>La Grande Observer | Union and Wallowa Counties' News Leader

Listen closely, come dusk: Is there slightly less of a high-pitched whine in the air?

Union County Vector Control conducted aerial spraying from a fixed-wing aircraft over a little under 20,000 acres last Tuesday, primarily targeting the rural surroundings of Imbler and Union and overflow from the Grande Ronde River and Catherine and Willow creeks.

Kelly Beehler, vector control coordinator for the county, said he considered the spraying a success.

“It went extremely well,” he said.

He’s been monitoring mosquito numbers using traps, comparing the statistics before and after the aerial control.

Some traps are showing under 100 mosquitoes where, prior to the spraying, there were 1,200 to 1,300.

“In the main spray blocks, mainly in the middle, we got 90 to 95 percent reduction,” he noted.

Along the peripheries, the local mosquito population was culled by some 80 to 85 percent.

As vector control’s goal is an “acceptable level” of mosquitoes, Beehler said the results show “all the improvement we could hope for.”

The control plane generally flies at 300 feet while engaged, and Beehler said its course is sometimes slightly offset from the margins of the spray boundary to account for the effects of wind.

Before Tuesday night’s action, Beehler and his crew went door to door in the spray zone to inform those residents affected.

He said he hopes to ground-spray shortly in the Elgin area, where mosquito numbers have been elevated, and possibly also around North Powder, Cove and Foothill Road and the fairgrounds on the outskirts of La Grande.

No further aerial spraying is currently scheduled, although it could be a possibility later in the summer, Beehler said.

He’s on watch for this weekend’s high temperatures triggering the hatch cycle of permanent-water mosquitoes. The primary target of last week’s control were floodwater species. (The difference primarily involves the insects’ egg-laying habitat.)

Beehler also noted that the heat — forecasted to be close to 100 degrees on Sunday — will probably kill a certain number of birds in the area. But he urged people to only call vector control to report carcasses of corvids — crows, ravens, magpies and jays — or robins, which will be analyzed for West Nile virus prevalence.

To notify Union County Vector Control of such finds, report mosquito problems or seek assistance with standing water mitigation, call 963-2974.