The Four Most Terrifying Words: Enormous Communal Spider Webs

The spider Tetragnatha guatemalensis is responsible for the giant communal webs in Texas. Philippe Blanchot/Hemis/Corbis
The spider Tetragnatha guatemalensis is responsible for the giant communal webs in Texas. Philippe Blanchot/Hemis/Corbis

A giant parking-lot-sized spider web enshrouds a row of trees, spanning silky tendrils from wild grass to leafy apex. For some, this giant spider web is an architectural wonder of the animal kingdom. For others, the web and its inhabitants — thousands upon thousands of long-jawed spiders — are the stuff of nightmares.

Whatever your feelings about spiders, a web the length of a football field is probably something you never get used to. Yet some Texas residents are encountering the eerie sight for the second time since 2007. This Dallas newscast below shows that things truly are bigger in Texas.

An extraordinary gathering of spiders took place over the summer in the Dallas suburb of Rowlett, which borders 30 miles (48 kilometers) of Lake Ray Hubbard shoreline. There, members of the Tetragnathidae family have taken up residence en masse. They are a slender and long-legged bunch, and sport sizable fangs. 

At a lakeside park, they have collaborated to construct a colossal web worthy of a horror meme. "Lots of people are going out and looking at it," says Mike Merchant, a Texas A&M AgriLife Extension Service urban entomologist.

Parking-lot sized spider webs blanket trees in Texas.
Parking-lot sized spider webs blanket trees in Texas.
Anna May Knittle/Demotix/Corbis

Normally, these spiders are solitary beings, content to weave individual webs designed to snare flying insects, says Merchant.

However, when environmental conditions are ideal, localized populations of long-jawed spiders tend to skyrocket. This is especially true when there is an abundance of the spiders' favorite food source: an aquatic insect known as a midge.

"Big blooms of midges correlate with times of massive webs, and a huge amount of prey allows for huge amount of predators," says Roy Vogtsberger, a professor at Midwestern State University in Wichita Falls, Texas. "With so many in tight quarters, spinning all this webbing less than an inch apart from each other, the webs are going to become communal. And with plenty of food to go around, there's no aggression."

Even with all this willingness to hold hands as they sing around the campfire, long-jawed spiders aren't truly social arachnids. The technical "social" classification is reserved for spiders that lean in to family life by raising each other's young and sharing meals from the same food source, says Vogtsberger.

In contrast, the long-jawed spiders seem to tolerate each other more than anything. And why not? With full bellies and an abundant insect buffet, there's not much to get upset about.

Although rare, these "arachnotopias" are becoming increasingly well-documented. In October 2009, a wastewater treatment plant in Baltimore, Maryland, was home to a 4-acre (1.6-hectare) communal web. It spanned the facility's ceilings and catwalks, and when workers attempted to remove parts of the spider web, it was so dense that it formed thick, rope-like debris. The millions of spiders-in-residence quickly made repairs, and consequently, several employees became reluctant to report for duty.

Even when they number into the thousands, the venomous, fanged spiders typically remain docile, says Vogtsberger, who has caught them by hand without being bitten. "They're not interested in us," he says. "They're interested in catching their food, which does not include humans."

So much for a B-movie plot. We were really looking forward to "Arachnado."