Indoors, many spiders may be found in basements, crawl spaces and other areas where it is somewhat damp. Other spiders, however, prefer a drier situation and can be found in the upper corners of rooms, in attics or in floor vents. After mating, female spiders lay eggs in clusters called egg sacs. A few species lay their eggs in dark hiding areas and not in a silken sac. A female may produce several egg sacs in her life.
Eggs usually hatch into small spiders within three weeks.
Mating and egg laying can occur at any time of the year, depending upon species. Most spiders are not considered dangerous. These two spiders are not aggressive and bites are uncommon. Their bites are rarely fatal but can cause serious illness. The black widow spider, Latrodectus hesperus, is common throughout Colorado.