Daniel P. Molloy has been trying to get rid of an unwelcome guest for more than a decade. He may finally have found a solution: a bacterial toxin that can kill the uninvited caller.
No need to alert the homicide squad. The focus of Molloy's wrath is the lowly invertebrate Dreissena polymorpha, better known as the zebra mussel.
After entering North America more than a decade ago, probably in the ballast water of a ship from Europe, these mussels have proliferated rapidly in waters of eastern Canada and the United States. In doing so, they've driven out native mussels, altered the ecology of freshwater lakes and streams, and blocked the water-carrying pipes of power plants and many other industrial facilities (SN: 5/4/91, p. 282).