Baby millipedes hatch from eggs after an incubation period of about three weeks. The newly emerged hatchlings generally resemble smaller versions of adult millipedes. However, while fully grown adults typically have about 60 legs (2 per body segement), millipede young are born with only three pairs of the appendages. Baby millipedes grow by molting, which replaces the existing exoskeleton with a new and larger one. Prior to reaching adulthood, developing millipedes complete about seven to 10 different molts. Each molt results in the creation of additional body segments and subsequently additional pairs of legs. Millipedes typically molt in hiding, as the process of shedding the exoskeleton temporarily leaves the body in a soft and vulnerable state. The occasionally invading pests stop molting after reaching sexual maturity, which usually takes between two and five years.
In addition to resembling adults physically, baby millipedes share many behavioral characteristics with their fully developed counterparts. Nocturnal and herbivorous like adult members of the species, immature millipedes become most active at night and primarily feed on moist organic matter such as rotting leaves and other decaying plant material. The wormlike arthropods also demonstrate a strong attraction to light and often aggregate near well-lit areas outside the home like driveways, patios, and swimming pools. Millipedes live for several years, with most of their life spent in the soil.