Family Theridiidae - Cobweb Spiders
There are more than 200 species in this family, which includes both brown and black widow spiders.
Spider Index | Spider Main | Orb Web | Cobweb
Custom Search
Female house spider
Female house spider

Cobweb spiders are common in North America, and can be found almost anywhere that they can find weeds, fences, trees, walls, or other upright structures. Cobweb spiders are predators, and they will eat almost anything that is small enough to get trapped in their webs.

Common house spider male
Common house spider male

Like most web-building spiders, cobweb spiders tend to have poor vision - they don't need to see very well because they can "feel" prey when it gets caught in their webs. Most cobweb spiders are considered beneficial to humans. They eat flies, mosquitoes, and other creatures. However, The black widow spider is a cobweb spider, and its bite can be dangerous.

Female house spider and egg cases
Female house spider and egg cases. Each papery case contains dozens of eggs.

Cobweb spiders' webs are disorganized, unlike the circular webs made by orb-weavers and other web-building spiders. Cobweb spiders have 8 eyes and 8 legs, 2 body parts, and fang-like mouthparts called chelicerae. Most cobweb spiders live for less than 1 year. At the end of the summer, female cobweb spiders produce a large amount of eggs they wrap in an egg sac made of silk.
Also called comb-footed spiders, after the inconspicuous comb like bristles on the hind tarsi of many species. These spiders spin irregular webs and use their combs to fling silk over any  prey that gets caught. Thus swathed, the  victim is then hauled to a rest site, injected with venom, and eaten.

Black Widow Spider - Latrodectus mactans
Black Widow
Brown Widow Spider
Brown Widow

Female Cobweb Spider
Female Cobweb Spider - Enoplognatha ovata
Common House Spider
Common House Spider
Cobweb Spider
Steatoda triangulosa
Cobweb Spider
Theridion sp.
References
  1. Paul Hillyard, Private Life of Spiders (New Holland Publishers Ltd, 2007)
Wondering how to get that bug identified? Please see the kind folks at Bugguide.net. (North America)
North American Insects & Spiders is dedicated to macro photography of live, wild organisms in situ.
Custom Search
Class Arachnida / Order Araneae: Spiders are the largest group of arachnids.  They are easily recognized by their eight legs, and there are few creatures great or small that elicit such irrational fear in mankind. The vast majority of spiders are completely harmless and offer beneficial services, chief of which is keeping the burgeoning insect population in check. I am continually amazed at the resourcefulness of these supremely successful predators. Spider Index | Spider Main
© Red Planet Inc.