Bug Bytes

Fly Control in Food Processing Facilities: Reducing Seasonal Risks

By Patricia Hottel
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May 7, 2026


• Categories: Bug Bytes, Food Manufacturing, Food Safety Consortium, Foodservice & Retail

Flies are often dismissed as a nuisance, but in food processing environments they present a real risk as vectors of disease and a potential source of costly operational disruptions. They follow the conditions they need to survive — moisture, residue and access.¹ By addressing those conditions early, food processing facility managers can help reduce fly risks.

Under Section 402(a)(4) of the Federal Food, Drug and Cosmetic Act, food may be deemed adulterated if exposed to conditions where contamination is possible.⁴ Fly activity fits squarely within that definition, as these insects move freely between waste sources and food-contact surfaces, potentially spreading pathogens.³

Pest Prevention Pre-Requisites must demonstrate that risks are identified, recorded and corrective action is taken through documented procedures. Modern food safety systems, including FSMA Preventive Controls and GFSI-benchmarked standards, rely on integrated pest management (IPM) practices as part of a Pest Management Pre-Requisite.

IPM is a science-based pest control strategy that focuses on prevention, monitoring, documentation and targeted treatment using the lowest risk methods that are effective to minimize pest risks in regulated environments such as food processing facilities.

Where Fly Activity Signals Breakdown in Preventive Controls

Small structure-infesting flies like drain and phorid flies are weak fliers and tend to stay close to the conditions they need to survive — places with moisture, organic materials or waste and gaps to get indoors.

Drains and Biofilm

Drains are a common breeding site for small structure-infesting flies. Organic material accumulates below the surface, forming biofilm that supports larval development. Surface cleaning may improve appearance, but without removing that buildup, the food source remains.²

Bleach doesn’t remove biofilm­ — it just slides right over it. Instead, facilities should use a biological drain cleaner with enzymes that can eat through the gunk.

Waste Handling and Dumpster Areas

Waste zones create strong odor signals that attract multiple species of flies including filth flies like the house fly and small flies like phorid flies. Inadequate cleaning or dumpsters located close to buildings can sustain fly populations that migrate toward production areas.²

Dumpsters should be cleaned regularly, including pressure-washing the concrete pad beneath them to eliminate residue that can attract and support fly populations. When waste haulers replace dumpsters, they should be cleaned prior to delivery.

Moisture and Condensation

Flies need moisture to survive. Condensation lines, leaks and standing water create ideal breeding conditions. Organic material with a high moisture content is required for successful fly development.³

Receiving and Loading Docks

Food processing facilities are especially vulnerable to fly activity near building entrances and loading docks, where flies can enter a facility from outside. Doors should not be left open when not use.  When closed, there should be a tight seal around all sides. Mechanical controls, such as air curtains, can help create barriers that flies cannot penetrate.

How Does Fly Activity Impact Audit Readiness?

Within the modern regulatory landscape, auditors review documentation as evidence of preventive pest management, including fly control. To meet FSMA-aligned Food Safety Plan standards, Pest Prevention Pre-Requisites must demonstrate that issues are resolved through documented monitoring procedures, activity thresholds, pest sighting logs, corrective actions and verification.

If fly activity is observed, auditors will evaluate how the facility responded. Was the source of the issue identified? Were corrective actions taken? Was the treatment effective?

When looking for a pest management partner, consider partners that offer documentation, like a digital pest management reporting platform as part of services. For example, Orkin InSite® helps facility managers easily locate reports, manage multiple locations, track pest trends and receive proactive program recommendations.

In food processing facilities, many types of documentation are necessary to meet auditor standards, including but not limited to:

• Initial risk assessments and defined action thresholds for preventive controls
• Detailed service reports documenting activity and actions
• Pest sighting logs and trend reports
• Compliance documents such as licenses, insurance, training verification and other certifications

The Orkin InSite system is designed to house and archive all your documentation requirements for quick and easy retrieval as required by FSMA.

