What are the life cycles of the black widow and the brown recluse spiders?
Black widow females lays 300-400 eggs in a globular, white silken sac, about ½” in diameter. The sac turns pale brown in later stages of development. They may produce four to nine egg sacs during the summer. Most of the developing spiders are cannibalized during the 14-30 days of egg incubation and only 1-12 survives from each egg sac. Black widow spiders take two to four months to develop, depending on the availability of food. Females molt six to eight times and males only three to six times before becoming adults. Females mature about 21 days later than males and start to mate and lay egg sacs soon after maturation. Adult females live approximately 179 days, whereas adult males live only about 30 days. Black widow spiders often consume their mates. However, a well-fed female will not eat her mate, allowing him to mate again. Brown recluse females lay about 300 eggs from May to August. The egg sacs are off-white, about 1/3″ in diameter, and contain more than 40 eggs. The egg sacs are
