The photos are truly the stuff of nightmares: Swarms of desert locusts blocking out the sun, blanketing fields, and devouring crops in East Africa, the Middle East, and South Asia. It’s the worst outbreak those regions have seen in decades. The locusts were already becoming a crisis , threatening food security and livelihoods in Kenya and Ethiopia by the time the novel coronavirus began crossing borders in late January. Since then the situation has only gotten worse — a wet spring created the right conditions for the bugs to keep multiplying. Scientists don’t know what causes locusts to flock together in the first place. The creature has a mysterious split personality. Locusts can be “solitary” — antisocial, independent, relatively benign. But under certain conditions, which are not fully understood, they can become “gregarious” — traveling together in masses that rival the size of cities, with more than a hundred […]