A band of bee-toting activists is about to haul a truckload of 2.5 million dead bees up to the front doors of America’s environmental regulator in Washington.

On June 22, in the heat of National Pollinator Week, the political theater is meant to urge Congress and the Environmental Protection Agency (EPA) to limit pesticide use they believe has caused a massive honey bee die-off. James Cook, a Minnesotan commercial bee keeper, has teamed up with environmental group Friends of the Earth and others to deliver the dead bees—many of which are from Cook’s farm—to the US capital.

Although some US states have implemented protection plans for pollinators that limit pesticide use, there is no overarching national regulation to address the plight of bees. In 2015, the EPA proposed some limits on insecticides, but they didn’t cover widely-used insecticide-coated seeds. Lobbying (pdf) from big pesticide companies, including Monsanto and Dow Chemical, has also hindered national action.

Earlier this year, beekeepers across the US reported they lost 44% of their colonies between April 2015 and April 2016, a statistic that was detailed in a May report by The Bee Informed Partnership, which works with the US Department of Agriculture to better understand and track the state of the honey bee population.

Scientists have yet to pinpoint a singular cause for honey bees’ rapid decline. Some have speculated the downfall is related to an abundance of varroa mites. Others have blamed it on stress, habitat loss, auto exhaust and the human use of class of insecticides called neonicotinoids (which are widely used on corn and soybean crops).

Many researchers point to a 2013 study published in PLOS One, which found traces of a pair of fungicides in hives hired out to pollinate crops that may compromise bees’ health.

For his part, US president Barack Obama created a task force in 2014 to try and sustain honey bee colonies—to little avail.