Thresholds

A mite count only tells you something once you compare it to a threshold, and the threshold moves through the season.

• In spring, while the colony is still building up, two to three mites per hundred bees is enough to start planning a treatment: the colony has months of brood rearing ahead of it, and every one of those mites has time to become a dozen.
• By late summer, treat above three mites per hundred bees rather than waiting to see if the count gets worse: the mites present now are the ones that will feed on the bees your colony is about to raise for winter.

The tolerance tightens rather than loosens, even though the number looks similar.