Reducing exposure to ticks is the best defense against tickborne diseases. Steps to take after a tick bite including removing a tick and watching for signs and symptoms. Maps showing the general distribution of medically important human-biting ticks in the U.S.

Understanding the Context

Ticks are most active in spring, summer and fall. They can be found in cooler areas where trees, brush, leaf litter and tall grasses provide cover and shade from the sun. Ticks avoid heat and direct sunlight. Ticks feed on blood and will wait for a person or animal to walk by to grab onto.

Key Insights

There are over 800 species of ticks throughout the world, but only two families of ticks, Ixodidae (hard ticks) and Argasidae (soft ticks), are known to transmit diseases or illness to humans. Ticks can transmit diseases like Lyme disease, Rocky Mountain spotted fever, and Colorado tick fever, so prompt removal and medical attention are crucial. To remove a tick, use fine-tipped... As of 2019, Lyme disease is the most often diagnosed tick-borne illness. Here are images of unfed, human-biting ticks.

Final Thoughts

The images also show where the ticks might be found in the U.S. and the diseases they're known to carry. Ticks are external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. The timing of the origin of ticks is uncertain, though the oldest known tick fossils are around 100 million years old, and come from the Cretaceous period. A list of types of ticks found in the United States that are known to bite and transmit disease to humans. Learn about ticks and the diseases they spread, and how you can limit your risk of exposure to potentially harmful chemicals.