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One way to characterize the types of pests likely to infect a food processing facility is through the products made. In this article, we cover the most common pests and the most vulnerable locations for these pests in wet processing plants. Examples of wet processing plants are those that produce beverages, canned goods, dairy products, and frozen foods. They usually use water in processing and cleaning, and water is a key factor in the profile of the pests that infest the site.

Pests have certain food preferences and vital environmental needs. When these conditions are met, pests thrive. Liquid processing plants share certain environmental profiles, and we can use these similarities to predict pests. Hygiene, employee practices, facility processes, and construction and equipment design can all be used to manage these potential risks. In addition, not all areas within a facility meet the needs of the pest equally and certain areas are less at risk for the development of the pest. Here is a list of the 10 most common areas of pest activity by product type, structural design, and practices. Use this list to prioritize areas for inspection and monitoring as part of a pest control program. We can assign these areas / conditions for the inspection as pest-endangered zones (PVZs).


Since a lot of water, pressurized water and caustic cleaners can be used in cleaning programs, floors in wet processing systems are a challenge. Floor coatings and tile grout can wear out, allowing food and moisture to soak into deteriorating floors. Soil repairs can be expensive, but soil integrity must be preserved. Water and food residues can also get into wall cavities via floor / wall connections if the connections are not properly sealed. The coving of floors along the wall / floor intersection helps reduce this problem. When moist organic debris is left behind, small flies such as Drosophila flies and Phoride flies can develop.


In order to cope with the large amounts of water on the construction site, extensive drainage systems are required. Floor drains will be numerous, with sewer drains or trench drains being common. Floor drains can be intricate and allow areas of organic matter to build up. Improperly designed drainage systems can cause major problems with small flies and other insects. Canal drains can be particularly problematic as they are more likely to hold back moisture and dirt. The correct slope of the sewer drain is required to ensure drainage of water and debris. Sewer drains also provide a larger surface area at the drain-floor junctions to damage the flooring. As mentioned earlier, soil deteriorating can mean water and food debris are building up.

Drains, especially if the water trap is not maintained, can be a route for drain flies and American cockroaches to enter a facility. It is an underground passageway for pests that inhabit sewer systems to gain access. Special one-way valves can be used that allow the water to flow downwards but prevent pests from entering the construction site. Appropriate grids that can be removed by staff for cleaning can help keep cockroaches out. Square gratings are available for this.

Finally, greater fly infestation can be linked to under-plate pipe bursts and this can become a major problem as the system ages. If there are problems with the subfloor, areas of the flooring will need to be removed to remove soil and carry out pipe repairs. This is costly from the standpoint of labor costs and materials, and also production downtime.


If we ranked the areas listed in this article by importance, the dumpster / compactor area would be number 1. Odors emanating from trash can attract a wide variety of pests into the building, including rodents, dirt flies, and birds. Odors attract and food availability encourages the pests to stay. If the dumpster and the inside of the dumpster are not cleaned regularly, flies can lay eggs and maggots form in the wet leftover food.

Pests can also be transported from one location to another if no garbage containers are assigned to a location. The food factory staff and / or the waste transporter should be assigned to clean the interior of the waste container and the pad when collecting the waste. Seasonality and weather can dictate feasibility. The dumpster should be checked regularly for cracks and surface integrity. If necessary, repairs should be made to remove crevices where moist organic waste can build up.

Particular attention is paid to pest control of the structure in and around the dumpster as pests are attracted to this area. All slides, doors, and walls should be well sealed to prevent pests lured into the area from entering the building.


Americans waste a lot of food, and reusing food for animal feed or other uses makes sense. The same applies to empty packaging materials. Food processors may have zero waste programs and may even recycle items like hairnets and disposable gowns. All of these programs are beneficial, but the potential for pest attraction needs to be understood and the correct preventive measures taken.

It is not uncommon for tags used for ballboard to be deployed on an open dock door. Despite seals in the area of ​​the door opening of the trailer, there are often gaps in the area where the ramp to the trailer bridges. This can provide a large pest-prone opening for rodents, birds, insects, and pesky wildlife. While easy access is required for staff to load trailers, the best practice is to keep the doors closed when not actively loading. Roll-top doors for trailers are preferred over doors that swing outward. Outward swinging doors cannot be closed while the trailer is secured to the dock.

If chutes are used for food waste, the chutes must be checked for pest control and should be subjected to a regular cleaning program. The area where the slide connects to the trailer should be tight to prevent birds, rodents and wildlife from accessing the feed. Trailers used for food waste, like dumpsters, should undergo a cleaning program. Trailers should be checked for pest infestation. Pests such as rodents can get to food facilities on food reuse tags.


Roofs can be one of the most overlooked areas for pest activity. Pests can be attracted to the environment for warmth and protection. Stinging insects can build nests along eaves or other remote areas. Piling up water on roofs can provide sources of moisture for pests and development sites. Although weekly maintenance is not normally required, at least quarterly inspections of the area are recommended. This frequency can be adjusted based on conditions, seasonality, and historical pest pressures.


Not all sites have a mass unloading system, but when a liquid processing facility does, it is generally corn syrup. This sweet substance can attract honey bees, yellow vests and other wasps. Keeping the area as clean as possible and reducing leaks in the system is important to manage the risks. The area should be included in the inspection list at least seasonally.


Certain types of packaging are more likely than others to be damaged during storage. Pop-top tabs on cans and soft juice containers are more susceptible to damage. Phorid flies can cause problems in canned food and soups like chilli if cans are damaged and undiagnosed. The way the manufacturer packs and stacks these items on a pallet will also make a difference. The protection of the cans against incorrect handling by forklifts is a plus. It is important to understand the products and risks and to assign inspection times to these areas.


Corrugated metal walls are a common building material, but they can be damaged by forklifts and are more difficult to protect against pests and to keep tight. Damaged walls can provide pests with access from the outside and shelter inside. In some facilities, rolled and laminated insulation is placed over the corrugated wall for temperature control. This practice makes it a perfect place for rodents to travel and nest.

Glass fiber reinforced panel walls are widely used because of their cleanability and moisture resistance. However, over time, these panels can peel off the walls and create docks for German cockroaches. It can be difficult to get insecticides into the cracks and openings effectively. Walls must be checked regularly and made pest-proof.

9. Break rooms / changing rooms

There are several pests that trample on employee property. These include the German cockroach and the bed bug. Areas where employees eat and store their personal belongings can see insect activity. Strict guidelines for storing these items in designated areas must be followed by food processing personnel. Regular locker cleaning and guidelines for removing lunch boxes from break rooms at the end of the shift must be established and followed. Using cool boxes in break rooms to store lunch can help reduce cockroach problems. Both changing rooms and break rooms should be monitored by the pest controller.


The moisture and organic matter from washes and floor washer units can aid pests such as flies. Improperly stored and maintained wet vacuums, mops, and mop buckets are another potential problem. The drains, floors and walls in the wash halls must be cleaned and maintained.

Patricia Hottel has over 40 years of pest control experience. She is a board certified entomologist and a member of the National Pest Management Association (NPMA) fumigation committee. She is also a past member of the board of directors of the NPMA and the Illinois Pest Control Association (IPCA). She served on the board of Pi Chi Omega. Hottel is the technical manager for McCloud Services, Elgin, Illinois. McCloud is a member of the Copesan network of local service providers.

Copesan is an alliance of pest control companies with locations across North America. To learn more, visit www.copesan.com.

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