Categories: Common Pests, Country Services, Residential and Urban Services, Wasps and Hornets, Mice and Rats, Lady Bugs, Pine Seed Bugs, Flies, Boxelder Bugs

Fall is just around the corner and change is in the air. The leaves are beginning to turn vibrant shades of yellow, orange, and red, the weather is cooling, and overwintering pests are looking for a new place to call home. That could be your home or business. 

the exterior of a home in the fall with trees with bright orange leaves


What are Overwintering Pests?

Overwintering pests are bugs, insects and rodents that seek warm places to hibernate and safely wait out winter in, so that they can emerge again in the spring. They are quite common and problematic for people living in the country, rural areas, or in new developments built near forested areas or top of areas that were previously forested or used as farmland.

Most overwintering pests invade and hibernate indoors in huge masses and then come spring or an unseasonably warm winter day, they catch a homeowner or business owner by surprise by waking up and crawling out of their hiding space (likely wall voids and attics) and congregate around windows, doors and lights. We get a lot calls in the winter and spring from concerned people who have suddenly discovered that their home or business has been infested with tons of pests, and they have no idea where they came from, and why there are so many.

Because overwintering pests are experts at finding refuge indoors from late fall to early spring, and invade in large numbers, they can quickly become a serious problem. This is why it’s really important to prevent them from getting inside your home or business in the first place, and to address them at first sign, to prevent them from becoming a bigger, more challenging issue to solve.

Most of these pests are common nuisance which means that by simply being present in a home or business, they are annoying and bothersome. Some overwintering pests are more of a concern as they sting, bite, or have the potential to cause sickness in people or damage to personal property or the structure they have infested.


What Pests Overwinter?

There are 6 main common overwintering pests - cluster flies, wasps and hornetsboxelder bugspine seed bugs, Asian lady beetles and mice.  Let’s go into more detail about each type of pest:

a single cluster fly on a white backgroundCluster flies are typically the first to overwinter. Cluster flies are large, noisy, sluggish flies, that appear dazed and confused as they fly about a home or business, bumping into things. They are a common nuisance pest. They like to congregate around your windows and light fixtures when lit up. How did they get inside your home or building? Well, from late summer to early onset of fall, cluster flies bask in the warm sunshine on walls of homes and businesses in rural and country living areas. When evening approaches with cooler temperatures, cluster flies enter these structures through holes, cracks, and crevices in and around doors, windows, foundations, siding, fascia, etc. As daily temperatures continue to fluctuate through fall, cluster flies may come out when it is warm and duck back in when it’s cold. They continue this until the cooler weather is here to stay. This is when they will remain safe and warm indoors hibernating until spring. Once inside a home or business, cluster flies seek out secluded areas like attics and wall voids. Learn more on how to get rid of cluster flies.


a single wasp on a white backgroundWasps & hornets overwinter around the time as cluster flies. In late summer to early fall, the queen lay eggs that will develop into adult males and fertile females. Upon mating, newly fertilized female wasps & hornets leave their colonies in pursuit of a new warm and secure place to overwinter. They enter homes and buildings similar to cluster flies and seek out dark, quiet, low traffic areas to hibernate in. The wasps & hornets left behind in the colonies will to die over the winter season, which means that these newly fertilized females will become not only the new queens in the upcoming spring, but that they are responsible for building brand new colonies. Because wasps and hornets sting and in some people can cause mild to serious allergic reactions, they are a more serious concern compared to other overwintering pests. Learn more about the most common wasp and hornet species here in Ontario, prevention tips, and advice on How to get rid of wasps and how to get rid of hornets, in our online Pest Library.


a single boxelder bug on a white background

Boxelder bugs are a common and well-known insect here in Ontario. Boxelder bugs, identifiable by their long, flattened bodies with black & red/reddish orange colouring, live, feed, and reproduce on trees like boxelders, maples, & ashes, shrubs, and other plants in the summer. They become nuisance pests in the fall when they leave plants in pursuit of a new home or winter. Boxelder bugs, like cluster flies and pine seed bugs, are attracted to the exposed south sides of homes and buildings which are perfect for taking in the warmth of the late summer and early fall sun. After sunset, when cool temperatures settle in, boxelder bugs will crawl into a building’s wall voids and attics through gaps and cracks in and around windows and doors, siding, eaves, or the foundation. They remain inactive during the cold, awaiting spring. Learn more about how to get rid of boxelder bugs by visiting our pest library.


a single western conifer seed bug on a white background

Next come the overwintering pine seed bugs or Western Conifer Seed bugs. They are also referred to as ‘stink bugs’ because they emit a stinky odour when smushed. Pine seed bugs are dull reddish brown in colour and average ¾ of an inch to 1 inch long. Their antennae are almost the full length of their body, which can give them a creep appearance. They appear pointed at both ends and some have a light white zigzag line across the centre of their back. Like boxelder bugs, and cluster flies, these pests are also attracted to the exposed south sides of houses and buildings to soak in the heat from the sun in late summer and early fall. They enter homes in a similar fashion as other overwintering pests, and remain inactive during the cold, hiding in wall voids and attics.). Pine seed bugs do not sting, bite or feed on humans or animals, nor do not carry or transmit diseases. They are a huge annoyance simply by their presence (in large numbers), and the stinky smell they emit when squished. Visit our pest library for tips and advice for how to get rid of pine seed bugs.


