Laura Sirot studies mosquito borne diseases at the College of Wooster.

She says the Zika virus is primarily carried by a mosquito called Aedes aegypti, also known as the Yellow Fever mosquito. That species is already present in parts of Florida, Texas, Arizona and California, and could eventually carry Zika.

The virus is also carried by a cousin called the Asian tiger mosquito, which has been found as far north as Ohio.

Sirot says these mosquitoes breed in discarded tires.

“And those tires would be transported from one state to another, and then if it rained again, the eggs can hatch out," says Sirot, "And so they can be transported unintentionally and then hatch out in a new place.”

This month about a dozen cases of Zika virus have turned up in people returning to the U.S from abroad.

Sirot says there’s no evidence yet that any mosquitoes in North America carry the disease.