Rats and mice - Belfast City Council's winter warning
The pitter patter of little feet is not always an excuse for a party.
Belfast City Council's pest control manager has urged people to winter proof against unwelcome Christmas guests.
"A grown mouse can fit through a very small hole - 3/8th of an inch," Earl d'Hulst told the BBC's Good Morning Ulster programme.
A rat, can get through the same small space - use a pen to punch a hole in a piece of paper - that's all the space they need, he warned.
Mice are grazers - if you leave 50 chocolate bars out a mouse will have a nibble at all 50 of them; a rat would eat one and leave the other 49.
Mice are more difficult to get rid of than rats because they are so agile.
"Rats and mice are a normal problem at this time of year but about six years ago we had a bigger problem," said Mr d'Hulst.
"On average, we receive about 2,500 requests a year to treat domestic properties for rats and that's about half of the total number of calls we receive."
He said rats were easier in one respect to kill because of their feeding habits. But they can prove more difficult to catch.
"They suffer from a condition called neophobia. It means if you introduce something new, the rat will stay away from it for four or five days until he gets used to it," he explained.
If you corner a rat, it will stand its ground, he said.
"But if you shout 'boo' loud enough, the mouse will drop dead of fright."
The problem with poisoning a rat or a mouse is that, if it is trapped somewhere and is dead, it attracts other pests.
"With a dead rat, the smell is not pleasant and then, the female bluebottle can only lay her eggs in rotting meat.
"If you have a rotting rat or mouse, five months later, you could end up with 200 bluebottles in your property," said Mr d'Hulst.
The message from the expert is very simple.
"Keep your gardens maintained well, pick up litter, make sure your sheds are 18in off the ground and don't leave food around," said Mr d'Hulst.
"We would encourage people not to feed the birds, particularly in the winter, as the fodder from that attracts the rodents."
Another piece of advice is to fill in any holes in the walls.
As for getting a cat? Bad news, the expert from the city council said they don't work either.