Butterfly Deaths Being Investigated

The government began an investigation into allegations that millions of monarch butterflies have been killed by pesticides at their winter nesting grounds in central Mexico.

Unusually high numbers of dead butterflies have been found in the forest where they spend the winter, according to an environmental group.

Police reported smelling the pesticide DDT around the time the dead butterflies were found, but they were unable to locate the source, Grupo de los Cien said. Biologist Xiomara Mora said the butterflies may have been killed by cold weather.