If there’s anything mosquitoes need more than blood it’s water, and Baker County is pretty soggy this spring.
This has Matt Hutchinson worried.
Hutchinson is starting his seventh season as the area’s chief mosquito killer, and he’s bracing for an active stretch.
“I’m preparing for a busy season — busier than last year,” Hutchinson said Tuesday afternoon.
The 2018 season started relatively fast but it ended slow, mainly due to the severe drought that dried some of the water sources where mosquitoes lay their eggs, said Hutchinson, who manages the 200,000-acre Baker Valley Vector Control District.
He’s responsible for dealing with mosquitoes in the property tax-funded district, which includes much of Baker Valley (including Baker City) as well as Bowen and Keating valleys.
But 2019 much more resembles 2017, when the melted remnants of a heavy snowpack gave mosquitoes an abundance of breeding areas.
“2017 was a busy year start to finish,” Hutchinson said. “This looks more like that.”
Hutchinson said he and a co-worker have been checking some notorious breeding sites for the past week or so, looking for larvae.
They apply products, sometimes from the ground and occasionally from the air, that kill larvae before they hatch into adults that can fly and, in the case of female mosquitoes, bite people and other mammals to procure the “blood meal” the insects need to nourish their eggs.
This approach isn’t always successful, so Hutchinson also has at his disposal insecticides that kill adult mosquitoes.
The biggest pests around here by far are floodwater mosquitoes, Hutchinson said. They breed in both natural water sources — ponds and the like — and in flood-irrigated fields and pastures.
The combination of heavy rain and melting snow earlier this month created plenty of temporary pools around the county, but Hutchinson said he has seen little evidence that those are harboring mosquitoes.
The reason, he said, is temperature.
The warmer the water the faster the bugs progress through their life cycle, and when the pools were most plentiful the temperatures were low enough to slow the process.
“Temperature definitely plays a big role,” Hutchinson said.
Fortunately, much of the water has soaked into the ground, leaving the larvae, in effect, high and dry.
“With the lower temperatures mosquitoes aren’t going to have enough time to hatch out before the water dries up,” he said.
But with a warming trend over the past week or so, Hutchinson expects to start seeing a proliferation of larvae.
He has already received a few phone calls from residents reporting adult mosquitoes (he encourages people to call his office at 541-523-1151 and leave a message if he’s out).
Hutchinson said he’s seen some in his own yard.
The culprits, he said, aren’t floodwater mosquitoes but rather anopheles species that can survive winter, as adults, by sheltering in garages or other relatively warm spots.
When temperatures rise to around 70 or above — as it did at the Baker City Airport on Thursday and Friday, and again Monday and Tuesday — those mosquitoes rouse from their winter sluggishness.
And the females are hungry.
“They’re looking for a blood meal so they can go lay their eggs,” Hutchinson said. “They’re pretty aggressive at this time of year.”
As the season progresses the floodwater species — mainly from the aedes genus — become the predominant problem in the area, he said.
Another common summer mosquito is the culex tarsalis, the type that most frequently carries the West Nile virus.
Last year was the first in Hutchinson’s tenure with the Baker Valley Vector Control District in which none of the more than 260 samples of mosquitoes he trapped for testing, the majority of those culex tarsalis, was infected with that virus.
The absence of a positive test was “really surprising,” he said.
“I kept expecting it to pop up,” Hutchinson said.