LAKE WACCAMAW, N.C. (WNCN) — Residents at a North Carolina lake are still stunned by a rare sight of a swarm of insects earlier this month.

Around Lake Waccamaw in Columbus County, large groups of mayflies are known to gather around the lake every April.

But, residents in the area said this year’s massive swarm of millions of aquatic insects was the worst in 30 years.

Lake Waccamaw has about 9,000 acres of surface area and about 14 miles of shoreline.

The yearly swarm of the mayflies is known by Lake Waccamaw fishermen to mark a point when the fish in the lake become more active.

On April 13 and 14, there was a large “invasion” according to one resident who took photos of the mayflies swarming on her truck, home and around lights.

The insects even covered a nearby road.

“The invasion of the mayflies!!!! Unreal!!” one woman wrote on Facebook.

The gathering earlier this month was on vertical surfaces, but also included large amounts on the ground — enough to sweep in some areas.