The Periodical Cicada, "the 17-year Locust"

The Department of Agriculture is the executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. As such, they're also responsible for keeping track of widespread patterns in the flora and fauna. One of the most important records they kept was on the cicada cycle, which causes millions of these insects to infest parts of the country every 17 years.