Why have Mediterranean fruit flies led to quarantine rules for imported fruit?

The Mediterranean fruit fly (Ceratitis capitata) is a highly destructive insect pest that poses a significant threat to agriculture. The female fly lays up to 500 eggs inside citrus fruits, and the resulting larvae tunnel into the flesh, rendering the fruit unfit for human consumption.12

Because these flies can cause extensive economic losses and are capable of establishing populations in new regions—as seen in their recurring appearances in the United States—worldwide quarantine laws were established to regulate the international movement of produce. These measures are essential to prevent the spread of the pest into non-infested areas and to protect global agricultural stability.12