While raining cats and dogs is only a metaphor, raining spiders is a reality in Australia. The latest arachnid shower took place last week in a town called Goulburn, in New South Wales, approximately 195 km south-west of Sydney, where millions of tiny spiders rained down from the sky and blanketed the countryside with their webs. Unlike the rare frog rains and fish rains, that’s not entirely understood, arachnid showers is a well documented phenomenon called “ballooning” which is used by spiders and some other invertebrates to migrate from one pace to another.

During a “ballooning” event, the spiders will climb up as high as they can, stand on raised legs with its abdomen pointed upwards and release several silk threads into the air. These strands form triangular shaped parachutes that allow them to be carried away by the wind hundreds of miles to a new territory. In windless conditions, the Earth's static electric field may also provide lift.

Spider webs cover the ground in the Australian town of Goulburn. Photo credit: Daniel Munoz / Reuters