Just in time for Halloween, a University of Georgia scientist has posted photographic evidence of “spirits”—his term for the distinctive markings resembling a human skull that are found on the backs of Texas Gray moths (Glenoides texanaria).

John Pickering, an associate professor of ecology at UGA and the founder of DiscoverLife.org, an online interactive encyclopedia of biodiversity, created the special gallery of spirit photography as a way to engage readers in the scientific process.

“For fun and brevity, I define the markings on the moths as ‘spirits’ if they appear to have eyes and a mouth. I define moths that display or carry a spirit as ‘possessed,’” writes Pickering. “Thus, after presenting evidence to document spirits on possessed moths, our goal is to consider possible hypotheses that might explain them.”

Pickering presents several hypotheses that could explain the spooky phenomenon, ranging from scientific fraud to protective patterning to scare off predators to actual spirits. You can see the photographs for yourself and decide which hypothesis you think is correct at http://www.discoverlife.org/ghosts/.