Moth Balls – as Animal Repellent

Q: I heard something scratching in the attic last fall. I tried to use a cage trap to catch the varmint but was unsuccessful. I then scattered three boxes of moth balls up there and that seemed to stop the noise. Did I do the right thing by using the moth balls?

A: If the animal disappeared, it probably wasn’t because of the moth balls. Back when we didn’t know any better, Extension service wildlife specialists told me that it took five pounds of moth balls per 2000 cubic feet of attic space to have any repellent action. Homeowners quickly discovered that a rate that high also repelled humans living below. Moth ball vapors are heavier than air, after all, so folks would have to clamber back into the attic to retrieve the smelly chemical. “Steamed” would be an accurate description of their attitude when they called me to complain.

If that weren’t enough, napthalene and para-dichlorobenzene are health risks. Exposure to large amounts of naphthalene may damage or destroy some of your red blood cells. The Department of Health and Human Services has determined that para-dichlorobenzene may reasonably be anticipated to be a carcinogen. I do not recommend moth balls under any circumstances – even for their eponymous intended use for repelling moths!


Toxicity of Napthalene

Napthalene Fact Sheet

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