Black widow spiders are present in Pennsylvania, though encounters with them are not particularly common. Both the Southern black widow (Latrodectus mactans) and the Northern black widow (Latrodectus variolus) can be found within the state. While these spiders possess venom, the risk they pose to humans is often overstated, and bites are rarely life-threatening.
Identifying Black Widows
Identifying black widows focuses on the female’s distinct characteristics. Female black widows are jet black and shiny, measuring 8 to 19 millimeters long. Their most recognizable feature is a bright red or orange hourglass-shaped marking on the underside of their rounded abdomen. This marking can also appear as two separate triangles or have additional red spots on the top of the abdomen.
Male black widows are about half their size and exhibit lighter coloration. They may have white underbody markings and red spots, or white and tan patterns. Males generally do not pose a threat to humans, as their mouthparts are too small to penetrate human skin. Juvenile black widows are orange, brown, and white, gradually darkening to black with each molt.
Typical Habitats
Black widow spiders prefer dark, secluded, and undisturbed environments for building their irregular, messy webs. Outdoors, they are found in woodpiles, under stones, stumps, or other debris. They also inhabit outdoor structures like sheds, barns, and garages, often near the ground. Occasionally, they are found around vacant animal burrows.
Indoors, black widows seek similar quiet, low-traffic areas. Common indoor habitats include basements, crawl spaces, and dark corners of closets or garages. They avoid moist areas, preferring dry conditions. Their webs are constructed close to the ground, reflecting their preference for undisturbed locations to capture prey.
Responding to Encounters
Encounters with black widow spiders, and subsequent bites, are rare and usually occur as a defensive measure when the spider feels threatened or its web is disturbed. If a black widow is sighted, avoid direct contact. Using a broom or vacuum to remove the spider can be effective. Wearing gloves when gardening or handling materials in areas like woodpiles or sheds helps prevent accidental bites.
A black widow bite may initially feel like a pinprick or go unnoticed. Within minutes to hours, symptoms can develop and spread from the bite site. Common reactions include localized pain that can intensify and radiate to other parts of the body, often feeling like a dull muscle ache. Muscle cramps, particularly in the abdomen, chest, or back, are a hallmark symptom and can become severe. Other symptoms include nausea, vomiting, sweating, fever, headache, and general weakness.
In rare cases, severe reactions like trouble breathing may occur. If a black widow bite is suspected, wash the bite area with soap and water. Apply ice to the wound to help reduce swelling and pain.
Seek medical attention promptly for any suspected black widow bite, especially if symptoms spread beyond the bite site or become severe. While antivenom is available, it is reserved for severe cases, and fatalities from black widow bites in the United States are exceedingly rare. Recovery is usually complete within 24 to 48 hours, though some effects may linger for a few days.