Or at least that’s what they tell you at the company’s Bee Care Center on its sprawling campus here between Düsseldorf and Cologne. Outside the cozy two-story building that houses the center is a whimsical yellow sculpture of a bee. Inside, the same image is fashioned into paper clips, or printed on napkins and mugs.

“Bayer is strictly committed to bee health,” said Gillian Mansfield, an official specializing in strategic messaging at the company’s Bayer CropScience division. She was sitting at the center’s semicircular coffee bar, which has a formidable espresso maker and, if you ask, homegrown Bayer honey. On the surrounding walls, bee fun facts are written in English, like “A bee can fly at roughly 16 miles an hour” or, it takes “nectar from some two million flowers in order to produce a pound of honey.” Next year, Bayer will open another Bee Care Center in Raleigh, N.C., and has not ruled out more in other parts of the world.

There is, of course, a slight caveat to all this buzzy good will.

Bayer is one of the major producers of a type of pesticide that the European Union has linked to the large-scale die-offs of honey bee populations in North America and Western Europe. They are known as neonicotinoids, a relatively new nicotine-derived class of pesticide. The pesticide was
banned this year for use on many flowering crops in Europe that attract honey bees.

Bayer and two competitors, Syngenta and BASF, have disagreed vociferously with the ban, and are fighting in the European courts to overturn it — leading one advocacy group, Corporate Europe Observatory, to call the three companies “the bee killers.”

The Environmental Protection Agency has said its “scientific conclusions are similar to those expressed” by European regulators, but has not seen enough grounds to put into effect its own ban. An internal E.P.A. document leaked in 2010 said the “major risk concern” of one of the pesticides, Bayer’s clothianidin, which is used to coat cotton and mustard seeds, “is to nontarget insects (that is, honey bees),” calling it “highly toxic.” A coalition of beekeepers and environmental groups is suing the agency to press for a ban.

Not everyone believes Bayer cares about bees.

Hans Muilerman, a chemicals expert at Pesticide Action Network Europe, an environmental group, accused Bayer of doing “almost anything that helps their products remaining on the market. Massive lobbying, hiring P.R. firms to frame and spin, inviting commissioners to show their plants and their sustainability.”

“Since they learned people care about bees, they are happy to start the type of actions you mention, ‘bee care centers’ and such,” he said.

There is a bad guy lurking at the Bee Care Center — a killer of bees, if you will. It’s just not a pesticide.

Bayer’s culprit in the mysterious mass deaths of bees can be found around the corner from the coffee bar. Looming next to another sculpture of a bee is a sculpture of a parasite known as a varroa mite, which resembles a gargantuan cooked crab with spiky hair.

The varroa, sometimes called the vampire mite, appears to be chasing the bee next to it, which already has a smaller mite stuck to it. And in case the message was not clear, images of the mites, which are actually quite small, flash on a screen at the center.

While others point at pesticides, Bayer has funded research that blames mites for the bee die-off. And the center combines resources from two of the company’s divisions, Bayer CropScience and Bayer Animal Health, to further study the mite menace.

“The varroa is the biggest threat we have” said Manuel Tritschler, 28, a third-generation beekeeper who works for Bayer. “It’s very easy see to them, the mites, on the bees,” he said, holding a test tube with dead mites suspended in liquid. “They suck the bee blood, from the adults and from the larvae, and in this way they transport a lot of different pathogens, virus, bacteria, fungus to the bees,” he said.

Conveniently, Bayer markets products to kill the mites too — one is called CheckMite — and Mr. Tritschler’s work at the center included helping design a “gate” to affix to hives that coats bees with such chemical compounds.

There is no disputing that varroa mites are a problem, but Mr. Muilerman said they could not be seen as the only threat.

The varroa mite “cannot explain the massive die-off on its own,” he said. “We think the bee die-off is a result of exposure to multiple stressors.”