a single asian lady beetle on a white background

Asian Lady beetles are common throughout Ontario and are often mistaken for lady bugs. To identify an Asian lady beetle, look for exceptionally large white cheeks, which is a major distinguishing feature for this nuisance pest. They are also most often a deep orange colour, but red, yellow, and tan colouring are possible too. Homes and businesses located in country or wooded areas or near farm fields are especially prone to severe Asian lady beetle infestations. These pests begin overwintering once farm fields are harvested for the season and aphids (what they eat) disappear. With no food source and cooler weather present, they seek a new place to call home. Asian lady beetles are very well known for their annoying habit of accumulating in huge swarms on the sides of homes and buildings and wandering indoors during the fall through the same cracks, crevices, and gaps that other overwintering pests invade through. Asian lady beetles are aggressive and can spread over time to become very challenging to get rid. Learn more on how to get rid of Asian lady beetles.


a single mouse on a white background

Last, and unwanted the most, are mice.  Mice can and often are, an issue any time of year, however they tend to be more problematic in the fall when they are driven away from fields during harvesting. With insufficient shelter, food, and water outdoors, mice scurry inside nearby homes and businesses (where they are not welcome) to survive the freezing cold winter. These nocturnal, omnivorous critters have endless appetites and foraging, burrowing, chewing, and biting tendencies. They contaminate surfaces and can spread diseases (hantavirus, salmonella, listeria, etc.) through their droppings, urine, saliva, and nesting materials. Mice consistently chew to keep their teeth short. This chewing poses damage, costly repairs, and danger to both a home, and those who live in it. Mice chew through wires (which can cause electrical fires), books, wood, soft concrete, drywall, insulation, rubber, plastic pipes, aluminum, gas lines and more. And since mice breed year-round, their populations quickly grow in numbers, and quickly out of control. Our online pest library is filled with lot of great information about mice, how to prevent them, and how to get rid of mice. And make sure you check out our blog post on how to get rid of mice fast, where we talk about how long it really takes to solve rodent issues, and also why mouse traps prolong rodent issues.


How to Deal with Overwintering Pests

When it comes to dealing with overwintering pests, there are 2 things main things you can do:

1. Pest Proof! Pest proofing is an ongoing effort and there are things you do each season to help keep pests where they belong – outside. If you are successful in preventing overwintering pests from getting into your home or business, you will be more likely to avoid pest control issues or be able to minimize future issues. Here are our Top 10 Fall Pest Proofing Tips to help you with pest proofing.

2. Get an Annual Fall Pest Control Treatment from a Licensed Pest Control Professional. A good fall treatment means getting the exterior of your home, building or structure sprayed with a high quality professional product (heavily focused on the doors, windows, eves and soffits) by a licensed pest control professional with years of knowledge and experience in dealing with fall pests. Fall is the ideal season to prevent and get ahead of overwintering pests. This is the time of year when these nuisance pests are actively trying to find a new home to make it through the winter. If these pests are successful at overwintering in a home or business, they will emerge in the spring, and will be mistaken for a ‘spring-time’ pest control issue, which they are not.


What About Doing a DIY Pest Control Treatment Yourself in the Fall? 

You can, but they just don’t work and are ineffective.

DIY pest control and ‘over the counter’ pest control products you buy at the local store don’t have the same strong, enduring residuals that professional pest control products have, which are crucial in treating and prevent overwintering pests. A strong residual means that the product that is applied will not quickly fade or wash away quickly in the sun or rain. This means that after the treatment has been applied, the product continues to work on pests that encounter it for long time after. As overwintering pests will come in and out of homes and businesses during the fall depending on the temperatures, this residual has the lasting wear to allow a large number of these nuisance pests to come in contact with it.


Can Overwintering Pest Issues be 100% Eliminated?

Depending on where you live, eliminating an overwintering pest issue 100% may not be possible, even with the most dedicated pest proofing habits, and professional help. In these cases, managing overwintering pests and minimizing their impact is the best course of action to get relief, and one that requires ongoing pest proofing and professional help. Over time and consistent efforts, the volume and impact of overwintering pests will be reduced.

For the best protection and results, consider combining an annual fall pest control program with a spring pest control program, and keep up with ongoing pest proofing. This combination works together to prevent overwintering pests from getting indoors now in the fall, when they need the shelter the most, and it addresses overwintering pests that did make it inside in the fall, which will become a nuisance when they wake up in the spring (or in a very mild winter). Pest proofing year-round helps you keep all types of pests out of your home (or helps minimize them) in the first place.


Need Help with Overwintering Pests?

We hope you find success with pest proofing this fall, and be sure to visit our blog for lots of helpful information, tips and advice on different pest challenges, pest prevention, and pest proofing.

And if you need any professional pest control help, we hope you’ll contact us. Environmental Pest Control was founded 30+ years ago on understanding overwinter pests like boxelder bugspine seed bugsAsian lady beetlescluster fliesmice and wasps and hornets, and how to expertly manage, control and eliminate them.  We offer safe solutions and guarantee results.

We wish you a happy, pest-free fall!


Call 1 (800) 263-5055

Our Professional Team is Happy to Help!