Man's intentional and incidental meddling with the natural environment accounts for such pernicious transplants as walking catfish, fire ants, stinging (""killer"") bees, starlings, and water hyacinths. The Milnes, detailing the results of these noxious relocations, also look at castoff pets (giant land snails, caimans), species for sport (feral rabbits, pheasants), escaped laboratory animals, and the insects and seeds inadvertently carried by ships to foreign ports. They regret the accidental transports, the careless ignorance of vacationers, and the often ill-considered actions of government officials to right the balance. In addition, they examine puzzling but apparently natural disasters such as red tides and the few auspicious or harmless instances of transplants without complications--monarch butterflies and milkweed moving north, the Ross's gull appearance in New England. What they advise, as others have, is an ecological policy that establishes the value of each species as part of an interdependent network and coordinates preservation measures instead of expecting isolated efforts to suffice. A serviceable compendium from two concerned journeymen.