Ixodes scapularis (Acari: Ixodidae) at the edge of its range in southern Wisconsin.

This study examined the density and distribution of the blacklegged tick, Ixodes scapularis Say, at the edge of its range in southern Wisconsin in 1988 and 1989. The study area encompassed sites with ticks at densities ranging from the highest recorded in the state to no ticks detected, as known from previous surveys of white-tailed deer, Odocoileus virginianus Zimmerman, infestation. Ticks were collected from trapped mice, Peromyscus spp., and hunter-killed white-tailed deer. A sharp west-to-east decline in I. scapularis density was identified based on deer infestation rates. At the edge of the ticks range in southern Wisconsin, I. scapularis infestation of Peromyscus Gloger was 1-2 orders of magnitude less than in the middle of the range. In this study, white-tailed deer were more effective than mice for sampling ticks at low density, as is expected given the home range of the hosts and the spatial pattern of ticks. This data set is a baseline for judging changes in the distribution and density of I. scapularis in southern Wisconsin.