Shifting Shores Leave Spiders in a Sticky Situation on the Great Salt Lake

As parched, late-summer days grow a little shorter, bulbous and colorful spiders dot the sagebrush of northern Utah’s Antelope Island. The arachnid peak is unlike any in the entire Southwest. Adult western spotted orb weavers, thumb-sized spiders shaded in purples and yellows and reds, spin their webs and clamber over the scrubby island’s vegetation—as many as 20 spiders setting up silken hammocks in the same bush. 

But as drought has sipped away at the Great Salt Lake’s super-saline waters, the spiders have had to adapt. Their staple insect food is closely tied to the lake shore, a receding line that has increasingly pulled back from where the spiders can make their webs.

Antelope Island, managed by Utah as a state park of the same name, has hosted an annual Spiderfest on the craggy spot for years. The public event celebrates all manner of arachnids, from misunderstood black widows to tiny, jewel-like jumping spiders. But the big draw are the western spotted orb weavers, known to experts as Neoscona oaxacensis. While the web-weaving species is found over a broad geographic range, from Kansas to Peru, their summer aggregations on Antelope Island are like nowhere else in the world. 

“Seeing them in this abundance, I don’t think you’ll see that anywhere else,” says Natural History Museum of Utah entomologist Christy Bills, who’s been involved with Spiderfest for over a decade.

In other places, even where the orb weavers are otherwise found, the invertebrates don’t gather in such numbers. Often, Bills points out, spiders aren’t found in dense numbers for a range of reasons such as abundance of prey and the fact that many spider species eat other spiders. 

What makes Antelope Island special are the harsh lake conditions that have hosted brine flies along the shores of the Great Salt Lake. When the flies become especially numerous late in the summer, Bills points out, there are so many winged morsels that multiple spiders can live close together because there’s food enough for all. 

“The flies feed the spiders; they feed the birds; they feed so much,” she says.

The lives of the innumerable brine flies are directly tied to the super-salty waters of the Great Salt Lake. After mating, the brine flies lay eggs that sink to the lake bottom before hatching, feeding on detritus in the salty water, and form a chrysalis buoyed by an air bubble before emerging as adult flies—and, perhaps, blundering into spider webs to become snacks. 

But year by year, their required habitat is disappearing. In 1986, the Great Salt Lake was up to 4,211 feet deep. By 2022, that figure had dropped by 22 feet to a new record low, and in the summer of 2024 researchers warned that the vast saltwater lake had lost 73 percent of its water volume. The drying lake has led to a cascade of effects, from releasing greenhouse gases to arsenic-laden dust blowing into local Utah communities, including putting new pressures on spiders.

Antelope Island sits in a relatively shallow part of the Great Salt Lake, on the south end. Water levels have dropped so much that even heavier-than-usual rains late in the summer of 2025 did little to ease the drought. And as the lives of brine flies are tied to the water, the survival of their predators is tied to the brine flies. While the annual Spiderfest was centered around Antelope Island’s visitor center in past years, recent festivals have moved to the dried-out marina on the island’s shore where the orb weavers crawl over dry docked boats as if reenacting the creature feature Kingdom of the Spiders.

Of course, the orb weavers don't intend to come off as creepy. They’re just doing their best to survive, Bills notes. The orb weavers are “a giant spider that’s harmless, that doesn’t bite people, just serene and majestic.” 

If anything, we give the spiders more trouble than the other way around, especially as human-caused climate change keeps spiders reaching toward the furthest sagebrush in order to build their webs and catch food. After all, orb weavers need some sort of plant or structure to climb in order to catch their meals. 

As the Great Salt Lake recedes, and new plants are slow to spring up, the spiders can’t follow the flies they rely on. To put it another way, it's like if Spider-Man decided to take up heroics in the Great Plains with no skyscrapers to spin webs onto.

While western spotted orb weavers are not under threat of extinction from these shifting pressures, the human-caused changes to the Great Salt Lake may cause us to lose something incredibly unique. Changes to the lake affect the brine flies and, among many other forms of life, the spiders, stressing a singular bloom of western spotted orb weavers that can only occur because of the island’s peculiar conditions. “There are a lot of hidden, gorgeous things out here,” Bills says. It's not a desolate place but a stunning web of life.