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By Lisa Lupo

Flying insects can be difficult to control. Flies are naturally attracted to food facilities; there are many ways they can get in; and they have plenty of options for feeding and breeding once inside. Following are four food facility fly facts — and what you can do to defeat them.

1. Food facilities attract flies.

“Unmaintained trash areas are always conducive to flies,” said VM Products President Ethan Vickery. Flies are attracted not only by the refuse and decaying product odors but also by leaky compactor trash systems where spillage gathers under the units, he said. “Unless cleaning facilities are available for the compactors when they are emptied, they will become fly production units thanks to the filth buildup inside.” Additionally, trash and debris often will collect in landscaped areas, such as parking lot islands, providing flies with cover and food. Irrigation in these areas then compounds the problem if they are not properly maintained.

McCloud Services Technical Director Pat Hottel agreed that odors will attract flies and need to be minimized. “An example of ways to minimize odors that attract flies is to use trash receptacles with self-closing lids and keep dumpster lids closed and dumpster pads clean,” she said. Food facilities also need to look for areas where moist organic material can accumulate. In addition to trash areas, this can include areas of spillage around bulk unloading.

But not all flying insects come in from outdoors, Hottel cautioned. “Flying insects can be transported (through the supply chain) when damaged containers are shipped from one site to another.” This is particularly true of small flies, such as Drosophila “fruit” flies, phorid flies, and ham and cheese skippers. Small flies, especially fruit flies, also can be transported in produce and be brought in with over-ripe fruit and fermenting foods. “Facilities can bring these pests in with fruit, vegetables, and containers being reused and recycled,” she said.

And once inside, flies can be attracted to common problem areas including waste receptacles and processing areas where there is both moisture and organic material. Sanitation efforts are especially important in reducing small fly breeding sites on the interior, she added.

Other exterior places that can attract flies are employee break areas if not regularly cleaned. “Since they are normally close to the structure and entry areas, flies are drawn in and allowed access,” Vickery said.

Unmaintained fence lines can allow the development of moisture-holding environments, and winds blowing toward the structure will worsen the problem; leaky roof tops can cause issues with flies as they penetrate from above; and improper lighting can attract flying insects to the structure. Changing to a less-attractive light and moving the lighting out and directing it back toward the building can help reduce attraction.

“Within the more than 50% of the facility that is unseen and often unclean, heat, available water, nutrition, cryptic recesses, and shelter-in-place come together to attract and support significant fly pressures,” said PestWest Principal Technical Specialist Stuart Mitchell. Essentially, said Excel Pest Services Director of Business Development Sam Hagopian for SeaHawk, “Any area that is exposed to organic matter or sweet, sugary substances can be attractive to flies.” But you can reduce this attraction by adhering to strict standards, cleaning up frequently, and keeping doors, windows, and other entry points sealed.

2. Flies will find ways to get inside.

Because most large filth flies enter food plants from the exterior, Hottel said, “Removal of food sources is #1”; and exclusion is critical. Both large and small filth flies can enter from the exterior, although it is more common for the larger filth flies like house flies and bottle flies to enter from the exterior versus originating indoors.

To prevent this, exclusion practices should include:

  • Begin flying insect exclusion with exterior sanitation (grounds, odor release, landscaping, etc.) then flow to the interior (construction integrity, positive pressure, lighting, etc.).
  • With a variety of materials registered for fly control around food facilities, fly baits, insect growth regulators, and insecticide residuals can be particularly useful in supplementing sanitation and exclusion.
  • Try fly bait stations in vulnerable exterior areas to help reduce the numbers of insects that can access the site.
  • Use good seals on dock and employee doors, with screens used on doors where needed for ventilation.
  • All doors should be kept closed while not in use — leave nothing open beyond what is required for the entrance and exit of stock, supplies, equipment, or personnel.
  • Use properly installed, operational, and well-maintained air doors and pressure walls.
  • Install insect light traps at key areas inside the facility to monitor and control flying insects. Regularly reviewing the catch in the units can help identify penetration zones and possibly the source of an insect issue.
  • Practice behavioral control as a cyclical process of IPM or mutually verifiable systems cooperation between the PCO or PMP(s) and the food plant.
  • Ensure the grounds, building, and equipment are all maintained to the highest level possible. All must perform properly and not create conditions conducive to pests.
  • Rotate product employing first in/first out (FIFO) practices so all supplies, equipment, ingredients, and other related items are maintained within their useful lives and code dates.
  • Use positive air pressure in the structure.
3. Keep it clean. Or they will breed.

“Moist organic material that is not removed as part of sanitation can provide food for small and large filth fly maggots,” Hottel said. It also provides a breeding site because flies lay their eggs in organic material. Because of this, sanitation can greatly impact fly management.

This is, in part, because, “Flies have particularly sensitive taste receptors and can detect substances that they believe have nutritional value,” Hagopian said. “If a fly identifies an area containing organic matter, or sweet substances, it will breed there. This is an instinctive action, as it will reproduce in areas that are most conducive for the larvae.”

Unsanitary conditions are attractive to most pests, including flies, and these will draw them into an area. “These conditions also allow the growth of filth and bacteria that pests feed on and carry to other zones causing additional problems,” Vickery said. “So long as proper sanitation is taken care of, pests will have less to attract them and fewer resources to enable their survival.”

On the other hand, continuous sanitation failures can cause flies to “establish morphologically non-competitive, serviceable niches within micro-spaces and certainly macro-spaces,” Mitchell said. A lack of sanitation can create conducive niches and “refugia” in which some flies can survive and thrive even if the widespread population is controlled.

In fact, he said, the emergence, presence, and persistence of flying insects within a food facility is a symptom, “and eventually a disease,” of sanitation system failure.

4. Sanitation tools can be problematic too.

Compressed air and pressure washers can push debris nto cracks and hard-to-reach areas where they create micro environments that serve as a resource and harborage point for pests, Vickery said. “Controlled use of these tools in a precise manner will help prevent this from happening. Run off and uncontrolled dust cannot be allowed to move uncontrolled in the work area.”

“Cleaning practices can also contribute to floor deterioration, which can lead to moist organic material accumulating in deteriorated floors,” Hottel said. “Since moisture is a critical component in providing the right conditions for larval development, management of all water on site is important.” It is for such reasons as well that all equipment should be used according the manufacturer’s directions. The cleaning and sanitation tools, themselves, also must be properly cleaned and maintained so as not to act as a source of contaminant introduction to the site.

Integrating the Steps. Eliminating flying insect attraction around the facility, implementing exclusion practices to keep flies from entering, and reducing food and harborage through cleaning and sanitizing (of both the facility and the tools used for cleaning and sanitizing) are all critical components of a complete fly management program. Alone, none are likely to keep your facility fly-free; but integrated as a four-step program, they can be the difference between safe, quality food and contamination.

The author is Editor of QA magazine. She can be reached at llupo@gie.net.