Ghosts of weather past? Impact of past and present weather-related factors on the seasonal questing activity of Ixodes ricinus nymphs in southwestern Finland

Increasing nymph densities were observed during a 10-year study period. While temperature measurements taken during the time of dragging did not appear to greatly influence the observed tick numbers, the recent past temperature variables were significant in all the natural biotopes. The results suggest that, in the clearly seasonal climate of southwestern Finland, the main factors shaping phenological patterns of I. ricinus nymphs during their main activity period are the progress of the season and a heat-related reduction in questing activity.