Baltimore Wastewater Treatment Plant Extreme spider infest

[dragon]

107 million spiders thats a lot of creepy crawlies.

ow many spiders does it take to creep you out? 10? 100? How many spiders make an “extreme spider situation”?

The Baltimore Wastewater Treatment Plant put out a call for “extreme spider” help in 2009, when a giant spiderweb covered almost 4 acres of their facility. Scientists eventually estimated over 107 million spiders were living in the structure, with densities of 35,176 spiders per m³ in spots.

Greene, A et al. (2010). An Immense Concentration of Orb-Weaving Spiders With Communal Webbing in a Man-Made Structural Habitat (Arachnida: Araneae: Tetragnathidae, Araneidae). American Entomologist, 56 (3), 146-156.

The “immense” in their title doesn’t really begin to cover it. From the paper:

“We were unprepared for the sheer scale of the spider population and the extraordinary masses of both three dimensional and sheet-like webbing that blanketed much of the facility’s cavernous interior. Far greater in magnitude than any previously recorded aggregation of orb-weavers, the visual impact of the spectacle was was nothing less than astonishing.

In places where the plant workers had swept aside the webbing to access equipment, the silk lay piled on the floor in rope-like clumps as thick as a fire hose.”

Remember, that paragraph was written by 5 mid-career professional entomologists and arachnologists. If they were a bit startled by the size of the web….it was a big freakin’ web.
light fixture

Hanging light fixture (2.44 m long) pulled out of place by spider webbing. Entomological Society of America/ Greene et al. 2010

In some areas of the plant over 95% of space was filled with spider web. The webbing was so dense that it pulled 8-foot long fluorescent light fixtures out of place.

The scientists described their estimate of 35,176 spiders/m³ as “markedly conservative” and “representing a minimum volume” of spiders, by the way.

Question: do you measure spiders in Metric ShitTons? Or in Imperial ShitLoads?

Either way, it’s an awful lot of spiders.

Giant multi-species webs actually aren’t that rare. In 2007, a huge communal spiderweb was reported in Texas, and many of the same spider species were found to be the architects. Megawebs in the United States are usually dominated by two spider species, Tetragnatha guatemalensis and Larinioides sclopetarius.

All recorded US megawebs have occurred near water. That makes sense, because spiders have to eat, and midges emerge in huge quantities from water where they breed and live.

link

[Jaepheth]

We should learn to induce this behavior in a controlled environment to produce spider silk fabrics.

[Broomstick]

I've seen fabric made from spider silk. It's absolutely freakin' beautiful.

But, as an arachnophobe, just the title of this thread gave me willies.

I guess the facility no longer has a problem with flies?

[Thanas]

Poor employees. Having spiders crawling all over you is not anybody's idea of a great workplace.

[LaCroix]

It could be worse...

[White Haven]

So, napalm it is.

[Borgholio]

Poor employees. Having spiders crawling all over you is not anybody's idea of a great workplace.

Yeah, instead of starting my day with a hot cup of coffee, I'd start it with a flamethrower.

[Elheru Aran]

It's from 2009, so old news. It's probably been cleaned up by now.

That said... yikes. I suspect not many people, arachnophobes or not, would like to venture in there.

[Purple]

I actually would. Just for the sake of seeing something like that. I mean when are you going to get a chance to do that ever?

[Simon_Jester]

What did all those spiders even eat?

[Iroscato]

What did all those spiders even eat?

For the sake of whatever dregs of innocence may still rattle around in your soul, don't ask that question.

[Borgholio]

It's a wastewater treatment plant. There are probably oodles and oodles of mosquitoes and other waterbugs they could eat.

[RogueIce]

Unless the spiders did that web overnight, I'm wondering how and why it apparently was allowed to go on for as long as it did.

[Borgholio]

Unless the spiders did that web overnight, I'm wondering how and why it apparently was allowed to go on for as long as it did.

Yeah that one that was so heavy it was pulling the overhead light....I highly doubt it was done overnight unless you have a spider the size of a beagle.

[Simon_Jester]

It's a wastewater treatment plant. There are probably oodles and oodles of mosquitoes and other waterbugs they could eat.

Good point.

[Broomstick]

It's a wastewater treatment plant. There are probably oodles and oodles of mosquitoes and other waterbugs they could eat.

Good point.

The expression "flies on shit" also applies.

[LadyTevar]

If you read the paper submitted by the scientists (.pdf link on the site), it states that the web had been there the year before. It also states that the waste beds had an overabundance of midges, even with the spiders there to prey upon them. Also, the majority of the 31,000+ spiders were hatchings or juveniles, leading the the conclusion that the web's population was self-sustaining.

The scientists suggested several ways of dealing with the infestation, but the mostly boiled down to these two:
1. Get used to it. They weren't poisonous to humans, and they were eating the midges, and the web is a marvel of nature and tourists will come see it.
2. Get rid of the midges, then the spiders would leave.

Since the midge larvae were growing in the sandpit filtration units, where food was plentiful, getting rid of the midges would be very difficult. The spiders could be cleaned from areas (like the light fixture), but the thickest webs were where the midges swarmed.
The web, however, is a marvel, with 5 different taxa all sharing the web with non-aggressive tendencies towards their neighbor. The scientists even noted spiders fleeing them into another spider's territory, with no signs of hostility. If the scientist kept coming, the neighbor would join the flight, so there could be a number of spiders fleeing across what should be 'enemy territory', without aggression or hostile actions.

BTW: I looked up the names of the two main species in the web. The largest percentage were the "Big Jawed Orb Weaver", whose palps are very crab-like, while the rest of the body long and narrow, like a grain of rice. The second largest percentage were the "Bridge Spiders", which are usually found on bridges or other metal structures near or over bodies of water. They look more traditionally 'spidery'; rounded, flat abdomen, narrow thorax, with two 'boxing glove' palps. The third most common was the ordinary house spider.

[Vendetta]

It could be worse...

Could be these guys...

[LadyTevar]

Yeah, Vendetta, there was an article out recently about a photographer coming face to face with one of those.

[Vendetta]

Yeah, the pictures I linked to are the ones he took.

[mr friendly guy]

I must be weird because I like spiders. Also snakes and reptiles which a lot of people are creeped out by for some reason.

Not that I would like so many spiders in my house, but I do tend to throw them out rather than kill them.

Back on topic, its pretty cool. And in regards to the giant spider someone post a link to, I am not sure tarantulas or ginormous spiders actually make webs. Don't they just hide under rocks to get their prey?

[Vendetta]

IIRC most larger spiders don't actually use webs to catch prey, they actively hunt. Some of them build webs to sleep in though (helps detect things trying to sneak up on them).

[LadyTevar]

The Golianth Birdeater seems to do a bit of both. While it can hunt, it also will take a temporary refuge and lay down trigger-strands. Prey touch the strands, and the spider can pounce. The trap-door spider uses the same technique, but out of a permanant lair with a 'locking door' to protect from predators.

[LaCroix]

At a certain size, nets aren't a viable strategy, anymore. The prey size needed to subside on it is not worth the expense of making a huge net of the needed tensile strenght and the amount of glue needed.

Insects are plentyful and tend to fly around between branches, so you will catch a lot more than the value of the net before you need to redo it. Catching birds in a stationary net is a lot harder - they usually fly above the foliage to avoid ambush hunters, and they are quite scarce in comparison to insect life for the same area.

[Thanas]

That large spider doesn't scare me, it rather triggers my "wonder how it will taste if grilled properly" instinct. It is of sufficient size to be noticed so less fear of an ambush I assume.