As you trim your Christmas tree this year, keep an eye out for an unexpected (and unwelcome) surprise that could be lurking in the branches. While it might look like a tiny pinecone, if you spot one of these walnut-like masses in your tree, you’ll want to take immediate action. According to Philadelphia native Daniel Reed, these brown clumps are actually a cluster of more than a hundred praying mantis eggs called “oothecas.” This year alone, he found two on his own Christmas tree. To warn others, he shared the photo on Facebook earlier this month, and it quickly went viral, racking up more than 65,000 shares.
A reporter at WOIO showed Daniel’s photo to Dr. Gavin J Svenson, an invertebrate zoology expert at the Cleveland Museum of Natural History, who verified that the image is of a praying mantis nest and explained that the hard exterior helps protect the eggs during the cold winter months. He also warned that bringing one of these egg masses inside a warm house could potentially trigger an early hatching. (Read: you’ll have praying mantises all over your house—yikes!)
If you find one of these on your tree, the best thing to do is clip the branch off ASAP, then carefully move the nest outside and place it on a bush or in a tree. (Basically, keep it off the ground and away from any place where it could get too moist and rot, according to Dr. Svenson.)
“Putting the egg case outside quickly is critical if you want them to survive normally to hatch in the spring,” Dr. Svenson told WOIO. “Going from cold to warm and then back to cold can cause problems and reduce their chances of survival.” The good news is that praying mantises are great at protecting your garden against unwanted critters, so you’ll be feeling grateful for ’em come spring.