False widow spiders, belonging to the genus Steatoda, are a common subject of public concern, often confused with more dangerous species. Understanding their characteristics and the effects of their bites can help alleviate apprehension. This article provides information on identifying false widow spiders, understanding their venom and symptoms, distinguishing them from true widows, and how to respond to a bite.
Identifying False Widow Spiders
False widow spiders, such as the noble false widow (Steatoda nobilis), cupboard spider (Steatoda grossa), and rabbit hutch spider (Steatoda bipunctata), are dark in color, ranging from black to brown or purplish-brown. They possess a rounded, glossy abdomen, with adult females being larger, up to 15 mm in body length. Many species display distinctive markings on their abdomen, often described as skull-shaped or featuring cream-colored patterns, though these can vary or be faded.
Their legs are reddish to brown; some species, like the rabbit hutch spider, have visible dark stripes. False widows construct tangled, irregular webs, which may appear dense in the center. These spiders commonly inhabit sheds, outbuildings, wall crevices, and under logs, preferring hidden areas near the ground or elevated positions in homes like conservatories and top corners of rooms. They are not aggressive; bites occur only when a spider feels threatened or is accidentally trapped.
Understanding False Widow Venom and Bite Symptoms
False widow spiders are venomous, injecting venom through a bite. Their venom is not considered medically significant or life-threatening to humans. Bites are comparable to a wasp or bee sting, causing localized pain that may radiate from the bite site.
Common symptoms include redness, swelling, and itching at the affected area. Pain lasts between one and twelve hours, seldom exceeding 24 hours.
Less common symptoms include mild and transient nausea, headache, mild fever, or dizziness. Severe reactions like blistering, tissue necrosis, or bacterial infection are uncommon and linked to secondary infection or individual allergic sensitivity, not the venom itself.
Differentiating False Widows from True Widows
False widow spiders (genus Steatoda) are confused with true widow spiders (genus Latrodectus), including black widows and redbacks. A primary visual distinction is that false widows lack the prominent red hourglass marking found on the underside of true widow spiders.
True widows are glossy jet black, while false widows are brown, purplish-brown, or black, often with lighter cream or skull-shaped markings on their abdomen. True widow spiders have a more globular, rounded abdomen that comes to a point, and their legs are longer in comparison to their body size than those of false widows.
The venom of true widows is neurotoxic and can cause severe systemic effects, including intense pain, muscle cramps, and increased blood pressure, a significant difference from the localized symptoms associated with false widow bites. Accurate identification helps in understanding the actual risk and responding appropriately.
What to Do After a Bite and Prevention
If bitten by a false widow spider, immediate first aid involves cleaning the wound thoroughly with mild soap and water to prevent infection. Applying a cool compress or ice pack to the affected area for about 10-15 minutes can help reduce pain and swelling. Elevating the bitten limb, if possible, aids in minimizing swelling. Over-the-counter pain relievers and antihistamines can be used to manage discomfort and itching.
Medical attention should be sought if symptoms worsen or signs of infection appear, such as spreading redness, pus, or increased pain. Additionally, seek care if an individual experiences a severe allergic reaction like difficulty breathing or a widespread rash.
To prevent false widow spider encounters, seal cracks and gaps around doors, windows, and walls to block entry points. Regularly vacuuming and cleaning to remove webs and clutter, especially in corners and secluded areas, can also discourage their presence. Wearing gloves when handling garden waste or cleaning neglected outdoor areas can also reduce the risk of accidental bites.