This week on We Dig Plants Carmen and Alice explore the world of INVADERS: very small plants or animal species that can be very large headaches, and can be the cause of everything from a minor nuisance to a major catastrophe. Tune in to hear Alan Green, Brooklyn-born director of PPQ Plant Health Programs (within the Animal Plant Health Inspection Service), discuss his work fighting pests: APHIS are guys that check everything from people to plants to parcels to prevent the spread of exotic pests and diseases. This episode was sponsored by Hearst Ranch.