This is an adult female deer tick, Ixodes dammini. It transmits Lyme disease and babesiosis to humans. (Image courtesy of the Centers for Disease Control and Prevention.)
Review Date: 2/27/2012 Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.