Overview

• Male tarantulas have emerged from their burrows and are migrating across Arizona and California deserts in search of mates, forming visible nighttime 'hordes' on roads.
• There are 29 tarantula species in the United States, including more than a dozen in Arizona and ten in California, each adapted to desert and woodland habitats.
• During mating season—late summer in Arizona and August through December in California—males leave at dusk and can travel up to 20 miles in a single season.
• Courtship involves rhythmic tapping and vibration by males to signal their presence, after which females may consume the male and successful females produce egg sacs that hatch spiderlings next spring or summer.
• Tarantulas are non-aggressive with venom comparable to a bee sting and rarely harmful; wildlife agencies advise observing them at night without disturbing their burrows to appreciate their role as pest controllers and prey for larger species.