Where do insects go in the winter?

Photo by Jan Hygnstrom, UNL Department of Agronomy & Horticulture
Photo by Jan Hygnstrom, UNL Department of Agronomy & Horticulture

With winter on its way and a few freezes behind us, it leaves us thankful that the mosquitos and other insects have finally quit bugging us for the winter months. But, where do insects go in the winter? Do they all just die? How do they always come right back to my yard, garden, and home next spring? Some insects head south for the winter, others overwinter in the garden, some spend the winter in cracks and crevices outside, and others come indoors to join us in a heated home for the winter.

Many of our ‘snowbirds’ or insects that move south for the winter are the lepidopterans, the insect order that contains butterflies, skippers, and moths. Some of the snowbirds include armyworm, corn earworm (also known as tomato fruitworm) and striped and spotted cucumber beetles. Since these insects do not overwinter in the garden, sanitation is not considered a control method for them.

Many insects overwinter in the garden so cleaning up and destroying plant debris can reduce their numbers. Reducing the population of insect pests limits the amount of damage they cause and provides more control options. Insects that overwinter on plant debris in the garden include cabbageworm, cabbage loopers, and squash bugs. The cabbage caterpillars overwinter as pupae inside cocoons attached to plant debris, usually the host plant. Squash bugs spend the winter as adults hiding in plant debris. This is why it is a best management practice to clean up the garden in the fall and not leave the plants in the garden to harbor insects over the winter months. Some insects will even spend the winter on weeds near the garden. Fall sanitation not only includes cleaning up or tilling under vegetable debris in the garden, but control of nearby weeds as well.

Squash bug-NH-pic monkey

Some of the insects that overwinter in the garden do so in the soil. These insects would include the adults of Colorado potato beetles, the eggs of grasshoppers, and the pupae of squash vine borers and onion maggots. Fall tillage of soil reduces these insects by exposing the insects to colder temperatures. Removing plant debris removes an insulating layer that also protects insects from extreme temperatures.

squash vine borer damage

When cleaning up plant debris, the general recommendation is to not add insect infested plants, diseased plant debris, or weed seeds to home compost piles. Most plant diseases and weed seeds, as well as some insects, are destroyed during composting when temperatures in the pile center reach 140° to 150°F. However, in many home compost piles, it is difficult to mix materials thoroughly enough to bring all waste to the center where it will be exposed to these temperatures.

It is often asked if insecticides applied to bare soil in fall will kill overwintering insects. The answer is not very often, if at all. Overwintering insects are often in the pupal or egg stage where they are protected from insecticides. Applying insecticides to the soil to try and control overwintering insects is not a responsible or effective use of a pesticide.

Many other insects come into our homes during the winter months to avoid freezing temperatures outside. Boxelder bugs, multicolored Asian ladybeetles, and stink bugs move inside in the fall and then leave in the spring. These insects survive the winter in our homes and other buildings. These insects can find places to survive outdoors under leaf litter and in other plant debris, but they are much more comfortable in our homes, as we are. They do not do any damage in our homes and should be vacuumed up or smashed when they are found in our homes.

Center photo by S. Cochran, Lancaster County Extension
Center photo by S. Cochran, Lancaster County Extension

This article comes from an article written by Kelly Feehan, Extension Educator in Platte County, Nebraska.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s