(CNN) -- Add another giant bug to the list of things Washington state is working to handle right now, and experts say it could quickly spread across the nation. Earlier this week, scientists said they had spotted Asian giant hornets in the state -- and it's still unknown how they got there. Such a threat, in fact, that Washington state Gov. The threat is posed by both Asian gypsy moths and Asian-European hybrid gypsy moths, according to the proclamation. "Large (Asian gypsy moth) infestations can completely defoliate trees," according to the US Department of Agriculture's Animal and Plant Health Inspection Service.