We don’t often get a new tool in the fight against Varroa but at the end of September, the EPA approved a new miticide called Norroa.
This works in a very different way than miticides we’ve seen in the past. In fact, it isn’t technically even a miticide since it does not kill mites. What it does do, however, is prevent the mites you do have from reproducing. Think of it as birth control for varroa mites.
What is it? Norroa comes as a sugar syrup packet. You peel off the label, exposing holes for the bees to take in the sugar syrup. The appropriate dosing is two bags per brood box.
How does it work? Once the bees take up the syrup, they use it to make brood food. Mites, doing what mites do, hide under the larvae in the brood food before the cell gets capped. Once the mite comes into contact with the brood food, the active ingredient, Vadescana, silences the calmodulin gene which the varroa mite needs in order to reproduce. The Varroa mite does not die from this exposure but can no longer reproduce. This effect has been shown in studies to last for approximately 18 weeks.
How do I apply it? There are no temperature restrictions for this product. For maximum efficacy, it is best to use this product when mite levels are already low since this will not prevent your current mite population from parasitizing bees. This means that it is best applied in early spring or during a natural dearth period. You want the product to be used for rearing brood, not for storing in honey supers so it is best applied when honey supers are not present. It is not harmful if used with honey supers but may be less effective if the bees store it rather than use it for producing brood. No special PPE is required and the bags can be removed as soon as they are empty, usually within a few days.
Is it safe? Vadescana is targeted specifically to interfere with the RNA in Varroa. It has not been shown to harm developing or adult bees or humans.
How can I get it? Mann Lake is the exclusive distributor of this product. Although the EPA has approved it, each state must also submit approval before it can be shipped to you. At the time of publication, this has been approved in CT but not NY. Mann Lake has not yet updated their website to reflect Connecticut’s approval.