Food processing managers should also keep logs of reported pest sightings. Not only are they expected by auditors, but pest sighting logs can help facilities identify pest issues early on, recognize patterns and be used to verify the Pest Prevention Pre-Requisite through trending analysis, easily conducted through the InSite system. To give auditors an accurate picture of your facility’s IPM plan, log entries should include matching documentation of  actions in place and preventive controls taken.

Each log should document these details of the pest sighting:

• Date and time
• Individual reporting the activity
• Pest identification, including a sample if captured
• Exact location
• Actions taken to avoid future occurrences ⁴

Fly Prevention Strategies Within a Pest Prevention Pre-Requisite

Effective fly control is grounded in structured, evidence-based IPM programs that emphasize prevention, monitoring and documentation.¹ These programs reflect standards-driven methodologies backed by trained professionals who understand regulatory expectations and facility operations.

Inspection: Finding the Source

Effective fly control begins with a structured inspection protocol targeting the four conditions that support fly survival and reproduction inside and around commercial food environments:

1. Drains and Pipe Systems: Check for organic accumulation and biofilm formation, primary breeding sites for phorid flies and drain flies.
2. Ingredient Storage Zones: Identify improperly stored or exposed raw materials that attract house flies and blow flies.
3. Waste and Dumpster Areas: Assess proximity to building entrances and organic residue buildup. Use self-closing lids on exterior trash receptacles, including those used in exterior employee break areas and truck driver entrances.
4. Structural Access Points²: Document gaps, failing door seals and screen integrity at loading docks, vents, windows and receiving areas.

Commercial technicians should conduct facility-specific inspections as part of a structured IPM program, generating documented findings that support FSMA Preventive Controls compliance and GFSI audit readiness.

Sanitation: Removing the Breeding Sites

Flies depend on moist organic material to eat and complete their life cycle. Sanitation practices can help remove the organic material that flies need to survive and reproduce.

• Mechanically remove heavy accumulations of debris from drains and supplement drain cleaning with biological cleaners. Enzymes in biological cleaners help remove biofilm, not just surface residue
• Keep waste containers away from building entrances, use self-closing lids on trash receptacles and clean them regularly
• Deploy sanitation and cleaning practices to remove debris and organic buildup from production zones³

Exclusion: Controlling Access

Exclusion measures help keep flies outside where they belong:

• Maintain door sweeps and test them with the “dollar bill test.” If you can slide a dollar bill under the door sweep, it’s no longer effective and should be replaced immediately.
• A 16 mesh screen will exclude most flies. Fungus gnats and Drosophila fruit flies require an even smaller mesh size of 20. Make sure all screens are tight fitting without any gaps.
• Use air curtains at entry points, which create a blast of air that is difficult for flies to penetrate.
• Work with a HVAC professional to maintain the building’s positive air pressure.  Negative air pressure can draw and pull flies into the structure through air currents.²

Mechanical Controls: Monitoring Activity

Monitoring tools support verification of effectiveness and trend analysis.

• To maximize capture rates and facilitate trap service, install Insect Light Traps (ILTs)   at approximately 5 feet off the ground. This will facilitate proper functionality and provide the recommended height for maximizing capture rates.
• Avoid placement near food or food contact surfaces to prevent attracting flies to these areas.
• Use capture data to identify patterns of fly activity in your facility.²

How Fly Control Involves the Whole Team

Sustained fly control requires coordination across teams and consistent execution.

• Sanitation teams address organic buildup and prompt waste removal.
• Maintenance teams keep exclusion measures, like door sweeps, in good working condition.
• Quality and operations teams verify documentation and corrective actions to reinforce cGMP compliance and stay audit-ready

Facilities that integrate these functions into day-to-day operations are better positioned to protect the integrity of the food produced and avoid costly operational disruptions and  damaging shutdowns tied to audit findings.

Working with pest control partners who understand the demands of food processing environments — and who provide proactive guidance, structured programs and audit-ready documentation — helps facilities stay prepared year after year.