. >> hneybee sses havbeen lied to muiple facrs, like sticideshabitat degradatn, malnuition, patgens, anvarroa me nfestatis. for pesticide manufacturer bayer crop science, the issue is clear. >> most experts agree that the single greatest threat to honeybee health is the varroa mite, an invasive blood-sucking pest that both directly parasiizes yog and adt bees and vectors bee diseases. where varroa mites are absent or well controlled, honeybees are thriving. >> but jim says he knows why his bees are dying. >> we had a multitude of neonics that were showing up in our bees. it doesn't take much to kill a bee. >> neonicotinoids are a relatively new class of insecticide and coming on the scene in the 1990s. it is the fastest-growing group of insecticides in the united states. >> for the companies that make them, neonicotinoids, or neonics, are big business. they bring in over $2.6 billion a year in global sales. they are widely used as seed treatments, applied as soil drench, or sprayed onto foliage. in the u.s., they are used on some 200 million acres of cropland, on almost all corn, can