Fall Tarantula Migration on the Comanche National Grassland

Each year – in the fall – tarantulas appear en masse in La Junta and Southeast Colorado.  Yes, tarantulas! The large, hairy spiders and all species found in Colorado are generally dark brown to black.  

Photo taken on the Comanche National Grassland – Photo Credit
U.S. Forest Service

Whitney Cranshaw, Entomology Professor/Extension Specialist at Colorado State University, explains that the spiders, which are of the Oklahoma brown variety, are common in Southeast Colorado because the females like to make their burrows in undisturbed prairie rangeland. Those females then stick close to their burrows for the entirety of lives, which can be 25 years long.

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.

For species that are present in Southeast Colorado the migration of the adult males take place from late August through September (into early October) and it is at this time of the season when Colorado tarantulas are most often observed.

Viewing Tips

  • September is the ideal time of year to view the tarantula migration – specifically around September 10.
  • There will still be some in October, and some are crawling about before that. 
  • Venture out on a day that is warm, and preferably not too windy.
  • Some tarantulas will be active in late afternoon. 
  • Things really pick up in the hour before sunset. 
  • Around 5:45 p.m. -6:00 p.m. or so, and peak lasts about an hour. 
  • Scout area where there are tarantula hawks, the spider hunting wasps that prey on tarantulas and other large spiders.
  • Ideal viewing south of La Junta on Highway 109 on the Comanche National Grassland
  • There are cars and trucks traveling the road at all times.  People have to keep them on their radar!

Tarantula Links