What you need to know about fall household pests

Farm Forum

BROOKINGS — This fall many South Dakota homes are playing host to uninvited, visiting insects.

“During the fall, insects that spend the winter as adults begin looking for shelter. These are the critters most commonly finding their way inside our homes,” said Amanda Bachmann, SDSU Extension Pesticide Education & Urban Entomology Field Specialist.

Bachmann noted that the best way to prevent insects from entering the home is to determine their point of entry and close it.

Check around windows and doors and inspect any cracks or crevices in walls and foundations. “In most cases, an insecticide is not necessary and the insects can be managed with a vacuum or a broom,” she explained.

Below Bachmann discusses some of the most common household pests and the best ways to discourage them from entering you home.


Cluster flies will survive the winter indoors and are often noticed on mild winter days. They do not reproduce indoors.

Picture winged flies however, don’t survive the winter.

House flies are also active. They reproduce on decaying organic matter, so it is possible to have a breeding population inside that is active all winter.

The best way to reduce indoor populations of house flies is by taking out trash regularly and keeping other areas of the home free of food wastes.

Boxelder bugs

Adult boxelder bugs spend the winter indoors. These bugs are harmless and should just be swept up or vacuumed.

Western conifer seed bug

Western conifer seed bugs overwinter as adults in sheltered locations but they do not congregate in large numbers like some of the other insects mentioned.

These bugs are distinguished by the leaf like appearance of their hind legs. Western conifer seed bugs do not feed or reproduce indoors, and they are not considered to be a major pest in the landscape.

Minute pirate bug

Although these are not insects that move indoors the minute pirate bugs are making a nuisance of themselves outdoors this fall.

These tiny insects are usually found in crop fields where they feed on aphids and mites. As they move off crops and search for other food sources they may bite people.

A hard freeze will kill them, and no other control is recommended.

Multicolored Asian lady beetle

This is one of our introduced lady beetle (aka ladybug) species and it will congregate in structures as the weather cools.

They can be more aggressive than our native lady beetle species and may bite if handled. These ladybugs can be distinguished by the black ‘M’ or ‘W’ on their thorax (white segment right behind the head).


Mosquitoes will remain active until the first frost.

It is important to continue to wear protective clothing and personal repellents when engaged in outdoor activities, as it is still possible to get West Nile Virus in the fall.

For the weekly mosquito activity reports, visit South Dakota Mosquito Information Systems at http://mosquito.sdstate.edu/.

Other arthropods

Spiders and millipedes are two of the most common non-insect fall invaders. Wolf spiders will find their way inside, and their large size generates concern.

These spiders are looking for prey or shelter and would be happier outdoors.

Millipedes normally live in dark, damp locations like in mulch or leaf piles where they feed on decaying organic material.

Since they need moisture to survive, they often die quickly when trapped inside.

Need help with identification?

If you have an insect indoors and would like help identifying it, please submit a clear picture to the Plant Diagnostic Clinic at http://www.sdstate.edu/agronomy-horticulture-plant-science or contact Amanda Bachmann, amanda.bachmann@sdstate.edu or 605.773.8120.