Fly Control STAT!

Flies are the most prolific and problematic insect pests found in the health-care environment. Flies are extremely mobile and can quickly make their way to nearly any part of the facility no matter where they are breeding or entering the building. The potential for contamination of sterile environments and equipment is very high and might go unnoticed due to the small size of many fly species.

HUMPBACKED FLIES. These flies (of which there are different species) are perfect examples of highly mobile flies that breed in filth, and they are extremely important pests for which the technician must actively inspect and take precautionary measures. Insect light traps are an excellent monitoring tool and can have some impact on the adult population (the damaging life stage in this case). However, light traps alone will not resolve an ongoing problem in a health-care account.

Top image: © tommaso79 | Thinkstock.com; insect images: Bugwood.org

In some instances, these flies can breed in the soil beneath concrete slab foundations if there are cracks in the slab allowing soiled water to seep through or there are plumbing leaks below the slab. If evidence suggests that flies are breeding under the slab, the concrete must be cut, the soil beneath the slab replaced and the source of the moisture corrected. Sub-slab pesticide applications will not be effective.

DRAIN FLIES. Drain flies are considerably less mobile than humpbacked flies and tend to remain in the vicinity of the breeding site where they can be found resting on vertical surfaces during daylight hours. As its name implies, the most common breeding site for this fly is in drains where it lives beneath the surface of slimy, organic film that builds up in plumbing. Typically the control of populations is simple, and is accomplished by the cleaning of drains with a scouring brush and application of microbial agents to degrade the biological film. Occasionally, problems can be persistent due to unusual breeding sites. Don’t overlook any area with excessive moisture, such as air-conditioning drains, clogged gutters, cracks in tile flooring, condensation drip pans or the pans beneath potted plants.

FUNGUS GNATS. Fungus gnats occasionally present challenges in health-care facilities where adult flies accumulate in dark, moist areas during the day. These flies are sometimes plentiful outdoors, and adults are moderately strong fliers that may fly into the building. They are attracted to lights and are active at night. So, reviewing outdoor entrance lighting is recommended. However, if large numbers are found indoors, it is likely that they are breeding within the facility. Larvae typically feed on the fungus associated with the decay of plant materials but also can feed directly on moist, organic material.

TIPS FOR CONTROL.  As with all of the flies discussed, the identification and elimination of breeding sites is the only long-term solution. Indoors, the primary breeding site of these flies is in the overwatered soil of potted plants or the soil of indoor landscaping in atriums or entrances. In these cases, the soil must be dried or removed.

Top image: © tommaso79 | Thinkstock.com; insect images: Bugwood.org

Occasionally fungus gnats may breed because of faulty construction in the facility itself. Flat-topped roofs are notorious sources of water leaks, and most health-care facilities have such roofs. Sometimes new facilities will support fungus gnats when wet plaster or green lumber are used in construction and proper ventilation is not built into void areas. The solution to these problems must involve the client working with the pest management professional to repair of any water leaks and the replacement or drying of wood that supports fungal growth. Larvae breed in moist, decaying organic matter and even have been found in the open wounds of patients. This is a pest that commonly breeds in drains, which are plentiful in health-care facilities. Finding and eliminating the breeding sources is the only long-term solution. A simple way to identify problem drains is to temporarily place clear plastic cups upside down over the drains. After a few hours the cups can be inspected, and drains producing adult flies should be revealed. Then, elimination can be accomplished through cleaning, with the application of microbial cleaning agents generally being most effective.