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Oregon headed for bad summer of mosquitoes

Wet conditions and hot summer temperatures could mean a big year for mosquitoes in Oregon, officials said.

SALEM, Ore. -- Time to stock up on mosquito repellant.

Wet conditions and hot summer temperatures could mean a big year for mosquitoes in Oregon, officials said.

Multiple counties have already reported substantial mosquito activity, and that could continue late into the summer, said Emilio DeBess, state public health veterinarian.

“Will it be a big bug year? At this point, I’d say probably so,” DeBess said. “They’re certainly active already, and it’s pretty early.”

More: Oregon mosquitoes to be tested for Zika virus

The two conditions that drive mosquito populations are the amount of water and temperature, DeBess said.

Oregon’s wet winter and spring — plus a robust snowpack — mean the state is overflowing with H2O. That’s a good thing for mosquitoes.

“The more standing water — and running water to an extent — the easier it is for the female to lay eggs, hatch them and move on to get another blood meal and lay more eggs,” DeBess said. “So, based on the amount of water available, there is higher probability that there would be a lot of mosquitoes.”

The big question is how warm the summer will be. Hot temperatures could mean what DeBess called a “perfect storm” of conditions for mosquitoes.

And that’s exactly what long-term forecasts are predicting.

Oregon has a 60 to 70 percent chance of a hotter-than-normal July, August, and September, according to the National Weather Service’s climate prediction service.

“Warmer temperatures — especially above 80 degrees — basically allows the female to be more active in biting to get a blood meal, which helps them lay eggs,” DeBess said. “They don’t just get blood by biting humans, they get it by biting dogs, cats, deer, mice, birds, really any animal.”

The last time Oregon had a “big bug year” was 2013, DeBess said. Lots of rain plus a hot summer led to high mosquito activity. The last two summers have been hot but fairly dry, he said, leading to more normal mosquito populations.

The Oregon Health Authority does testing each year for diseases such as West Nile Virus, carried by mosquitoes, DeBess said. He said most West Nile cases occur in eastern and southern Oregon.

“But obviously, if there’s more mosquitoes there’s a higher likelihood of more West Nile infections,” he said. “That’s why we always encourage people to protect themselves. Most mosquito and tick-borne illnesses are preventable. The key is to enjoy summer, but protect yourself.”

OHA also has funding to test mosquitoes for the Zika virus, although Oregon is not considered a likely area for an outbreak of the disease.

Included below are methods for protecting yourself from mosquitoes and ticks from the Centers for Disease Control and Prevention.

Prevent Mosquito Bites

Insect repellent: Use an Environmental Protection Agency (EPA)-registered insect repellent with one of the following active ingredients. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women.

  • DEET. Products containing DEET include, but are not limited to, Off!, Cutter, Sawyer, and Ultrathon.
  • Picaridin and icaridin outside the United States. Products containing picaridin include, but are not limited to, Cutter Advanced, Skin So Soft Bug Guard Plus, and Autan (outside the United States).
  • Oil of lemon eucalyptus (OLE) or PMD, the synthesized version of OLE. Products containing OLE and PMD include, but are not limited to, Repel and Off! Botanicals. This recommendation refers to EPA-registered repellent products containing the active ingredient OLE (or PMD). “Pure” oil of lemon eucalyptus (essential oil not formulated as a repellent) is not recommended; it has not undergone similar, validated testing for safety and efficacy, is not registered with EPA as an insect repellent, and is not covered by this recommendation.
  • IR3535. Products containing IR3535 include, but are not limited to, Skin So Soft Bug Guard Plus Expedition and SkinSmart.


Cover up: Wear long-sleeved shirts and long pants.

Keep mosquitoes outside: Stay in places with air conditioning or that use window and door screens. If you are not able to protect yourself from mosquitoes inside your home or hotel, sleep under a mosquito bed net.

Tick protection

  • Avoid Direct Contact with Ticks
  • Avoid wooded and brushy areas with high grass and leaf litter.
  • Walk in the center of trails.

Repel Ticks on Skin and Clothing

  • Use repellent that contains 20 percent or more DEET, picaridin, or IR3535 on exposed skin for protection that lasts several hours.
  • Always follow product instructions. Parents should apply this product to their children, avoiding hands, eyes, and mouth.
  • Use products that contain permethrin on clothing. Treat clothing and gear, such as boots, pants, socks and tents with products containing 0.5% permethrin. It remains protective through several washings. Pre-treated clothing is available and may be protective longer.
  • The Environmental Protection Agency (EPA) has an online tool to help you select the repellent that is best for you and your family.

Find and Remove Ticks from Your Body

  • Bathe or shower as soon as possible after coming indoors (preferably within two hours) to wash off and more easily find ticks that are crawling on you.
  • Conduct a full-body tick check using a hand-held or full-length mirror to view all parts of your body upon return from tick-infested areas. Parents should check their children for ticks under the arms, in and around the ears, inside the belly button, behind the knees, between the legs, around the waist, and especially in their hair.
  • Examine gear and pets. Ticks can ride into the home on clothing and pets, then attach to a person later, so carefully examine pets, coats, and day packs.
  • Tumble dry clothes in a dryer on high heat for 10 minutes to kill ticks on dry clothing after you come indoors.
  • If the clothes are damp, additional time may be needed.
  • If the clothes require washing first, hot water is recommended. Cold and medium temperature water will not kill ticks effectively. If the clothes cannot be washed in hot water, tumble dry on low heat for 90 minutes or high heat for 60 minutes. The clothes should be warm and completely dry.

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