Practical Guide: 1.3.1 Spray Treatment

Important safety instructions from the Bee Health Service

• Oxalic acid is highly irritating and harmful to human health.
• Wear protective goggles, acid-resistant rubber gloves, an appropriate protective mask and long-sleeved clothing.
• Use an FFP2 or FFP3 mask for spray treatment.
• Do not stand in the oxalic acid spray mist. Outdoors, a smoking bee smoker can help determine wind direction.
• Keep water available for promptly washing away any acid splashes.
• The treatment does not affect mites inside capped brood cells.
• According to the Bee Health Service, honey from colonies previously treated with oxalic acid during the same season should not be harvested or marketed because residues may be present.

Monitoring winter treatment: If more than 500 mites fall onto the Varroa floor insert within two weeks after oxalic acid winter treatment, the treatment must be repeated.

Additional Swiss product information – Summer use of Oxuvar 5.7%

The Swiss Oxuvar 5.7% package leaflet also provides for spray treatment in spring and summer (April to August) in broodless swarms, artificial swarms and other broodless colonies. Treatment is carried out when most bees are inside the hive (in the evening).

The package leaflet requires broodlessness for this application. The possibility mentioned in the Bee Health Service guide of treating colonies containing exclusively open brood must therefore not automatically be extended to all authorised summer applications.

Oxuvar must not be applied during a nectar flow. Combs used for honey production in the current year must not be sprayed. Following summer treatment of swarms, artificial swarms or broodless nucleus colonies, the package leaflet also specifies an autumn or winter treatment.

The package leaflet states that no withdrawal period is required for honey when the product is used correctly. This differs from the precautionary Bee Health Service recommendation not to harvest or market honey from colonies previously treated with oxalic acid in the same season. The current product information must be consulted.

Source: Swiss package leaflet for Oxuvar 5.7% ad us. vet. (Swissmedic 65'776), particularly sections 4, 5, 8, 10 and 12. This additional information comes from the veterinary product leaflet and does not constitute a standalone summer treatment protocol. Swiss veterinary product information for Oxuvar 5.7%.

• Spray treatment is not restricted to winter. The Swiss Oxuvar product information also provides for spring and summer use in broodless colonies.
• The Bee Health Service guide describes treatment of broodless colonies or colonies containing exclusively open brood. For summer applications, the stricter conditions in the package leaflet must be followed.
• The outdoor temperature should be at least 8°C.
• Prepare Oxuvar 5.7% according to the package leaflet and spray each side of the frames with 3–4 ml of solution.
• Wear the required protective equipment and spray frames containing open brood at a 45° angle to avoid direct exposure of the brood.
• Repeat winter treatment if more than 500 mites fall within two weeks after treatment.
• For summer applications, observe the restrictions concerning nectar flow, honey production and the other requirements of the Swiss package leaflet.

Application notice

This summary is provided for information purposes and does not replace the official Bee Health Service guide. Before practical application, consult the current product information, authorisation conditions and safety instructions.