During the first weeks of December, the Extension office usually receives calls from local homeowners concerned with insects massing in and around their homes. Most of the sightings have been in the basement area inside homes or around driveways and patios outside. From the samples local homeowners have shown me, these mass infestations are millipedes.
Millipedes are not insects, but actually more closely related to lobsters and shrimp, according to UGA entomologist Dr. Beverly Sparks. They are also known as rain worms or 1,000-legged worms. Most millipedes are brown to black in color, and can range from less than one inch to more than 2 inches in length. They typically feed on decaying vegetation and are often found in damp areas.
Millipedes are known for mass migrations, usually in the spring during heavy rains. However, wet weather during early winter, combined with the predicted mild winter temperatures, millipedes may try to make their way indoors.
Luckily, millipedes cause little harm to humans. They are not poisonous, but some species do emit fluids that may cause allergic reactions in certain people. They do not carry diseases and are not known to damage any food inside the home. However, millipedes will often produce a foul odor or leave a stain when disturbed.
Large numbers of millipedes massing inside your home is an indicator of a large population living normally outside your home, according to Clemson University entomologist Eric Benson. Removing some of their preferred shelter, such as rocks, mulch, leaf litter, and thick grass, can help control large buildups of millipedes.
Millipedes enter homes through small exterior openings and cracks. Caulking cracks and crevices can help prevent entry points. Proper fitting of windows and doors should also be checked.
If millipedes have already entered your home, it is best to sweep or vacuum them up. Indoor pesticide use against millipedes is often not warranted. If needed, dust insecticides, like those used for roaches, can help control millipedes more quickly. Dusts may not work well in areas that are consistently moist, such as basements.
If millipedes are a persistent issue, you can use insecticides labeled for outdoor use around your home and driveway. Sprinkle granules around affected areas in a 24-inch wide band, especially around your home’s foundation. There should be no need to treat the entire yard. Remember, millipedes are beneficial in consuming decaying plant tissue, so we want to keep them around, just not in our homes.