For the past two weeks, I have been recovering from pneumonia and was unable to get out and inspect my hives. The imagery below is a classic example of why is important to check your hives weekly just before and during a nectar flow.
The leaves on Black Locust trees around my house started to bud around 14 April. This means the nectar flow is less than two weeks from starting.
With the impending nectar flow coming, the impulse for your bees to swarm is very strong. When the bees swarm, more than half of the colonies’ foragers will leave with the queen bee. With only one true nectar flow in our area (from the Black Locust tree), if any of your hives swarm, it's very likely the remaining foragers will not be able to bring back enough pollen and nectar for storage to survive the coming winter without starving.
That's why it's crucial that you inspect your colonies every 7 days, 1 week prior to the nectar flow, during the actual flow, and probably 2 weeks to a month, following the flow. In our area, here in Northeastern Maryland, that would be from 15 April through 15 June.
The most important thing you should look for during a nectar flow is bee space and the presence of active queen cells. It's critical that the bees don't come close to running out of frames to store honey or to raise brood, for if they do, it will activate the swarm impulse or force them to fill the brood area with honey, causing the colony to become honey-bound. As seen above, most swarm cells will be found on the bottom of the frames.