It's hard to describe the jarring sensation of having your bees abscond. Whether they abscond right after you hive a package, or later on in the season - arriving at what used to be a thriving hive only to find it abandoned and empty - it's just tough not to take it personally when your bees leave.
Late season absconding all too often turns out to be a response to a problematic or toxic environment. High mite loads can contribute to having your bees "go on walkabout," since when they abscond, they leave behind all their brood, which contains the vast majority of the mites. Nothing like a break in the brood cycle to drop your mite load. (Which by the way, is one reason that swarming is a GOOD thing!)
But the beekeeper can choose to be proactive in this arena, by using a simple monitoring technique in order to know just what the mite load is in their hive. Monitor, monitor, monitor - then you are in the know about the pressure your bees may be feeling due to varroa mites. Armed with this knowledge, you can choose to take action against them.
Please - don't believe that just because you don't SEE any mites that there AREN'T any mites. The mites spend most of their time either sealed up inside a capped brood cell reproducing, or tucked up into the articulated abdomens of your bees - where you will never see them, but they can still feed - on the pupal bee inside its cell, or the adult bee through its inter-segmental membranes.
The BEST way to get good information about the mite load in your hive is to use a monitoring technique that knocks the mites loose from the bees so that you can literally COUNT them.
In this video, the technique uses powdered sugar - which is said to make things quite slippery, like "marbles under the mite's feet" - which causes them to lose their grip and fall from the bees, and makes them visible to the beekeeper for counting. We like the use of powdered sugar more than alcohol when monitoring, as it does not harm the bees!
We'd like to offer our appreciation to the Pollinator Partnership, The University of Minnesota, University of Maryland, and Michigan State University for their work to raise awareness around monitoring for mites, and to Brushy Mountain Bee Farm for producing the original video that we incorporated into this work.