In October, agricultural officials in California discovered two fruit flies in the Leimert Park neighborhood of Los Angeles, prompting a 69-square-mile quarantine. Now, officials plan to release more than two million sterile male fruit flies into the city in an attempt to eradicate the insects.

While this might seem like an overreaction, these were not just any flies. Called Mediterranean fruit flies (Ceratitis capitata), or medflies for short, they are an invasive species that can infest more than 250 types of fruits and vegetables. This makes them the “most important agricultural pest in the world,” per the United States Department of Agriculture.

Female medflies lay their eggs inside produce, and when the eggs hatch into maggots, they’re destructive. The larvae tunnel through the crops, causing them to rot and become inedible.