Can I use clothes moth traps to control leek moth?
Paul Richards, by email
Stefan says: Let's consider what clothes moth traps are and how they work. They're pheromone traps; a pheromone is a chemical produced by an animal that activates a response in another individual. They're especially well understood in insects where sex pheromones produced by females serve to attract males.
By producing artificial equivalents of natural pheromones, it’s possible to trick male insects into believing a female is the source. And if the pheromone is incorporated onto a sticky card (which constitutes the actual trap) it traps the male. But what good does that do? Not much, as it's not the male moths that eat clothes! All it tells you is how many male moths are around. Unless you trap every male moth in the area, which is impossible, you won't reduce the number of breeding pairs or the number of larvae that do the damage.
In horticulture, pheromone traps are available for several pest species, including leek moth, plum moth, codling moth and box tree moth, but most importantly, all are species specific. In other words, a codling moth trap will not attract plum moths and a clothes moth trap will not attract leek moths.
In commercial horticulture, pheromone traps are used principally to monitor the number of insects present at any one time in order to indicate when a chemical spray needs to be applied. They aren't used, therefore, as control measures in themselves. In the smaller scale horticulture of gardens however, they are of some merit in reducing the population of male insects and so will go part of the way towards protecting your crop, although they won't provide a complete answer. If it offers you any encouragement, I use plum moth traps in my own garden and find they do help, but codling moth traps, I've found, have less impact.