Lest we forget how valuable the customs procedures are at our ports of entry, look at this article from abc news:

http://abcnews.go.com/Weird/wireStory/giant-african-snails-seized-los-angeles-airport-24556879

These giant African land snails (article doesn't say, but very likely a species of the genus Achatina) are enormous, and can get up to 2 lbs in weight and according to the article are "seriously harmful" because they "eat any kind of crop they can get to".   Good thing this shipment was stopped at the airport and came no further into our state, because quite frankly we aren't even close to having the tools to controlling these in an agricultural setting.