The Black Lace Weaver Spider, known scientifically as Amaurobius ferox, is a common arachnid often encountered in gardens, sheds, and basements across North America and Europe. These spiders are frequently mistaken for more dangerous species due to their dark appearance and tendency to reside near human dwellings. This article clarifies the level of danger the Black Lace Weaver poses to humans.
The Direct Answer: Toxicity Status
The Black Lace Weaver Spider is venomous, as are the vast majority of spider species, but its venom is generally considered mild and not a health concern for healthy humans. The term “poisonous” is often incorrectly used for spiders, which are venomous because they inject toxins through a bite. An encounter with this spider rarely results in a bite, as they are typically shy and prefer to retreat from disturbances. A bite almost exclusively occurs as a defensive measure when the spider is accidentally trapped or squeezed against the skin. The venom is used to quickly subdue small insect prey and is not potent enough to cause medically significant harm to people.
Identifying the Black Lace Weaver
Recognizing the Black Lace Weaver involves looking for its physical characteristics. Females are the larger individuals, typically measuring between 11 and 16 millimeters in body length, while males are slightly smaller. Their coloration is predominantly a deep, velvet-like black or dark brown.
The abdomen is rounded and may display faint, pale yellow or tan markings, sometimes described as a marbled appearance. The web is not a traditional wheel-shaped orb but is a tangled, irregular mesh of silk surrounding a tubular retreat leading into a crevice. This web is made of cribellate silk, giving it a characteristic woolly or “lace-like” texture that is sticky to small insects. These webs are commonly found in dark, moist, and protected areas like under stones, logs, rock walls, or in the corners of basements and sheds.
Symptoms Following a Bite and Medical Response
A bite from a Black Lace Weaver Spider is usually felt immediately, often described as a sharp, localized sting similar to a wasp or bee sting. The most common symptoms are localized to the bite site and include mild pain, minor swelling, and a ring of redness surrounding the area. These mild symptoms are transient, with the pain usually reaching its peak intensity within an hour or two and then resolving completely within 12 to 48 hours.
For immediate first aid, the bite area should be thoroughly cleaned with soap and water to prevent secondary bacterial infection. Applying a cold compress or ice pack can help reduce localized swelling and discomfort. Medical attention is rarely necessary, but seek professional advice if you experience signs of an allergic reaction, such as difficulty breathing or widespread rash, or if symptoms worsen or persist beyond two days.