A few leg ticks turn a grasshopper into a plague
Locusts are not a separate taxonomic clan—they are ordinary short-horned grasshoppers that flip into a swarming lifestyle. Crowd the hind legs with several touches a minute for about four hours and brain serotonin surges. Colour, appetite, and sociability rewrite themselves; bands of hoppers become clouds that can hold eighty million insects per square kilometre.
At least eighteen genera across five subfamilies evolved swarming independently. Solitary insects stay scarce and harmless until drought breaks into flush vegetation; then breeding explodes and density triggers the gregaria phase Boris Uvarov first analysed—work that helped found the Anti-Locust Research Centre after he showed Locusta migratoria’s “two species” were one insect’s phases. Juvenile desert locust columns are partly goaded forward by cannibalistic nips from behind; cutting the nerve that feels those bites slows the group and raises true cannibalism.
Scale can stagger. A large swarm may span thousands of square kilometres. In the 1966–69 desert locust plague across Africa, the Middle East, and Asia, numbers rose from two billion to thirty billion in two generations even as occupied area shrank from over 100,000 to about 5,000 square kilometres. The 2003–05 West African upsurge, fed by heavy rains from Mauritania to Sudan and later into Morocco, Egypt, Jordan, and Israel, cost about $122 million to fight and damaged crops by as much as $2.5 billion. Madagascar’s 2013 migratory locust emergency fielded many billion-insect swarms across roughly half the island.
North America lost its worst native swarmers: the Rocky Mountain locust vanished in 1902, and the High Plains locust, plague-level in the Dust Bowl 1930s, is now rare—leaving the continent without regularly swarming locusts. Cultural memory runs deeper: Egyptian tomb carvings from 2470–2220 BCE, the Iliad, Mahabharata, Bible, and Quran, plus Chinese anti-locust officers by the ninth century BCE. A fossil wing from Iran’s Early Oligocene Pabdeh Formation implies trans-oceanic flights already thirty million years ago as grasslands spread.
Source: Locust
