A pioneering trial to protect treasures at Norfolk's Blickling Hall by using parasitic wasps to wipe out moths munching through materials has been discontinued.

The National Trust carried out a trial at the historic house using microscopic wasps and moth hormones to target common clothes moths, which eat carpets, furniture, clothing and other wool and silk objects.

Eastern Daily Press: Tiny parasitic wasps were used at Blickling Hall to control common clothes moths. Pic: National TrustTiny parasitic wasps were used at Blickling Hall to control common clothes moths. Pic: National Trust (Image: National Trust)

The tiny wasps lay their own eggs inside moth eggs, so a wasp, rather than a moth larva, hatches.

But the trial found the wasps were no more effective in cutting clothes moths numbers than the use of pheromones to emulate the natural chemicals female moths give off, confusing the males at mating time.

Eastern Daily Press: Evidence of clothes moth damage on a carpet in the state bedroom at Blickling Hall. Pic: National Trust / Kenny GrayEvidence of clothes moth damage on a carpet in the state bedroom at Blickling Hall. Pic: National Trust / Kenny Gray (Image: National Trust / Kenny Gray)

Assistant national conservator Hilary Jarvis said: "The microwasps performed well in terms of reducing moth populations in combination with pheromones, but no better than where we’d used pheromones alone."

Eastern Daily Press: Blickling Hall. Pic: National TrustBlickling Hall. Pic: National Trust (Image: National Trust)

The trust may still use microwasps to tackle moths in small collection stores or where the source of the infestation is known, but the trial will now focus exclusively on testing natural moth pheromones.