cobweb spiders

Theridiidae is a large family of spiders known as cobweb spiders, cobweb weavers, comb-footed spiders, and tangle-web spiders. There are more than 3,000 species in 124 genera worldwide, about 230 species in more than 18 genera in North America north of Mexico, and at least 28 species in 18 genera in Minnesota. They are found almost anywhere, in fields on low plants, on tree trunks, in leaf litter, on fences, and in human houses. The family includes the poisonous black widow spider as well as the often feared but completely harmless common house spider.

Many cobweb weaver species build webs that are a haphazard arrangement of tangled threads, often with a sheet in the middle. This is the feature that gives the family two of its common names. However many other web types are constructed by other species in the family. Many species hang upside down in the center of their web. Others hide nearby with signal threads leading to their web.

Cobweb weavers are medium-sized spiders. Adults are ⅛″ to ⅝″ (3 to 15 mm) long. The upper side of the front part of the body (carapace) is flat and usually shiny with few hairs. The eyes and jaws are small. The abdomen is rounded and is usually globe-shaped, oval, or pointed.

Almost all species have a row of 6 to 10 slightly curved bristles (“comb”) on the last segment (tarsus) of each hind leg. This is the feature that gives the family one of its common names. They also have three claws at the end of each tarsus, but these are not visible to the naked eye.

Sources

24, 29, 30, 82.

Cobweb Weaver with Prey

Location: Woodbury, MN

Cobweb Weaver with Prey