Locust: The devastating rise and mysterious disappearance of the insect that shaped the American frontier by Jeffrey A. Lockwood, Basic Books/Perseus, 拢14.99/$25, ISBN 0738208949
MUCH of Locust is not about the Rocky Mountain locust Melanoplus spretus itself, but about its impact on the history of the American west. Early settlers survived the 鈥渃hill of hypothermia and the scourge of cholera鈥� on their trek westward, then locusts brought poverty and starvation. They prayed and they waited, largely in vain, for help from state governments.
These victims were seen as foreigners and idle beggars, hardly citizens at all. Handouts would lead to permanent dependency on the rich of society. Means-tested benefits were gained only after farmers gave up their last cow or draft horse 鈥� and with them any hope of regaining self-sufficiency. Locust bounties were introduced: $5 per bushel (35 litres) of eggs, $1 per bushel of nymphs. These provided work and payment for destitute farmers, but had little impact on the locust.
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In 1876 the federal government finally funded a Locust Commission that pioneered complementary methods of control used synergistically, although 鈥渋ntegrated pest management鈥� had yet to be invented. About a year later the plagues started to decline, and the last small swarm was recorded in 1902 in Manitoba.
Why did M. spretus disappear? Lockwood recounts and refutes various theories. The work of a Russian entomologist Boris Uvarov suggested to many that it could be the migratory form of a species that is known today only in its non-migratory form; the spotlight fell on Melanoplus sanguinipes.
The mystery remained until Jeffrey Lockwood and his colleagues went in search of M. spretus, frozen for hundreds of years in Grasshopper Glacier, 3000 metres above sea level just north of Yellowstone national park. They finally obtained well-preserved frozen locusts and used modern analytical techniques to show that M. sanguinipes is not M. spretus in disguise.
Eventually it dawned on Lockwood that everyone had concentrated on changes in the outbreak areas, the habitat of the migratory form of M. spretus, to explain its disappearance. But it was the permanent zone that had been changed by farming in the fertile valleys of the Rocky Mountains. Ploughing and trampling of the land by cattle, irrigation and flooding destroyed locust eggs and made the habitat unsuitable for M. spretus.
This is an entertaining and informative book on many levels. It will be enjoyed by all scientists and, I suspect, by anyone who likes a good story well told.