This may be long enough to protect the bees from some pesticides that do not have a prolonged residual effect. Hives may be covered with wet burlap for a day or more, even during the hottest weather, and the bees will not suffer from lack of air and water. Hives should be covered at night when all the bees are inside During the day, soak the burlap with water at least once every hour. Covering the colonies is usually not practical where repeated applications are made. Burlap probably would not give complete protection to colonies located in a field treated with a pesticide that has fumigating action.
Bees use water in their food and for cooling the hive.
Colonies under confinement soon become stressed if they lack water. Water shortage causes symptoms similar to spray poisoning. If wet burlap is used to cover colonies, it provides water for the bees and helps cool the colony. If your colonies are in danger of repeated exposure to a pesticide, the safest way to protect them is to move them to a new site. Since colonies often must be moved to a less satisfactory location where they may still be in danger of pesticide poisoning, moving is recommended only as an emergency measure.