Adult male black widows wander around in search of a female. During this time, males do not bite or feed. First, a male black widow spins a very small web, and then he places a drop of sperm on the web or the silk. He then takes the sperm into special receptacles on the ends of his pedipalps. Afterwards, he searches for a female so that he can place the sperm into the female's genital opening. After the female and male mate in this way, the female lays several bunches of eggs, which contain about 750 eggs. A single bunch of eggs is suspended in a web so that nothing happens to to the eggs before they hatch. A single egg case is about 1 cm in diameter. The egg sac can either be tan or white, and usually has a paper-like texture. Within a given summer, a female may make between 4 and 9 egg sacs. Incubation lasts about 14 days, and the young spiders are cannabalistic. Only one to twelve spiders from an egg sac actually live to be 30 days old.
After males are born, it takes about 70 days for them to mature, and then they die after about a month to two months. In part, this is because females sometimes eat a male after mating takes place. Females, on the other hand, only take about 90 days to mature. Female black widows usually live up to a year and a half.
Average gestation period: 14 days.
Average age at sexual or reproductive maturity (female): 90 days.
Average age at sexual or reproductive maturity (male): 70 days.
Key Reproductive Features: sexual ; fertilization (Internal ); oviparous
- Desert USA, 1996. "Black Widow Spiders/Latrodectus hesperus" (On-line). Accessed March 21, 2001 at http://www.desertusa.com/july97/du_bwindow.html.
- Jones, S. 1991. "Ohio State University Extension Factsheet/ Black Widow Spider" (On-line). Accessed February 15, 2005 at http://ohioline.osu.edu/hyg-fact/2000/2061A.html.