The polar bear at Norwich Castle Museum - Credit: Steve Adams

Scores of exhibits at Norwich Castle Museum - including the iconic 9ft polar bear - had to go into deep freeze to protect them from an insect invasion.

When the museum was practically empty during the Covid pandemic, it led to conditions which sparked an outbreak of the highly damaging clothes moth.

Female clothes moths - small, shiny golden-coloured insects with the Latin name Tineola bisselliella - laid eggs in between the hair of exhibits in the natural history collection at the museum.

Larvae from the clothes moth (Tineola bisselliella) meant exhibits in the natural history collection at Norwich Castle Museum had to be frozen - Credit: Olaf Leillinger By Olaf Leillinger https://commons.wikimedia.org/w/index.php?curid=929181

Once hatched, the tiny larvae like to eat animal-based material, feasting on the stuffed animals which are such a popular part of the museum.

To protect the exhibits and kill off the larvae, museum bosses launched a major cleaning and freezing project.

The specimens were frozen in huge freezers to kill off the moth adults, larvae and eggs without the use of harmful chemicals.

In the meantime, the cases the exhibits are displayed in were thoroughly cleaned before re-installation in recent months.

Council staff then helped to get the animals, including the largest specimen - the polar bear - back in their cases.

The polar bear at Norwich Castle Museum was among specimens frozen to kill off damaging clothes moths larvae - Credit: Steve Adams

Part of the castle is currently off-limits to the public while work on the multi-million pound Royal Palace Reborn project continues.

The ambitious project, which museum bosses hope will attract 100,000 more visitors to the castle each year, is recreating the keep's original 12th century layout.

Norwich Castle Museum - Credit: Norwich Castle

This is not the first time the castle museum has had to tackle a insect infestation among its collection.

In 2007, more than 1,000 specimens had to be frozen after the larvae of carpet beetles started chomping on exhibits.

On that occasion, a large walk-in freezer was installed in the bird gallery to freeze the specimens, including the polar bear and lions.

And in February, staff at Norwich's Strangers' Hall Museum embarked on a deep clean to protect the medieval merchant house and its collections.

Clothes moths had also become an issue at the Charing Cross museum, with the textiles collections threatened by the munching larvae.

Textiles identified as an issue were frozen in a walk-in freezer facility at the Norfolk Collections Centre in Gressenhall.