Formic Acid 60%
Behandlungsmittel
Formic acid in a 60% preparation is the classic remedy for summer treatment of production colonies.
Formic acid in a 60% preparation is the classic remedy for summer treatment of production colonies. It is not applied directly to the bees but evaporates within the colony. The vapor acts directly caustically on the mite and additionally disrupts its respiratory chain, leading to acidification of the mite's tissue. Bees can buffer and break down the acid faster than the mites can, and this is the basis of the selective effect.
Formic acid holds a special position among all active substances approved in Germany: it is the only one that diffuses through the cell capping into the capped brood, where it kills mainly the nymphal stages of the mites. This is exactly why it is suited to late summer, when the colonies are still brooding and the majority of the mite population sits in the brood cells. It is applied via evaporators such as the Liebig dispenser or the Nassenheider Professional evaporator. The sponge cloth is now considered only an emergency solution for extended cold, damp weather phases, because it releases the acid in bursts.
The evaporation rate depends heavily on outdoor temperature and humidity, and with it the success of the treatment. As a guideline, the bee institutes give outdoor temperatures of about 12 to 25 °C; the Baden-Württemberg control concept states 20 to 30 °C as favorable, depending on the evaporator system. At daytime temperatures above 25 °C, treatment should be carried out in the evening. In thunderstorms, rain, or high humidity, the treatment remains largely ineffective. The standard authorization states 15 to 20 grams per box per day for single- and double-box colonies after extracting, and 6 to 10 grams per box per day before the brood break, based on a box volume of about 40 liters. If the hive volume differs, the amount must be adjusted.
Typical mistakes are treating without a prior infestation assessment, evaporation that is too fast on hot days, and a colony that is too small or too weak. If the acid is released too quickly, there is a risk of unrest, brood damage, and queen losses through balling. Nucleus colonies should only be treated once they have sufficient colony strength. After treatment, a renewed hive debris diagnosis is recommended, and about twelve days later, once the capped brood has hatched, a further check.
Legally: formic acid 60% ad us. vet. is approved as a veterinary medicinal product for bees and subject to pharmacy sale, but not prescription-only. Application is only permitted after the last honey harvest of the year; during the nectar flow it is contraindicated. Because formic acid is water-soluble, it does not accumulate in the wax, but if applied at the wrong time it settles in the honey and changes its taste. When handling it, acid-resistant gloves and safety goggles are mandatory, vapors must not be inhaled, and sufficient water for rinsing should always be on hand.
Quellen (4)
- BfArM: Wortlaut der Standardzulassungen für Bienentherapeutika (Monographie Ameisensäure 60 % ad us. vet.)
- Emmerich, I.: Zugelassene Arzneimittel für Honigbienen in Deutschland, Berliner und Münchener Tierärztliche Wochenschrift 2018
- LAVES Institut für Bienenkunde Celle: Varroa-Sommerbehandlung (Infodienst 62)
- Varroose-Bekämpfungskonzept Baden-Württemberg, Landesanstalt für Bienenkunde Hohenheim, Stand 11/2024