Pennsylvania ? A mysterious illness that’s killing tens of thousands of honeybee colonies across the country is stinging researchers and beekeepers.

The bug is threatening honey production, the livelihood of beekeepers and possibly crops that need bees for pollination. Researchers are scrambling to find the cause of the ailment, called Colony Collapse Disorder.

Reports of unusual colony deaths have come from at least 22 states. Some affected commercial beekeepers have reported losing more than 50 percent of their bees.

The country’s bee population already had been shocked in recent years by a tiny, parasitic bug called the varroa mite, which has destroyed more than half of some beekeepers’ hives and devastated most wild honeybee populations.