04/11/2014 11:36 GMT | Updated 05/11/2014 11:59 GMT

107 Million Orb-Weaving Spiders Built A 4-Acre Web In This Baltimore Water Treatment Plant

If you’re frightened of spiders, welcome to your worst nightmare.

For this Baltimore water treatment plant was at one point infested with 107million orb-weaving arachnids.

That 'conservative' estimate is equivalent to 35,176 spiders per cubic metre of space.


107 million orb-weaving spiders got busy making this web in a Baltimore water treatment plant

And boy did they get busy. The infestation was reported in 2009, where the spiders were found to have constructed webbing covering approximately 95% of the 4-acre building – that’s almost 16,099m2.


The “exceptional arachnid productivity” at the Back River Wastewater Treatment Plant was recorded by in 2010 in the American Entomologist journal.


The infestation saw a web measuring covering a surface area of approximately 4-acres


The experts determined a 'conservative estimate' of 35,176 spiders per cubic square metre of space

The authors wrote: “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 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.”


Some of the webbing managed to full 8-ft long light fixtures out of place


And some of the webbing was found to be as 'thick as a fire hose'

Some of the webbing was so thick it had managed to pull 8-foot long fluorescent light fixtures out of place.

More than 31,000 species were extracted from web samples, with the majority made up of Tetragnatha guatemalensis and Larinioides sclopetarius.


The spiders were surviving on the plentiful supply of midges from the water


The report noted the spiders were not dangerous and said the webs should be removed with basic maintenance.

Though four years old, these remarkable pictures resurfaced thanks to a Halloween feature by Wired, which points out: “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.”

tetragnatha guatemalensis

Tetragnatha guatemalensis was one of the species which made up the majority of the arachnids in the building