Millipedes are long, slow-moving, worm like animals with many body segments. There are two pairs of legs on most body segments. They are often called thousand leggers. They should not be confused with centipedes that have one pair of legs on most body segments and are very fast runners. While centipedes have venomous jaws and eat small insects, millipedes mainly eat decaying vegetation and do not bite people or pets.
There are many different types of millipede. Black and red species several inches in length are often seen and pose no danger or threat as a pest. These large millipedes should be left alone.
The millipede that most often invades homes in large numbers is the garden millipede. Garden millipedes are gray to brown and 1/2 3/4 inch long. They mainly feed on dead plant material and occasionally, young plants. They are most active at night.
Garden millipedes usually live outdoors in moist, protected areas such as under mulch and rocks. They can also live on trees, in tree holes and even in clogged gutters. Unfortunately, these millipedes sometimes migrate in huge numbers, especially after heavy rains in the spring. It is during mass migrations that they often enter homes. They climb walls easily and enter through any small opening.
Millipedes do not carry serious diseases and do not damage food or belongings in the home, but their mere presence is a nuisance. If crushed, millipedes can leave stains. Many millipedes have glands which produce fluids which are irritating and can cause allergic reactions. These fluids can be harmful to the eyes and produce a nauseating odor. It is important to wash hands thoroughly after touching a millipede.
Nonchemical Control
If garden millipedes are occurring in great numbers indoors, it is usually an indication that there is a large population in the area surrounding the home. To control these pests, the most important step is to remove materials that give them shelter in the immediate area around the home. This includes excessive mulch, leaf litter, thick grass, rocks, boards and similar materials.
De-thatching the lawn and mowing closely allows for drier conditions, which reduces the areas where they can live. Watering in the morning rather than the evening, also gives the lawn a chance to dry before they become active at night.
Try to prevent garden millipedes from entering the house by making sure doors and windows fit tightly, and as many cracks and crevices are caulked as possible. Remember that they may be entering your home from high areas just as easily as low areas.
In most situations, garden millipedes found indoors can be easily removed with a broom or vacuum.
Chemical Control
Pesticides provide only temporary control unless the non-chemical measures are taken as described above. However, if necessary, pesticide dusts such as boric acid powder applied to cracks, crevices and indoor void areas where millipedes enter homes will help kill them more quickly. Many pesticide powders will not work well if applied in areas that are too moist.
For millipedes found outside, pesticide sprays applied to foundation walls or other entry points can help reduce entry. When treating leaf litter or mulch, use enough water to penetrate the ground cover or rake the ground cover back before spraying to ensure that the pesticide reaches the areas where millipedes live. For pesticide applications both indoors and outdoors, make sure you only use products appropriately labeled for millipede control in the areas you are making your applications.
If garden millipede numbers are extremely high and difficult to control on your own, consider hiring a licensed pest control operator. Pest control professionals have special equipment and pesticide formulations such as wettable powders, suspension concentrates, or microencapsulated products that may be able to provide better control than common, non-professional equipment and materials. For tips on hiring a professional, see our Insect Information Fact Sheet: Choosing a Pest Control Company, IIS/HS-23.
Originally published 05/99
