Instruction: Based on the provided passage, extract the main reason that the Rocky Mountain Locust went extinct.
Context: Rocky Mountain locusts caused farm damage in Maine from 1743 to 1756 and Vermont in 1797–1798.[16] The locusts became more of a problem in the 19th century, as farming expanded westward into the grasshoppers' favored habitat. Outbreaks of varying severity emerged in 1828, 1838, 1846, and 1855, affecting areas throughout the West. Plagues visited Minnesota in 1856–1857 and again in 1865, and Nebraska suffered repeated infestations between 1856 and 1874.[16]


1875 cartoon by Henry Worrall showing Kansas farmers battling giant grasshoppers
The last major swarms of Rocky Mountain locust were between 1873 and 1877, when the locust caused $200 million in crop damage in Colorado, Kansas, Minnesota, Missouri, Nebraska and other states. One farmer reported that the locusts seemed "like a great white cloud, like a snowstorm, blocking out the sun like vapor".[16] The locusts ate not only the grass and valuable crops, but also leather, wood, sheep's wool, and—in extreme cases—even clothes off peoples' backs. Trains were sometimes brought to a halt after skidding over large numbers of locusts run over on the rails.[17][15] As the swarms worsened, farmers attempted to control them using gunpowder, fires (sometimes dug in trenches to burn as many of the locusts as possible), smearing them with "hopperdozers", a type of plow device pulled behind horses that had a shield that knocked jumping locusts into a pan of liquid poison or fuel, even sucking them into vacuum cleaner–like contraptions, but all of these were ultimately ineffective in stopping the hordes. Charles Valentine Riley, a Missouri entomologist, came up with a recipe for locusts seasoned with salt and pepper and pan-fried in butter. The recipe sold, but some stated that they "would just as soon starve as eat those horrible creatures".[16] Farmers finally responded in force to the swarm's destruction; an 1877 Nebraska law said that anyone between the ages of 16 and 60 had to work at least two days eliminating locusts at hatching time or face a $10 fine. That same year Missouri offered a bounty of $1 a bushel for locusts collected in March, 50 cents a bushel in April, 25 cents in May, and 10 cents in June. Other Great Plains states made similar bounty offers. In the 1880s farmers had recovered sufficiently from their locust woes to be able to send carloads of corn to flood victims in Ohio. They also switched to such resilient crops as winter wheat, which matured in the early summer, before locusts were able to migrate. These new agricultural practices effectively reduced the threat of locusts and greatly contributed to the species' downfall.[16]

It has been hypothesized that plowing and irrigation by settlers as well as trampling by cattle and other farm animals near streams and rivers in the Rocky Mountains destroyed their eggs in the areas they permanently lived, which ultimately caused their demise.[18] For example, reports from this era suggest that farmers killed over 150 egg cases per square inch while plowing, harrowing or flooding.[18]: 11–12  It appeared that this species lived and reproduced in the prairie only temporarily during swarming years, with each generation being smaller than the previous one and swarming ever further from the Rocky Mountains,[19] while the permanent breeding grounds of this species seemed to be restricted to an area somewhere between 3 and 3,000 square miles of sandy soils near streams and rivers in the Rockies, which coincided with arable and pastoral lands exploited by settlers.[18]

Because locusts are a form of grasshopper that appear when grasshopper populations reach high densities, it was theorized that M. spretus might not be extinct, that "solitary phase" individuals of a migratory grasshopper might be able to turn into the Rocky Mountain locust given the right environmental conditions; however, breeding experiments using many grasshopper species in high-density environments failed to invoke the famous insect. The status of M. spretus as a distinct species was confirmed by a 2004 DNA analysis of North American species of the genus Melanoplus.[14]

Melanoplus spretus was formally declared extinct by the IUCN in 2014.[1] It has been suggested that the now critically endangered Eskimo curlew fed on the locust during its spring migration and that its extinction may have added to the pressures on already declining curlew populations including hunting and the conversion of its grassland habitat to agriculture.[20][21]
Response: The Rocky Mountain Locust went extinct as a result of local farmers irrigating and plowing their habitat, which destroyed their eggs led to their demise.