A Wilsonville, Oregon, Target parking lot has seen what could be the biggest-recorded mass bumblebee die-off in the Western US. The 25,000 deaths were first noticed on Saturday, as bees tumbled from 55 linden trees in bloom, the Oregonian reports. "They were literally falling out of the trees," a biologist tells the Portland Tribune; he calculated that some 150 colonies likely met their end. Adds an agriculture official: "I've never encountered anything quite like it in 30 years in the business."
Pesticides—particularly a neonicotinoid called Safari that may have been sprayed by a landscape company on the trees on Saturday—could be to blame, though test results might not be in until the weekend. A Safari product label apparently warns that it's "highly toxic" for bees and shouldn't be used when they're around. Officials are now putting bee-blocking nets over the trees to halt the deaths, the Oregonian reports. Honeybee deaths have been widely reported, but bumblebees have also been in decline, the paper notes. "Bumblebees are the single most important natural pollinator in Oregon," says a conservation advocate. Interestingly, it's currently National Pollinator Week. (Read more bumblebees stories.)