Scientific Name

Lactrodectus mactans

 

Habitat

The webs of these spiders are usually built in or beneath objects close to the ground such as under porches, under foundations of buildings, and in basements.

 

Life Cycle

Egg sacs are brown, papery, about ½ inch long and oval. They hold from 25 to 900 or more eggs, which have an incubation period of 20 days. Growth requires two to three months, with older females dying in autumn after egg laying.

 

Description

The black widow spider can be recognized by the red hourglass marking on its ventral side of the abdomen. The black widow spider is about 1 to 1.5 inches in size and is a lustrous black color except for the red colored hourglass marking. The male usually has light streaks on its abdomen and is much smaller than the female. The female eats the male after mating. She hangs belly upward and rarely leaves the web.

 

Bite

Only the bite of the female, usually the adult female, is potentially dangerous. Widow spiders inject a toxin that affects the nervous system (neurotoxin). Muscle and chest pain or tightness are some of the most common reactions to the widow toxin. The pain also may spread to the abdomen, producing cramping and nausea. Other general symptoms include: restlessness, anxiety, breathing and speech difficulty, and sweating. Swelling may be noticed in extremities and eyelids but rarely at the bite site. Often there is a general sense of discomfort shortly after the bite, and acute symptoms increase in severity during the first day after a bite. Symptoms usually decline after two to three days but some mild symptoms may continue for several weeks after recovery. The very old, very young, and those with a history of high blood pressure (hypertensive) are at greatest risk. Prompt medical treatment can greatly reduce the danger from widow bites and has reduced fatalities to extremely low rates in recent years.

 

Control

Please contact your local county extension office for current information.