Reproductive Biology

Semelparous (reproduces once during lifetime, after which it dies). Requires blood meal before developing into its next life stage and for egg development. Mating takes place primarily on host, with female usually on top of male. Males do not become engorged. After feeding for 4-17 days, mated female descends from host and seeks protected area to lay eggs. In spring, after a preoviposition period of usually 3-11 days, she lays single cluster of usually 3,000-5,500 (but possibly 2,500-7,400) yellowish brown ellipsoidal eggs over period of 10-33 days. Female then dies within 1-14 days. During next 7-38 days, eggs hatch if temperature is 72-90°F (22-32°C).

Young six-legged larvae begin crawling in search for small rodent host (such as mice, voles, and chipmunks), dying within 30 days if unsuccessful. Unengorged first instar larva is about 0.0236 in (0.6 mm) in length. Usually feeds for 2-8 days (usually three) to engorgement, and then drops to ground to molt within 6-21 days. May survive for more than 300 days if unfed during this time. After finding suitable small-to medium-sized host (such as rabbits, ground squirrels, marmots, and skunks), nymphs reach engorgement in 3-11 days. Second instar eight-legged nymphs are 0.0551-0.0591 in (1.4-1.5 mm) in length. After completing engorgement, they drop off again and molt into adults usually in 14-15 days (possibly in 12-120 days). Adults can survive more than a year (usually about 600 days) unfed, but after finding a suitable medium- to large-sized host (such as dogs, deer, and humans), they mate on host after partial feeding. Life cycle is 1-3 years (typically 20 months), depending primarily on host availability and various environmental stresses and conditions.


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