Ask a Master Beekeeper - Moth Balls

I stored my supers with moth balls – not the kind meant for bee equipment - the “regular” kind. Is my equipment ruined? - Steve, New Jersey

A. Oh dear, I’m afraid I have bad news. If the moth balls you used contained napthalene, it is likely that at the very least, all the wax comb is now permanently contaminated with the chemical. This will make the equipment unsafe to use for either honey storage or brood raising.  It could taint the honey that is intended for human consumption, and it may cause bee or brood deaths if used in the brood area.

Napthalene is highly lipophilic, meaning it is readily absorbed into waxy or fatty materials such as beeswax comb.

It will also affect solid materials such as wood and plastic, but generally can be scrubbed off as a decontamination strategy.  So, for instance, you could scrape all the wax off plastic foundation, or cut out wax foundation and discard those parts of the combs.  Carefully scrape off any wax stuck in crevices and then scrub the frames and box interiors with hot soapy water, followed by a thorough rinse.  Air dry completely before putting the equipment back in service.  One authority that I read suggested sanding the interiors of the boxes to remove the last traces of the chemical.  (Sanding is often recommended in order to encourage increased propolization of box interiors. This potential benefit may make the chore seem less onerous.)

This is the correct product to use on bee equipment.

I’m not sure I’d want to take the trouble of trying to get wood frames meticulously scraped free of contaminated wax.  I might just replace those.  As for plastic foundation or plastic combo frames: I think I’d scrub some test ones in hot soapy water, rinse well and air dry. If they have even a faint trace of the smell of the moth treatment remaining, then I’d replace those, too.  If you do re-use them, be sure to give them a fresh coating of extra wax to make them more enticing to the bees.  Here’s how: Waxing plastic foundation. 

But there is one sliver of hope: the chemical para-Dichlorobenzene that is used in the beekeeping-approved moth treatment, Para-Moth, is also sometimes used in generic “moth balls” intended for non-bee purposes.  If you happen to still have the container for the product that you used, please check the active ingredient on the label.  (Both chemicals may smell the same, so only the label will give you the information you need.)  Maybe you’ll get lucky and find that the “regular moth balls” that you used didn’t contain any napthalene after all. And in that case, all you need to do is to give your equipment a good airing for a couple of days and it will be safe to use. I sure hope that’s what you discover!

**UPDATE: Steve emailed back. He checked the container and the active ingredient was para-Dichlorobenzene. So all he has to do is give the supers a good airing out and they will be safe to use. We love a happy ending!