Triangulate cobweb spider

Taxobox
name = Triangulate cobweb spider
regnum = Animalia
phylum = Arthropoda
classis = Arachnida
ordo = Araneae
familia = Theridiidae
genus = "Steatoda"
species = "S. triangulosa"
binomial = "Steatoda triangulosa"
binomial_authority = C. A. Walckenaer, 1802

The Triangulate cobweb spider (scientific name: "Steatoda triangulosa"; also called the triangulate bud spider) is a common house spider in the genus "Steatoda". As the name indicates, it is well-known for the triangle-shaped pattern on the dorsal side of its abdomen.

Description

The adult female triangulate cobweb spider is 1/8 to 1/4 inch long (3 mm to 6 mm), with a brownish-orange cephalothorax and spindly, yellowish legs. The round, bulbous abdomen is creamy in color, with parallel purply-brown zigzag lines running front to back. This distinctive pattern sets it apart from other Theridiids in its area. .

The triangulate cobweb spider is known to prey on many other types of arthropods, including ants (including fire ants), other spiders, pillbugs, and ticks. It preys on several other spiders believed to be harmful to humans, including the hobo spider and the brown recluse.

The egg sac of the triangulated cobweb spider is made from loosely woven silk, and is about the same size as the spider itself. Each egg sac contains approximately 30 eggs.

Habitat and range

In common with other members of the "Theridiidae" family, "S. triangulosa" constructs a cobweb, i.e. an irregular tangle of sticky silken fibers. As with other web-weavers, these spiders have very poor eyesight and depend mostly on vibrations reaching them through their webs to orient themselves to prey or warn them of larger animals that could injure or kill them. They are not aggressive. Other, larger members of the "Steatoda" genus do have medically significant bites, but there are no recorded bites or envenomations by this spider.

"S. triangulosa" is a cosmopolitan species, and is found in many parts of the world, including all three coasts in North America, in southern Russia and New Zealand, and in Europe. The spider is believed to be native to Eurasia. This species is primarily a house spider, and builds webs in dark corners of buildings and other man-made structures.

External links

* [http://lancaster.unl.edu/pest/resources/TriangulateSpider.shtml Triangulate Household Spider]
* [http://research.amnh.org/entomology/spiders/catalog/BIB5.html The World Spider Catalog]
* [http://www.uark.edu/depts/entomolo/museum/steatoda.html University of Arkansas Arthropod Museum Notes: Triangulate cobweb spider]
* http://www.puyallup.wsu.edu/plantclinic/resources/pdf/pls107steatodaspider.pdf
* [http://www.ento.psu.edu/extension/factsheets/Spider/spiders.htm Penn State University Dept. of Entomology: Commonly Encountered Pennsylvania Spiders]
* Levi, H.W. 1957. "The spider genera Crustulina and Steatoda in North America, Central America, and the West Indies (Araneae, Theridiidae)." Bull. Mus. Comp. Zool. 117(3):367-424
* [https://www.rsnz.org/publish/nzjz/1994/18.php Descriptions of four "Steatoda" species found in New Zealand]
* [http://www.cirrusimage.com/spider_cobweb_Steatoda.htm pictures]
* [http://www.srv.net/~dkv/hobospider/steatoda.html Hobospider.com: Steatoda spiders as competitors/predators of the hobo spider]