Soaring temperatures bring tales of eight-legged invaders as huge numbers of communal species spin invisible webs in the sky

This article is more than 1 year old

This article is more than 1 year old

Summer in south-east Brazil has brought soaring temperatures and some disconcerting eight-legged visitors.

Residents in a rural area of southern Minas Gerais state have reported skies “raining spiders”, a phenomenon which experts say is typical in the region during hot, humid weather.

Photos and videos shared on social media show hundreds of spiders hanging in the sky.

João Pedro Martinelli Fonseca, who filmed one of the most widely shared clips, was traveling with his family to his grandparents’ farm in Espírito Santo do Dourado, about 250km north-east of São Paulo, when he realized the sky was covered with black dots.

He told a local newspaper that he was “stunned and scared” – especially when one of the spiders fell through the open window.

The boy’s grandmother, Jercina Martinelli, told another local paper: “There were many more webs and spiders than you can see in the video. We’ve seen this before, always at dusk on days when it’s been really hot.”

In 2013, the same phenomenon made international headlines when residents of Santo Antônio da Platina in southern Brazil registered “raining spiders” around telephone poles.

While it looks like the spiders are falling from the sky, they are actually hanging in a giant web to catch prey, said Adalberto dos Santos, a biology professor specialising in arachnology at the Federal University of Minas Gerais.

The species parawixia bistriata, is a rare “social” spider and the community web they build is so fine that it is nearly impossible for the human eye to see, giving the illusion that the spiders are floating on air.

During the day, the spiders nest in a giant ball in the vegetation, emerging in the early evening to construct the giant web ceiling which hangs between trees and bushes, said Dos Santos. Each web can measure up to four meters wide and three meters thick.

At dawn, they feast on prey they have caught overnight – usually small insects, but sometimes even small birds – before retreating to the vegetation again.

Witnessing a sky full of spiders may be unnerving, but Dos Santos said humans have nothing to fear: the venom of this species is not harmful to humans and its bite causes little more discomfort than a red ant bite.

Dos Santos said that the spiders’ vast net serves to regulate insects like flies and mosquitoes that come out during the muggy early evenings.

“They benefit us far more than they harm us,” he said.