The damned things are now becoming an issue here in Oregon. All of the major entry ports (truck scales) now do inspections on any water craft entering the State. When this started (bit over a year ago?) it didn't take the OSP two days before they found guy (I-5 coming out of California) with a 'butt load' of the things hanging on his trailer and motor mount.
Boat-trailer hadn't been around water for well over a week in 105 degree weather. Things were alive and well!!