Paul Curtis: Pest Proofing Your Facility for Winter

Curtis Headshot

As a resident of a hot, humid southern state, I always welcome the cooler temperatures of the changing season. However, falling leaves and falling temperatures can also serve as a trigger for unwelcome pests to seek out a warm place to over-winter.

Many pests have adapted successfully to living in close proximity to humans. They often nest and live in buildings, and can squeeze through very small spaces. Some of these pests, such as mice and rats, are familiar to our structures year-round and some are considered occasional invaders.

The term “occasional invader” is used to describe a wide range of seasonal pests that do not typically prefer to infest structures. Whether they’re stink bugs, paper wasps, lady beetles or earwigs, occasional invaders typically live and reproduce outdoors. They invade structures when conditions indoors are better for them than outdoor conditions.

The most common problem with occasional invaders is that they become a nuisance. Some can bite, pinch, secrete foul odors, damage plants, stain indoor furnishings, and damage products. Even after they are dead, they may continue to cause problems. The bodies of insects can attract other pests that feed on them. The carcasses, shed skins, and secretions of insects can cause allergic responses and even trigger asthma.

Compared to other types of wildlife, mice and rats pose a particular challenge due to their small size, their year-round prolific breeding capacity, and their ability to thrive in an indoor environment. While a lady beetle may not cause concern for some, there is typically a very low threshold of tolerance for rodents.

The presence of mice and rats in our structures often causes significant concern and fear among residents, employees and customers. Mice and rats can do considerable damage by gnawing their way through wood, drywall, and other materials to get into places of harborage and food. They cause food safety concerns, and can damage electronics and wiring. They may also carry diseases or parasites.

Altering environmental conditions can exclude pests, or make structures inhospitable for pests – an important component of integrated pest management.

Be proactive – the best way to keep unwanted pests from moving into your facility this winter is to make sure your building is pest-tight before they get inside.

Now is the time to get started, if you have not already secured your structure. Depending on temperature and moisture levels, over-wintering pests can begin looking for warm, protected harborage sites by mid-October, and sealing the exterior of the structure after the insects have already gotten into the ceiling and/or wall voids can actually be counter-productive.

This is because some insects might be unable to exit the following spring, and will be more likely to end up making their way into the interior of the structure where they are more visible to occupants.

Every structure is unique. Some take very little effort to exclude pests, and can be done as a ‘do-it-yourself project’ with a tube of silicone caulking and a can of sealant. Other structures are more complex and challenging. Complex structures may require the exclusion work to be performed by professionals.

Begin by performing a thorough inspection of the building’s exterior. Look for cracks in the foundation or walls of the building, older windows, broken screens and wall penetrations that are not properly sealed. Take the time to seal these access points before the cooler weather settles in and you will help keep unwanted pests out of the structure.

Check all exterior doors and use weather stripping, spring steel strips, door sweeps and thresholds, and appropriate sealants and caulking to keep insects and rodents from being able to get under or around the door. Make sure exterior man and dock door are kept closed when not in use.

Check around plumbing and utility entry points and around dryer duct exits, air conditioners, and similar sites and seal these if necessary. Copper wool or steel wool is often useful for sealing such places, but various other types of sealants may also work, depending on the situation. Be sure to take appropriate precautions when working around electrical wiring.

Check for cracks and crevices around eaves, corners, places where siding overlaps, and other such sites. Keep in mind that lady beetles can enter cracks larger than 1/16 inch. Pay particular attention to cracks, crevices or holes in areas where insects can enter. Roof -mounted HVAC systems can also provide insulation for harborage, warmth, water, and a ready access point into the structure. Be sure to ask your HVAC service professional to inspect your roof-mounted HVAC for pest activity on their next visit.

Look at your outdoor landscaping from the eyes of a pest. Does it offer shelter from the elements? Or provide a highway onto your roof or near your home? Maintain a “sanitation line” around the exterior of the building.

  • Garbage containers should be closed, and cleaned regularly.
  • Don’t allow water sources around the structure to attract pests and rodents. Leaky pipes, stopped up gutters, a leaky roof and other water around the building can serve as an attractant for pests and rodents. Any standing water should be eliminated immediately.
  • If pests are living around your building, they will naturally seek shelter inside when the weather turns cold and food becomes scarce. Grass should be cut short. Trim tree limbs that extend near or over the building. Cut back shrubs that touch the exterior of the building and remove ground cover near the facility.
  • Outdoor lighting can also be attractive to many pests. Sodium Vapor lights are less attractive to most pests. Lighting positioned directly over doors, windows and ventilation points can attract pests right to entry points. If possible, lighting should be positioned away from entry points.

Use your resources. Have your pest management company assist you with a professional assessment of exclusionary measures you can take to protect your structure. They are experts on insect and rodent exclusion, and can help identify the exclusionary steps that will have the most impact.

Paul Curtis is a board certified entomologist and manager of technical services for Terminix International, Curtis can be reached via e-mail at or (855) 466-2578.