Lactic Acid Treatment

Lactic acid (milk acid) is an organic acid that is sprayed onto the bees on the frames and kills the mites by contact. It has no effect on mites in capped brood, so it is useful in swarms, package bees, artificial swarms and small broodless colonies. Bees tolerate it well, but because every frame has to be handled one by one, it is not suited to large operations.

How does it work?

Lactic acid occurs naturally in fermented foods such as yoghurt and pickles, and is also present in small amounts in honey. In the hive it is sprayed onto the bees as a dilute solution and kills the mites on the bees by contact.

• It acts only on mites on the bees. Mites reproducing in the brood beneath the cappings are protected.
• It gives good results in a broodless colony; when capped brood is present, its effectiveness drops markedly.
• There is no known resistance problem, and when used correctly the risk of persistent residues in honey is low.
• It does not act by evaporation. Unlike formic acid, it is not placed in the hive and left; every bee has to be reached by spraying.

Which colonies, and when?

• Swarms and shook-swarm (artificial swarm) colonies: After they have been hived and before the first brood is capped.
• Package bees: Shortly after they have been transferred to the hive, before brood is capped.
• Colonies and nuclei given a brood break: After all the capped brood has emerged.
• Natural broodless period: In late autumn, while the bees have not yet formed a tight cluster and the weather is mild. Do not treat on cold days when the bees would get wet and chilled.

Step-by-step application

1. Choose the product: If there is an authorised lactic acid product in your country, use it and follow the solution strength and the amount per frame given on the label. If no authorised product is available, consult the official veterinary service / local agriculture authority or a veterinarian specialising in bee health.
2. Equipment: Prepare a fine-mist hand sprayer, acid-resistant gloves and protective goggles.
3. Choose the weather: A mild, windless day, while the bees are sitting calmly on the frames.
4. Take the frames out one by one: Cover the bees on both sides of each frame evenly with a mist fine enough that it does not wet them or form droplets. Do not forget the bees on the hive walls and floor.
5. Close the hive quickly: The operation should be brief and the colony should not be chilled unnecessarily.
6. Monitor the result: Check the effect with a mite drop tray or a count some time later.

Strengths and weaknesses

Safety and rules

• Even when diluted it irritates the eyes and skin; wear gloves and goggles and avoid breathing in the mist.
• Do not treat while supers are on.
• Store the concentrated acid and the solution you prepare in labelled containers, away from children and food.
• Record the product used, the date and the hive number.

Common mistakes

• Expecting results from a single spraying in a colony with brood.
• Squirting the solution haphazardly into the hive and over the frames; acid that does not reach the bees has no effect.
• Using a coarse garden sprayer and soaking the bees.
• Giving lactic acid to bees in feed or syrup; its effectiveness against mites when given this way has not been proven.
• Not counting after the treatment.