Illinois Natural History Survey - University of Illinois

Illinois River Valley Ticks

During this past spring, INHS entomologist John Bouseman and INHS affiliate Dr. Jeffrey Nelson found blacklegged ticks, Ixodes scapularis, at sites in Fulton and Peoria counties. The investigators collected the ticks by dragging cloth flags at sites where people had previously reported that they had encountered "deer ticks" in the environment.

The blacklegged tick was reported from many of the Illinois Valley corridor counties in the late l980s and early l990s on the basis of the collection of ticks from deer at check stations in those counties during the fall firearm seasons. Thus, the tick was detected in Kankakee and Putnam counties in l988; in Brown and Peoria counties in l989; in Bureau, Grundy, LaSalle, Scott, Schuyler, and Will counties in l990; and in Marshall and Tazewell counties in l992.

A female blacklegged ("deer") tick. Scale is in millimeters.

In l997, Bouseman and Nelson found significant numbers of the blacklegged tick in Grundy and Will counties, and it was determined that the ticks were infected with the causative agent of Lyme disease. As of this writing, it remains unknown whether or not the Fulton and Peoria county populations are infected with the Lyme disease spirochete.

It appears that blacklegged tick populations are increasing in the Illinois Valley, and those engaging in outdoor activities in the area should take precautions to avoid tick bite.

John K. Bouseman, Center for Economic Entomology, and Jeffrey A. Nelson, M.D., Rush Medical College, Chicago

Charlie Warwick, editor

Illinois Natural History Survey

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Champaign, IL 61820

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