The False Black Widow (Steatoda species) is a common household spider frequently mistaken for the true Black Widow (Latrodectus species). This confusion stems from their similar dark, glossy appearance and rounded body shape, leading many to question the False Black Widow’s safety. While these spiders are venomous, the key question for humans is whether their venom is medically significant or dangerous. This article will examine the False Black Widow’s characteristics, the nature of its bite, and the specific differences that set it apart from its infamous relative.
Identifying the False Black Widow
The False Black Widow belongs to the Steatoda genus, often referred to as cupboard spiders due to their preferred habitat. Females are generally dark brown to purplish-black and relatively small. They feature a distinctively large, bulbous abdomen that contributes to the misleading resemblance to the true Black Widow.
The abdomen is usually glossy and may display lighter markings, such as a crescent shape near the front or pale triangular spots, though these patterns can be subtle or entirely absent in the darkest specimens. False Black Widows are frequently found inside or around human dwellings, preferring dark, sheltered, and undisturbed locations such as clutter, sheds, garages, and basements. They construct irregular, tangled webs known as cobwebs, which they use to capture small insects and other invertebrates.
Toxicity and Symptoms of a Bite
Like nearly all spiders, the False Black Widow is venomous. However, its venom is generally considered to be of low potency to humans, and bites are usually defensive, occurring when the spider is accidentally squeezed or trapped. The effects of a bite are often mild, comparable to a bee or wasp sting, involving an immediate, sharp pain followed by localized redness and swelling at the site.
The condition resulting from a Steatoda bite is sometimes called steatodism, which is a milder form of the neurotoxic reaction seen with true Black Widows. While typically localized, some individuals may experience mild systemic symptoms that resolve within one to three days. These can include a general feeling of malaise, mild nausea, or a headache, though such reactions are uncommon.
The venom of the False Black Widow is a neurotoxin, similar to its relative, but it is significantly less potent. Reports of severe reactions are rare, and the most serious complications often involve secondary bacterial infection introduced at the bite site, rather than the venom itself. Keeping the wound clean is important to prevent such infections.
Key Differences from True Black Widows
The most reliable way to distinguish the False Black Widow (Steatoda) from the True Black Widow (Latrodectus) involves observing specific physical markings. True Black Widows are identified by the presence of a distinct, bright red or orange hourglass marking on the underside of their abdomen. The False Black Widow lacks this prominent hourglass marking.
Beyond the markings, there are subtle differences in body shape and leg structure. The abdomen of a True Black Widow tends to be more spherical and globular. In contrast, the False Black Widow’s abdomen is often slightly more elongated or egg-shaped. True Black Widows also tend to have longer legs relative to their body size compared to the False Black Widow, which has shorter, somewhat more slender legs.
Both species build irregular, tangled webs. The Steatoda genus is also known to prey on actual Black Widows, highlighting a distinct ecological difference despite their superficial resemblance. Recognizing the absence of the red hourglass is the primary method for confirming a spider is a False Black Widow.
When to Seek Medical Help
Although False Black Widow bites are typically mild, seeking medical attention is prudent in certain specific circumstances. You should consult a healthcare provider if you develop signs of a severe allergic reaction, such as difficulty breathing, swelling of the face or throat, or a widespread rash. This type of systemic reaction requires immediate treatment.
Medical help is also necessary if the bite site develops signs of a secondary bacterial infection, which is the most common reason for serious complications. These signs include increasing redness spreading far from the bite, excessive warmth, intense swelling, or the development of pus or an ulceration. Furthermore, if you are unsure of the spider’s identity and begin to experience severe, widespread systemic symptoms like intense, persistent muscle cramps or severe abdominal pain, immediate medical evaluation is warranted.