It is with dismay that I must report on another bumblebee kill, this time only about a mile away from the bees in my yard. All of the details are not in yet, but the basic picture is clear. Insecticide was sprayed early Monday morning, 6/16, on blooming linden trees in an apartment complex in northwest Eugene. Residents reported that the sidewalks were littered with dead and dying bees. Apparently officials from the Oregon Department of Agriculture (ODA) and Oregon State University were on the scene to collect samples and initiate an investigation. I’m sure we will know soon what was sprayed and who did it. [We know now that the chemical sprayed was imidacloprid.]
Recall that about this time last year more than 50,000 bumblebees were killed in Wilsonville. That prompted the ODA to issue restrictions on the neonicotinoids dinotefuran and imidacloprid, banning their use on linden trees. It is also against label directions to spray pesticides on blooming plants when there bees present.
I went to survey the bee kill scene this evening. The ODA and OSU investigators had gone, but the dying bees were still falling from the trees. Walking around the complex I identified eleven blooming linden trees that had been sprayed and had dead and dying bees on the ground under the trees. [I located two more sprayed lindens, bringing my total to 13 trees; the official report is that 17 trees were sprayed.] Under one set of three trees I counted about 300 bees on the side-walk. Easily there was 200 more in the grass and shrubbery. I later learned from one of the residents that she and others had swept the bees up already once and she was dismayed to continue to see them fall from the trees. My brief survey was apparently just the more recent victims. The eventual body count will depend significantly on what was sprayed. If the insecticide is one of the neonics, the chemical is designed to be taken up in the plant tissues, and the trees will be lethal to bees until after they stop blooming. If they were sprayed with a pyrethrin, then the worst toxicity will probably be gone in about a week.
That such a thoughtless act falls in the middle of Pollinator Week just illustrates how far we still have to go. Eugene may be the first city to ban the use of neonicotinoids on city property, but that action helps little when these chemicals are actively promoted and used by thousands of homeowners, landscapers, residential maintenance companies and pesticide applicator on private lands.
All this matters to me because my bees are in range of those trees. Right now the blackberry honey flow is still keeping most of the bees occupied, but the blackberry flowers are beginning to dry up and the bees will be looking further afield. Bees heading west from my house that find their way across the industrial railroad yard will come upon the very attractive linden blossoms.
The residents mentioned that the trees in their neighborhood often dripped a sticky mist from aphids in the summer. Apparently, this is not the first time that the trees have been sprayed, but this year they sprayed earlier than in previous years.
Although bee kills like this one will make headlines, it is the less dramatic impact of pesticides that are even much more troubling. Have these trees been poisoning my bees for years at sub lethal levels? How many pounds of these toxic pesticides are spread about in my bees’ foraging range? Is residential beekeeping doomed by thoughtless policy and people? The pollinators are weak this week.
[On a return trip Thursday afternoon, I wanted to see if more bees were finding the site during prime foraging hours. Indeed, I saw both bumblebees and honeybees visiting the trees, though not heavily. Curiously, there were no honeybees on the ground, just the bumblebees. I passed several more blooming lindens along River Road on my bike trip home. These trees were abuzz with activity, sporting ample numbers of both bumblebees and honeybees. ]