On May Day, or more particularly, May morning, witches are traditionally believed to be able to steal their neighbour’s milk or butter, so that no amount of churning will create butter. These witches, or hags as they were often known, were usually widowed women, frequently they were poor, and invariably they were known in their community as odd. Anyone visiting a household between sunset on May Eve and sunset on May Day would be treated with great suspicion. People were particular in not giving anything away, especially fire, milk, salt and water as to do so was considered to be risking the household’s luck and milk-profit for the coming year. Tradesmen who worked about the house would have to smoke by the hearth, and extinguish their pipes before they left the dwelling, while beggars who regularly received hospitality at other times of the year would know to avoid calling at Maytime.
See the rest of the article here: