I think there's a very good chance you're right. But! Unless you know where the bees are coming from another very likely scenario is the colony just died. A ne

I think there's a very good chance you're right. But! Unless you know where the bees are coming from another very likely scenario is the colony just died. A newly established wild hive has only like a 20% chance to survive its first winter so if that's the first summer you saw them that likely explains it. If you're near two highways it's likely you're in a fairly dense area and feeding a nearby beekeeper's hives. But a lot of beekeepers are hobbyists and like all hobbies, people give up on beekeeping all the time. Even if it was a managed hive a likely explanation is that the colony simply isn't there anymore.