Continuing the Screwworm Barrier
New World screwworm, once eradicated from the continental United States, is again commanding attention from livestock health officials. After resurfacing in Mexico in late 2024, the pest has become a key focus for prevention efforts, especially in warmer states such as California.
Treatment and prevention tools have expanded in response. Emergency approval has been granted for macrocyclic lactone products including Ivomec® (ivermectin) and Dectomax® (doramectin). ExZolt Cattle-CA1® (fluralaner) has also been conditionally approved as a topical solution for prevention and treatment. These products may be used under veterinary guidance and, in some instances, through extra label drug use provisions.
USDA marked a significant milestone in mid February with the opening of a sterile fly dispersal facility in Edinburg, Texas, enabling distribution of millions of sterile male flies to reinforce the biological barrier. Plans for a nearby $750 million sterile fly production plant capable of producing up to 300 million flies per week, paired with up to $100 million in research funding through the USDA NWS Grand Challenge, highlight an intensified effort to strengthen preparedness and protect California livestock.
