this is a good time of year to check hives for yellow jacket queens. they won't be inside the hives, so there's no need to disturb the bees, but yellow jacket queens, and other wasps, frequently overwinter under the roof of beehives. it's a nice dry spot kept warm by the honey bees underneath. wait much longer, and they'll be headed out to start new colonies that will prey on your bees later in the year. pick a dry day, and check all your hives.
in Warré hives, the quilt is a very likely spot to find them. in Langstroth, they'll be between the telescoping roof and the inner cover. in horizontal top bar hives, they'll hide between the roof and the top bars.
every hive I checked today had at least four yellow jacket queens under the roof.