New World Screwworm (NWS, Cochliomyia hominivorax) is a devastating pest. When NWS fly larvae (maggots) burrow into the flesh of a living animal, they cause serious, often deadly damage to the animal. NWS can infest livestock, pets, wildlife, occasionally birds, and in rare cases, people.
The name screwworm refers to the maggots' feeding behavior as they burrow (screw) into the wound, feeding as they go like a screw being driven into wood. Maggots cause extensive damage by tearing at the hosts’ tissue with sharp mouth hooks. The wound can become larger and deepen as more maggots hatch and feed on living tissue. As a result, NWS can cause serious, often deadly damage to the animal.
Adult screwworm flies are about the size of a common housefly (or slightly larger). They have orange eyes, a metallic blue or green body, and three dark stripes along their backs.
Report mammals and birds with the following signs:
- Irritated behavior
- Head shaking
- The smell of decay
- Evidence of fly strike
- Presence of fly larvae (maggots) in wounds
The best way to keep screwworm out of this country is to prevent introductions. NWS can infest mammals, including people, and birds. Here are steps you can take to avoid infestation:
- Be alert for NWS symptoms in pets and livestock.
- Ensure that pets traveling internationally are inspected for screwworm.
- Check your vehicle for screwworm flies if you are in an NWS-infested area.
Eradicating NWS is only possible through sterile insect technique (237.54 KB). With this method, sterile flies are released into an area where a known population has become established. The sterile male screwworm flies mate with fertile female screwworm flies, causing the population of screwworm flies to decrease until it eventually dies out. Animals infested with NWS should be treated according to the recommendations of their veterinarian.
For more information about NWS related to animals, please contact the ADAI 's State Veterinarian’s office at 334-240-7253.
