We bought some spray-in stuff for wasps nests last year although as it was buried deep, it wasn't all that successful. Believe it's better if you can get to more of the nest. And, yes, they moved over the winter. Hive bees can defend against wasps (which only want to rob their honey) but you can make it easier for them by reducing the hive entrance to a really small size. Best about August when the wasps are most active and the summer nectar flow is slowing for the bees. I guess at this time of the year, they're all getting less active (reminds me, mouse guard now needed on hives),
H