Thursday, August 6, 2009

Female Common House Spider (Parasteatoda tepidariorum)

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A Female Common House Spider (Parasteatoda tepidariorum). A male of the species is posted above. Notice how large and bulbous the female abdomen is. Also notice the small palps.

They are generally dull in appearance, with patterns consisting of brown shades for coloration, often giving a vague spotted appearance that is particularly noticeable on the legs. Their average body size is a quarter-inch long, but they can be an inch or more across with legs outspread. These traits combined allow the spiders to blend into the background and escape notice.

Like some other species of the family Theridiidae, P. tepidariorum shares a body shape and size that makes it similar to widow spiders, which have venom that is classified as potentially dangerous.

These spiders are not aggressive. They are not known to bite people frequently, nor is their venom known to be dangerous to human beings. When removed from their webs their poor vision and bulbous abdomen renders them nearly helpless. Their only concern seems to be to find and return to their own web or build another one. They do not wander around inside houses except to find a secure place to build a web. Since these spiders are harmless and their diet consists of pests such as flies and mosquitos, as well as other small invertebrates found in houses, tolerating their presence in human homes is beneficial.

Raynox DCR-150 and Raynox DCR-250, stacked and mounted on my Panasonic Lumix FZ8.

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