One of the most common pests in honey bee hives are sweet ants.
Most beekeepers see them under the cover and on top of the inner cover. Sometimes they are even under the tin on the cover. I have seen many beekeepers go a bit overboard trying to keep ants out of a hive. In our area of SW Missouri ants hold no threat to a colony of bees. Mostly they are just looking for a warm dry home and maybe an occasional bit of sweet food usually from the beekeeper. They do get into the hives on very weak hives but in most cases they are still not the problem or even a threat. The video below discusses the sweet ants in more detail and possible solutions like cinnamon.
We went on a swarm call the other day to a house in east Springfield, MO. The caller has a bee tree in their yard with a nice colony of bees about 20' off the ground. Well its swarm season and apparently these guys want a little nicotine in there diet lol. The swarm was hanging under a metal patio table and connected to an ash tray full of cigarettes. Yeah first thought was ewww and second thought "Free Bees!", lol.
The home owner had closed off the area with stakes and plastic ribbon. The air was filled with a lot of honeybees and we were concerned they were getting ready to leave. Apparently this swarm was here for 2 days before we finally got the call late on the 3rd day (two of those nights were in the cold low to mid 40's). The home owner explained to us that it started out on the side of the tree, then moved to a limb and finally flat on the ground in the grass.