A sharp increase in pest control costs in the Palace of Westminster has been blamed on the amount of work being done on the crumbling estate.
Explaining last year's £132,619 bill, Commons authorities said increased maintenance projects had "disturbed pests and made them more visible".
The mouse problem has got so bad, with sightings reported daily, that one MP brought her cats to the Commons.
The official pest control measures included hawk-flying to scare pigeons.
Figured showed a total of 217 mice sightings in the first six months of 2017 and over 1,000 "moth detections" every month.
Conservative MP Penny Mordaunt confirmed she had resorted to her own methods but had fallen foul of Parliament's strict rules.
"I have four cats that have periodically deterred mouse activity by patrolling offices and corridors," she told the BBC.
"Their services are often requested by colleagues, but palace authorities have ruled such initiatives out of order."
Parliamentary authorities distributed a note to MPs last year which read: "No animals other than assistance dogs and security dogs are allowed in the Palace or any of its outbuildings (other than residences).
"This rule is in place because of the duty of care that would arise in relation to animal welfare and the health, safety and wellbeing of Members, staff and visitors on the Parliamentary Estate."
This cost of using hawks to deter pests was just over £16,000 in 2016-17 - £10,000 higher than the previous year.
"Moth deterrents" cost just under £9,000 and "general controls" - including a full-time pest control technician - came to £106,000.
In 2015-2016, the overall pest control bill came to £103,157.
The costs - which are split 60/40 between the Commons and the Lords - were revealed following a Freedom of Information request.
A great believer in credible deterrence, I'm applying the principle to the lower ministerial corridor mouse problem. pic.twitter.com/HNuulWF0i5— Penny Mordaunt MP (@PennyMordaunt) September 14, 2016
A spokesman said the parliamentary estate is "vulnerable to populations of animals which can cause significant damage to the fabric of the buildings and health and safety issues".
The spokesman added that "mice populations need to be controlled for hygiene reasons, including compliance with regulations, and to prevent accidents caused by mice chewing through electric cables," while moths posed a danger to historic furnishings and the Parliamentary Art Collection.
It is a different story in Downing Street, where Number 10, the Treasury, the Foreign Office and Cabinet office have recruited cats for pest control.
Downing Street's website describes Larry as "the first cat at Number 10 to be bestowed with the official title Chief Mouser".
Foreign Office cat Palmerston was, like Larry, a rescue cat from Battersea Dogs and Cats Home.
Gladstone is on pest control duty at the Treasury while Evie and Ossie, rescue cats from the Celia Hammond Trust, are on duty at the Cabinet Office.