Cobweb spiders, from the scientific family Theridiidae, are a widespread group often found in homes and outdoor spaces. They are known for the irregular, tangled webs commonly called “cobwebs.” While nearly all spiders possess venom, their potential for harm to humans varies significantly.
Understanding Cobweb Spider Venom
Almost all spiders produce venom, primarily to subdue prey. The presence of venom does not automatically imply danger to humans, as many spider venoms have little to no effect on people. Some cobweb spider species are medically significant due to their venom’s effects.
The most recognized medically significant cobweb spiders are the black widow and brown widow spiders. Black widow spiders produce a neurotoxic venom that affects the nervous system. A bite can lead to severe muscle pain and cramping, often spreading to the abdomen, chest, or back, along with nausea, vomiting, and sweating. While these symptoms can be intense, fatalities from black widow bites are rare. Brown widow spiders also have neurotoxic venom, but their bites cause milder, more localized reactions compared to black widows. Effects include a burning sensation at the bite site that may spread, usually resolving within a day or two.
Identifying Common Cobweb Spiders
Cobweb spiders construct messy, three-dimensional webs in secluded areas like corners, basements, or garages. These spiders have small bodies with a distinctive rounded or globular abdomen. Many common house spiders, types of cobweb spiders, are small, dull brown or gray, and have irregular patterns on their bodies.
Black widow spiders are identifiable by their glossy black body and a prominent red or orange hourglass-shaped marking on the underside of their abdomen. This hourglass can vary in intensity or may appear as two separate triangles. Brown widow spiders, a close relative, are tan to dark brown with a mottled coloration and have an orange or yellowish hourglass marking on their underside. A distinguishing feature of brown widows is their unique egg sacs, which are round and spiky, resembling a sandspur or a large pollen grain.
What to Do After a Cobweb Spider Bite
If a cobweb spider bite occurs, basic first aid can help manage symptoms. Clean the bite area gently with mild soap and water. Applying a cool compress or ice pack to the site for 15 minutes each hour can reduce pain and swelling, and elevating the affected area may also be beneficial. Over-the-counter pain relievers and antihistamines can help alleviate discomfort and itching.
Prompt medical attention is advised if symptoms are severe or worsen. Seek professional care if you experience intense pain, spreading redness, or systemic reactions such as muscle cramping, abdominal pain, nausea, vomiting, or difficulty breathing. Seek medical help if a black widow bite is suspected, or if the bite affects a child, older adult, or someone with pre-existing medical conditions. While identifying the spider can be helpful for medical professionals, prioritize safety and avoid risking additional bites.