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

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.

Beginning in late August, Oklahoma brown tarantulas ( Aphonopelma hentzi, also known as Texas brown tarantulas) will begin their trek through the La Junta, Colorado, area, a journey to undisturbed grasslands that typically lasts through early October, according to a report by The Gazette , a newspaper that serves Colorado Springs.

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.

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 .

A huge tarantula migration is about to start in parts of Colorado as thousands of the hairy arachnids set out on a search for mates.

The Gazette reports that the annual migration starts in La Junta, about 176 miles southeast of Denver, and the southeastern part of the state in late August. It continues through October.

Officials say that the migration involves Oklahoma brown tarantulas. Experts say the majority of the spiders are 10-year-old males looking to mate with females hidden in Colorado’s grasslands.

“Male spiders are leaving their burrows to find suitable mates,” tweeted the Denver Museum of Nature and Science Thursday.

The Comanche National Grassland spans more than 440,000 acres of southeastern Colorado.

“The male tarantulas — when they reach about 8 years old — gang up in groups and set out, using their senses of touch and vibration to locate the females,” says the Visit La Junta website.

September is the best time of year to view the tarantula migration, according to the website, which says that around Sept 10 is the peak viewing time. Of course, depending on your feelings about spiders, this may also be the best time to avoid the tarantulas on their trek.

Officials say tarantulas are mostly harmless to humans but have bites that can cause injury or allergic reaction. They also have hairs that can be irritating to the eyes, mouth and nose.