Before you open the hive look at the entrances. Much can be learnt about the internal state of a hive by observing them at the entrance and given bellow points gives you an idea of what you are looking for.
1) Robbing– Bees fighting at the entrance gate.
2) Poison- Find piles of dead bees at the entrance gate.
3) Virus Disease- Dead Bees still moving.
4) Period of the dearth or Lack of storage- Dead drones at the entrance or drones get removed by the workers.
5) Chalk brood disease- Mummified larvae littering entrance gate.
6) Possible Starvation- Dead larvae being thrown out but not carried away.
7) Healthy colony- Pollen being carried in to the hive by worker.
8) Orientation flight- Many bee’s flying at the entrance. No fighting Bees facing the hive appear to be bobbing up and down.
9) Swarm- Many bees issuing from the hive in a swirling ascending mass.
Some of these observations may still a bit vague, but all will become clear. This inspection can be carried out every time you pass the hives, even if you don’t have the time for a full, open inspection at that time. it takes only a couple of minutes. This may alert you if there is any possible problem in the bee hives.