Mosquitoes are many, and they're hungry for your blood

(TROY WAYRYNEN/Columbian files)

An abundant mountain snowpack has created perfect conditions for mosquitoes to thrive in Southwest Washington.

Nels Madsen Jr. and his family found out the hard way on the Fourth of July.

The Skamania County resident spent Independence Day at Captain William Clark Park on the Columbia River with his family, including his wife, daughter, son-in-law and their twin babies. He said the family enjoyed the day picnicking at Cottonwood Beach, right up until dusk began to fall.

About an hour and half before the big fireworks show, the bugs emerged.

"My whole shirt was completely black from the mosquitoes," Madsen said. "They were just eating me right through the shirt."

Other residents have reported similar clouds of pesky mosquitoes this year.

The nine employees of the Clark County Mosquito Control District have been kept busy since early May setting out sampling traps and spraying larvicide by the gallon. Most of their quarry is the native and relatively harmless floodwater mosquitoes.

"These are basically nuisance mosquitoes," said Jonnie Hyde, public health services manager for Clark County. "When there are this many breeding spots because of floodwater infiltrating to the lowlands, it's very difficult for them to totally maintain the absence of mosquitoes."

Employees are also sampling to find a type called the culex, which can carry West Nile Virus.

Steve Kessler, the district's operations manager, said the district has already treated 2,130 acres with 15,900 pounds of Bti, a bacterial toxin that infects and kills mosquito larvae. That's almost 2½ times the acreage and volume as last year, and it only includes aerial application by helicopter.

"We have done a lot more on the ground," he said.

The reason for this year's booming population? Kessler, who's been on the job for 25 years, cites two culprits working in tandem — Mother Nature and the Army Corps of Engineers. A bountiful mountain snowpack last winter has resulted in plenty of snowmelt pouring into the Columbia River and its tributaries. The Corps of Engineers, which operates federal dams on the Columbia River, has adjusted by passing the water downstream.

At Vancouver, some 40 miles below Bonneville Dam, a relatively high Columbia River has backed up smaller streams such as Salmon Creek and the Washougal River.

After taking a blood meal, adult mosquitoes will deposit their eggs in the receding water line. Kessler said these eggs can lay dormant for as long as 15 years. If the water comes back up, as it has several times this spring and early summer, the eggs will hatch.

"What this does is, it keeps this cycle going and it creates another hatch," Kessler said.

On Tuesday afternoon, district employees Kevin Hart and Fred Bartow ventured into a state wildlife reserve in the Vancouver Lake lowlands. Hart hung a small trap filled with dry ice, which attracts mosquitoes by emitting carbon dioxide. A battery-powered LED light attracts even more mosquitoes during the night, and a small fan keeps them from leaving the net.

"I would not be surprised if there are a thousand mosquitoes in there tomorrow," said Hart, who, like Bartow, has a full-time job as a Vancouver firefighter.

If more than 25 are of the culex variety, they'll send them on to the University of California-Davis to test for West Nile Virus.

In the meantime, employees will continue spraying larvicide in low-lying areas and hot spots. By the time the season ends in September, the district will have treated some 35,000 storm drains and catch basins at least twice. "The product will keep working up to 30 days in ideal conditions, so we have to come back and re-treat," Kessler said.

In hot spots such as Cottonwood Beach, mosquitoes can take over.

Madsen, whose father happens to lead the Mosquito Control District in Skamania County, said he had applied bug spray and took care to cover up. It didn't seem to matter. Mosquitoes emerged en masse just as the breeze died down and the sun dropped, he said.

The family skipped the fireworks.

"I watched on TV at home," Madsen said, "where the mosquitoes weren't going to eat me alive."