Millions of millipedes! #485295 - Ask Extension


Millions of millipedes! #485295

Asked September 17, 2018, 9:59 AM EDT

Hello, Can you tell me how to get rid of millipedes? They stink and look disgusting. They are showing up in two areas; mainly where concrete slabs meet the house. Our north facing front stoop has it the worst, there is a 2” gap that we’ve filled with pea gravel. They come by the thousands and we vacuum them out and they fill it up again! We’ve used several insect sprays around the area. Most of them are dead by the time we see them. There is no leaf debris in the area, which I know would attract them. The first 10 years we lived in Elk River we didn’t have any millipedes, and they are worse now than in the last few years. Please help!!!

Sherburne County Minnesota

Expert Response

Although the problem you have described is rather common, it's also usually relatively brief.

You may already have read the following publications, but they do contain reliable information about how to deal with millipedes:

Bob Bystrom Replied September 17, 2018, 12:37 PM EDT
Thank you for your help. Do you know if they come up from under the house? It appears that the more we vacuum, the more keep coming.  It looks like they are coming from underground. 
The Question Asker Replied September 19, 2018, 6:15 PM EDT
Apparently their movement is motivated mostly by soil conditions. When it's very dry, they seek moist places. When it's very wet, they move to dryer places. What's causing their movement in your location is difficult to say. They might be coming from under the house if conditions there are too wet or too dry to satisfy their needs.

Here is yet another excerpt from a university publication that may or may not shed more light on the subject:

"Millipedes often leave their natural habitats at night and crawl about over sidewalks, patios, and foundations. At certain times of the year, especially during autumn, they may migrate into buildings in great numbers. Fall movement into structures appears to be accidental, occurring in the course of searching for humid overwintering sites. Migration into buildings also is common during spring and summer, in conjunction with periods of excessively wet or dry weather.

Millipedes often invade crawl spaces, damp basements and first floors of houses at ground level. Common points of entry include door thresholds (especially at the base of sliding glass doors), expansion joints, and through the voids of concrete block walls. Frequent sightings of these pests indoors usually means that there are large numbers breeding on the outside in the lawn, or beneath mulch, leaf litter or debris close to the foundation. Because of their moisture requirement, they do not survive indoors more than a few days unless there are very moist or damp conditions.


  • Minimize Moisture, Remove Debris - Problems with these pests in Kentucky often coincides with excessively wet weather; patience and drier conditions often will correct the problem. The most effective, long-term measure for reducing entry of millipedes (and many other pests) is to minimize moisture and hiding places, especially near the foundation. Leaves, grass clippings, heavy accumulations of mulch, boards, stones, boxes, and similar items laying on the ground beside the foundation should be removed, since these often attract and harbor pests. Items that cannot be removed should be elevated off the ground.

    Don't allow water to accumulate near the foundation or in the crawl space. Water should be diverted away from the foundation wall with properly functioning gutters, down spouts and splash blocks. Leaking faucets, water pipes and air conditioning units should be repaired, and lawn sprinklers should be adjusted to minimize puddling. Homes with poor drainage may need to have tiles or drains installed, or the ground sloped to so that surface water drains away from the building. Humidity in crawl spaces and basements should be reduced by providing adequate ventilation, sump pumps, polyethylene soil covers, etc.

    Since millipedes often thrive in the moist, dense thatch layer of poorly maintained turf, de-thatching the lawn and keeping the grass mowed close should make the lawn less suitable for millipedes. Over-watering or watering during the evening may also contribute to millipede problems."

Bob Bystrom Replied September 19, 2018, 9:48 PM EDT

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