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Lone star tick

Tick ID,Adult female, Lone star tick on leaf, CDC

Lone star tick

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Lone star tick

Amblyomma americanum


The lone star tick, has a long record of occasional introductions to Colorado, usually arriving on animals traveling with their owners from the eastern or midwestern USA, where it has an extensive and expanding distribution, from Florida north to Maine and west to Nebraska and Texas. It also occurs in the northern states of Mexico. This hard tick is not yet known as an established resident in Colorado. This tick is high risk as an invasive species as demonstrated by its recent expansion to the northeastern region of the country. The adult female is distinguished by a white dot or “lone star” on her back.


Hosts of this species include a wide variety of mammals and ground-dwelling birds, and humans. The nymph and adult females are the most common biters. This is an aggressive tick that actively seeks hosts and frequently bites humans.

Vector Status

The lone star tick may transmit the agents of canine and human monocytic ehrlichiosis (HME), canine and human granulocytic ehrlichiosis (HGE), Tularemia, Q-fever and southern tick-associated rash illness (STARI).  It has also been implicated in transmission of the Heartland and Bourbon viruses, and other Lyme-like illnesses. The bite of this tick may cause potentially fatal host paralysis via toxins in their saliva, as well as Alpha-gal syndrome or “meat allergies” is occurring in a growing number of people.


H Joel Hutcheson, James W Mertins, Boris C Kondratieff, Monica M White, Ticks and Tick-Borne Diseases of Colorado, Including New State Records for Argas radiatus (Ixodida: Argasidae) and Ixodes brunneus (Ixodida: Ixodidae)Journal of Medical Entomology, tjaa232,

Centers for Disease Control and Prevention

Colorado Department of Public Heath and  Environment webpage and personal communication, with Dr. Leah Colton (former CDPHE, Entomological Epidemiologist).

Lone star tick

Tick ID-Lone star tick female and engorged
Photo by CDC: Lone star tick, adult female and fed female

Lone star tick distribution in Colorado: 2014-2019

Lone Star Tick Distribution Map in Colorado
Occurrence Map from Colorado Department of Public Health and Environment: 2014-2019 collections. This map indicates presence only, it does not indicate an established population of tick.

Lone star tick distribution in the United States: 2019

CDC Distribution Map: This map is not meant to represent risks for a specific tick-borne disease, because disease transmission is influenced by multiple factors beyond mere tick presence. This map has been designed to answer the question “What ticks should I be concerned about at a regional scale?” Please consult a local public health authority or USDA Agricultural Extension Office to determine more specific information at the state, county, or municipal level. Background data for this map is from the US National Atlas. Naturally occurring populations of the Lone star tick are not known to occur in Alaska or Hawaii.