Female Tick (IMAGE) Penn State Caption A "questing" female Ixodes scapularis (blacklegged tick) reaches out in hopes of climbing aboard a host. Researchers say the blacklegged tick, the primary vector of Lyme disease, was almost nonexistent in Pennsylvania in the 1960s but now is the state's dominant tick species. Credit Joyce Sakamoto/Penn State Usage Restrictions Non commercial use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.