Dog Tick


Dog TIcks.png


  • Dermacentor variabilis
  • Dog tick
  • Wood tick


Female: Brown with white dorsal shield

Male: Brown and white mottled

Size: ¼” and rounder than the winter tick

The American dog tick (Dermacentor variabilis), aka Wood tick, is the most frequently encountered tick in New Hampshire.

Dog ticks have a two-year life cycle and have three hosts. The tick is most active from May through July in New Hampshire.

The dog tick begins life as an egg, one of hundreds laid in a mass on the ground by a female tick. The egg hatches into a larva, which has six legs. The larva remains on the ground in leaf litter, or in low vegetation while waiting for a small mammal (usually a rodent) to brush by. It attaches to the animal and feeds for several days. Then it drops off and molts to the nymph stage, which has eight legs. Again it waits for a host (usually a rodent) to brush by. When that happens, the tick attaches and feeds on it for several days. When fully fed it drops off and molts to the adult stage. Adult ticks wait on shrubs or tall grass and attach to larger mammals such as people, deer, or pets. They also take several days to fully engorge (feed). A female fully engorged with a blood meal can be almost the size of a dime, appearing smooth and shiny. Mating takes place on the host, and when fully fed, the females drop off and lay eggs.

This species can transmit the organism that causes Rocky Mountain Spotted Fever, which is rare in New England but more common farther south. Dog ticks can also transmit tick paralysis toxins and Francisella tularensis or Tularemia, which are both rare.




  • Rocky Mountain Spotted Fever (Rickettsia rickettsii)
  • Tularemia (Francisella tularensis)
  • Anaplasmosis (Anaplasma phagoycytophilum)
  • Human monocytic ehrlichiosis (Ehrlichia chaffeensis)
  • Tick paralysis
  • Learn more about tick-borne diseases on our Diseases Page →