U.S. House Republicans are threatening to exterminate a proposal that would require school districts to notify parents of pesticide use on school grounds. Senate leaders added the measure to President Bush’s education bill after consulting with educators, environmentalists, and representatives of the pesticide industry. Some pesticide manufacturers and school officials argue, however, that the measure would discourage pest control and increase costs and legal liability at schools. More than 30 states have similar pesticide-notification regulations on the books.