Thousands of Tarantulas Are About to Set Off on Their Annual Migration in Colorado

Oklahoma brown tarantulas (Aphonopelma hentzi) will soon be on the move and looking for love. — Oklahoma brown tarantulas (*Aphonopelma hentzi*) will soon be on the move and looking for love. (Image credit: Shutterstock)

Southeastern Colorado will soon be experiencing the pitter-patter of little feet — tens of thousands of them — as thousands of male tarantulas begin their annual migration to the prairies to find a mate.

Female tarantulas hunker down in their prairie burrows for most of their lives, but the males walk for up to 1 mile (2 kilometers) to find a mate, according to CNN. However, this epic migration will look more like a steady trickle of spiders than a dense carpet of hairy brown bodies, as the tarantulas aren't social and usually travel alone, Mario Padilla, head entomologist at the Butterfly Pavilion, a nonprofit invertebrate zoo in Westminster, Colorado, told CNN.

Oklahoma brown tarantulas are fuzzy, brownish spiders; females' bodies measure 3 inches (7.6 centimeters) long and weigh about 0.7 ounces (20 grams), while males are somewhat smaller, according to the U.S. Fish and Wildlife Service (FWS).

The spiders produce venom to subdue their prey, though the toxins are not harmful to people. However, tarantulas' sharp fangs can pierce human skin, and bites can lead to bacterial infection. Tarantulas also defend themselves by brushing off stinging hairs on their abdomen, which can irritate a person’s skin, eyes and respiratory tract, FWS says.

Males typically embark on a female-finding trek when they reach sexual maturity at around 10 years old, CNN reported. And the spiders' first migration is also their last; while males may remain active through the fall, nearly all of them will be dead by November, according to a fact sheet posted on Colorado State University's Western Colorado Entomology (WCI) website.

The spiders are most active at dusk in the hour before sunset, and tarantula enthusiasts hoping for a glimpse of the leggy travelers will find plenty of amorous arachnids on Highway 109 on the Comanche National Grassland, according to a recommendation by a La Junta tourism site.

Originally published on Live Science.

Mindy Weisberger is a science journalist and author of "Rise of the Zombie Bugs: The Surprising Science of Parasitic Mind-Control" (Hopkins Press). She formerly edited for Scholastic and was a channel editor and senior writer for Live Science. She has reported on general science, covering climate change, paleontology, biology and space. Mindy studied film at Columbia University; prior to LS, she produced, wrote and directed media for the American Museum of Natural History in NYC. Her videos about dinosaurs, astrophysics, biodiversity and evolution appear in museums and science centers worldwide, earning awards such as the CINE Golden Eagle and the Communicator Award of Excellence. Her writing has also appeared in Scientific American, The Washington Post, How It Works Magazine and CNN.