mn_newbee · Minnesota, US · Pests & Disease · Sep 17, 2026

Wax moth webbing in the supers I stored two weeks ago — freeze them, Certan/B401, and are moth crystals ever OK?

First year in Minnesota, two hives. I extracted four mediums in late August, let the bees clean them for a day, then stacked them in the garage with a lid on top and forgot about them. Opened the stack yesterday: silky webbing across two frames, tunnels through the comb, cocoons chewed into the wooden frame bars, and a lot of little dark frass. Only two frames are really bad but there are small tunnels on more. My plan is to freeze every frame in the chest freezer, but then what? A guy at club says PDB moth crystals on the stack, another said absolutely never mothballs, and a third said spray Certan (B401). And since Minnesota is going to be minus 20 in a couple months, can I just put them in the unheated shed and let winter do the job?

#wax-moth#comb-storage#b401#first-year

▲ 2 votes 💬 2 replies

2 replies

MieleMarco · Sep 17, 2026

48 hours at -18°C kills every stage, so freeze everything — the eggs are invisible. After that the rule is light and air: moths want dark, still, warm stacks. Stand the supers criss-cross with gaps, or stack them with a queen excluder top and bottom so mice stay out and air moves. Certan/B401 is Bacillus thuringiensis aizawai, a biological spray on both faces of each comb before storage, safe for honey later. Never naphthalene mothballs — it goes into the wax and never comes out. PDB is a different chemical some countries allow for stored comb; air it for days, never on comb with honey in it.

MayaBees · Sep 17, 2026

Your unheated shed is your friend from November on. Wax moth stops developing somewhere below about 10°C, and a Minnesota winter sterilises the stack. The danger months are now until the freeze, and again in April when the shed warms before you use the comb. Freeze now, then keep them cold. One more thing: moths go for comb that has had brood or pollen in it. Pure white honey comb barely interests them — so if these supers got hit hard, I'd guess the queen laid in them or there's pollen packed in the corners.

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