Lone-star Tick (IMAGE) Washington University in St. Louis Caption A. americanum, known as the lone-star tick because adult females sport a star on their backs, is the tick of concern in the St. Louis area. The most common tick in this region of the country, it has been shown to be the vector for several new diseases. Credit US Centers for Disease Control Usage Restrictions None 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.