A pest control firm has been called to St James's Hospital more than 100 times in the past two years to deal with cockroaches, mice, beetles and ants.
Black clock beetles - large carnivorous insects with sharp jaws - were found in a specialised unit for patients undergoing bone-marrow transplants.
Other vermin were discovered in an endoscopy theatre and on bedside tables.
In 2015, the company attended the hospital sterile services unit (HSSU) four times, acc- ording to documents released under the Freedom of Information Act.
On one occasion, a mouse was caught in the kitchen. Another mouse was thought to have scuttled into a sterilisation machine.
The firm was also called four times to the hospital's breast care clinic where problems included a rodent in a staff tearoom, an infestation of flies in reception and a "bad smell" that staff said was "a common occurrence".
Towards the end of last year, the company was called to a kitchenette in a private ward where it found a mouse feeding off bait.
Another rodent was reported in an endoscopy theatre. Traps were set, and three days later a mouse was caught in the theatre's observatory room.
The company was also called to inspect droppings found in a cupboard beside an operating theatre.
On closer inspection, dead woodlice were found.
On two occasions in August, pigeons that had entered Mercer's Institute for Successful Ageing (MISA) could not be removed, despite the pest control company's best efforts.
"Could not remove pigeon," the technician noted in his inspection report. "May leave eventually."
Two days later, the pigeon was joined by another.
"Two pigeons flying around atrium in MISA," it was reported. "Technician couldn't remove them due to height and area involved. Door left open to assist pigeons out."
In April 2015, two dead birds in a ceiling cavity caused an infestation of bluebottles in a meeting room in the administration building. Insecticide treatment was carried out.
Ants were a recurring problem at the hospital during the two-year period.
Up to 150 were found behind a locker in the department of clinical nutrition, while others were found in locations including a dialysis room and on a bedside table.
More than €35,000 was spent on pest-control services by the hospital in the past two years.
This included an outlay of €275 in February last year for a plastic hawk to scare away pigeons and gulls.
St James's Hospital was contacted for comment in relation to pest control.
It acknowledged the request but did not provide a response.