State Sprays for Mosquitoes in Montgomery County, What You Can Do at Home

By Eliza Cava , Director of Conservation for Audubon Naturalist Society
Aedes Mosquito. Photo credited to Maryland Department of Health and Mental Hygiene

Aedes Mosquito. Photo credited to Maryland Department of Health and Mental Hygiene

Two ANS members recently told us about spraying to kill adult mosquitoes on Monday night, August 22, in several locations in Montgomery County. We looked into it and here’s what we learned. The Maryland Department of Agriculture (MDA) conducts mosquito spraying in some counties on a regular basis, and statewide in response to specific public health concerns. Mosquito spraying is not regularly conducted in Montgomery County.  However, some homeowners’ associations and specific developments contract directly with the MDA for the service. According to MDA, this week’s mosquito spraying in Montgomery County was a one-time action in response to a public health concern related to Zika or West Nile virus, and will not be regularly scheduled going forward unless mosquito-related public health concerns arise again. What You Can Do At Home to Control Mosquitoes
  • Reduce standing water in puddles, drainage ditches, gutters, structures, plastic objects, etc. The Asian Tiger Mosquito can breed in as little as a bottlecap of standing water.
  • Residents, schools, churches, and business owners should patrol properties and drain, cover, or overturn any container that holds or could hold water.
  • Add an aerator or fountain to birdbaths or ornamental ponds. Mosquitoes do not breed in moving water.
  • Dump and scrub saucers under potted plants and flush birdbaths at least once a week.
  • If you own a rain barrel, make sure that you use debris screens, keep the barrel tightly closed, and use collected water within a week.
  • Fix dripping outdoors water faucets, and get rid of any puddles that form under window air conditioners.
  • Reduce your exposure by wearing light colored long sleeves and pants while working outside, and follow the CDC guidelines for applying insect repellent.
Hmm . . . Keeping Our Streams Clean This issue raises some questions for us about protecting our waterways, fish and the aquatic life that live in them from toxins. While a targeted, one-time spray presents limited risk to human, animal, and even aquatic life, with climate change we may see more disease-carrying mosquitoes like the Asian Tiger Mosquito (Aedes albopictus) and other Aedes species. Any increased presence of these mosquitoes and the ongoing incidences of travelers coming home with Zika virus means that we will likely have more one-time sprays in the future. The MDA uses the insecticide permethrin for ground-based spraying. Permethrin is a synthetic version of chemicals such as those produced by chrysanthemums and is in a class known as pyrethroids. Pyrethroids are considered to be less harmful to birds and mammals than older-style organophosphate chemicals. However, pyrethroids still pose substantial risk to wildlife. Besides being deadly to beneficial insects like honeybees if they are exposed, they are highly toxic to fish and aquatic life if they get into streams. A pyrethroid spill in 2000 caused the deaths of tens of thousands of fish in Rock Creek, and even very low concentrations in water can be toxic to the insects that form the basis of the aquatic food web—the very same Creek Critters that ANS monitors to determine water quality. It is essential that creeks and streams be protected from pyrethroid exposure to protect the wildlife that live within them. According to the MDA, the US Environmental Protection Agency (EPA), which regulates pesticides, removed a requirement that users avoid spraying permethrin within 100 feet of lakes, streams, ponds, rivers and other water. The state’s practice is to continue to use a 100’ buffer for spraying if the wind is blowing in the direction of a water body. ANS will be reaching out to the EPA to find out what happened to the mandatory buffer requirement and will continue to work with public sector partners to keep our creeks and streams protected from contamination. MDA Mosquito Resources              

About Eliza Cava

Eliza Cava is the ANS Director of Conservation, where she leads our MD & DC policy, advocacy, and conservation outreach work, supervises our citizen science programs and VA advocacy work, and supports Woodend restoration as a demonstration landscape for the region.
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