The noble false widow spider, Steatoda nobilis, is a species frequently encountered in human environments. While its name suggests a connection to the notorious black widow, it is venomous, like most spiders, but its bite is generally not considered dangerous to humans. The effects of a bite are typically mild and temporary.
Identifying False Black Widows
Steatoda nobilis can be identified by several distinct physical characteristics. Females typically range from 9.5 to 14 millimeters in body length, while males are slightly smaller, measuring 7 to 11 millimeters. These spiders possess a brown, bulbous abdomen, often marked with cream-colored patterns resembling a skull or pentagon. The legs are usually reddish-orange or uniformly red to brown.
False black widows construct an irregular, tangled web, known as a cobweb. This web features sticky silken fibers and often includes a tubular retreat, a hidden silk tunnel or sac where the spider rests. The silk of their webs is notably strong.
Understanding Their Venom
The venom of the noble false widow spider, Steatoda nobilis, is primarily neurotoxic, meaning it affects the nervous system. This venom contains compounds similar to those found in true black widow venom, such as alpha-latrotoxins, which can disrupt nerve function. However, despite these similarities in venom components, the overall potency of its venom is significantly milder than that of true black widows.
The venom’s primary purpose is to immobilize prey, including both invertebrates and small vertebrates. It also contains enzymes that aid in pre-digestion. Its impact on humans typically results in less severe reactions compared to its more infamous relatives.
What to Do if Bitten
A bite from a noble false widow spider typically causes immediate pain, often compared to a bee or wasp sting. This pain may radiate from the bite site and can be accompanied by localized swelling, redness, and sometimes a pale, raised area around the bite. In some instances, individuals may experience mild systemic symptoms like feverishness, general malaise, headache, or nausea. These symptoms usually subside within 1 to 3 days.
If bitten, cleaning the wound thoroughly with soap and water is important to prevent secondary bacterial infections. Applying a cold pack to the affected area can help reduce pain and swelling. While most bites resolve without medical intervention, seeking medical attention is advisable if symptoms worsen, persist, or if there are signs of infection such as increasing redness, pus formation, or worsening pain after 24 hours.
Differentiating from True Black Widows
Differentiating the noble false widow (Steatoda nobilis) from true black widow spiders (Latrodectus species) is important due to their differing bite severities. True black widows are glossy black with a distinct red hourglass marking on the underside of their abdomen. In contrast, false black widows are dark brown to purplish-brown and lack this iconic hourglass.
Both spider types construct tangled, irregular cobwebs. However, the primary difference lies in their venom’s medical significance. True black widow bites are associated with more severe neurotoxic symptoms, whereas noble false widow bites, while painful, are much milder and rarely lead to serious complications. The pain from a true black widow bite often has a delayed onset, unlike the immediate pain from a false black widow bite.