Question: This is the second year I have had black widow spiders in my yard. Is there a way to permanently get rid of them?
Answer: There are 300 species of spiders found in the United States. Those belonging to the genus Latrodectus are commonly known as widow spiders. There are two species of black widow spiders found in New Jersey - the southern L. mactans and the northern black L. variolus. Both have similar appearances, but differ in the shape of their hour-glass marking.
According to Rutgers entomologist Joseph Ingerson-Mahar, there also may be other species of black widows that have been transported here accidentally, occasionally arriving in shipments of household goods. Even though the black widow is an uncommon spider they can be found frequently in quiet out-of-the-way places such as basements, sheds, wood piles and under porches.
Adult females have a body length of approximately 1/2-inch long, 1 1/2-inches total in the leg span. Males are much smaller, the body is around 1/4 inch, and 1/2 inch including the leg span. The females body is shiny black on top with the classic red hour-glass markings on the underside. The hour glass may be divided into three separate triangular shapes. The web of widow spiders is not an orderly geometric web, but rather a tangled mass. Young spiders are mostly white or yellowish and gradually change color to the typical black with red markings.
Black widow spiders are not considered aggressive spiders, but will bite when threatened. The venom is a neurotoxin and will interfere with muscle contraction. To accurately identify the black widow look for a red hour-glass shape on the underside of the abdomen. They are generally black or dark brown, and their web is not an organized design, but rather a haphazard mess of strands.
The bite is initially not painful but within 15 to 60 minutes more severe symptoms occur. These may include sweating, nausea, a rise in blood pressure, abdominal cramps, leg cramps, heartbeat irregularities and vomiting. Young children and elderly are most susceptible. If you believe you have been bitten by a black widow, you should seek medical attention immediately. If possible you should try to bring the spider with you for identification.
Preventing the bite is the best control. Entry places into your home should be sealed with weather stripping or expandable foam. Eliminate habitats by removing clutter indoors and out. Wear gloves when handing items stored outdoors. If spotted, use a vacuum cleaner and immediately throw the bag away outdoors.
Mona Bawgus is a certified master gardener and consumer horticulturist with Rutgers Cooperative Extension of Atlantic County. Write to her c/o Rutgers Cooperative Extension, 6260 Old Harding Highway, Mays Landing, NJ 08330. Email: