Thousands of Tarantulas Are About to Crawl Across Colorado as Old Males Hunt for Females in Mass Migration

Arachaphobes might want to skip Colorado in the next few weeks, as thousands of tarantulas are set to emerge for their annual migration.

From around late August, the hairy, brown and black spiders appear in La Junta in Otero County and southeast Colorado looking for mates, The Gazette reported.

These male Oklahoma Brown tarantulas will be looking for females who tend to stay put by their burrows, Whitney Cranshaw, a professor of entomology at Colorado State University, explained to La Junta Tourism. In fact, apart from the migration period, these homebody spiders stay in their burrows for their entire lives.

To mate, the male tarantula spins a web where he leaves his sperm and copulates with appendages near his mouth. He then dashes off in case the female devours him. Next, females bind the sperm and egg in a cocoon. Six to nine weeks later, up to 1,000 babies will hatch.

As cultivation of the land destroys their habitats, the burrows are located on prairies. These silk-reinforced homes can measure up to a foot deep. There, the arachnids wait for insects, like scarab and ground beetles, to pass at night before attacking and injecting them with venom.

"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," according to La Junta Tourism.

Paula Cushing, a biologist at the Denver Museum of Nature & Science, told The Gazette the males heading to Colorado will be about 10 years old. On average, female tarantulas can live for up to 30 years while males have a lifespan of up to 12 years; grow between 4.75 to 11 inches; and weigh between one to three ounces.

tarantula, spider, arachnid, stock, getty,
A stock image of a tarantula. These animals appear in Colorado in August. Getty

Those who wish to see the phenomenon first hand have the best chance in September, particularly around the 10th, but you can still spot the insects in October. Head out on a warm, wind-free day, in the late afternoon at around 5:45pm to 6pm for about an hour. La Junta on Highway 109 on the Comanche National Grassland is the best spot, according to the tourism board.

"Things really pick up in the hour before sunset," La Junta Tourism states.

Tarantula hawks, the wasps which feast on big spiders, can act as a clue as to whether the insects are in the area.

While tarantulas might make an arachnophobe's skin crawl, the bugs can't harm humans, according to National Geographic. In fact, the venom of an average bee is more poisonous to us.