WILLS POINT, Tex., Aug. 29 — Most spiders are solitary creatures. So the discovery of a vast web crawling with millions of spiders that is spreading across several acres of a North Texas park is causing a stir among scientists, and park visitors.

Sheets of web have encased several mature oak trees and are thick enough in places to block out the sun along a nature trail at Lake Tawakoni State Park, near this town about 50 miles east of Dallas.

The gossamer strands, slowly overtaking a lakefront peninsula, emit a fetid odor, perhaps from the dead insects entwined in the silk. The web whines with the sound of countless mosquitoes and flies trapped in its folds.

Allen Dean, a spider expert at Texas A&M University, has seen a lot of webs, but even he described this one as “rather spooky, kind of like Halloween.”