The Spruce-Fir Moss Spider, known by its scientific name Microhexura montivaga, lives exclusively at high altitudes, above 5,400 feet, most commonly in the Pisgah-Nantahala National Forest and Cherokee National Forest. It’s about the size of a BB pellet, and as its name implies, this little arachnid likes being near spruce and fir trees. They enjoy humid environments and hide in moss mats that grow on rocks in the shade.
They are a federally endangered species facing dire threats. According to the U.S. Fish and Wildlife Service, suitable moss mats have been diminishing. Any change in environment, like the destruction of moss mats or loss of trees that shade the mats, can result in the loss of a population of the spiders, or even extinction of the species as a whole.
Recently, the balsam wooly adelgid, a nonnative insect, has decimated Fraser fir trees in Southern Appalachia. Logging and climate change are also causing spruce-fir moss spider habitat to dry up and disappear.
Spruce-fir moss spiders are at the top of the food chain in their microhabitat. They eat and control the populations of mites and springtails which live in the leaf litter where the spider hunts.
These tiny tarantulas are completely harmless to humans. But the opposite is not true: we are the biggest threat to their survival. The best way to save these endangered spiders, native only to our mountains and forests, is to protect more of their high-elevation habitat. The Pisgah-Nantahala National Forest Plan is the best and most important opportunity to protect habitat for the spruce-fir moss spider and hundreds of other species that depend on the Pisgah-Nantahala for survival. A draft is expected to be released this spring, and your input is vital.