The last half of 2024 was devastating for U.S. honeybees. Over 60% of commercial colonies were decimated — and that followed a 50% die-off the previous year.

Funding cuts and layoffs earlier this year affected the speed at which the U.S. Department of Agriculture could determine the cause of the deaths. But now the culprit is clear: viruses spread by varroa [vah-ROW-ah] mites. Pesticide exposure and poor nutrition may also have contributed.

Virtually all bees studied were resistant to amitraz [AM-ǐ-traz], the only miticide still safe for bees and historically effective against varroa mites.

If honeybee populations suffer too consecutive die-offs, they may not bounce back. They pollinate more than 90 of the nation’s commercial crops, so that could spell all kinds of trouble.