Local fellow had a late swarm show up at his place last fall, and settled in a lilac bush. Having no experience or equipment whatever, he read enough that he decided to open feed them close to 75 pounds of sugar before winter set in. Last winter was a mild one for us, only dropping to minus 10 once, and only getting below zero less than a dozen times. We also did not get as many of the unholy bitter strong winds that are usual during our winter. His bees survived the winter, hanging right out in the open in the leafless lilac bush. He hived them this spring, and they did a good job for him over the summer. Proves just how tough they are.
In spite of that, I'm thinking about wrapping my one hive with something for the winter.