The Triangulate Cobweb Spider (Steatoda triangulosa), also known as the Triangulate Bud Spider, is a species of common house spider that is found throughout the world. It is found along the coasts in North America, in southern Russia, in New Zealand, and in Europe. It is largely believed to be native to Eurasia.
This spider is well known for the triangle-shaped pattern on the upper side of its abdomen. The adult female is 0.13 to 0.25 inches long. It has a brown-orange cephalothorax (anterior section including the fused head and thorax) and spindled, yellowy legs. The abdomen is cream colored, with purple-brown zigzag lines running front to back.
The Cobweb Spider builds a cobweb that consists of an irregular tangle of sticky silk fibers. This species has poor eyesight and depends largely on vibrations on the web when prey make contact or also to alert them of possible danger when larger animals are nearby and could possibly injure or kill it. This spider preys on many types of arthropods, including ants, spiders, pillbugs, and ticks. It preys on a number of spiders that are considered dangerous or poisonous to humans, such as the hobo spider and the brown recluse. The egg sac is made from loosely woven silk, and is about the same size as the spider. Each egg sac contains up to 30 eggs.
Although larger members of the genus are known to have significant venom and produce a harmful bite, this species is not aggressive and no recorded bites or envenomations are known.