If not previously infected, the nymph may become infected if its host carries the Lyme disease spirochete from previous infectious tick bites. Although the nymphs' preferred hosts are small mammals and birds, humans and their pets are suitable substitutes. Because nymphs are about the size of a poppy seed, they often go unnoticed until fully engorged, and are therefore responsible for the majority of human Lyme disease cases. Adult - Once engorged, the nymph drops off its host into the leaf litter and molts into an adult. Peak activity for adult deer ticks occurs in late October and early November.
Adult deer tick questing for a host.
Adult deer tick seeking a suitable spot to feed. At this time, they resume the quest for hosts in a last-ditch effort to obtain a blood meal allowing them to mate and reproduce. This second activity peak typically occurs in March and early April. Adult female ticks that attach to deer, whether in the fall or spring, feed for approximately one week. Males feed only intermittently.