Thursday, September 06, 2007

That's A Sound I Like

Ok I will accept the charge of speciesism when it comes to mosquitoes. In this case we can thank the arachnids for effectively doing what pesticides can't. And I am partial to spiders after all.

A real monster spider’s web has been found in Lake Tawakoni State Park in Texas, USA. Apparently the web, stretching 180 metres, is the result of millions of spiders working together, to the mystification of park rangers.

The web is proving effective in controlling the mosquito population. Donna Garde, park superintendent, said that “There are times you can literally hear the screech of millions of mosquitoes caught in those webs.”

Though scientists are yet to explain why, or which species, the spiders built this.


Donna Garde, park manager at Lake Tawakoni State Park, sees tens of thousands of mosquito carcasses weighing down the webs.

Entomologist Professor John Jackman of A&M University said that similar webs were reported every couple of years. They are either created by social cobweb spiders working together, or by spiders spreading out from a central point. He commented that “until we get some samples sent to us, we really won’t know what species of spider we’re talking about”.

There is much debate amongst experts over the reasons for the web's construction, with some believing it was created by social spiders living as a colony, and others suggesting it is possibly a system of mass dispersal, with the spiders building webs in order to spread out. There is also uncertainty over the species of spider responsible, although it is known that smaller webs of an otherwise similar nature have been discovered elsewhere in the park, on another trail. It is thought that the species is likely a member of the genus Tetragnatha.

John Jackman, a professor and extension entomologist for Texas A&M University and author of "A Field Guide to the Spiders and Scorpions of Texas," said that the phenomenon is not particularly unusual and that reports are submitted to him every few years detailing similar webs. "There are a lot of folks that don't realize spiders do that," Jackman said. "Until we get some samples sent to us, we really won't know what species of spider we're talking about."

However, other experts disagree over the unusual nature of the discovery. "From what I'm hearing, it could be a once-in-a-lifetime event," said Herbert "Joe" Pase, a Texas Forest Service entomologist. "It's very, very unusual."

Norman Horner, an emeritus biology professor at Midwestern State University in Wichita Falls, has been studying spiders in Texas since 1965 and he says he's never seen anything like this. In 2002, there were reports of a massive spider web in northern British Columbia. And there have been anecdotal reports in other locations over the years.

"Social spiders," the rare exception, typically only form colonies in tropical areas across the southern hemisphere, said Dr. Horner, but they have been spotted in South Texas. After seeing pictures and learning that the webs would have been weaved in only a few weeks, Mr. Quinn decided this was probably not the work of social spiders.

Another theory is that the spiders secreted silk that lifted them into the air and landed them at this location. Dr. Horner, who has not visited the site, guessed these spiders dispersed together and landed on a windy day.

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Multiple species of spiders helped weave the gargantuan spider web at Lake Tawakoni State Park, a Texas Parks and Wildlife biologist determined Friday.

But the highly unusual discovery of both frontal web and long-jawed spiders together raises more questions about just how the eye-catching phenomenon occurred, said Mike Quinn, the parks department biologist. He plans to send web and spider samples to Texas A&M University for definitive identification. The web spans an area estimated at 200 square yards. Once snowy white, the web has turned brown from the masses of mosquitoes and other bugs trapped in it.

Based on his preliminary evaluation, Mr. Quinn believes that it could only have resulted from what scientists call a “dispersal event.” Essentially, that means that baby spiders drifting in the wind all ended up in the same place somehow, for some reason.

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