For many Texans, the New World Screwworm (NWS) feels like a problem of the past. It was eradicated from the United States in the 1960s and is rarely discussed outside of history or veterinary textbooks. In Episode 12 of The Land Steward Podcast, we take a closer look at why the screwworm is once again a concern for Texans. 

This episode review was also prompted by the Texas Department of Agriculture's announcement earlier this month confirming a new case about 200 miles south of the Texas-Mexico border. We wanted to share insight from the latest Texas A&M AgriLife fact sheet designed to help Texans better understand how to monitor, detect, and report NWS infestations in wildlife. As the parasite continues to move north through Mexico, early detection and reporting are essential to protecting wildlife, livestock, and rural economies.

Texas is home to more than 100 mammal species that may be at high risk if NWS becomes reestablished, including an estimated 5 million white-tailed deer. In a 2023 report on the economic value of white-tailed deer in Texas, we found that the management and hunting of white-tailed deer alone contribute more than $9 billion annually to the economy. If deer populations are significantly impacted by NWS, there is also potential for great economic harm to rural communities and landowners.

What to watch for on your property

How infestation occurs

NWS infestation occurs when adult flies lay their eggs in or around the open wounds or mucous membranes of warm-blooded mammals. Once hatched, the larvae will burrow and begin feeding on live tissue. This can lead to rapid health decline and death, especially for free-ranging wildlife that are not closely monitored and able to receive veterinary care. The following recommendations are designed to help Texans feel equipped with the information they need to monitor and report NWS infestations in wildlife from black bears to mule deer to squirrels.

Check for wounds

Landowners who are monitoring their property first need to visually scan wildlife for open sores and tissue damage. A wound as small as a tick bite can become infested, typically in the head and neck region. Newborn animals will be susceptible in all areas, including the umbilical region. Susceptibility of certain species may change seasonally. White-tailed deer bucks, for example, may have more open wounds during rut when they have increased territorial fights with one another.

Pay attention to smell and behavior

Landowners may also detect certain smells as infestations of NWS often produce a strong, foul odor. They can also cause strange behavior in wildlife, including head shaking, general discomfort, irritability, lethargy, and isolation from other animals.

Monitoring and safety tips

Make sure to not approach wildlife closer than a reasonable viewing distance (about 25 yards), especially if you suspect they are infested. Use binoculars, field scopes, or other monitoring tools to get a better view of any free-ranging animal populations on your property every few days, if possible.

Trail cameras are another useful tool for identifying wildlife displaying clinical signs of NWS infestation. To get the best results, place cameras in a place where wildlife frequent, such as water and food sources, trails, and crossings. Place them roughly two to three feet off the ground and approximately 15 feet from the target area. Orienting the camera to face north minimizes false triggers and low-quality photos caused by shadows and sun rays.

Keeping daily observation records with dates and locations will help you better track any major changes over time. While monitoring wildlife can be challenging, increased vigilance helps us better support our state and federal agencies in responding to any outbreaks of NWS.

Urban wildlife monitoring

For those in suburban or urban areas, monitoring animals that frequent residential areas like deer, squirrels, raccoons, and coyotes is a meaningful step towards early detection. Using binoculars or cameras on security systems are good methods to maintain safe distance.

Reporting NWS

If you suspect that you have located an animal infested with New World screwworm, please immediately report the sighting to your local Texas Parks and Wildlife Department biologist or the Texas Animal Health Commission. You will be required to comply with any movement and treatment requirements that state and federal agencies may implement for either captive wildlife or exotic hoof stock. Do NOT attempt to interfere with or remove any wildlife that you suspect is infested.

All in all, the key is early detection, and it comes down to knowing what "normal" looks like on your piece of Texas. 

Read the fact sheet from Texas A&M AgriLife: Wildlife Monitoring and Management for New World Screwworm