Mosquito Control District to Begin Spraying Areas of Umatilla County


The West Umatilla Mosquito Control District has begun implementing its 2020 mosquito control program and is also taking measures to keep the public and its employees as safe as possible during the COVID-19 pandemic while achieving its goal of protecting the public from mosquito-borne disease.

Policy changes include:

  • The district office will be closed to the public until further notice
  • Face to face service requests with the public will be avoided
  • Only established regular mosquito control activities will be performed until further notice
  • All communication with the public will be via phone at (541) 567-5201

The district, which serves a 525-square-mile area in Western Umatilla County, including the towns of Hermiston, Umatilla, Stanfield and Echo, will target areas of standing water where mosquito larvae thrive. Large water bodies will be sprayed with a helicopter while smaller areas will be treated by hand.

To control adult mosquitoes, the district plans to make treatments using truck-mounted, ultra-low volume sprayers. This spraying will be done after sunset in areas of the district that have large populations of adult mosquitoes. In rural areas, the district will begin aerial spraying to control adult mosquitoes when mosquito trap collections indicate the need for large scale spraying. Aerial spraying for adult mosquitoes will be done in the early evening hours just after sunset.

About 45 species of mosquitoes are found in Oregon. Within the district boundaries, 12 of these species are commonly found in a variety of habitats. The common house mosquito (Culex pipiens), along with the Culex tarsalis, species very common in the district, have been targeted as vectors of West Nile virus.

West Nile is primarily a bird disease, and some birds, including magpies, blue jays and crows are especially susceptible. Mosquitoes become infected by feeding on an infected bird and can pass the virus to humans, horses or other hosts when they bite. The public is encouraged to continue to alert district officials when they come across dead birds, so the district can track the spread of the virus.

The risk of West Nile is low but people are encouraged to take appropriate precautions to protect themselves against mosquito bites. Most people who become infected with West Nile Virus do not become ill. Some may develop mild flu-like symptoms such as fever, headache, body aches, and occasionally swollen lymph glands or a rash. In rare cases West Nile may cause encephalitis, or inflammation of the brain. Individuals with severe or unusual headaches should seek medical care as soon as possible.

Now that the COVID-19 has spread throughout Oregon and the world, the district has received some questions from concerned residents about whether mosquitoes can transmit the virus. According to information obtained from the American Mosquito Control Association website, the Center for Disease Control and Prevention has stated that “Mosquitoes and ticks can’t spread all types of viruses. At this time, we have no data to suggest that Covid-19 or other similar coronaviruses (e.g. SARS, MERS) are spread by mosquitoes or ticks. For a virus to pass to a person through a mosquito or tick bite, the virus must be able to replicate inside the mosquito or tick.”

The district will continue to monitor the situation through its association with the AMCA and its public health partners.

To prevent mosquito bites, residents are encouraged to:

  • Vaccinate horses for West Nile virus
  • Wear repellents while outdoors at dusk and dawn when mosquitoes are most active
  • Wear long-sleeved shirts and long pants when in mosquito-infested areas
  • Use mosquito repellents containing DEET, Oil of Lemon Eucalyptus, Picaridin or 2-undecanone, making sure to follow the label directions on the container
  • Use EPA registered residual insect sprays on horses making sure to follow the label directions on the container
  • Make sure all screen doors and windows are in good repair and fit tightly
  • Eliminate all sources of standing water which act as a breeding ground for biting mosquitoes. This includes flooded fields, birdbaths, unused wading pools and swimming pools, clogged gutters and old tires. If it holds water for 7 days, it can produce mosquitoes
  • Stock mosquito fish in water troughs and ornamental ponds. They are available for free at the district office

If for any reason you do not wish to have your property sprayed, please call the mosquito control hotline at 541-567-5201 and asked to be placed on the no-spray list.

For more information on West Nile Virus, go to the Oregon Department of Human Services web page.


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