Labour’s Baroness Farrington of Ribbleton issued the cautionary tale at question time in the Lords.
To laughter from all sides, she told environment, food and rural affairs spokesman Lord Gardiner of Kimble that he ought to be careful dealing with ferrets.
“We had a ferret belonging to my son, called Rikki-Tikki-Tavi, and she did enjoy trouser legs and it’s very important for people to take care.”
Lady Farrington said a former colleague of hers started a ferret appreciation society in Wigan.
“And I had to warn him that I would turn up with said ferret and that he had to beware of her interest in going up trouser legs.”
Lord Kimble said the 75-year-old baroness had given peers a “splendid reason as to why one should be extremely cautious of ferrets”.
He said 68 ferrets had come into the country last year under the pet passport scheme and added: “I hope everyone has taken note of what you’ve said about trousers.”
The exchanges came as peers protested about the failure of Eurostar to allow passengers to take dogs and other pets on board with them when travelling abroad.
Lord Gardiner said the Government did not impose any obligation on transport companies to carry pets. It was a commercial decision for them.
Eurostar did offer carriage for guide dogs, he added.
But Tory Baroness Sharples said: “Passports for pets has been 100% successful. Why oh why will Eurostar not take pets? You can take your dog on a sleeper to Scotland and all the ferries take them. Why not Eurostar?”