Temporal and spatial dynamics of Ixodes scapularis (Acari: Ixodidae) in a rural landscape.

We studied seasonal, interannual, and both small- and large-scale spatial variation in the abundance of blacklegged ticks, Ixodes scapularis Say, in a semirural landscape in southeastern New York. Using transect drag sampling, we found that ticks were approximately twice as abundant in 1994 as in the preceding 2 yr. In 1994, larval ticks showed a strong peak in activity in late spring, coincident with the nymphal peak that year. All post-egg life stages were more abundant in forested than in shrubby or herbaceous habitat types, but peak abundance of larvae shifted from oak-dominated forest in 1992 to maple-dominated forest in 1993 and 1994. All life stages were highly clumped at small spatial scales, but larvae were the most aggregated. Within the forested habitat types, we observed an initial increase followed by a decrease in small-scale clumping during seasonal activity for each life stage. We discuss potential effects of the observed temporal and spatial variation on risk of Lyme disease. Because of pronounced variation in abundance and activity patterns among years and habitat types, we caution against generalizing from short-term or spatially limited studies.