The longhorned tick, or Haemaphysalis longicornis, was first confirmed in the U-S last year, on a sheep in New Jersey.
A few weeks ago, one was found on a wild deer in Centre County, Pennsylvania.
Ticks have also been found in several other states - but scientists don't know how they got there.
Female longhorned ticks don't need a male to reproduce.
They can spawn asexually.
After feeding, a single female can lay around 2,000 eggs, according to the Pennsylvania Department of Health.
The U.S. Department of Agriculture says that's enough to establish a tick population in a new location.
The longhorned tick can cause infestations in livestock, sucking so much blood, it causes anemia, and even death.
In most life stages, longhorned ticks are the size of a poppy see.
Adult longhorned ticks grow to the size of a pea when they are fully engorged with blood.
Its impact on humans is unknown, but people are urged to step up tick prevention.