Dispenser for formic acid vapour and method for mite control in beehives

A dispenser for receiving and evaporating a liquid formic acid preparation for combating varroa mites in a bee hive, comprising:

• an evaporation surface;
• an evaporation container with dimensions adapted to one of:
• insertion into an air-flowing honeycomb alley leading through a brood nest;
• and
• placing on upper beams of honeycomb frames of brood nest without spatial extension of the bee hive;
• a storage container connected to the evaporation container and sealed from an outside in a vapour-tight manner for storing an entire treatment dose of the liquid formic acid preparation until a time of combatting varroa mites by a formic acid treatment;
• and
• a closable liquid-conducting connection between the storage container and the evaporation container for transferring the liquid formic acid preparation from the storage container to the evaporation container;
• wherein the evaporation surface comprises a liquid-impermeable and a gas-permeable, fine-pored membrane with a solid content of less than 70% and continuous, exclusively gas-filled pores with a width of between 10 nm and 1000 nm as part of an outer boundary of the evaporation container, wherein said membrane is impermeable to liquid mixtures of formic acid and water and liquid-tight during a treatment period under a dynamic pressure of the liquid formic acid preparation;
• and
• wherein, for dispensing formic acid vapour, the gas-permeable, fine-pored membrane is arranged adjacent to a space through which a gas can flow including one of:
• one or more honeycomb alleys;
• and
• a channel integrated in the evaporation container and leading through the one or more honeycomb alleys.