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Sending moths confusing sex signals is saving Museum specimens

Convincing male clothes moths to chase other males instead of females is reducing the population of a pest damaging the Museum’s collection.

Clothes moths are increasingly attacking irreplaceable taxidermy specimens at the Museum. But Museum staff have found a way around the problem by coating male clothes moths in female pheromones – natural sex chemicals. This leads males to waste time chasing other males instead of females, thereby reducing the number of offspring produced.

The moths find shelter in the dark corners of the Museum and lay their eggs on specimens on display at night. The pheromone technique has reduced the numbers of moths in the public galleries to manageable levels, with up to 50 per cent fewer moths observed since the worst outbreak.

Museum pest management co-ordinator Armando Mendez explained how the technique works. He said: ‘The moths only live between 15 and 30 days, and during that time there is only a small window in which they can reproduce. If they spend this unknowingly attempting to attract and fertilise male moths, then it reduces the offspring we are up against.’

Problem pests

Clothes moths have become a major problem for Museum specimens in the last six years. Mendez says this is likely due to a combination of factors including more human activity, which means there is more food around, and warmer temperatures, which lead to three or four breeding cycles per season rather than the usual two.   

To curb the spread, female pheromones are sprayed in an infected area, which attracts male moths who are then covered in the chemical. Other male moths follow these chemical signals, but find another male at the end of the trail instead of a female they can mate with.

The environmentally friendly technique doesn’t kill moths or use traditional pesticides. It is part of the Museum’s larger integrated pest management scheme, aimed at reducing pests by understanding their biology rather than broadly applying potentially dangerous chemicals.

The whole picture

By collecting data on where pest outbreaks occur, Mendez and his team can look for patterns in environmental conditions with a view to understanding what drives up certain pest population numbers. For example, silverfish are often associated with dampness and clothes moths are often found near rodent habitats.

Simple methods can then be used to reduce potential infestations, such as fixing leaky pipes that can cause dampness, or reducing available food to prevent the spread of mice or beetles. ‘The solutions are simpler, but you have to know the biology of the pest,’ said Mendez.

The Museum also employs high-tech methods to reduce pests, such as a -30°C deep freeze large enough to fit an adult rhinoceros, and heating and drying treatments for damaged and incoming specimens. These methods kill any larvae or eggs on specimens to prevent potential infestations.