The six-legged larvae are active July-September and can be found in moist leaf litter. Larvae hatch nearly pathogen-free from eggs (only Borrelia miyamotoi is known to infect blacklegged tick larvae), and remain in the leaf litter where they will attach to nearly any small, medium or large-sized mammal and many species of birds. Preferred hosts are white-footed mice.
Adult males and females are active October-May, as long as the daytime temperature remains above freezing. Preferring larger hosts, such as deer, adult blacklegged ticks can be found questing about knee-high on the tips of branches of low growing shrubs. Adult females readily attack humans and pets.
An insidious pest is killing about 70 percent of moose calves across Maine and New Hampshire, and their deadly work is being aided by warming temperatures and shorter winters that allow the parasites to survive longer, scientists believe. They are winter ticks, which attach themselves to a single moose by the tens of thousands. Adult females can expand to the size of a grape and engorge themselves with up to four milliliters of blood.