It looks like they fall from the sky.Frame from video
A resident of Brazil filmed “rain from hundreds of spiders” in the countryside of the municipality of Espírito Santo do Dorado, which is about 250 kilometers from São Paulo. The author of the video published on Facebook explained that he drew attention to this during a trip with relatives.
In fact, the spiders did not “fall from the sky”, as the author suggested, but weaved a huge web of web-like dome. The arachnologists, whose opinion is cited by local media, explained that this situation is quite typical for regions with a hot climate and humidity. Using such networks in open areas, spiders make it easy to catch prey.
As the specialist noted, the spiders caught in the video can belong to the genus Parawixia, which is often found in neotropics. The toxins they emit cannot harm a person. A similar phenomenon is observed not for the first time, for example, such a “dome” of spiders was noticed in Brazil in 2013.