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Keep Fall Pests in Your Sights

Pests may try to get into your food processing facility looking for places to survive the winter. They usually go into hiding where no one can see them, which means they often go unnoticed and forgotten until emerging, looking to get back outside when spring rolls around.

This article originally appeared in Food Manufacturing's October 2014 print edition.

You’ve probably heard of the saying, “Out of sight, out of mind.” It’s true: once we turn our attention away from looking for something, we tend to forget it entirely.

This phrase can create trouble when it comes to pest management, especially in the fall and winter months. When pest activity appears to slow this time of year, it can be easy to grow a little more lax with a pest management program. 

That’s just what some pests hope for. And that’s why lady bug beetles, cluster flies, stink bugs and other fall seasonal invaders pose such a threat to food processing facilities.

These pests may try to get into your food processing facility looking for places to survive the winter. They usually go into hiding where no one can see them, which means they often go unnoticed and forgotten until emerging, looking to get back outside when spring rolls around. 

By the time occasional invaders are recognized as a problem, the pest population can be fairly large and it may be too late for simple control measures. 

Here’s a snapshot of some of the seasonal invaders you need to look out for:

Lady bug beetles

The Asian lady beetle was brought to the United States in 1988 to help reduce native aphid populations that can ruin crops and other types of vegetation. Unfortunately, these lady beetles became a major issue themselves in many areas of the country.

Today, Asian lady beetles are common throughout most of the United States and parts of Canada – they’re commonly known as ladybugs. They occur in a wide spectrum of colors ranging from yellow to orange to red and have a varying number of spots.

In the fall, Asian lady beetles gather in large numbers on the outside of light-colored buildings. As they gather on walls, some find cracks or holes they can use to get inside. They hibernate through the winter and become active again in spring. 

Stink bugs and box elder bugs

Stink bugs, box elder bugs and other fall pests have the ability to detect various environmental conditions, which is why they can often be found on the south- and west-facing walls of a structure where the sun hits. These insects congregate here to seek warmth from the sun, so consider taking extra precautions against their activity on the south- and west-facing walls before they crawl inside.

While stink bugs and box elder bugs don’t pose any serious health risks, they can make a big mess. Stink bugs are named for the smelly odor they produce when they’re threatened, and box elder bugs’ droppings, which are reddish-orange in color, are unsightly and can leave stains on equipment. 

Cluster flies

Cluster flies, also known as attic flies, are pests that can work their way inside of food processing facilities. They are slightly larger and darker than the common housefly and move more sluggishly. Much like box elder bugs and stink bugs, these flies also appear on the sunny side of buildings in heaviest concentrations in the late fall and early winter, as they seek warmth.

Cluster flies are often seen buzzing and congregating at windows, which may not provide enough of a barrier even when closed. Cluster flies are capable of crawling through small openings in screens, doors and walls to find a secluded place to hide out for the winter. 

On sunny winter days, the wall voids where cluster flies are hiding inside a facility can become warm, causing them to think it is spring. If this happens, they may come out of hiding prematurely and move toward the light coming in through windows. They will cluster around the inside of the windows trying to get back outside and can leave stains on walls if crushed.

Keep your facility on guard

While all of these pests are different, they do share some similarities when it comes to managing them. It’s important to plan ahead and implement exclusion efforts before temperatures drop and drive these pests indoors.

 To help keep these pests out, inspect the outside of your facility regularly and carefully. Seal any cracks around windows and doors with metal mesh and caulk. Check the weather stripping on all exterior doors and repair any damaged window screens. 

Fall is also a good time to revisit your sanitation program, which can help reduce breeding conditions and keep flies and other pests away. Clean up spilled ingredients or finished products quickly. Request that employees clean food and liquid spills immediately in and around interior and exterior break areas. Also, now is the time to request replacement dumpsters or to clean these units to remove fly-attracting residues. 

These tactics are part of a broader Integrated Pest Management (IPM) program. If your facility doesn’t have an IPM plan in place, talk with your pest management provider about setting one up to protect your entire facility from pests all year long.

Ron Harrison, Entomologist, Ph.D., is Director of Technical Services for Orkin and an acknowledged leader in the field of pest management.  Contact Dr. Harrison at [email protected] or visit for more information.