We are surrounded by electricity. It moves through the Earth’s air. Although we don’t notice it, some spiders can.
Certain spiders are known for flying through the air at the end of the silk strands they have created. This is called ballooning.
Spiders may fly to find a new place to hunt, or maybe to get away from something that will eat them.
Before flying, spiders use tiny hairs on their legs to sense the wind. These hairs are called trichobothria. These very sensitive hairs are used by other spiders that don't fly to sense movement of the insects they are hunting.
Before flying, spiders will stick their front legs up into the air to get a better idea about the wind, where it’s blowing from and how strong. Once they find the conditions just right, they shoot out some silk that they use to make webs and float away. It’s like they can make their own tiny parachute to carry them off.
On certain days, thousands of spiders may launch and fly off at about the same time. No one is sure why.
Sometimes spiders are seen floating in the air when there seems to be no wind. Curious about this, scientists set up an experiment. What they found is that those same spider leg hairs can also detect very faint electrical currents in the air. These electrical currents can also float spiders upward and across the land.
In the laboratory experiment, the scientists could turn the electrical current on and off. When they turned off the electricity the ballooning spiders dropped. When they turned it back on the spiders floated up.
The clue that there is electricity in the air becomes obvious when there is a lightning storm. Although those bolts of bright light appear to be shooting down from the clouds, the flash is actually rising up from the ground.
— Brett French, firstname.lastname@example.org