In a historic move, a portion of Los Angeles County in California has been placed under quarantine after the detection of the Tau fruit fly, an invasive species native to Asia. This is the first ever quarantine caused by the Tau fruit fly in the Western Hemisphere, according to state officials. The quarantine encompasses an area of nearly 80 square miles in the Stevenson Ranch area near Santa Clarita.

The California Department of Food and Agriculture reported that over 20 Tau fruit flies were discovered in the unincorporated area of Stevenson Ranch. The adult Tau fly is approximately 7 millimeters in length and has a yellow body with black markings. Its wings are characterized by two dark stripes. The fly is known to originate in Southeast Asia and is considered a serious agricultural pest, posing a threat to natural resources. It has a wide host range, affecting numerous fruits, vegetables, and select native plants in California.

It is believed that the fly was introduced into the state by travelers who brought uninspected produce, a common pathway for invasive species. In an effort to prevent further spread, residents living within the quarantine area are urged not to transport any fruits or vegetables from their property. Female flies lay eggs under the skin of fruits, and the eggs typically hatch within a couple of days, with larvae tunneling through the fruit and consuming it as they grow. Among the produce that could be impacted by the fly are melons, okras, peppers, papayas, citrus fruits, cucumbers, pumpkins, avocados, tomatoes, and gourds.

If no presence of the flies is detected on the produce, it can still be consumed or processed at the property where it was picked. However, if the produce is not consumed, officials advise double-bagging it in plastic and disposing of it in a designated garbage bin.

The California Department of Food and Agriculture is working in collaboration with the U.S. Department of Agriculture and the Los Angeles County Agricultural Commissioner to tackle the infestation. Properties within 200 meters of the fly detections will be subject to treatment, whereby staff will cut host fruit and vegetables to inspect for any fruit fly larvae. These properties will be treated with a naturally derived organic-approved material called Spinosad, which aims to remove live adult fruit flies and reduce the population density.

In a broader treatment area, fly traps incorporating a pheromone lure and a minute amount of pesticide will be used. The quarantine zone covers the Stevenson Ranch community, which is home to approximately 6,426 households.

Although this is the first time the Tau fruit fly has caused a quarantine in California, it was first detected in San Bernardino County in 2016. Since then, the department has successfully eradicated the fly on three separate occasions.

This quarantine serves as a crucial measure to prevent the Tau fruit fly from reproducing and spreading further throughout the region, safeguarding agriculture and natural resources from the invasive species.