Creepy, crawly love: Colorado's annual tarantula 'migration' has begun

Posted at 1:44 PM, Sep 07, 2021

Over the next few weeks, the setting sun over the Rocky Mountains will lure thousands of hairy, eight-legged creatures out of their burrows across the eastern plains in search of love.

It's that time of year again — Colorado's tarantula "migration" is underway.

This annual phenomenon has gathered an increase in public interest and fascination over the past few years.

Here's what you need to know about the tarantula "migration" in Colorado.

Q. What is the tarantula "migration?"

The quotes around migration are there for a reason. It's not quite accurate to call their movements a migration, as they're simply just visible more than other times of the year and appear to be marching around on a mission. But the phrase caught on.

This time of year, male tarantulas in the southeastern part of Colorado will leave the safety of their burrows to search for females, who stay hidden in their own holes, said Mario Padilla, a lead entomologist at the Butterfly Pavilion in Westminster.

2021 tarantula migration_Megan Starcevich
Megan Starcevich captured this photo of a tarantula south of La Junta on Sept. 3, 2021.

"People see them out walking around, so they're like, 'Where are they going? They must be migrating,'" Padilla said. "They're not truly migrating. And it's only the males that walk around. You don't see the females at all."

When the males find a female's burrow, they drum their legs at the entrance — like rapid, soft knocking on a front door — and wait for the female to come out to breed.

The males don't live long after mating. Death by predator, car or starvation — or rather, lack of interest in eating anything — typically follows. And in some cases, if the female is cranky, she may eat him, said Paula Cushing, a biologist with the Denver Museum of Nature and Science.

Q. When does the tarantula "migration" happen?

The mating season starts once the temperatures cool at night, which is typically around the start of September.

Some residents in the southeastern region of Colorado have posted on Facebook that the critters are already on the move.

This "migration" will continue through early October or whenever hard freezes begin, Padilla said.

Q. Where is this happening?

The tarantulas are all around the eastern plains, particularly the southeastern part of the state.

"Mini" tarantulas also live on the western side of the state in areas like Montezuma, Montrose, and San Miguel, according to Colorado State University's College of Cultural Sciences.

Tarantulas out by the thousands in southeast Colorado for mating season

Q. Can I see it for myself?

There are a few things to know beforehand for those who want to see the critters in action.

One of the best places to go to see the tarantulas is the Comanche National Grassland near La Junta and Springfield. The scrubby grassland, which is at a lower altitude compared to the Front Range, contains more than 400,000 acres for recreating, said Michelle Stevens, recreation program manager for the grassland.

She said drivers often see tarantulas crossing the road because they're easy to pick out on the pavement. She recommends driving on Highway 350 between La Junta and Trinidad or Highway 109 between La Junta and the town of Kim to see them. It's also not a bad idea to stop in a local restaurant and ask residents where they've seen them, she said.

Cushing said that any given evening would likely produce a dozen or so tarantulas in an undisturbed area.

Be prepared to head out around sunset and stay late into the evening.

Those visiting the area should be aware of the lines between public and private property.

Q. What kind of tarantulas live in Colorado?

When Scripps station KMGH in Denver published a feature story on the tarantula "migration" in 2018, many readers and viewers said that despite living in the state their whole lives, they had never heard of it before.

"Here in Colorado, we don't always think that we have habitat for tarantulas," Padilla said. "A lot of people think tarantulas are super exotic, like they live in South America or Africa or Asia or wherever. And they do live in those places. But we do have beautiful, western tarantulas that live here too."

All of the tarantulas that call Colorado home fall under the genus Aphonopelma, Padilla said. They're usually a "drab brown color" that helps them camouflage into their environment, he said. Their bodies, excluding their legs, are typically two to three inches long.

They're large, and that's why people typically reel when they see them, he said.

"Seeing a really big spider — they're bigger than any wolf spider," he said. "They're the largest spider in the state, for sure. So, seeing that spider is kind of like, 'Whoa!'"

The on-the-move tarantulas — the males — are longer, with a small abdomen and long, spindly legs to help them get around quickly. The females, on the other hand, don't need that kind of biological adaptation and are often larger.

Male tarantulas are sexually mature once they reach about 7 years old and can live for about a decade. Females can live well beyond that — up to 30 years.

2021 tarantula migration_Lori Gapter
Lori Gapter snapped this photo of a tarantula north of Ordway on Highway 71 in September 2021.

Q. Can a tarantula hurt me?

Tarantulas are much more terrified of you than you are of them, Padilla said.

Despite common misconceptions, they're not aggressive animals and won't jump or attack a person.

Their first choice in the face of a larger-than-life human being? Flee.

It takes a lot of stress for a tarantula to try to bite a person, but it will happen under certain circumstances.

Those that find themselves in the unfortunate position of being bit can find a little peace of mind knowing that tarantula venom is not deadly to humans but may cause discomfort for a few days.

As with any wildlife, don't get too close and never harass or touch a wild tarantula.

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This story was originally published by Stephanie Butzer on Scripps station KMGH in Denver.