Tarantulas are found in the Colorado Springs area, though sightings are uncommon for most of the year. The native spiders inhabit the lower-elevation plains and grasslands surrounding the region, as the city is near the northern edge of their distribution. Their presence becomes much more noticeable during a short seasonal window in the late summer and fall. This temporary spike in visibility is related to a biological imperative that draws the spiders out of their secluded underground homes.
Confirming the Presence and Species
The primary large tarantula species found in eastern Colorado is Aphonopelma hentzi, commonly known as the Texas Brown or Oklahoma Brown Tarantula. This species is native to the state, with its range extending across the southern and eastern plains, including areas accessible to Colorado Springs residents. It is a true terrestrial burrower, spending most of its life hidden beneath the soil.
Aphonopelma hentzi is a New World tarantula, characterized by its use of urticating hairs as a primary defense. It is identifiable by its robust size, reaching a leg span of up to four inches, and its dark brown to black coloration. It is the most commonly encountered large spider in the southeastern grasslands near the city.
The Colorado Springs area sits close to the northern geographic limit for this species, resulting in a lower population density than in warmer climates further south. These tarantulas prefer drier, less-developed prairie habitats, generally located away from the higher elevations of the mountains. They thrive in arid scrublands and grasslands where they excavate silk-lined burrows.
The Annual Migration Phenomenon
The sudden appearance of tarantulas is not a true migration but an annual mating event carried out exclusively by mature males. They abandon the safety of their burrows to wander across the landscape in search of a female’s burrow, sometimes traveling over a mile from home.
This wandering typically begins in late August and continues through September and October, peaking around mid-September as the weather cools. Males take seven to ten years to reach reproductive readiness, and this wandering stage marks the final phase of their lives. Females remain hidden in their established burrows, awaiting a partner.
Because the males travel across open areas and roads during daylight hours, they become highly visible. The most active time for these wandering males is often the hour just before sunset, making late afternoon the peak time for accidental sightings. This brief period is the only time most people see a tarantula in this region.
Safety, Behavior, and Local Habitat
Despite their intimidating appearance, Aphonopelma hentzi is known for its docile temperament and is not aggressive toward humans. Their first instinct when confronted is to flee or retreat into a defensive posture. A bite is extremely rare and occurs only if the spider is handled roughly or accidentally stepped on.
If a bite occurs, the venom is not medically significant to humans, with effects comparable to a mild bee sting. A more common defense mechanism is the flicking of urticating hairs, which are small, barbed bristles on the abdomen. When disturbed, the tarantula kicks these hairs into the air, causing localized skin irritation, itching, or a rash.
When not engaged in the fall mating trek, these spiders are solitary and spend their time in deep, vertical burrows that can extend a foot or more into the soil. They line the inside of the burrow with silk to maintain a stable microclimate and detect vibrations from passing prey. If a tarantula is encountered, the best course of action is to simply leave it alone.