In 2002, the Bloomington Drosophila Stock Center at Indiana University – one of the world's best known sources of fruit flies – had a consignment destined for overseas returned by the US Postal Service (USPS). The center's codirector, Kevin Cook, learned that the package had been deemed in contravention of USPS international postal regulations. The Bloomington center mails tens of thousands of fly cultures overseas each year, and "this was only the first time a postal inspector had sent back a package," says Cook.