David Ng (right) and Amanda Furrow, Customs and Border Protection agricultural specialists, inspect wheat for insects and alien seeds at a port in Baltimore, Md. Dan Charles/NPR hide caption

itoggle caption Dan Charles/NPR

A worker unloads a truck full of Mexican limes at a citrus packing plant in La Ruana, in the state of Michoacan, Mexico. Dario Lopez-Mills/AP hide caption

itoggle caption Dario Lopez-Mills/AP