We remove everything from boxes in the dinghy prior to handing it onto the boat. No cardboard ever goes onto the boat. One thing that I have found works really well to kill them is a spray can of break cleaner. One jumped out of the laundry bag we had just picked up at a hotel in Jamaca. The thing was 2 inches long and ran over the bed and up under the overhead. You could just see him sitting there but couldn't swat him. Trying to would have just caused him to go farther up anyway. I was looking around for something, anything, to kill the little bastard with when I saw a spray can of break cleaner I had been using to clean the dinghy carburetor. I picked it up and shot it at the critter. The thing fell out and was deader'en hell. I always keep a can around for my carburetor and the off chance we get another hitchhiker.