The Golden State’s citrus industry faced a lethal threat. The solution would herald a new kind of pest control
Martin J. Kernan
In the early 1870s, ambitious farmers were cultivating the first seedless navel and sweet Valencia oranges amid the bountiful sunshine of California’s citrus groves. Soon these groves would become the proving grounds for the new science of biological pest control, pitting a rare species of ladybugs against an invading horde of pests in a battle for the future of citrus agriculture in California—and the world.
Commercial agriculture drove the largest economic expansion in California since the discovery of gold at Sutter’s Mill. And oranges, initially brought there by Spanish missionaries, had become California’s most valuable commodity. The number of acres under citrus cultivation in Southern California increased sevenfold between 1877 and 1890, while the number of railroad boxcars exporting these juicy treasures doubled to nearly 6,000 a year, spurred on by the Southern Pacific railroad line, which reached Los Angeles in 1876, and by the Southern Pacific's use of train compartments cooled by huge blocks of ice beginning in 1888. Fruit traveling east was now worth $20 million annually, having increased by a factor of ten in as many years. Nothing, it seemed, could stop what many were calling a second gold rush. Then a fuzzy white bug suddenly appeared, touching off an environmental crisis.
How the cottony cushion scale, a virulent tree pest native to Australia, was unleashed upon the citrus trees of the world is a bit of a mystery. Its populations exploded in New Zealand in 1878; entomologists there identified it as the new species Icerya purchasi. By the early 1880s, it was ravaging San Francisco’s trees and quickly migrating south, its tiny red larvae hitching rides on anything that moved, even the wind.