Non-Chemical Varroa Control

Natural and organic varroa control aims to keep the mite load low without using synthetic acaricides: by combining, at the right time, biotechnical methods that make use of bee biology (drone brood removal, brood break, artificial swarm) with substances such as organic acids and thymol. Staying "medicine-free" on its own is not enough in most apiaries; success depends on regular counts and a well-planned calendar.

First, two misconceptions

• "Natural substances are harmless": Formic and oxalic acid are corrosive and, if misused, lead to bee and queen losses; thymol can leave an odour in honey. Substances of natural origin must also be used according to the label and with protective equipment.
• "A strong colony will beat varroa by itself": Without intervention, the vast majority of ordinary colonies collapse within two to three years because of varroa and the associated viruses. A strong colony is important, but it does not clear the mites on its own.

Biotechnical methods

These methods target the mite's life cycle: varroa reproduces in capped brood and prefers drone brood to worker brood.

Drone brood removal

In spring, an empty frame or a shallow frame open at the bottom is placed at the edge of the brood nest. The bees build drone comb here, the queen lays in it and the mites enter these cells. Once the drone brood is capped, it is cut out and discarded before the bees emerge. Several rounds can be carried out during the spring.

Caution: If you miss the moment to cut out the capped drone brood, the mites multiply in the colony along with the emerging drones; the method backfires. Stick to the schedule.

Brood break (caging the queen)

The queen is shut in a cage inside the hive so that she stops laying. As worker brood emerges in about three weeks, at the end of this period there is no capped brood left in the colony and all the mites are on the bees. A single oxalic or lactic acid treatment at this point is very effective. The queen is then released.

It is usually done immediately after the honey harvest; it should be planned so that the colony has time to rear its winter bees.

Artificial swarm, splitting and shook swarm

When a colony is split, or when the bees are shaken into a new hive onto foundation, a colony that is broodless for a while is created. This broodless period is an opportunity for an organic acid treatment. The part with brood left over from the old colony, however, must be monitored separately and, if necessary, treated separately after the brood has emerged.

Trap comb

At set intervals the queen is confined to a single frame with an excluder partition. The mites enter the brood on this frame; once it is capped, the frame is removed from the hive. It is effective but very labour-intensive, and it also slows down colony development.

Substances permitted in organic beekeeping

Organic farming legislation (the organic farming regulation in Türkiye and the EU rules) generally permits organic acids (formic, oxalic, lactic, acetic acid) and essential oil components such as thymol, menthol, eucalyptol and camphor for varroa control; it does not permit synthetic acaricides. Confirm the current list with your certification body.

• Formic acid: Can act on capped brood; very sensitive to temperature.
• Oxalic and lactic acid: Act only on mites on the bees; used in the broodless period.
• Thymol: Acts by evaporation; temperature-dependent, not applied while supers are on. During treatment the bees may gather at the entrance.

Supporting measures

• Varroa-tolerant lines: Selecting queens from lines with strong hygienic behaviour that remove mite-infested brood reduces the load in the long term. On its own it is no substitute for treatment.
• Mesh floor: Prevents some of the fallen mites from returning to the hive and makes counting easier; on its own it does not markedly reduce the load.
• Apiary layout: Placing hives with different colours and orientations reduces drifting; preventing robbing limits the transfer of mites between hives.

Practices with weak evidence or drawbacks

• Dusting with icing sugar: It knocks down some mites but is not an effective treatment on its own; it is more valuable as a counting method.
• Home-made mixtures (garlic, raw plant oils, tobacco smoke, etc.): Their effectiveness has not been proven, they can leave residues in honey and wax, and they are not legal.
• Heat treatment (hyperthermia): A method under investigation; results are inconsistent, and at the wrong temperature brood and bees are harmed.
• Biological agents (fungi, bacteria etc. against the mite): Still at the research stage; there is no proven product ready for field use.

Sample organic calendar

1. Spring: Count; start drone brood removal.
2. Swarming season: Make use of the broodless period in splits and artificial swarms with an organic acid.
3. Immediately after the harvest: Brood break + oxalic or lactic acid, or formic acid or thymol at temperatures in line with the label.
4. Early winter: Oxalic acid in the broodless period.
5. After every step: Check the result with a count.