Locust by Jeffrey A. Lockwood Read Free Book Online Page A

estimates. But in his accounts of these observations, his awe at the scale of the phenomenon began to sneak into the technical report:
    The swarm I estimated from one-quarter to one-half mile deep. It seemed like piercing the milky-way of the heavens; my glass found no limits to them. They might have been a mile or more in depth.
    Like any good scientist, Dr. Child took his data and transformed the raw numbers into a complete picture of what he had witnessed. The mathematics were simple, but the results were nearly beyond imagination. When Dr. Child presented his straightforward calculations of the aggregate size of the locust swarm that was passing over Nebraska, he was incredulous of his own findings:
    They were visible from six to seven hours of each of the successive five days, and I can see no reason to suppose that their flight was checked during the whole five days. If so, the army in the line of advance would be 120 hours by 15 miles per hour = 1,800 miles in length, and say at even 110 miles in width, an area of 198,000 square miles! and then from one-quarter to one-half mile deep. This is utterly incredible, yet how can we put it aside?
    An area of 198,000 square miles would encompass the combined areas of Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont. The swarm was probably an elongated stream of insects, but if it had been configured in a more familiar geometric shape, it would have comprised a square 450 miles on a side. The frontier of the New World was revealing marvels and terrors of a scale unparalleled in written history. The largest swarm of locusts outside of North America was reported in 1954, when fewer than a hundred square miles were covered by the notorious Desert locust in Kenya. No insect outbreak has ever approached the magnitude of the Rocky Mountain locust.
    Trying to estimate the number of locusts in Albert’s Swarm is quite a challenge, but we can use some values from the scientific literature to approximate the size of the population. We might safely assume a settled density similar to that of the famed locust swarms in Africa (which involve a larger locust and likely have fewer individuals packed
into each square yard). If so, then the 1875 swarm that passed over North America had 3.5 trillion locusts, outnumbering the current human population on earth by a factor of 600 to 1. The swarm outweighed a man to the same degree that the biomass of a whale exceeds that of a mouse. Such quantities are unfathomable, but newspaper reports of damage from neighboring townships clearly substantiate Dr. Child’s account.
    Although Isaac Cline never managed to associate weather patterns with locust outbreaks, we can now deduce the biological and meteorological conditions that conspired to create Albert’s Swarm. Scientists of the nineteenth century had begun to piece together the life cycle of the Rocky Mountain locust, and it appears that Albert’s swarm was qualitatively typical of the species. In an outbreak cycle, the locust swarms descended from the northern Rockies in early June. Carried by prevailing winds, these insects swept across the countryside, settling wherever there was abundant food. As the locusts advanced to the south and east, they began to mate, and soon after, females began laying eggs. Cylindrical clusters or “pods” of about thirty eggs were buried in the soil, and so the swarms left behind denuded fields riddled with eggs. The adult locusts would live for perhaps a couple of months, seeding the countryside with the next generation. The embryos would mature through the summer and then hibernate—a physiological state called diapause in insects—for the winter. The following spring, the ground would appear to boil as the nymphs hatched on warm days. Forming into immense aggregations or “bands” these immature locusts would march across the land, stripping the vegetation to fuel their