Helicoverpa armigeraÂ has recentlyÂ been discovered in South America. Â It has since been tracked spreading into the Caribbean. Â Pest risk modelling has revealed that most of the US crop productionÂ may be at some degree of risk from this pest, which has developed resistance to most pesticides. Â The rapid northward spread in the Americas suggests that it is now a matter of when, rather than if itÂ will invade the USA. Â The pest risk research has been published in PLOSÂ One.