New World Screwworm Outbreak in the United States: Sterile Flies to the Rescue

New World screwworm maggots on an endangered Key deer. The injuries on rutting males are particularly vulnerable to the fly. Early infestations can be treated effectively in pets, livestock, and people. But identifying and treating infested wildlife is difficult. Charles Hoots

New World screwworm maggots on an endangered Key deer. The injuries on rutting males are particularly vulnerable to the fly. Early infestations can be treated effectively in pets, livestock, and people. But identifying and treating infested wildlife is difficult.             Charles Hoots

When the presence of New World Screwworm (Cochliomyia hominivorax) was confirmed in the Florida Keys in September 2016, it was the first non-isolated appearance of the parasite in the United States in over 30 years. While the devastation to endangered wildlife on this archipelago has been significant, if the fly spreads unchecked to the mainland it could result in losses approaching $1 billion annually.

The release of large numbers of sterile male flies is the only known method to eliminate established New World Screwworm (NWS) populations. Identifying the geographical extent of the invaders is the critical first step. The flies typically are not great wanderers and refuse to cross open water. But when those in Florida began turning up on nearby islands with no land links to neighboring islands, the sterile fly release campaign became that much more complicated.

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