Officials have confirmed that invasive mites, which can be lethal to cattle, are spreading into new states.
The Asian longhorned tick, first identified in the U.S. in 2017, was recently found in Maine, according to the University of Maine and state conservation officials. This marks the farthest north this invasive species has been detected.
As of September 2025, these mites have been reported in nearly 20 states.
Here’s what you should know.
What are Asian longhorned ticks?
Even though they’re invasive, Asian longhorned ticks are somewhat similar to the native ticks you might be accustomed to.
Before feeding, they have a bright reddish appearance, sometimes looking dark red. They can be quite small, even smaller than a sesame seed. After they feed—primarily females, since males are uncommon—they can grow to the size of a pea and take on a yellowish-green hue.
Female Asian longhorned ticks have the unique ability to lay eggs without mating, which aids their spread into new areas.
Where have these ticks been found?
Since their initial detection in 2017, Asian longhorned ticks have managed to expand into almost 20 states.
By April 2025, reports indicated they had been found in various states including Arkansas, Connecticut, and Georgia, among others. The USDA has noted their presence in Illinois, Kentucky, and Tennessee, to name a few.
Additionally, reports earlier this year confirmed their spread into areas like Michigan.
Are Asian longhorned ticks a threat?
Research indicates that these ticks can carry pathogens causing Rocky Mountain spotted fever (RMSF), which is transmitted through bites from infected ticks. Symptoms typically include fever, headache, and stomach pain, though the longhorned ticks in the U.S. are not known to be carriers of this bacteria.
For livestock, these ticks pose a significant risk. They can thrive in large numbers on a single cow, leading to severe blood loss and, potentially, death. Dr. Jonathan Cammack from OSU highlighted that a female tick can lay up to 2,500 eggs on an animal, compounding the problem.
The USDA advises regular tick treatments effective against Asian longhorned ticks. If you suspect your livestock or pets may be exposed, it’s best to consult a veterinarian.
