Certain plants from large garden centers such as Home Depot are labeled as "bee friendly," but many of them are pre-treated with hazardous pesticides.

Seven out of 13 samples taken of plants from top retailers in various states tested positive for pesticides, a Friends of the Earth press release reported.

"Our investigation is the first to show that so called 'bee-friendly' garden plants contain pesticides that can poison bees, with no warning to gardeners," Lisa Archer, director of the Food and Technology Program at Friends of the Earth, said. "Bees are essential to our food system and they are dying at alarming rates. Neonic pesticides are a key part of the problem we can start to fix right now in our own backyards."

Neonicotinoids are pesticides commonly used in cosmetic garden treatments and agriculture, it has been suggested these chemicals are a key factor in declining bee populations.

Beekeepers have reported a 40 to 90 percent decline in bee populations over the past winter.

Tree in the parking lot of an Oregon Target were sprayed with a neonic pesticide, resulting in the death of over 25,000 bees, a Pesticide Research Institute press release reported.

Europe is set to ban the pesticides later this year; a European Food Safety Authority found the neonicotinoids pose an "unacceptably high risk," to pollinating insects.

"We must take immediate action to address this crisis. Europe has banned bee-harming pesticides, retailers in the UK are refusing to sell them, and stores like Home Depot and Lowe's have a moral obligation to make the same commitment here in the U.S.," Lisa Archer, said. "In the meantime, gardeners should start their plants from untreated seeds or choose organic plants for their gardens."

Even if the neonic dose is not high enough to kill the bees, it can still "weaken [the bees'] immune systems and impair critical brain functions, making it hard for bees to find their food sources and return to the hive," Emily Marquez, staff scientist at Pesticide Action Network said.