The San Francisco Examiner reports that the city employs six bicycle messengers as part of the mosquito-abatement efforts. The Chronicle has a simliar story, noting the name of the curiously effective pellets:
The pellets, a larvicide called Altosid, target only mosquitoes and will not disturb fish or other animals, health officials said. Cyclists will drop about 150 to 200 pellets a day and will distribute them multiple times to various catch basins throughout mosquito season, which runs through October.