Just in time for Halloween, webs full of baby spiders are falling from the sky across the Bay Area. Biologists insist they are harmless, but this sounds like an awesome set-up for a horror movie.

People are seeing them all over the Bay Area lately, from San Francisco, to East Bay communities and beyond to Modesto, and in the South Bay and beyond to Monterey. Webs of baby spiders are falling from the skies across northern California, and NBC Bay Area explains that it’s a normal spider process entomologists call “ballooning.” But it’s an occurrence people are seeing far more than usual this particular autumn, following spider mating season.  

“What they are is strands of silk that spiderlings, baby spiders, use to disperse,” San Jose State University assistant professor of biology  Fred Larabee tells the Chronicle. “To get away from where they’re originally born, they spin these silk strands and they get caught by the wind, which pulls the spiders to a new place to live, to new habitats, so they’re not competing with their siblings.”

And sometimes multiple different threads can clump, leading to the larger clumps that many NorCal residents are seeing.

So what kind of baby spiders are these with their webs flying from the skies? They are many different kinds of spiders. KGO explains that “There are about 50,000 spider species on the (planet) and this is just part of the normal spider lifecycle.”

That may be, but it’s odd we don’t see so many baby spider balloonings most years. This year’s prevalence may be related to 2023 being such an odd weather year, or the return of so much rain in the winter storms. It seems there’s a baby boom in the spider hatchling population this year, which may be weather- or climate-related.

According to KGO, “Experts say there's nothing to be alarmed about” with all of these spiders falling from the sky. But if I’ve learned anything from watching Invasion of the Body Snatchers, it’s that when the experts say there’s nothing to be alarmed about, that is definitely when it’s time to be alarmed.

Related: Tarantula Mating Season Begins on Mount Diablo [SFist]

Image: @TheMeatRind via Twitter