New World Screwworm: Identification, Monitoring, and Reporting Protocols for Wildlife

The New World screwworm (*Cochliomyia hominivorax*) is a parasitic fly that poses a severe threat to mammals and birds, as its larvae feed on living tissue, causing a condition known as myiasis. Because these parasites can lead to rapid health deterioration and death, particularly in free-roaming wildlife, state and federal agencies emphasize the importance of early detection and immediate reporting to prevent the spread of infestations.

Understanding the New World Screwworm Threat

The adult New World screwworm (NWS) deposits eggs in or near wounds and mucous membranes of warm-blooded animals. Upon hatching, the larvae burrow into the tissue to feed. This process causes significant tissue damage. Even minor wounds, such as those caused by tick bites or umbilical remnants in newborns, can become entry points for the parasite.

In Texas, where the white-tailed deer population is substantial, the economic and ecological stakes are high. A [2023 study by the Texas A&M Natural Resources Institute](https://tx.ag/NRIDeerStudy) highlights that the management and hunting of white-tailed deer contribute more than $9 billion annually to the state’s economy. Wildlife species—ranging from coyotes and squirrels to black bears—are all susceptible if they sustain open wounds.

Recognizing Signs of Infestation

Early detection is the most effective way to limit the impact of NWS. Observers should look for the following clinical signs in wildlife:

* Visible Larvae: The presence of larvae within an open wound.
* Foul Odor: A distinct, putrid smell emanating from the affected area, similar to rotting flesh.
* Behavioral Anomalies: Animals exhibiting lethargy, isolation from their group, or signs of extreme irritation, such as persistent head-shaking.
* High-Risk Areas: Wounds on the head, neck, umbilical region of newborns, or mucous membranes (eyes, nose, mouth, ears, and genitals) are primary targets for the fly.

Monitoring and Reporting Procedures

Monitoring free-roaming wildlife requires consistent observation and record-keeping. The Texas Parks and Wildlife Department (TPWD) suggests that landowners and managers maintain daily observation logs to identify changes in behavior or movement patterns that might indicate an infestation.

Surveillance Tools

* Trail Cameras: Place cameras near water sources, food plots, or known game trails. Position cameras approximately 2 to 3 feet above the ground and roughly 15 feet from the target area. Orienting cameras toward the north helps reduce false triggers caused by sunlight and shadows.
* Optical Equipment: Use high-quality binoculars or spotting scopes from a safe distance—at least 25 yards—to inspect animals for wounds or signs of distress.

Reporting Requirements

If you suspect an animal is infested with NWS, immediate action is necessary to contain the threat:

1. Report to Authorities: Contact your local TPWD wildlife biologist immediately. Do not attempt to move or handle the animal, as this can spread the larvae.
2. Consult Professionals: For captive wildlife or exotic artiodactyls, contact the Texas Animal Health Commission (TAHC) or a licensed local veterinarian.
3. Follow Official Guidance: Adhere strictly to any movement or treatment requirements issued by state or federal agencies.

Seasonal Risks and Demographic Vulnerability

The risk of NWS infection fluctuates based on the animal’s life cycle and environmental conditions.

* Females and Offspring: The birthing season is a high-risk period, as the umbilical region of newborns and the genital areas of females are highly susceptible to egg-laying if any trauma is present.
* Males: During the breeding season, males are prone to physical altercations, which create open wounds. Additionally, the growth and shedding of velvet on antlers provide further opportunities for infestation.

By maintaining detailed records of herd composition—including the ratio of males, females, and offspring—landowners can better assist biologists in assessing the impact of a potential outbreak. For specific management strategies or technical guidance on monitoring property populations, landowners are encouraged to consult with their regional TPWD office.