All life stages besides the egg must take a blood meal to develop, and the adult female must feed to mature the eggs. The larva has only three pairs of legs. They feed for about 3-4 days then drop from the host, seek a protected site under leaves, etc. The larva molts to the nymph stage the following spring. Larvae usually pick up the spirochaete from the rodent host and once they are infected, deer ticks will carry Lyme disease throughout the remainder of their lives.
Nymphs occur in late spring and summer, and are about the size of a poppy seed.
Nymphs may attach to humans, dogs, horses, cattle, rodents and other small to medium sized animals. When an infected nymph feeds on a rodent, it may transmit the spirochaete to that rodent. The rodent then serves as a reservoir capable of transmitting the disease to later feeding tick larvae. Birds frequenting the forest floor where nymphal ticks are present may also serve as hosts. It is believed that migrating birds may contribute to the spread of the tick.