Occasional Invaders: Prediction, Prevention, and Brand Protection

Published in Quality Assurance Magazine

Occasional Invaders: Prediction, Prevention, and Brand Protection

Stink bugs. Ground beetles. Earwigs. Thrips. Centipedes. Sowbugs. Crickets.

You generally see any of these invaders only occasionally, and when you do there is usually only one or two. But if even a single insect shows up in the food a consumer purchases or stuck in packaging a customer receives—or an inspector sees, it can put your product and brand at risk. Occasional invaders are insects or arthropods that are typically found outdoors but will occasionally make their way indoors seeking shelter from adverse conditions, or accidentally enter in search of food. These invaders are different than pests such as cockroaches, rodents, and stored product pests that will live and breed in your facility, because occasional invaders prefer to be outdoors, rarely survive well or breed indoors, and are fairly difficult to predict or prevent.

“These are pests that we don’t expect on a regular seasonal or monthly basis. They appear; then they don’t appear,” said Orkin Technical Services Director Ron Harrison. “They may be harder to predict, but they are still pests that cannot be allowed.”

“These pests are of concern even though they are not food infesting,” said McCloud Services Technical Director Pat Hottel. “You don’t want to have a problem with contamination from any type of insect.”

Not allowing these pests means taking measures to understand and correct the things that attract them and allow them to enter, enabling prediction, prevention—and brand protection.


The most common reason that occasional invaders enter structures is unfavorable outside conditions, Hottel said. A significant or sudden change in weather or extreme wet or dry period can cause these pests to seek better living conditions—and that may be inside your facility.  Additionally, if the environment around your plant has enabled the build-up of populations of any of these pests, you could end up with a heavy migration of the bugs or beetles into your plant as well.


So what attracts these pests to the proximity of your facility—and what can you do about it?

Light: Some occasional invaders are attracted to light. Thus lighting, particularly white lights, that are placed on the building near windows or doors can attract the pests toward entry points.

Prevention: Use yellow sodium-vapor lighting rather than white mercury-vapor lights, as the insects are more attracted to the bright white lights. When possible, place lighting on a pole away from the building and directed toward the area of the facility you wish to have lit.

Ground Cover: Because of its high moisture retention and organic properties, mulch that is placed directly around the perimeter of the facility can be a big problem, as it is very attractive to a number of insect pests, including sowbugs, pillbugs, centipedes, and millipedes. In addition, leaf litter in gutters or on the ground, accumulated brush, and wood piles can all be highly attractive to earwigs and other moisture-loving pests that thrive in these areas.

Prevention: Retain a two- to three-foot ground-cover-free zone around the building. Keep gutters clean and clear. Regularly clear leaf piles and other brush.

Moisture: Many occasional invaders have high moisture needs, so are attracted to moist or damp areas and standing water.

Prevention: If a vegetation barrier with or without gravel is used close to the building, be sure it is made of fabric or material that allows for drainage. “If you use black plastic, insects can live under it, and it is difficult to do any chemical control,” Hottel said. Also ensure that the ground is sloped away from the building to prevent pooling water and ensure drainage away from, rather than toward, the facility.

Plants: Certain plants and trees can attract certain insects. For example, as their names indicate, boxelder bugs are attracted to boxelder trees, and elm leaf beetles to elm trees. In addition, thrips are attracted to flowering plants and aphids—which attract numerous secondary insects themselves—are attracted to a wide variety of plants.

Prevention: Prior to investing in landscaping, a discussion should be had as to the plants being considered, proximity to the building, and potential related insect pests. In addition, if a particular pest is or has historically been an issue, an investigation should be made into its feeding preferences and any related plant life be considered for removal.

Dumpsters: Dumpsters are breeding and feeding grounds for a vast array of pests.

Prevention: Place dumpsters well away from the facility, particularly in relation to doors. Keep the area clean and lids closed.

Entry Points: Once attracted to the building, occasional invaders will enter through doors and windows as well as cracks and gaps in the foundation or façade.

Prevention: Keep doors closed—install automatic closures where possible; never allow employees to prop open doors; use air curtains or plastic strips in delivery areas; and maintain positive air flow to keep the pests out. Also, seal any gaps around doors, windows, and vents; and caulk or otherwise seal other cracks or gaps in the structure. Contrasting colors on a structure can also provide insects with the visual cue of a potential entry point, Hottel said. Thus, inspection and sealing should include a focus on any doors or windows with dark framing or junctures of contrasting color.

Cultural Conditions: Employees can introduce a number of attractants, including outdoor eating areas that are not kept clean; home-grown garden vegetables brought in to share (which can introduce as well as attract insects when left out in the lunch or break room); doors left ajar for smoking; etc.

Prevention: Train employees on the risks related to pests and the means of prevention, as related to these pest attractants and entry. Ensure that outdoor eating areas are well-maintained, regularly cleaned, and set away from doors when possible.

Brand Protection

If, despite your predictive and preventive attempts, occasional invaders do show up around or in your plant, there are control methods that can help to keep them from venturing further into your plant or product. The first consideration should always be an integrated pest management approach, Harrison said. “Can you use biological, physical, or mechanical measures?” Only after consideration of each of these should chemical means be employed, he said. Beyond that, Harrison said, the “best” means of control will vary from plant to plant based on various decision factors. “Should a pesticide approach be taken for control, or is the risk of pesticides bigger than the risk of the pest? That’s a big dilemma,” Harrison said.

It is a question to be considered not only for indoor control, but for the exterior as well. And determining the answer can be a matter of reviewing historical data to determine if it is a one-time thing, or if it has been a recurring (even if irregular) issue in the past. For example, crickets tend to be an issue in parts of Texas, so early baiting may be recommended.

A discussion needs to be held between plant management and the pest management professional focused on the company’s values and culture and the best preventive or control options to fit that. This is particularly important at organic facilities where chemicals are to be used as a last resort, and only approved products may be used.

To that point, Harrison said, the decision often depends on the threshold level of the plant, its processes, and product. An insect or two in animal feed may not be a major issue, but that same insect in baby food can be serious. “Baby food is zero tolerance, so what do we need to do to achieve that? The pest control professional needs to sit down with the customer and figure out these things,” he said.

Non-chemical control can be attained in structures through measures such as moisture and humidity reduction as well as physical removal with equipment such as vacuums and insect light traps, Hottel said.

When deemed appropriate, residual pesticides can be applied to the exterior. “Since occasional invaders are typically coming in from outside, focus chemical treatment on the outside,” she said.

Mechanical measures may also be necessary even if chemical control is desired. “If you have poor conditions such as mulch or black plastic, it may require rolling these back as part of the chemical treatment,” Hottel added. And whether or not chemical measures are used, plant personnel should expect to be a part of the solution, implementing structural and cultural controls and preventive measures to help keep even the occasional pest from invading.