The triangulate cobweb spider, Steatoda triangulosa, is a common arachnid often encountered in human dwellings. These spiders are frequently found in quiet corners of homes, basements, and sheds. This article provides information about identifying this species, understanding its venom and bite, and practical advice on its habitat, behavior, and how to minimize encounters.
Identifying Triangulate Cobweb Spiders
The triangulate cobweb spider is a relatively small species. Adult females typically measure 4 to 6 millimeters in body length, while males are slightly smaller, 2 to 4 millimeters. Their cephalothorax, the fused head and thorax, is usually brownish-orange, and their spindly legs are yellowish, often with darker bands. A distinguishing feature is their round, bulbous abdomen, which is creamy or tan and marked with a distinctive pattern of reddish-brown or purply-brown zigzag lines. These zigzag markings create a series of triangular shapes, giving the spider its common name. Like other members of the cobweb spider family, they construct irregular, tangled webs, often described as scaffold webs.
Understanding Their Venom and Bite
The triangulate cobweb spider belongs to the Steatoda genus, sometimes referred to as “false widows” due to their resemblance to true widow spiders. The venom produced by Steatoda triangulosa is primarily used for subduing insect prey. For humans, their venom can cause a mild toxic reaction, but bites are rare and typically occur only in self-defense if the spider is provoked or accidentally pressed against the skin. Documented cases of human envenomation by Steatoda triangulosa are uncommon.
Symptoms from a bite are generally mild and localized to the bite area, including pain, discomfort, localized redness, minor swelling, and itching. These effects are often compared to a bee sting and usually resolve without severe complications. While other species within the Steatoda genus might have more medically significant venom, the bites of Steatoda triangulosa are generally not considered to pose a significant health risk to humans. They typically do not require medical intervention.
Habitat, Behavior, and Prevention
Triangulate cobweb spiders are highly adaptable and thrive in peridomestic environments, making them a common sight in and around human structures. They frequently inhabit quiet, undisturbed areas within homes such as basements, attics, corners of rooms, and around windows. Outdoors, they can be found in sheds, outhouses, and under eaves. These spiders are not aggressive towards humans and typically fleeing when disturbed. They have poor eyesight and primarily rely on vibrations detected through their webs to locate prey and sense potential threats.
As efficient predators, Steatoda triangulosa feed on a variety of arthropods, including flies, mosquitoes, ants, ticks, and pillbugs. To minimize encounters with these spiders, several preventive measures can be taken. Reducing clutter in basements, attics, and storage areas can limit their hiding spots. Sealing cracks and gaps in foundations, walls, and around windows and doors helps prevent their entry into homes. Regular cleaning to remove their webs, especially in undisturbed corners, can also discourage their presence.