A helicopter hovering over the Laguna de Santa Rosa on Wednesday was dropping pellets laced with bacteria to kill mosquito larvae.

The operation by the Marin-Sonoma Mosquito Abatement District took about 55 minutes Wednesday morning and was conducted in the area between the two bridges on Occidental and Guerneville roads, said Erik Hawk, the district's biologist and projects manager.

Hawk blamed the outbreak of mosquitoes on the stagnant water and the thick ludwigia that is found in the laguna.

The helicopter was chartered from Alpine Helicopters of Lodi.