ST. LOUIS — If you find a dryer sheet in your mailbox, it’s not a prank. Postal workers use it to prevent getting stung by wasps while delivering mail.

This is because wasps often build nests in mailboxes, and opening the box can disturb them, resulting in painful stings. By placing a dryer sheet inside the mailbox, the scent deters the wasps from building their nest there.

“We’ve found that they hate scented dryer sheets. If we encounter a box that is a problem for nests, we’ll often put one in there and it does the trick.

So please, if you one day randomly see a dryer sheet at the back of your mailbox, just know that your carrier more than likely put it there to deter these Satanic creatures from building their home in it,” writes one postal carrier on Reddit.

However, if there is already a nest inside the mailbox, it needs to be removed immediately by a professional. If you suspect a wasp infestation in your mailbox, it’s best to call in an expert for safe removal.

What kind of dryer sheet should you stick in the mailbox?

“It really doesn’t matter so much what brand you buy, if it’s eco-friendly, or what scent it is. All that matters is that it is scented. The scent seems to be what deters them. So any scented dryer sheet should suffice!” writes the postal carrier on Reddit.