Figure 1. The mean (+/- SE) numbers of larval, nymphal, and adult Ixodes trianguliceps ticks counted per rodent at 4-week intervals, 1997–1998. Shaded areas of similar intensity indicate ticks of different instars that may have belonged to the same cohort, according to interstadial development times deduced by Randolph (21). Arrows indicate potential transmission cycles: bold arrows indicate potential transmission from infected nymphs to uninfected larvae by means of rodent infections. Fine arrows indicate potential transstadial transmission from infected engorged larvae to infected host-seeking nymphs. For clarity only one within-year (A) and one between-year (B) cycle involving nymphal and larval ticks are illustrated.