Role of the eastern chipmunk as a host for immature Ixodes dammini (Acari: Ixodidae) in northwestern Illinois.

Infestation of the eastern chipmunk, Tamias striatus L., by immature Ixodes dammini Spielman, Clifford, Piesman and Corwin was studied in Castle Rock State Park in northwestern Illinois during June-October 1991. Mean larval density peaked in August, while nymphal density declined steadily through the study period. Prevalence of tick infestation was high throughout the trapping period. Tick distribution on chipmunks was aggregated in most of the sampling periods. Levels of I. dammini infestation recorded on chipmunks in this survey are higher than previous results recorded in the northeastern and midwestern United States. Chipmunks had significantly higher levels of nymphal I. dammini infestation than white-footed mice (Peromyscus leucopus Rafinesque). A major role of the eastern chipmunk as a host for immature I. dammini in upland forest habitat in northwestern Illinois can be established. In bottomland and ecotone habitats where chipmunks were scarce, P. leucopus contributed most to the feeding of larval ticks.