The Rocky Mountain wood tick , Dermacentor andersoni , is a three-host species. Adult ticks appear in the spring. The Rocky Mountain wood tick mates during feeding. After feeding, the female detaches from the host and deposits several thousand eggs over a month. Hatched seed ticks attach to small rodents, feed, detach and develop into the nymphal stage.
Nymphs seek shelter and are inactive until the following spring.
In the spring, the nymphs attach to another animal, feed and drop off where they molt into the adult stage. The adult stage overwinters and the following spring they attach to a large animal, feed and start the life cycle over with the whole procedure requiring three to four years. Hides punctured by tick feeding are down-graded because of reduced tinsel strength. This tick is also a vector of Rocky Mountain spotted fever , a rickettsial disease of man. Dermacentor variabilis , the American dog tick , has a life cycle similar to its close relative, the Rocky Mountain wood tick.