Meet the lodgers

摘要

The German cockroach lives in buildings, nowhere else; outdoors it dies. Exactly when Blatella germanica threw in its lot with humans is unknown, though it is generally thought to be African in origin and may initially have inhabited caves, as many modern roach species do. Wherever it arose, it spread around the world, following our ancestors everywhere they went, being a pest, causing a nuisance. Then, in the early 1990s, it came to the attention of Jules Silverman in the city of Raleigh, North Carolina. An entomologist by training, Silverman's job was to develop chemicals to kill German roaches. For a decade, the best product on the market had been roach baits - enticing sugar treats laced with pesticides. Now something had gone wrong. The baits were becoming increasingly ineffective, and Silverman needed to find out why. Discovering that the roaches in his lab still succumbed to the pesticide, he thought the simplest explanation was that their housebound counterparts had learned to avoid sugar, and were passing the lesson on from one to another. But Silverman found that newborn roaches separated from their mothers weren't attracted to the baits either.