decaying vegetable matter like grass cuttings. Flies that invade cafeterias and kitchens are not only a nuisance; they also present a health hazard because they can contaminate food, utensils, and surfaces. Biting flies, like stable flies, can inflict painful bites.
The key to solving persistent fly problems is proper identification of the species. After the problem fly has been identified, information on life cycle, breeding sites, and effective management options can be readily obtained from a number of sources.
Flies most likely to be encountered in schools and other structures. Drain flies, fruit flies and fungus gnats are addressed in the next section.
|Common and species name||Geographic distribution|
|house fly, Musca domestica||Throughout the US.|
|little house fly, Fannia canicularis||Throughout the US.|
|dump fly, Hydrotaea aenescens||Throughout the southeastern US.|
|blow fly, Calliphora sp.||Throughout the US.|
|blue bottle fly, Phaenicia spp.||Throughout the US.|
|green bottle fly, Phaenicia spp.||Throughout the US.|
|face fly, Musca autumnalis||Throughout the US.|
|stable fly, Stomoxys calcitrans||Throughout the US.|
It is important to correctly identify problem flies and pinpoint their breeding sites. Some of their characteristics can help you with identification; alternatively specimens can be taken or sent to a county extension agent who should be able to assist in identification.
If they cannot identify the specimen they will be able to refer you to a specialist who can. To collect specimens inside, use sticky flypaper or gather dead specimens from window sills and light fixtures. Individual flies captured for identification purposes should be held in a small vial to preserve key identifying characters.
Inspection practices should include ensuring that trash cans or dumpsters are placed away from building entryways; proper use of plastic bag liners in trash cans; all trash disposed in dumpsters is enclosed in sealed bags; adequate clean up of spilled food and drinks; properly sealed openings throughout the building exterior; and tightly fitting doors, door sweeps and window seals.
To manage flies, you must find and reduce breeding sites, install and maintain screens to keep flies out of buildings, kill those flies that do get inside with a fly swatter or flypaper, and reduce or eliminate the odors that attract flies.
In schools that have programs where wastes are removed frequently, it is unlikely that flies are breeding on the school property. It is more likely that odors from dumpsters, garbage cans, kitchens, and cafeterias are attracting flies to the school from the surrounding neighborhood. House flies and blow flies, the species that most commonly invade buildings, usually develop outside and follow odors into the building. They can also be nuisance pests when students or staff eat outside of the building. In schools where waste removal is infrequent, fly populations can breed at the waste collection site.
Cultural, physical, and mechanical management options are preferred methods for management of flies and include the proper management of waste, physical methods such as screens and flyswatters, and properly maintained and fitting doors and windows.
Flies found inside a school building enter from the outside in almost all cases. Therefore, barriers preventing access of flies to the building are the first line of defense. Cracks around windows and doors where flies may enter should be sealed. Well-fitted screens will also limit their access to buildings. Outdoors, regular removal (at least once a week) and disposal of organic waste, including dog feces and rotting fruit, reduces the attractiveness of the area to adult flies and limits their breeding sites. Garbage should not be allowed to accumulate and should be placed in sealed plastic bags and held in containers with tight-fitting lids. Garbage should also be placed as far from a building entrance as is practicable. In general, poor exclusion and lack of sanitation are the major contributors to fly problems.
Sticky fly papers or ribbons are effective at eliminating low numbers of flies in relatively confined areas, but are not effective enough to manage heavy infestations or to provide control in an outdoor setting. A number of fly traps for outdoor control are commercially available and can be effective for periodic fly populations when they are not competing with nearby garbage or animal wastes. Indoor fly traps are also available.
Manufacturer‘s directions must be followed for the placement and use of these traps. For control of just a few flies, the time-tested fly swatter is appropriate. If fly swatters are used near food preparation areas, all food must be removed from the area and all food-contact surfaces thoroughly cleaned to avoid contaminating food with insect body parts.
Table 2 Commonly used products for physical, cultural or mechanical management of flies and uses.
|sticky traps||Catchmaster Gold Stick® Fly Trap Catchmaster Bug and Fly Bonide Fly Catcher Ribbons||Tapes or traps mounted in areas where flies are entering or resting. Avoid placing over food preparation areas.|
|light traps with sticky capture surface||Catchmaster Dynamite 911 Gilbert® 2002GT Flying Venus Fly Trap||Mounted in entryways or other areas where flies are encountered. Mount so that light is not visible from outside to avoid drawing flies to entryways.|
|light traps with electrocuting grids||Fly-Zapper 22/14 Electrocutor Gilbert® 220 Guerrilla Fly Electrocutor Trap||Mounted in entryways or other areas where flies are encountered. Mount so that light is not visible from outside to avoid drawing flies to entryways. Not for use in food preparation areas where insect body parts may come into contact with food or food preparation surfaces.|
While chemical pesticides may be effective for suppressing adult fly populations in some situations, they are not a substitute for proper sanitation and aggressive elimination of nuisance-fly-development sites. Because flies can quickly develop resistance to insecticides, use them only as a last resort to obtain immediate control of severe adult fly infestations, after all possible nonchemical strategies have been employed.
In most school situations, pesticides are not needed or recommended for fly management. Sanitation along with exclusion to keep flies out should be sufficient. In rare cases where non-chemical methods are not possible or effective, a non-residual aerosol may be used to knock down flies. Outside, a residual insecticide may be applied to surfaces such as walls and overhangs that are being used by the flies as resting areas. Fly baits used in trash or other areas may be effective in reducing the number of adult flies if proper sanitation practices are followed. However, when flies have access to garbage, baits will not effectively control them.
Table 3 Commonly used insecticide products for flies and uses.
a. Insecticides carrying a CAUTION label or exempt from EPA registration, in formulations that reduce potential for exposure
|Active Ingredient||Example Products||Uses|
|imidacloprid||Maxforce® Granular Fly Bait 432-1359||Granular formulation. To reduce ingestion and exposure hazard, use in a pre-manufactured bait station or inaccessible areas.|
|imidacloprid||Maxforce® Fly Spot Bait 432-1359||Liquid formulation. To reduce exposure hazard, apply to inaccessible non-human contact surfaces|
b. CAUTION-label formulations with greater potential for exposure.
|Active Ingredient||Example Products||Uses|
|2-phenethyl propionate, eugenol||EcoEXEMPT KO (EPA Exempt)||GNon-residual contact insecticides spray.|
c. CAUTION-label formulations with greater potential for toxicity and/or exposure.