I found mine at a chemical supply company locally here in Cleveland. When doing a search be sure to look for "Glacial" Acetic Acid. It's close to 100% and, as mentioned, will need to be cut to 80% with distilled water. ( be sure to add acid to the water, and not water to the acid when cutting )
Soak a rag with about 125ml - 150ml of solution and lay across the top bars of "each" box. Stack the boxes and seal off with tape for a week. I put inner covers and telescoping covers on the top and bottom of the stacks and treated them too.
To everything there is a season....
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