BOCA GRANDE, Fla. -- Death and taxes may be life's only certainties, but for folks in this upscale island town, add iguanas. And another tax. During the last three decades, the resort community on Florida's Gulf Coast has been overrun by the spiny-tailed, nonnative lizards that demolish gardens, nest in attics and weaken beach dunes with burrows. Last month, Lee County commissioners agreed to create a special tax for Boca Grande to cover costs of studying the infestation on the barrier island of Gasparilla, where scientists estimate there are up to 12,000 iguanas on the loose, more than 10 for...