Apply BT spray as a biological preventive

Spray stored combs lightly with a Bacillus thuringiensis var. aizawai (Bt-a) solution such as Certan or XenTari before stacking them for storage. Bt-a produces a crystal protein toxin that is lethal specifically to wax moth larvae when they ingest treated wax.

Why It Works

Bt-a toxin binds to receptors in the gut lining of Lepidoptera larvae, causing paralysis and death within 24-72 hours. It has no effect on bees, mammals, or beneficial insects and is approved for use in organic beekeeping by most certification bodies. A single application protects combs for one storage season.

Tips

• Mix according to label directions (typically 1 tbsp per gallon of water) and spray both sides of each frame
• Apply Bt-a before moths are present; it is preventive, not curative, since it must be ingested by larvae
• Reapply at the start of each storage season, as the toxin degrades over 12 months
• Store treated frames in a dry location; moisture accelerates Bt breakdown