Varroa Control Products

Varroa control products are veterinary products authorised for bees in the country and used in the hive to reduce the number of Varroa destructor mites. The main groups are organic acids (formic, oxalic, lactic acid), thymol-based products and synthetic acaricides (amitraz, pyrethroids). Choosing the right product depends on the season, the amount of capped brood in the hive, the temperature and the active ingredient you have used in recent years.

Before choosing a varroa treatment: measure

No product should be used by looking at the calendar; use it according to a mite count. Before treating, measure the mite load with an alcohol (or detergent-water) wash, the icing sugar method or a sticky board; after the treatment has finished, measure again with the same method. If the expected drop does not occur, the cause is often wrong timing, incomplete application, reinfestation from neighbouring hives or resistance.

A commonly used treatment threshold in summer and late summer is around 2–3 mites per 100 bees in a wash; in spring and in the broodless period, lower values should also be watched closely. If the official recommendation in your area is different, follow that. Counting tools and methods are described on separate pages.

What groups are varroa treatments divided into?

Trade names vary from country to country; what matters is the active ingredient on the packaging. For resistance management you need to change not the product name but the active ingredient group and mode of action.

In some countries other active ingredients, such as hop beta acids (hop), are also authorised. Find out which products are authorised in Türkiye (or in your country) from the authorisation details on the packaging and from your veterinarian; unauthorised products or medicines made for other animals must never go into the hive.

Organic acids: formic, oxalic and lactic acid

Formic acid

Formic acid (the acid found in ants) is one of the few options that can also reach mites in capped brood, because its vapour can pass through the cappings. That is why it can be used in late summer while the hive is full of brood. On the other hand, its effect depends entirely on outside temperature: in great heat it evaporates quickly and can cause queen and open brood losses, while in cool weather its effect may be insufficient. Do not apply it outside the temperature range on the label, and check the weather forecast before starting.

Oxalic acid

Oxalic acid kills only the mites on the bees. It gives the best results in the natural broodless period at the start of winter, after an artificial brood break, or on swarms and package bees. A solution made up with syrup is trickled between frames full of bees, or the crystals are sublimated with a special device. Trickling repeatedly in the same winter harms the bees.

Lactic acid

Lactic acid (the acid of soured milk) is sprayed as a fine mist onto the bees on the frames. Because every frame has to be handled, it is practical for swarms, artificial swarms and small colonies; it is not favoured in large operations.

No lasting resistance to organic acids has been reported so far, and when used correctly the risk of persistent residues in honey and wax is low. That is why they form the backbone of every good programme.

Thymol-based products

Thymol is a volatile compound also found in thyme; it works by evaporating inside the hive. It is usually used as a gel, tablet or impregnated carrier, in a treatment lasting several weeks. Its effectiveness depends on temperature; it falls short in cool weather, and in great heat it disturbs the bees and the colony may temporarily cut back on brood and food intake. Because it can leave odour and taste in honey, it is not used while supers are on.

Synthetic acaricides: strip products

Products containing amitraz and pyrethroids usually come as strips hung between the frames. As the bees touch the strip they spread the active ingredient through the colony; because the strip stays in the hive for weeks, mites emerging from capped brood are also caught over time.

• Placement: Strips are hung in the brood area where bees are densest, in the number and spacing given on the label. A strip hung on broodless outer frames does not get enough bee contact.
• Duration: When the period on the label is up, the strips must be removed. A strip forgotten in the hive, with its effect fading, gives the mites a constant low dose and speeds up resistance.
• Resistance: Resistance to pyrethroids and amitraz has been reported in many parts of the world. Tau-fluvalinate and flumethrin are in the same group; if there is resistance to one, the other usually does not work either.
• Residues: Some fat-soluble substances (especially pyrethroids and coumaphos) accumulate in wax and return to the hive through foundation.

Which product group in which season?

Resistance management and residue rules

1. Rotate active ingredient groups. Do not repeat the same group for years; make organic acids a regular part of the programme.
2. Follow the amount, duration and temperature conditions on the label. An underdose kills the susceptible mites and leaves the resistant ones.
3. Do not treat while supers are on or while the honey flow is under way; observe the withdrawal period on the label.
4. Treat all the hives in the apiary at the same time; if possible, coordinate with neighbouring beekeepers.
5. Do not use home-made strips, livestock medicines or unauthorised mixtures. They are the most common source of residues and resistance.
6. Measure and record the result: product, active ingredient, date, duration, hive number and before-and-after counts.

Safety, storage and waste

• Personal protective equipment: Organic acids are corrosive; use acid-resistant gloves, safety goggles and, for sublimation, a mask with a suitable filter.
• Storage: Keep products in their original packaging in a cool, dry place, away from children, food and feed. Do not use products past their expiry date.
• Waste: Do not throw used strips, pads and empty packaging carelessly around the hive, into the rubbish or onto the ground; follow the disposal instructions on the label.
• Records: In many countries keeping records of veterinary products used on bees is mandatory; these records are also the only way to notice resistance.