An outbreak of the Asian longhorned tick in New Jersey last year threatens to spread across north America and could carry deadly diseases.
In its native countries, about 15 per cent of the people who are bitten by the tick die of diseases they transmit.
So far there have been no human infections in the United States, although the tick has now been identified in eight states.
The Entomoglocal Society of America and the U.S. Centres for Disease Control have both issued news releases warning of the danger.
Researchers say the threat is across the continent based on comparisons of their habitat in Asia with North America.
The tick is "an important vector of human and animal disease agents," said the CDC report.
It is native to China, Japan, Korea, and the Russian Far East. The discovery on a sheep in New Jersey last year was the first sighting in the U.S.