Rocky Mountain locust

Rocky Mountain locust
Conservation status
Extinct (1902)  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Orthoptera
Suborder:	Caelifera
Superfamily:	Acridoidea
Family:	Acrididae
Subfamily:	Melanoplinae
Genus:	Melanoplus
Species:	†M. spretus
Binomial name
†Melanoplus spretus Walsh, 1866

The Rocky Mountain locust (Melanoplus spretus) was the locust species that ranged through almost the entire western half of the United States (and some western portions of Canada) until the end of the 19th century. Sightings often placed their swarms in numbers far larger than any other species of locust, with one famed sighting having been estimated at 198,000 square miles (513,000 km²) in size (greater than the area of California), weighing 27.5 million tons, and consisting of some 12.5 trillion insects - the greatest concentration of animals ever recorded, according to The Guinness Book of Records.

But less than 30 years later, the species was apparently extinct, with the last recorded sighting of a live specimen in 1902 in southern Canada. And because no one expected such a ubiquitous creature to become extinct, very few samples were ever collected (though a few preserved remains have been found in Grasshopper Glacier, Montana). Though grasshoppers still cause significant crop damage today, their populations do not even approach the densities of true locusts. Had the Rocky Mountain locust continued to survive, North American agriculture would likely have had to adapt to its presence (North America is the only continent without a major locust outside of Antarctica).

Distribution

The locust largely afflicted prairie areas, though they existed on both sides of the Rocky Mountains. Breeding in sandy areas and thriving in hot and dry conditions, they were often guaranteed a good food supply by prairie plants concentrating sugars in their stalks in times of drought. Movement of the locusts was probably assisted by a low-level jet stream that persists through much of central North America.

Extinction

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. The cause of their extinction is disputed, though it is possible that the plowing and irrigation by settlers disrupted the natural life cycle of the insects by disturbing the sandy riverbeds that locusts would use for breeding. Reports from this era state that farmers brought up thousands of egg cases while plowing.

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; "solitary phase" individuals of the migratory grasshopper might be able to turn into the Rocky Mountain locust given the right conditions, however breeding experiments using many grasshopper species in high-density environments have attempted to invoke the famous insect without success. Analysis of mitochondrial DNA from museum specimens and related species suggests that the Rocky Mountain locust may have been a distinct and now extinct species, possibly closely related to the Bruner spurthroat grasshopper (Melanoplus bruneri).

In fiction

A fictionalized description of the migration of Rocky Mountain locusts in the 1870s can be found in On the Banks of Plum Creek by Laura Ingalls Wilder and Rose Wilder Lane.

See also

• Albert's swarm

References

• Ryckman, Lisa Levitt (1999). The Great Locust Mystery. Colorado Millennium 2000. Denver Rocky Mountain News, June 22, 1999. Retrieved 9-SEP-2006.
• Samways, M. J. & Lockwood, J. A. (1998): Orthoptera conservation: pests and paradoxes. Journal of Insect Conservation 2(3-4): 143–149. doi:10.1023/A:1009652016332 (HTML abstract)
• Lockwood, Jeffrey A. 2004. Locust: The Devastating Rise and Mysterious Disappearance of the Insect that Shaped the American Frontier. Basic Books, New York. ISBN 0-7382-0894-9