Thoroughly modern millipedes
By Jim Janke
Every summer one or two people bring samples of ugly little insects into the plant clinic and ask how to get them out of their home. If the insects in the picture are also in your home, you have millipedes. Here are some ways to minimize this problem.
Millipedes are attracted to dark, cool, moist environments that are rich in organic matter, such as compost piles, mulched areas, or under logs. When conditions become too hot and dry they move to find moisture. In the fall they move in search of overwintering sites. They do not bite, sting, or transmit diseases. When disturbed they curl up into a circle and remain motionless. They crawl slowly and protect themselves by secreting a compound with an unpleasant odor. Millipedes do not survive indoors for very long unless they find moist conditions.
The best way to prevent a millipede infestation is to make them uncomfortable close to your home. Organic mulch in contact with the foundation is a primary home for millipedes, so moving it 6 inches or so away from the house wall will help quite a bit. Or use inorganic mulch like stone or gravel. Keep any other organic materials away from the foundation. Check your downspouts, faucets, and air conditioner drip lines to keep water from puddling. Keep your lawn de-thatched to make it a less millipede-friendly environment.
Keeping cracks sealed, having sweeps on entry doors, and caulking door thresholds where they contact the foundation will also help. My home is fairly new, and all of these joints are supposedly tight, but the millipedes find their way in anyway.
A pesticide application around the perimeter of the foundation will help. You must apply an adequate volume to coat all surfaces of the mulch or plant material, because the pesticide needs physical contact with the millipedes to kill them. A dilute application with a hose-end sprayer is best, but even this will not be 100 percent effective. Remember to read and understand the label of any chemical you use, and follow those instructions exactly.
Applications of insecticides along baseboards and other interior living areas of the home do not stop millipede invasions. Sticky mouse traps will collect those that are moving around on smooth floors. If you have an infestation larger than you can handle with a vacuum or broom, call in a professional exterminator.
Jim Janke is a Master Gardener Volunteer in Haywood County. For more information call the Haywood County Extension Center at 828.456.3575.