Life Cycle of Deer Tick
Life-cycle deer tick in the northeast United States. Larval deer ticks are active in August and September but these ticks are pathogen-free. Ticks become infected with pathogens when larvae (or nymphs) take a blood meal from infectious animal hosts. Engorged larvae molt over winter and emerge in May as poppy-seed sized nymphal deer ticks. Please note that most cases of Lyme disease are transmitted from May through July, when nymphal-stage ticks are active. Adult-stage deer ticks become active in October and remain active throughout the winter whenever the ground is not frozen. Blood-engorged females survive the winter in the forest leaf litter and begin laying their 1,500 or more eggs around Memorial Day (late May). These eggs hatch in July, and the life-cycle starts again when larvae become active in August.