The reason the bugs are attracted to this smell is that they use it to navigate back to their hidey-holes after a night of feeding. To develop the bait for the new trap, Dr Weeks therefore analysed the chemicals given off by bed-bug faeces and attempted to work out which of the components were acting as signposts. She did this by puffing air collected from a jar containing bed-bug faeces into a machine called a gas chromatograph, which separated the components from one another, and then through a mass spectrometer, to identify each component from its molecular weight. Having found what the smell consisted of, she wafted the chemicals in question, one by one, at bed bugs that had their antennae wired up to micro-electrodes, to see which of them provoked a response.

The result, the details of which the team is keeping secret for the moment for commercial reasons, is used to bait a trap, designed by Dr Logan, that is about the size of a standard mouse trap and has a sticky floor similar to fly paper. And it works. To paraphrase the slogan of Roach Motel, a brand of traps aimed at a different sort of insect pest, bed bugs check in, but they don’t check out.

The new trap could be used both to assess whether a hotel room or apartment is infested and also to kill the insects without dousing everything in insecticide—which is, in any case, an increasingly futile exercise, as many have now evolved resistance. Ralph Waldo Emerson, a 19th-century American sage, is supposed to have said that if a man built a better mousetrap than his neighbour, the world would make a beaten path to his door. Dr Logan and Dr Weeks are about to find out if the same thing applies to bed-bug traps.