Scimat Scimat / Getty Images Rosacea is a common but often misunderstood condition that is estimated to affect over 45 million people worldwide. It affects fair-skinned people of mostly north-western European descent, and has been nicknamed the curse of the Celts by some in Ireland.

In truly disgusting news, rosacea — a fairly common acne-like condition characterized by red, inflamed skin — may be caused by tiny bugs living in the pores of your face, reports a researcher at National University of Ireland.

The little eight-legged mites called Demodex, which are related to spiders, are apparently drawn to the hair follicles of eyebrows and eyelashes and to the oily pores on your nose, forehead and cheeks. They feed on the oil, or sebum, in your skin, and according to an article in New Scientist, they crawl around your face at night to mate, then crawl back into your pores to lay eggs and die.

(MORE: Morgellons Mystery: No Medical Explanation for ‘Crawling Skin’ Disease)

What causes the rosacea? In a recent study published in the Journal of Medical Microbiology, researcher Kevin Kavanagh says it may be a reaction to the bacteria in the mites’ poop. New Scientist reports:

Demodex does not have an anus and therefore cannot get rid of its feces. “Their abdomen just gets bigger and bigger, and when they die and decompose they release their feces all at once in the pore,” says Kavanagh. When the mites are numerous, he believes that the material is enough to trigger an immune reaction, inflammation and tissue damage.

Normally, adults have about one or two mites per square centimeter of facial skin, but those with rosacea may have 10 times as many, according to Kavanagh. The stress that often triggers rosacea flare-ups may do so by changing the makeup of your facial oils, making it more delectable to the mites.

If you can stomach more information, check out the full article on facial mites in New Scientist.