Volunteers trapping for Asian giant hornets next year won’t be asked to mail in all the insects they catch, Washington State Department of Agriculture spokeswoman Karla Salp said.
The department has examined thousands of captured specimens and found 1.5% were bees. The department was worried that the traps, baited with a sweet liquid mixture, would attract and drown a higher percentage of pollinators.
Thousand of collections still must be examined, but the department is satisfied the traps aren’t a threat to the bees that hornet trappers are trying to protect.
“The point of having people mail in everything was to make sure the traps weren’t having unintended consequences,” Salp said. “We’re not killing off a lot of bees with these traps, which was our main concern.”
Hundreds of people responded to the department’s call last summer to make and hang traps baited with orange juice and rice cooking wine. One volunteer caught an Asian giant hornet, and many faithfully submitted what they collected each week, either by mail or in drop boxes.
The collateral catch included moths, fruit flies, paper wasps, yellow jackets and spotted wing drosophila, an invasive pest that damages fruit. The department also reported detecting for the first time in the U.S. a parasitoid wasp, Leptopilina japonia, that preys on spotted wing drosophila. One was found in British Columbia last year, according to the department.
Next year, trappers will be asked to report suspected Asian giant hornets. The rest, though, can be tossed out.
Salp said she expects more people will set traps next year, knowing they won’t be asked to mail or take to drop boxes insect remains.
“It’s amazing the level of commitment people had,” she said. “But I think it’ll increase the level of participation and decrease the level of dropping out. It’s going to make it simpler.”
According to a department survey of about 380 volunteers, the most popular reason for hanging traps was to protect honey bees, followed by protecting agriculture. The least cited among eight motives was fear of Asian giant hornets.
The department invited comments on the “worst part” of trapping. Many said it was sealing up specimens and sending them in.
Asian giant hornets, the world’s largest stinging wasps, attack honey bee hives. They were unknown in the U.S. until a year ago.
Since then, the agriculture department has trapped hornets in several places in Whatcom County in northwest Washington. Hornets also have been found across the border in British Columbia.
The department found and eradicated one nest near Blaine in October. The department assumes there were other nests that were not found. Queens that could establish nests next year are hibernating, so the trapping season has ended.
Trapping Asian giant hornets was a new problem. The agriculture department circulated instructions on fashioning homemade traps from plastic bottles and straining out the trap’s contents each week before the liquid bait became too smelly.
The department also traps for Asian gypsy moths. The traps are baited with pheromones, so they rarely attract another type of insect and don’t grow odoriferous. The USDA is working on developing a pheromone-baited trap for Asian giant hornets, seen by entomologists as vital to efficient trapping.
Salp said volunteers will again be asked next year to bait traps with orange juice and rice cooking wine.