There is no single method against Varroa; there is a programme of methods that complement one another. Each has its own conditions, limits and costs.

Organic acids

This group carries no risk of resistance and is therefore the solid leg of the programme.

Formic acid

It is the only substance that penetrates sealed brood, which makes it effective even when brood is present.

Against that it is very sensitive to temperature. In heat, evaporation accelerates; the colony can be harmed and the queen lost. In cold it does not evaporate enough and is ineffective.

Oxalic acid

It reaches only the mites on the bees; it does not act on sealed brood. It is therefore very effective in a broodless period and weak when brood is present.

It is applied by dribbling or by sublimation. Repeated dribbling can harm the bees.

Lactic acid

It is sprayed onto the bees. Suitable for small colonies and artificial swarms; the labour is excessive at scale.

Synthetic acaricides

Usually in strip form, releasing over a long period. Effective and easy to apply.

They have two significant drawbacks:

• Resistance develops. Resistance in the amitraz and pyrethroid groups is reported worldwide
• They can leave residues in wax. Fat-soluble substances accumulate in wax and re-enter the cycle through foundation

Non-chemical methods

• Brood interruption: Caging the queen or making an artificial swarm leaves the mite defenceless
• Drone brood removal: The mite prefers drone brood; the drone frame is cut out regularly
• Trap comb: The queen is confined to one comb and the filled comb is removed

Building the programme

• Measure. Regular monitoring by sugar or alcohol wash
• Try the non-chemical option first
• Use a licensed product if required; rotate the active substance
• Measure the result. If the expected drop does not occur there is a problem of dose, timing or resistance

Timing

The critical moment of the year is late summer; the winter bees are reared then. The second critical window is the broodless period, when all the mites are on the bees.

Rules

• No treatment while supers are on
• Follow the dose and duration on the label; underdosing accelerates resistance
• Do not leave strips in beyond their period
• Do not prepare unlicensed mixtures
• Record the product used, the date and the dose

Licensed products and recommended protocols may differ in your region; check the current official advice before treating.