Bugs and spiders in Colorado

What to watch for in Colorado

The western black widow is the main spider to respect, and an adult female's bite can cause severe muscle pain and cramps, so get medical advice right away. The hobo spider is established and rated Be careful; adult males are searching for mates from August through October. The Arizona bark scorpion is listed for the far southwest edge only, and its sting is very painful, so call Poison Help right away if stung.

Three ticks are established: the American dog tick, the Rocky Mountain wood tick, which is most active from snowmelt through about mid-July, and the brown dog tick, which lives mostly indoors with dogs. All can carry disease, so remove any attached tick promptly. Brown recluse and lone star tick records exist, but neither is known to live in Colorado, and sightings are often misidentifications or hitchhikers. The number for Poison Help is 1-800-222-1222.

Through the year

Spring

Rocky Mountain wood ticks are active from snowmelt, American dog tick adults are out from about April, and European paper wasps are seen around the outside of the house.

Summer

Western black widows are most active from late spring through fall, and European paper wasps are around the outside of the house through late summer.

Fall

Boxelder bugs, western conifer seed bugs and Asian lady beetles move in, and hobo spider males are on the move from August through October.

Winter

Indianmeal moths are most often noticed from November through February, pavement ants can appear in heated homes, and a lone European paper wasp queen may turn up indoors.