As bee populations plummet in the US and Europe, people have been urged to plant bee-friendly gardens to create safe havens for the endangered little pollinators. But a first-of-its-kind study released today found that flowers and vegetables bought from American nurseries are contaminated with the same agricultural pesticides linked to the mass die-off of honey bees that pollinate a third of the food on your dinner plate.

An analysis of supposedly bee-safe backyard plants like daisies, tomatoes and salvia purchased from Home Depot, Lowe’s and other big-box US retailers discovered they were contaminated with neonicotinoids. That class of pesticide has been implicated in Colony Collapse Disorder, an affliction that has wiped out 10 million beehives over the past six years in the US. In April, European regulators banned the pesticide manufactured by Bayer CropScience and Syngenta for two years in response to crashing bee populations in France and elsewhere.

‘Gardeners may be unwittingly purchasing toxic seedlings and plants attractive to pollinators for bee-friendly gardens, only to poison them in the process,