Upon inspection, those "pincher bugs" were actually dozens of earwigs in the crevices of the mailbox.
Earwigs are slender, nocturnal insects that get their name from the old European myth that they crawl into people's ears and lay eggs in their brains while they are sleeping. Fortunately, that's just an old folks tale and NOT at all true.
Earwigs are strictly a nuisance pest and pose no harm to humans. They'll spend their days hiding in small, dark, and moist areas and invade homes through tiny exterior cracks in a foundation once the weather becomes too hot for them.
I treated the crevices and the underside of the mailbox with a residual aerosol. I also applied a granular bait around the base of the mailbox and, for good measure, treated the exterior of the home with a liquid residual. All these treatments are designed to rapidly eliminate the earwigs.
A homeowner in Wall Township, NJ called concerned about finding "pincher bugs" in her mailbox.