It's time to stock up on mosquito repellent.
A “perfect storm” of 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.”
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 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.