Roughly 7,500 types of millipedes have been documented worldwide. Only a very small portion approximately 30 species, of them live in Colorado. Their name is slightly deceptive in meaning as they do not have a million feet/legs. They actually have 47-197 pairs of legs depending on their species and stage of life. Their minuscule sized legs move in a wave-like motion propelling them along. For the most part, each body segment has 2 pairs of legs. Mouthparts are small and made for chewing. Vegetarian in nature, millipedes pose little threat to humans aside from consumption of garden plants. Millipedes over-winter as adults or nearly full-grown nymph stages. Eggs are laid between early spring and summer under moist ground debris. Eggs hatch within a few weeks, but young millipedes experience slow growth rates. Millipedes complete several molts, slowly increasing in size as well as gaining new body segments and legs with each molt. Overly ripe fruit such as strawberries and tomatoes which come in contact with soil are primary targets for hungry, growing millipedes; therefore, ripening fruits should be lifted off the soil. Additional food sources include soft plant matter, fungi and decaying plants.
Millipedes, like many other arthropods, require moist conditions in order to survive. They can commonly be found under rocks, leaf litter and other ground debris that promotes moist conditions. Millipedes will typically curl into tight spiral shaped coil when disturbed or threatened, but this response is also common during death. Millipedes do not purposely enter structures due to the lack of moisture typically found inside. When moisture is present indoors however, they are likely to accumulate in that area. Decreasing moisture by repairing water leaks and creating proper drainage around the foundation of the home will aid in decreasing activity. Insecticides may be applied around the base of the foundation and extending out into lawn areas to help reduce high activity levels. Sealing gaps and cracks around the foundation including around utility pipes will help to decrease activity levels as well. Fine mesh window screens will prevent entry by adults into the home.