powdered sugar roll

[mmurphoh]

     Started doing powdered sugar roll to check for varroa. I currently have 7 hives. Do I need to check them all or just sample a few then treat all accordingly?  How often should they be checked?

[Bakersdozen]

I would check them all.  There can be a lot of difference between two hives sitting next to each other.  If, after you find you need to treat, and would like to recheck to see if your treatment worked, you could do another check.  Or, as we get further into fall and the queen slows down her egg laying, and you want to continue to monitor the mite load, you could check again.  A sugar roll won't hurt your bees.  It is all much better than ignoring the situation and hoping that they are survivors.

[mmurphoh]

Thanks

[apisbees]

When you get the results from each hive compare the numbers and think back at what could have attributed to the lower numbers? Hive had a break in brood to raise a new queen? Hive swarmed or the hive was made from a captured swarm? Started from a package or a nuc? Once you remove these hives from the comparison look at the differences in the colonies that are survivors from previous years and see if any stand out as being less infested and that seem to be able to deal and handle the mites on their own. These hives may have a little more hygienic behavior than the other hives.