What Happens to Indoor Insects in Winter?

By Chris Williams on February 5, 2016.

I know that here in the Northeast, outdoor insects disappear in winter. I guess they either die from the cold or go into hiding. What happens to indoor insects like cockroaches in the winter? I’m hoping some of them will die too!

E. G., Natick, MA

Cockroaches and Other Indoor Pests Just Carry On

We have a number of indoor pests that are totally adapted to living in our homes, they generally never have to venture outside. Some examples are: German cockroaches, bed bugs, silverfish, centipedes, fleas, clothes moths, spiders, drain flies, and various food pests (see Why Do I Have Spiders Indoors in Winter?). These pests have no concern about what is happening outside. If you have a cockroach problem in your home, you will probably notice very little difference when the weather gets cold (see Why Cockroaches Are Year-Round Pests).

Over the winter, some indoor insects’ numbers may decrease somewhat as reproduction rates drop in slightly cooler indoor air, but then the warm weather of summer comes along and reproduction rates increase again along with the temperature. Those pests such as spiders and centipedes that feed on other insects might notice a decrease in their winter food supply as fewer flies, moths, etc. find their way indoors.

Some Indoor Pests Don’t Even Show Up Until Winter

Surprisingly, there are a few pests whose numbers can actually increase indoors in the winter. Mice are a good example. During warm weather, mice are pretty content to live outside. But in the fall when temperatures start to drop, mice start looking for warmer places to spend the winter and many of them end up finding their way into buildings. People who haven’t seen evidence of mice in their homes may notice their presence for the first time in fall or early winter.

Another group of insects that show up only in fall and winter are those that are temporarily hiding in your house to escape the cold (See Why Do I Have More Indoor Pests in Winter?). These are mostly plant-feeding outdoor pests that find ways to get into your house, often around the roofline. Examples of fall-invading insects are: Asian lady beetles, stink bugs, Western conifer seed bugs, cluster flies, boxelder bugs, and elm leaf beetles. Most of these end up in the attic or in wall voids or hidden behind draperies or baseboards. They remain inactive until spring or until unusually warm winter weather wakes them up.

For information on what happens to those pests not lucky enough to have an indoor lifestyle, see these Colonial blogs:

Photo Credit : “Cockroach (Blattodea) Laying an Egg”  Licensed under CC BY 2.0 via Wikimedia Commons.

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