Varroa Mite Control: Approved Methods in Sweden

Varroa destructor arrived in Sweden in the early 1990s and has been the defining challenge of modern beekeeping ever since. Without treatment, a colony will typically collapse within two to three years. The good news: with consistent, correctly timed treatment, varroa is manageable and your colonies can thrive for decades.

Understanding Varroa

Varroa is an external parasitic mite that feeds on developing bee pupae and adult bees. It reproduces exclusively inside capped brood cells — preferring drone brood but also using worker brood. A female mite enters a cell just before capping, lays eggs inside, and the offspring mate with their brothers before the bees emerge. The mites emerge with the young bee and immediately seek another cell or hitch a ride on adult bees.

The damage varroa causes is twofold: direct feeding weakens individual bees, and the mites vector several damaging bee viruses, particularly Deformed Wing Virus (DWV). High viral loads shorten worker lifespan dramatically, collapsing the colony's ability to maintain population.

Monitoring: Know Your Mite Load

Never treat blindly — always monitor first. There are two reliable methods:

Alcohol wash (alkoholtvätt): Take a sample of approximately 300 nurse bees from the brood area (not the entrance — foragers give inaccurate readings). Submerge in 70% alcohol or windshield washer fluid, shake, and count the mites in the liquid. Divide mites by bees × 100 for a percentage. In Sweden, most beekeepers treat when infestation exceeds 1–2% during the season, or at any level in late summer.

Sticky board count: Place a greased board under a mesh floor for 24–72 hours and count mite falls. This gives a rough trend but is less precise than alcohol wash.

Approved treatments in Sweden

Varroa medicines in Sweden are authorised by Läkemedelsverket. They are non-prescription, and they are sold through pharmacies such as Djurfarmacia and Swevet — not in beekeeping shops (Biodlarna). The record-keeping rules come from Jordbruksverket. As of September 2026, Läkemedelsverket's register lists these as authorised in Sweden. Whether each is actually on sale at a given moment varies, so check FASS before you plan around one:

• Oxybee — oxalic acid, trickled onto broodless colonies.
• VarroMed — oxalic and formic acid.
• Formic acid NOD — formic acid strips.
• Apiguard vet — thymol gel.
• Apivar vet — amitraz strips.
• Apistan vet — tau-fluvalinate strips.

Names you will meet in foreign guides — Api-Bioxal, MAQS, Formicpro, Thymovar, ApiLife Var — are not on the Swedish register. Whatever you use, follow its own leaflet (bipacksedel): the dose, the temperature range and how to handle the honey supers differ from product to product.

Oxalic acid is the workhorse of Swedish varroa management. It does not reach mites inside capped cells, so it belongs in the broodless period — usually November to January — where Friska bin puts its effect at around 90 %. Trickling is the method used with the authorised product. Sublimation (vaporising the crystals) is widely used by beekeepers with the pure acid, which Jordbruksverket does not class as a medicine; no product authorised in Sweden is approved for sublimation. The vapour is harmful to breathe — a respirator, gloves and goggles are not optional.

Formic acid reaches mites under the cappings, which makes it the summer treatment: a short treatment after the summer harvest, no later than mid-August (Friska bin). Its effect depends strongly on temperature and hive size (Steube et al., 2021), so keep to the leaflet's temperature range to the letter, and keep the honey supers off the hive as the leaflet directs.

Thymol (Apiguard vet) needs warmth to evaporate — above about 15 °C — which in Sweden limits it to July and August. The leaflet sets the number of treatments per year.

Amitraz (Apivar vet) and tau-fluvalinate (Apistan vet) are the synthetic options. They work where the mites are susceptible, but resistance is the recurring problem: tau-fluvalinate resistance was first found in Sweden in 2010 (Friska bin), and amitraz resistance is documented abroad. They also leave residues in wax more readily than the organic acids do. Use them, if at all, by the leaflet, and not as the only method year after year.

Recommended annual strategy in Sweden

Friska bin, the advisory project of Biodlarna and Biodlingsföretagarna, recommends two steps a year:

Summer — after the harvest, by mid-August: a short formic acid treatment once the summer honey is taken off, to bring the mite population down before the winter bees are raised in August and September. Winter bees must be as healthy as possible — they are the bees that carry the colony through to spring.

The Swedish autumn has a fixed order and its own vocabulary: slutskattning (the final harvest), then treatment, then invintring (the winter feeding). It runs in that order for a reason. Mites left in during August damage the very bees that have to live five months, and the winter feed has to go on while it is still warm enough for the colony to take it down and cap it. The feeding half is in Winter Feed for Bees.

Winter — November to January: oxalic acid when the colony is completely broodless and in winter cluster. With no brood to hide in, every mite is within reach, and the colony starts the spring clean.

Record keeping — the läkemedelsjournal

This is a legal duty, not a suggestion. Every treatment goes into a läkemedelsjournal — and that includes organic acids such as formic and oxalic acid, which are not classed as medicines, and organic acids used in the hive for cleaning and sanitation (Jordbruksverket). Each entry records the reason for the treatment, the product, the date and time, the amount used, where you got it, the withdrawal period — even when it is zero — and how long the treatment lasted. The journal is kept for five years. Friska bin publishes a ready-made template.

A simple mite log beside it — date, counting method, result — tells you which colonies to watch and whether a treatment worked.

Sources: Jordbruksverket, Bin och humlor (jordbruksverket.se; Friska bin, Varroa (friskabin.se; Biodlarna, Läkemedel mot varroa (biodlarna.se; Läkemedelsverket's product register and FASS (September 2026); Steube, Beinert & Kirchner (2021), Apidologie 52: 720–729 (doi.org.