Remove debris that can provide a hiding place for millipedes. Pull mulch away from the house because it retains moisture, creating a good hiding place for the millipedes. Water grass in the early morning so that it can dry during the day. If millipedes enter your house, vacuum them up and discard them outside. Some species can stain carpeting or fabric, especially if crushed.
Wettable powders provide longer residual activity.
Also treat doorways and other openings to the house with a material labeled for this use. Because millipedes are not insects, most insecticides alone are of little or no use. The non-chemical management practices outlined above should be implemented in conjunction with chemicals to enhance control. References Appel, A. G. 1988. Clean, dry surroundings impede migration of millipedes.