Two species of black widow spiders exist in Kentucky: the northern black widow and the southern black widow. Known as cobweb spiders because of the loosely spun webs that they create, black widows can cause potentially dangerous bites. However, black widows usually try to avoid contact with humans.
All female widow spiders have a shiny black abdomen. In the northern widow species, the female will have two red inverted triangles that touch. An hourglass marking is found on the female's underside. The southern widow female also has a red hourglass-shaped marking on the underside, but the marking can appear as fragmented. A southern male widow will have white streaks on its sides and will have a narrower abdomen than the female. Northern males can have white or red spotting.
Widow spiders prefer to develop webs beneath objects such as rocks, logs and other debris. They can also organize webs under overhanging embankments. A widow spider will sometimes develop webs within a home, usually under furniture or appliances. Widow spiders subsist on a diet of ants, flies, grasshoppers, beetles and even scorpions. Although female widows derive their name from devouring males after a brief mating, a female will often leave the male unharmed.
Black widows lead solitary lifestyles, with the exception of mating. A female will spin a large web to house her egg sacs. Each egg sac can contain up to 400 eggs. Females will stay close to their webs. It can take up to one month before spiderlings emerge from an egg sac. Spiderlings appear white to yellowish in coloration.
Widow spiders produce a potent neurotoxin. Indicators of a bite include two distinctive puncture wounds at the bite site. Chest tightness and abdominal stiffness occurs within hours after being bitten. Sweating, swelling at the bite site, a headache and nausea can occur. Only 5 percent of bite victims develop convulsions and mortality, notes the University of Kentucky College of Agriculture. However, victims who don't receive medical attention can die.
- University of Kentucky Entomology; Kentucky Spiders; Cobweb Spiders; Blake Newton; May 25, 2004
- University of Minnesota Extension; Potentially Dangerous Spiders; Phil Pellitteri, et al.; 2011
- Texas A&M University Entomology: Southern Black Widow Spider
- University of Kentucky College of Agriculture; Eliminating Spiders Around Homes and Buildings; Mike Potter