Pest Management: Occasional Invaders

Features - Pest Management

Prevention and protection

July 31, 2019

©AKKARA KS. | AdobeStock

In the May/June issue of QA, we sought the opinions of pest management experts on whether a food processing facility can be truly pest free. In their responses, the experts provided rationale for their views. In this issue, we delve deeper into this important topic, asking them to assess the threat posed by occasional invaders in food processing facilities. Following are the added questions, followed by the relevant sections of the experts’ prior responses, and how they see it applying to occasional invaders.


What existing or conducive conditions attract occasional invaders?

“Key stakeholders on both sides must instill a sense of value and commitment to observation, reporting, communicating, and action when existing or conducive pest conditions exist.”

For occasional invaders, these could include:

  • Poor drainage/storm water management provides high moisture levels against or close to building exterior.
  • Allowing natural vegetation to grow, including flowering weeds, around building perimeters will attract occasional invaders and provide shelter, food, and moisture.
  • Exterior lighting that attracts insects and placement of lights around entry sites, loading dock doors, and frequently opened windows will draw night-active pests to the structure. Use low-attraction light sources and remove lights from the building, aiming them at critical areas rather than mounting on the structure.
  • Heat and odor exhausts at ground level can attract many pests, especially during transition seasons.
  • Neglected cracks, utility penetrations, and structural joints can offer harborage and entry sites for pests.

– Joe Barile, Technical Service Lead, Bayer Environmental Science’s Professional Pest Management Team


“It takes monitoring for pests and a knowledge of past issues and conducive conditions that lead to pest pressure.”

A number of conditions can attract occasional invaders to a food processing facility, including food odors coming from inside. Moisture is a large draw, from standing water or even small sources like the drip from an air conditioner. In warmer areas, the cool air from inside a facility also can attract the pests to open doors or warehouse bays.

– Mel Whitson, Senior Field Technical Service Manager, Zoëcon Professional Products


What can food processing plants do to exclude pest entry from the exterior?

“In a commercial facility of this nature, an integrated pest management approach that pays close attention to hygiene, exclusion, and prevention is crucial for a successful control program.”

Today there are many options to prevent pest entry in a food processing plant or a commercial facility. Pay close attention to entry points starting with doors, windows, and vents in the building. Always use self-closing doors that lead directly to the outside; these are most important in high-traffic areas — by the front of the building or the loading docks in the back.

Sometimes employee breakrooms will have access to an outside patio that can provide entry points for different pests. Make sure doors and windows are fitted with weather stripping and/or screens and are in good repair. Air doors or plastic curtains are also widely used in commercial facilities to prevent the entry of flying insects.

Occasional invaders are pests that spend most of their time outdoors but will venture into structures in search of food, water, or shelter.
©korionov |

The best plan should always include targeting the pests on the exterior of the building by creating rings of defense. For example, an invisible barrier can be created by using repellent products with fast knockdown and long-lasting residual activity; the idea is to get to these pests before they make it into the building.

Another example is treating and maintaining the proper hygiene around dumpsters, trash cans, and recycling bins. Also pay attention to drains and other high-moisture areas. Be aware that many of these conducive conditions might be hidden from plain view by tall grass, shrubs, and other structural elements.

Inspect all utility line entry points and make sure they are properly sealed; ensure trees and shrubs are not touching the structures — these and the utility lines can serve as highways for many crawling pests. Also remember that employees can bring pests from their homes into locker rooms and offices; and loading docks and shipping trucks are ideal transport for unwanted visitors. Lastly, do not forget that used equipment can bring pests from other facilities.

– Freder Medina, Technical Market Manager – Pest Control, BASF


With dedication and adapting integrated pest management practices like exclusion and sanitation techniques, facilities can keep insect population levels at a very low level; one that will not cause economic loss.

While integrating physical barriers to exclude pests from food processing facilities is important to the success of your integrated pest management plan, it is not the only form of exclusion that should be considered. Eliminating the risk of bringing pests into the facility on raw ingredients and packaging is just as important as excluding them from the facility with insecticides and devices, so it is important to have supply chain protocols in place.

As with all integrated pest management programs, continuous monitoring of the facility and stored materials with traps is imperative to early detection of an insect pest before economic damage occurs. Finally, communication of inspection and control protocols should be communicated to initiate a quick response to an infestation.

– Cassie Krejci, Animal Health Technical Field Specialist, MGK


How does a food processing facility prevent occasional invaders in incoming goods?

On the trojan horse concept: “The trojan horse is a real danger to any pest control program because we cannot inspect 100% of every shipment or the people visiting.”

Incoming goods is one of the risky areas in any food plant that needs to be monitored at every delivery. During offloading, the product needs to be thoroughly inspected using a good flashlight, not just given a cursory once-over. Insects, like stored product pests, will seek harborage in the dark areas of the product, so attention to detail is vital.

The condition of the delivery vehicle also should be taken into consideration, as the product is confined during the transport phase and vulnerable to infestation. Finally, consider the staging area of the product to ensure it is monitored, especially if the product is stored near return product from the trade.

– Dominique Sauvage, Senior Director of Quality, Training and Field Operations, Copesan Services and Terminix Commercial


“(Have) a prevention-minded process for incoming goods and exterior pest pressures.”

A food processing facility can help prevent adulteration by occasional invaders from incoming goods by having third-party inspections of suppliers and trailer companies, and pre-loading inspections of the containers used in the shipment process prior to loading.

Once the goods are on-site, the company can ensure trailer doors remain closed and the IPM program for the exterior grounds is in good working order.

