This seems to be a case of guilt by association. Between 2008 and 2013, 30 percent of bees in the U.S. have either disappeared or failed to pollinate blossoms in the spring. It's even worse in some other countries — Spain has lost close to 80 percent of its beehives [source: Entine]. Some beekeepers and environmental activists have argued that the cause is a powerful class of pesticides called neonicontinoids, which are similar in structure and action to nicotine. Unlike the usual pesticide sprays, neonicontinoids are absorbed by plants and relocated through their vascular systems, so that boring insects will suck them up [sources: Wines, Oliver].
These pesticides are different from GMOs, though activists sometimes lump them together, possibly because the pesticides are sometimes used to treat seeds. There's no solid evidence that GMOs themselves are causing the bee collapse. That said, GMOs may not necessarily be so great for other insects. There are recent studies that indicate that in rare instances, they may inadvertently kill butterflies, ladybugs and other harmless or even beneficial insects [source: Jabr].