This rapid PRA shows that: Hyphantria cunea, which has many common names including fall webworm and American white moth, is a polyphagous defoliator of many deciduous trees and shrubs, having between one and four generations every year. Native to North America, this moth was accidentally introduced to Hungary in 1940 and Japan in 1945. Since then, it has spread in both Europe and Asia, occasionally causing outbreaks and severe damage. In 2014, two adults were trapped in the UK. Hence, the 1991 PRA has been updated to re-assess the suitability of the UK for establishment, as well as the potential for high levels of damage.