Even though it can be a sign of a strong, healthy colony, swarming can be bad for your colonies. Not only do you lose your queen and about 60% of your bees, but roughly 20% of the time, the remaining weakened colony fails to produce a well-mated new queen to replace her and may be doomed if you don’t notice and install a new queen soon enough. The bees who leave in the swarm also fill their honey stomachs with honey from the hive so they can start building wax at their new home and take pollen for the new brood. This means less resources for the remaining bees and beekeeper.
Swarming is a natural process for a honey bee colony. All colonies want to swarm because this is the way the colony reproduces as a superorganism. That being said, allowing your colonies to swarm, especially if you live in an urban or suburban environment, is not responsible beekeeping. Think of it as not spaying or neutering your dog and then expecting your neighbor to take care of all the puppies, or worse, no one taking care of the puppies and them all dying of disease and starvation. What I mean by this analogy is that swarms may take up residence in your neighbor’s siding or grill or attic where they do damage and aren’t welcome, also most swarms die (only 1 in 6 survives) because they cannot find a good new home and build up enough stores to survive a Northern winter with no beekeeper to care for them. Also, please remember that honey bees are not native to North America, so releasing them into the wild isn't good or nice for our native bee populations. Even though swarms aren’t good and get a bad reputation for being sting crazy, bees who are swarming are actually very docile because they have no home to defend.
Spring, when flowers are blooming and nectar is abundant is swarm season in Michigan. The incoming nectar, warm weather, the queen running out of space to lay eggs, crowding of the hive with new bees, and the related decrease in queen pheromone are all cues for the bees to swarm. Space issues in the hive are something the beekeeper can control for by adding boxes of drawn comb. One sign your hive is getting too crowded is backfilling of the brood nest with nectar or bees storing nectar in the middle of the brood chamber leaving the queen nowhere to lay her eggs. If you see queen cells, your hive will swarm or has already swarmed (i.e. it’s too late). Most beekeepers create an artificial swarm by splitting their hives in the spring to prevent their colonies from swarming on their own.
More Information: https://www.perfectbee.com/a-healthy-beehive/inspecting-your-hive/recognizing-and-avoiding-swarms