You may feel a spark when you talk to your sweetheart, but living things don’t require romance to make electricity. A study published on October 24 in iScience assumes that the electricity naturally produced by swarming insects such as honey bees and grasshoppers is an inestimable contribution to the total electric charge of the atmosphere.
“Particles in the atmosphere are easily charged,” said Joseph Dwyer, a physicist at the University of New Hampshire in Durham who was not involved in the research. “Insects are tiny particles moving through the atmosphere.” However, the potential for insect-induced static electricity to play a role in the atmosphere’s electric field, which affects the formation of water droplets, the movement of dust particles and lightning strikes, has not been considered before, he says.
Scientists have known about the minimal electrical charge carried by living things such as insects for a long time. However, the idea that an electric bug could change the charge in the air on a large scale came to the researchers purely by chance.
“We were actually interested in understanding how atmospheric electricity affects biology,” says Ellard Hunting, a biologist at the University of Bristol in England. But when a swarm of honey bees passed through a sensor designed to pick up background atmospheric electricity at the team’s field station, scientists began to suspect that the influence might flow in the opposite direction as well.
Hunting and colleagues, including biologists and physicists, measured the change in the strength of the electrical charge as other swarms of bees passed through the sensor, revealing an average increase in voltage of 100 volts per meter. The denser the swarm of insects, the greater the charge produced.
This inspired the team to think of even larger swarms of insects, such as the biblical hordes of locusts that plagued ancient Egypt (and in 2021 Las Vegas (SN: 03/30/21)). Flying objects, from animals to airplanes, build up static electricity as they move through the air. The team measured the charges of individual desert locusts (Schistocerca gregaria) while flying in a wind tunnel powered by a computer fan. Taking locust density data from other studies, the team then used a computer simulation based on the honey bee swarm data to scale up these single locust measurements into estimates of electrical charge for an entire locust swarm. Locust clouds can produce electricity per meter on par with storm clouds, scientists report.
Hunting says the results highlight the need to study the unknown life of airborne animals, which can sometimes reach much greater heights than honey bees or grasshoppers. Spiders, for example, can soar kilometers above the Earth when they “balloon” on silk threads to reach new habitats (SN: 7/5/18). “There’s a lot of biology in the sky,” he says, from insects and birds to microorganisms. “It all adds up.”
Although some insect swarms can be huge, Dwyer says the electrically charged flying animals are unlikely to ever reach the density needed to produce lightning, as storm clouds do. But their presence can hinder our efforts to monitor for upcoming strikes that could injure people or damage property.
“If you have something that confuses our measurements of the electric field, it can set off a false alarm,” he says, “or it can cause you to miss something that’s really important.” While the full effect that insects and other animals have on atmospheric electricity remains to be deduced, Dwyer says these results are an “interesting first look” at the phenomenon.
Hunting says this initial step into an exciting new area of research shows that working with scientists from different fields can produce shocking discoveries. “Being truly interdisciplinary,” he says, “allows for serendipitous moments like that.”