Since it takes a while for ships to get here, how about an inspection team (2 to 3 people) on each ship, to examine both the crates and the crew, it before it docks in our ports. Maybe have a dog with them, too? (A dog with a good nose and sharp teeth!)
(I'm not trying to be funny. If a ship wants to come here, they play by our rules.)
This is also an excellent idea, as was the one about fumigating containers with really toxic stuff.
Please send your idea to Homeland Security//I think it has merit (job creation as a side benefit!...2 for 1!).