Pakistan was hit by a plague: locusts. They came from Iran, and it is the worst invasion in the last two decades. Earlier this month, the authorities declared a national emergency. Pakistan is not the only affected country. East Africa and India also experienced mass crop destruction due to locust invasions. International help was asked in January by the UN. China dealt with this kind of invasion and put an end to it with the help of ducks. Recently Pakistan asked China for help in the worst affected areas: Sindh, Balochistan, and Punjab provinces. Although the Chinese initially said they would help Pakistan and send 100,000 ducks, now they\u2019ve changed their minds. Ducks need water, much more than other species of birds, and there is a reason for which Pakistan needs to import them. The reason? Pakistan\u2019s dry-desert environment. Instead, Chinese specialists recommended chemical or biological pesticides, deployed with an aircraft. Pakistan is facing a locust invasion, but Chinese ducks won't be sent there to help Pakistan is the world's fifth-most populous country with a population exceeding 207.8 million. The locust invasion puts to risk food security. It had already destroyed in large-scale cotton, wheat, maize, and other crops. A locust swarm can fly up to 150 km a day with the wind. It consumes as much in one day as about 35,000 people. So, Pakistan\u2019s worries are legitimate. Too bad, the authorities didn\u2019t start to worry sooner. The locusts began their invasion from Iran last June. These insects are usually solitary, but under certain circumstances, they become more abundant and change their behavior and habits, becoming gregarious. Under conditions of drought followed by rapid vegetation growth, serotonin in their brains triggers changes: they start to breed abundantly, becoming gregarious and nomadic when their populations become dense enough. Locusts form bands of wingless nymphs, which later become swarms of winged adults. Both the groups and the swarms move around and rapidly strip fields and cause damage to crops.