NHS officials have defended their decision to employ thousands of bats at a Scottish hospital.
The bats were brought into Ninewells Hospital in Dundee after unseasonably large numbers of common pests like moths, lizards, ants, cockroaches and bantams were spotted in general medical wards and specialist outpatient departments.
Facilities manager Bill McKay said: "We had a dreadful problem with moths in the operating theatre, buzzing around the light fittings and falling into patient's chest cavities or getting lodged in their throats.
"The bats have made a real difference. It's just the hornets we need to take care of now, but the bats won't go near them."
The Ninewells bat strategy is part of a UK-wide NHS initiative to reduce ward-based vermin levels to 420 per patient by 2011.
McKay added: "Initially we discovered a colony of pharaoh ants that were thriving off all the blood on the floor in A&E. To get rid of them properly would have cost something in the region of £100 so we had to start thinking outside the box.
"We simply transferred a load of giant dung beetles from radiography and they were gone in no time.
"What we didn't realise is that the beetles loved to crawl up patients' trousers and lay eggs in their genitals, so of course, they had to go. So that explains, to some extent, the disproportionate number of chameleons in there at the moment."
McKay has assured patients the bats and chameleons are a necessary measure to rid the hospital of pests, but insisted an end is in sight: "As you get further and further up the food chain, the less predators are required to keep numbers in check. For example, we envisage only needing two alligators to deal with the nuisance water buffalo in the canteen."