Friday, August 28, 2009

Grass Spider (Agelenopsis sp.)

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For this genus of spiders, the web is a horizontal, sheet-like web, with a small funnel-like tube off to a side and a 3-dimensional barrier web over the top. When a flying insect hits the barrier, it falls into the sheet below. The funnel (or tube) is what the family (Agelenidae) is named for, and is used by the spider for hunting. The spider will lie in wait in the funnel, and when an insect flies hits the barrier and falls on the web, the spider will rush out, very quickly check to see if it is prey, and if it is prey, bite it. The venom is fast-acting on the prey, so once the prey is subdued the spider will drag the prey back into the funnel (for safety while eating, and to prevent other insects from recognizing the danger that lurks below on the web).

For Agelenopsis spp. spiders, the web is not sticky. If the insect lands/falls on the web, the web will actually become tangled around the prey's feet, temporarily ensnaring it in the web. The funnel web for Agelenopsis is a distinctive web, and often is noticed in bushes and grass, especially in the early fall mornings, where the dew has collected on the web. The webs can be expansive, covering several square feet, or just small webs in the grass.

Raynox DCR-250 mounted on my Panasonic Lumix FZ8.

Saturday, August 8, 2009

Common Barn Spider (Araneus cavaticus)

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The Common Barn Spider (Araneus cavaticus) is a nocturnal, black and brown spider with striped legs. They also have markings on their underside that are typically a black background with two white marks inside the black, although color ranges can be quite magnificent. The photo above shows the classic pose these spiders exhibit, with the front four legs grouped together, and the back legs tucked similarly. They will sit quite still for pictures in this pose, but trust me, if you bump the table they will pop up and run like lightning!

Like many other species of orb weavers, it takes down its web and rebuilds another web every evening. Its "orb" web is the archetypical web that contains symmetrical spokes connected by a spiral inside. They hide during the day and at night will sit in the middle of the web and wait for an insect to land on the web when hunting.

These spiders are aggressive toward each other (and toward humans). They will attack each other if in close quarters, though many may inhabit the same structure or area at any given time. They are most commonly found in rafters and wooden structures in suburban and rural structures or areas, and on boats near lakes, thus getting their name, "barn spider".

They are mostly found in North America in late summer and through autumn. Barn spiders are most common in the Northeast US and Canada.

When agitated (by a puff of air, for instance) these spiders sometimes bounce up and down in the center of their webs, possibly in an attempt to look larger and more threatening.

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

Friday, August 7, 2009

Male Common House Spider (Parasteatoda tepidariorum)

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A Male Common House Spider (Parasteatoda tepidariorum). You can see the difference between this and the female of the species in the post below. Notice especially the much smaller abdomen and much larger black palps on the front.

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 body type 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.

Thursday, August 6, 2009

Female Common House Spider (Parasteatoda tepidariorum)

click for large

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.