Locust Swarms Are Getting So Big That We Need Radar To Track Them

The desert locust upsurge is yet another of 2020’s horrors. From a report: In June, remote sensing analyst Raj Bhagat noticed a strange signal on India’s weather radar. It looked like a small band of rain near Delhi, moving southwest, but Bhagat was convinced it was a locust swarm. “People began to report it,” he says, referring to sightings on the ground. Giant locust swarms had spread to northern India earlier in the year, ravaging crops and destroying people’s livelihoods. “The timelines were perfectly matching.” In mid-July, Bhagat, who works at the World Resources Institute India, identified a similar formation, this time near the city of Lucknow. He posted it to Twitter with the hashtag #LocustsAttack. The desert locust upsurge is yet another of 2020’s horrors. In dry years, the insects, which can grow up to four inches long and are shades of green, black, or yellow depending on their life stage, remain localized to the deserts of Africa, the Middle East, and southwest Asia. Lately, however, the weather has been wetter than usual. Desert locusts have bred prolifically and migrated in huge swarms to countries that don’t always see them in large numbers, including several nations along the horn of Africa. Other places, such as the state of Uttar Pradesh in India, haven’t had a locust invasion in decades. The locust outbreak is currently classed by the United Nations Food and Agricultural Organization (FAO) as an “upsurge.” If the insects begin migrating in large bands — which could happen within a couple years, should things worsen — they’ll be officially considered a plague. A swarm covering one square kilometer eats as much food as 35,000 people every day. The damage done so far is already appalling. The UN says the food supply of 25 million people in East Africa has been threatened by the insects. In Ethiopia alone, they’ve destroyed around 200,000 hectares of crops. Meanwhile, in India, the insects have chewed up 50,000 hectares. The recent outbreak may be just a hint of what is to come, thanks to the extreme weather expected as a result of climate change. Such conditions, including periods of excessive rainfall, would be adored by the locusts, says Keith Cressman, senior locust forecasting officer at the FAO. The locusts’ wanderlust has sparked efforts to develop tools to closely track the insects. The FAO already uses real-time reports from locust survey teams on the ground and satellite imagery of vegetation and weather events to help forecast how many locusts will breed and where they will go. Countries use data on locust migrations to determine where to send teams in efforts vanquish the insects en masse by dropping pesticide on them from planes. Among the technologies that could improve locust surveillance by pinpointing locations of multiple swarms at a given moment are radar and drones. The idea of using remote sensing technologies like radar to spy on locust swarms is not new. A 1955 letter in the journal Nature reported the first such sighting on British naval radar the previous year. HMS Wild Goose had detected a humongous 48-kilometer-wide swarm of desert locusts flying over the Persian Gulf. Bhagat says he thinks his sightings are the first weather radar detections of locusts in India, though his observations haven’t been confirmed yet. Ryan Neely III, an atmospheric scientist at the University of Leeds in the U.K., is building a specialized system to do the same kind of analysis. It is absolutely possible to use weather radar to spot the insects, he says. They are, after all, not that dissimilar from large raindrops.