Kevin Cokely, NBC 5 News
Dallas beekeepers oppose aerial spraying for mosquitoes, but state health officials say the risk to bees and animals is "very low."
Local beekeepers are circulating an online petition to stop aerial spraying for mosquitoes.
There are 502 human cases of West Nile virus in North Texas as of Tuesday. Fourteen people have died, including 10 people in Dallas County.
Dallas County has authorized aerial spraying to help fight West Nile virus. Garland, Mesquite, University Park and Highland Park have approved the spraying, while other cities in the county are still deciding whether to conduct it.
"They're very deadly to bees, and it's not just honeybees -- there's other invertebrates that are going to be compromised by this," said Brandon Pollard, a Dallas beekeeper.
The state health department said the risk to bees and animals is "very low" because of the low toxicity, concentration and volume used during aerial spraying.
"The spraying is done at night to reduce potential exposure and minimize the risk to insects such as bees and butterflies that are likely sheltered and not flying during that time," a Department of State Health Services representative said by email.
Mosquito control experts warn that covering hives and fishponds to protect them could do more
"if you do cover, do it very loosely because they need air during the night," said Dan Markowski, of Vector Disease Control.
The aerial spraying is approved for use in outdoor and residential areas and is applied at very low dosages -- less than an ounce per acre -- the DSHS said. The department also said the pesticide is applied in small droplets that quickly degrade and do not bioaccumulate.
Health officials say people can remove the pesticide dropped during aerial spraying from clothing and skin with soap and water.
Officials recommend people stay indoors with their windows closed and rinse homegrown fruits and vegetables. Because the chemical quickly breaks down, people do not take any special precautions for their swimming pools.
Tuesday night's thunderstorms could delay scheduled ground spraying for mosquitoes in the Park Cities and North Dallas. The trucks were positioned and waiting for the storms to pass as of late Tuesday night, but the rain was expected to continue for much of the night.
NBC 5's Kevin Cokely contributed to this report.