MILLIPEDES BY THE MILLIONS! #640948 - Ask Extension



Asked May 26, 2020, 1:20 AM EDT

Dear MSU Expert: My Mom has a newer home in Manistee County near Lake Michigan Last fall I noted millipedes TNT in garage. They have been noted in basement as well as in a main level bathroom but in far fewer numbers. Garage is not attached to house and has block foundation. Main house has poured foundation. Soil around house and garage is mostly sand. A water pipe broke in garage over the winter (plumbing was winterized). The millipedes even got into the plumbing. Local plumber who has lived in area his whole life said he has never seen millipede infestation like this. Please offer suggestions for treatment including frequency. So far, I have done the following: 1. GARAGE: Removed cedar mulch and dirt that was covering vinyl siding in places; replaced with pea gravel. Treated perimeter in one foot band with pyrethroid granules. Cleaned inside of garage (buckets of millipedes), getting as many things off the floor as possible. No chemical treatments done inside garage. The little buggers continue to migrate into garage. 2. HOUSE: There is cedar mulch in planted areas, well below lower edge of vinyl siding and sill plate, Gutters are cleaned and run into underground drainage pipes away from house. Same insecticide granules as used around garage were sprinkled around house including window wells. There are many decks around the house so am limited in treating soil next to foundation. Basement is dry with dehumidifier running in warm months. THANK YOU!!!

Manistee County Michigan

Expert Response

It sounds like you have already done many of the things that I would have recommended. Humidity and moisture are your biggest enemy in the fight against millipedes. I suspect that there may be some areas in the garage that are inaccessible to you and where there may be moisture and/or a food source for the millipedes. If you continue to see them in high numbers you might have to investigate further. Diatomaceous earth is a material that can be used indoors and might be useful in the garage to reduce their numbers. You could apply it to those out of the way areas where you see millipedes. As with any pesticide, follow the label directions to protect yourself and others, and to ensure the product's efficacy. Here is an MSU Extension article with some more information:
Nathaniel Walton Replied May 27, 2020, 4:06 PM EDT
Thank you for quick response as well as the useful information especially the suggestion to use diatomaceous earth.  The linked article is specific for a few pesticide options-all very helpful. 

The Question Asker Replied May 27, 2020, 9:49 PM EDT
You are welcome.
Rebecca Finneran Replied May 28, 2020, 7:31 AM EDT

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