200 Years. 200 Stories. Story 82: “Before It Went Bad ”

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photo of a colorado potato beetle
The Colorado potato beetle (Leptinotarsa decemlineata).

Before It Went Bad

The Colorado potato beetle (Leptinotarsa decemlineata) is an insect pest that targets potatoes. The first outbreaks were reported in northeastern Kansas in 1860, and within decades this insect had spread across the Midwest and along the East Coast. It became a serious pest in Europe by World War I and has since traveled throughout much of Asia. Despite its notoriety, this small beetle didn’t seem exceptional when Academy naturalist Thomas Say discovered it along the Missouri River during a famous expedition led by Major Stephen H. Long between 1819 and 1820. Say provided a scientific description of it, along with information on scores of other western beetles, in the Journal of the Academy of Natural Sciences in 1824. Say noted that the beetle was found on an unappealingly spiny shrub called the buffalo bur (Solanum rostratum).

Thomas Say’s encounter with the Colorado potato beetle occurred during an interim stage of its remarkable transformation from obscurity to an invasive species. In spite of its name, this beetle and its host plant are actually native to central Mexico instead of Colorado. Scientists suspect that the buffalo bur and the accompanying beetles were unintentionally transported north to the Great Plains by Spanish horses and cattle captured by Native Americans. Sometime after Say’s 1819 encounter with this beetle, it underwent a genetic mutation that allowed it to make the switch from buffalo bur to potatoes.

Learn more about the potential dangers of a 19th century expedition.

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