Trying to get through spring and summer without running into an insect invasion is near impossible, but sometimes it is non-insects that cause the chaos.
Millipedes — which we’ve received quite a few calls on recently — are not insects; they belong to the class of Diplopoda, which simply means “two footed.” Millipedes have two pairs of legs per segment which separates them from centipedes, which have one pair per segment.
This region has numerous kinds of millipedes, but the common garden millipede is the one most of us notice with hundreds gathering on driveways and entering garages this time of year. The garden millipede is brown-black and about one-half to three-fourth inch long and one-sixteenth inch wide. Seeing the sidewalk covered in hundreds of garden millipedes may catch you off guard, but they pose no threat. While centipedes are able to bite and inject venom from their jaws into their victims, millipedes do not bite or sting. However, if they do start migrating indoors, a vacuum is your best friend. Crushed or disturbed millipedes emit an offensive odor and can stain carpets or clothes.
Millipedes serve a beneficial role in our landscapes feeding on decaying plant matter like rotting leaves and composting material like lawns’ thatch layer, although they have also been found rummaging on garden fruits that come in contact with the ground like strawberries. Since millipedes feed on decaying plant material, they make their home under wood and large rocks, beneath pine bark or straw mulch, in well-kept lawns, and other moist areas around our landscapes. They lay their eggs in the soil during the spring and summer and usually overwinter as adults. Millipedes migrate in response to food and moisture — too much rain, or even dry conditions, may send them packing. They usually do not live long when they start to wander due to dry conditions, though.
To keep millipedes out of your house, seal off cracks and crevices, much the same way we keep out ladybugs in the fall. Millipede migrations do not last very long, usually only a couple of days or so, and garden millipedes really don’t do any damage (unless you have a problem in strawberries). Chemicals alone will only provide temporary control. For longer, lasting control, you need to implement an IPM, or integrated pest management plan.
Reduce the availability of moist resting places, starting with the lawn. Millipedes thrive in the dense layer of plant material just above the soil surface so dethatch the lawn if needed. Closely mow and edge the lawn so it dries more quickly, reducing millipede habitat. Remove debris that might provide a hiding place for millipedes such as wood piles, excessive mulch, boards or thick grass. Water grass in the early morning so it dries during the day.
Eliminating or reducing millipedes’ living quarters is the best strategy against millipedes but applying pesticides around the perimeter of the house may help with those that do try to come inside. Make sure the pesticide you use is labelled for millipedes and the area being treated, and use along with the methods mentioned above for better control.
For help on other home and garden questions, call the Master Gardener Horticulture Helpline at 1-877-ALA-GROW (1-877-252-4769) or visit us online at aces.edu.