Erin Rupp donned pipe-cleaner antennae and stood outside the Home Depot in northeast Minneapolis on Wednesday to make a point about helping bees survive.

"If you're a homeowner and you want to plant more bee forage — which is one of the major ways to help bees — right now you don't have many choices," Rupp said. Many plants and shrubs available to consumers, she said, have been "pre-treated with a systemic pesticide that kills bees."

Rupp, co-founder of Beez Kneez, a Minneapolis-based honey delivery and bee education business, was one of about 30 adults and children handing out cookies and handmade valentines Wednesday to protest Home Depot's sale of neonicotinoids, a group of pesticides, and plants treated with them. The Minneapolis demonstration was one of dozens at Home Depot and Lowe's stores across the country this week designed to encourage the retailers to sell pesticides and plants that are friendly to the threatened pollinators.

Scientists and pollinator advocacy groups say neonicotinoid pesticides are partly responsible for declining bee populations worldwide. The pesticides are classified as "systemic" because they spread throughout the plant, protecting it from insects. Opponents first focused on reducing use by farmers, but are now widening the effort to nursery plants and home gardens.

Home Depot spokesman Stephen Holmes said in a statement that the company makes alternative pesticides available to customers and is studying the connection between these pesticides and the plight of bees.

"We've been in communication with the EPA, the insecticide industry and our suppliers for many months to understand the science and monitor the research," he said. "We're happy to provide customers with alternative [insecticides] and are actively working with our nursery suppliers to find alternative insecticides for protecting live goods and the bees."

Although government regulators in the United States have yet to act, the research showing that neonicotinoids are harming bees is in consensus, said Vera Krischik, a University of Minnesota entomologist who studies insecticide effects on bees.

In large doses, neonicotinoids can kill bees outright. But in small doses, Krischik said, the chemicals can confuse bees, making them forget where their hives are. So the bees don't return to the hive with food and over time the hive collapses.

Because the U.S. government isn't pursuing a ban, advocates say it's up to consumers to encourage stores like Home Depot to stop selling the pesticides.

"Consumers can really make a difference every time we're buying anything," said Rose Welch, general manager of the Organic Consumers Association. "And sometimes we can really get these companies to listen to us."

Rebecca Harrington is a University of Minnesota student reporter on assignment for the Star Tribune.