– James Miller, Market Manager-PCO, Trécé

Why is a strong monitoring program for occasional invaders important?

“It is possible for facilities to proactively prevent pest entry from the ambient environment and create an environment within the facility wherein any pests are eradicated before they create a hazard. Both would require an integrated approach including environmental, mechanical and chemical eradication, coupled with a strong monitoring program, sanitation, and ‘pest proofing’ specific susceptible processes and areas.”

An inspection is a snapshot in time, monitoring is a video. Monitoring provides the information needed for early detection of potential pest problems, before they get out of hand and cause significant problems. A lot of pests spend their time in cracks, crevices, and out-of-the-way places and may become well established before they are noticed or found in a visual inspection. Monitoring is a key step in a comprehensive pest management program. The reasons for a particular pest problem can vary widely, but monitoring can detect them earlier, irrespective of the cause. Monitoring also can provide the foundation of a systems-guided approach to pest management. It involves deployment and inspection of monitoring devices at regular intervals which then should lead to follow-up actions based upon findings.

– Cisse Spragins, Founder/CEO, Rockwell Labs


“The critical factor is early detection. This can be accomplished reliably with a thorough quarantine and monitoring protocol, regular inspections and aggressive control measures when pest thresholds are breached.”

When occasional invaders are found inside processing facilities, they are often an indicator of structural exclusion deficiencies. It is important to identify the point of entry and determine if it was a one-time occurrence, like an exterior door left open, or a recurring issue, such as a malfunctioning air curtain. A comprehensive monitoring program with multiple devices can help pinpoint the recurrence and location of insect entry into the facility.

– Eric Paysen, Technical Services Manager, Professional Pest Management, Syngenta

What steps can be taken to detect occasional invaders that do gain access?

“As individuals in a pest population gain access to a facility, the inspection and maintenance practices should intercept these individuals before they can become a large reproducing population, thus keeping the facility free of pest infestation.”

Ideally catching occasional invaders before they enter the structure is the best option, but there are many options for detection of pests if they gain access. The most commonly used are mechanical devices such as monitors or sticky traps.

These small, non-toxic, inexpensive, and unobtrusive tools can be placed in many areas throughout the structure. They can provide loads of information to a pest management professional, such as the ability to identify an occasional invader, the areas of high incidence, and in some cases, which direction the pests are traveling.

Other monitoring devices such as fly lights, pheromone traps, and even game cameras can be used to monitor pest entry and activity in food processing facilities. When monitoring pests that are only occasionally gaining access, it’s often important to be flexible in your detection options. 

– Janis Reed, Technical Services Manager, PCO, Control Solutions, Inc.


Pests are going to interact with, and likely penetrate, even the most structurally sound buildings through frequently used doors, inbound ingredients, utility penetrations and so on. The key is to have detection systems in place to forewarn pest professionals when pests infiltrate the facility.

If occasional invaders do enter a structure, facilities should use insect light traps and interior rodent traps equipped with glue boards. Occasional invaders are frequently captured in interior rodent traps with glue boards. Proactive inspections should be conducted away from trap lines during routine pest services to actively seek and find hidden areas where occasional invaders may gain entrance. Inspections should focus on hard-to-reach areas such as interstitial spaces, utility rooms, and maintenance shops with special attention paid to door screens and seals, wall seals, and utility penetrations.

Annual pest management awareness training for food personnel can facilitate dialogue between the facility and the service specialists. Personnel can be instructed on how to report and log pest findings to help point service specialists in the right direction. A well-designed pest management program with emphasis on assessments, proactive inspections, and engaged clients will reduce occasional invader issues.

– Dan Collins, Regional Technical Director, McCloud Services

How does the concept of economic thresholds apply to occasional invaders?

“Inherent in Integrated Pest Management (IPM) are concepts of economic thresholds: the cost of pest control does not equal or exceed the cost of product damage. An IPM program includes action thresholds to prevent over-reactions and under-reactions to pest issues in order to not exceed economic thresholds.”

The concept of “action thresholds” can be confusing, and there is no single, simple number that can be assigned. Pests associated with food processing represent risks rather than clear-cut population levels that relate to a yield or quality loss. So, action thresholds for pests will usually be arbitrary numbers. It is logical that different pests and their respective threats in different zones of a facility could lead to a very complex matrix of action thresholds if the concept were to be developed fully. Then there is the question of “threshold for what action?” It might be a trigger for a technician to inspect carefully in an area, deploy more devices, or apply some control measure without further approval in certain areas. Invariably, however, pest levels are communicated and options discussed, or thresholds trigger communications to higher levels of management. Communication is really the key.

For occasional invaders, however, economic thresholds, per se, have not been established; it’s a risk assessment. The most important threats in food processing will be risks to food safety and quality. Normally they are predictable, or can be expected to be threats, and there are monitoring and preventive tools available. No doubt there are some serious seasonal invaders (which will differ by geographic location) that are being categorized as “occasional,” but are really serious enough and predictable enough to be prevented. Monitoring records should have these pests identified and timed fairly precisely. True “occasional invaders” will be those random creatures that occasionally or accidentally get inside. Most are harmless and pose little or no risk. But, something like occasional birds indoors call for advance planning: Take immediate steps to protect food safety, cover certain materials or isolate certain sensitive areas, offer the bird a way to get out, encourage the bird to move toward an exit, try to trap the bird, analyze the event for what went wrong that allowed the bird to enter, and correct the situation.

– Jerry Heath, Entomologist, Industrial Fumigant Company

The author is Editor of QA magazine. She can be reached at