Bayer cares about the bees.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. 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 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. “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.”