NWS Update: Aug. 22, 2026

Aug. 22, 2026

Dear TWA member,

Due to the relatively low number of confirmed NWS cases over the last several weeks, we are reducing the frequency of this update from weekly to bi-weekly. Should the caseload increase and remain sustained, we will make adjustments to our update schedule in order to keep you informed in a timely manner.

The Texas Wildlife Association and its partners continue to closely monitor developments around New World screwworm (NWS) spread in Texas since the initial detection on June 3. More detections are expected and response efforts continue to build. It is essential that landowners, particularly in impacted areas, vigilantly monitor wildlife and livestock and report suspicious cases to the appropriate authorities.

To provide you with timely and relevant information related to the presence of NWS in Texas, we are sharing this bi-weekly update as of 12 p.m. on Aug. 21, 2026. Cases confirmed since our Aug. 15 update are included below.

A full list of active and inactive cases is available at the USDA Dashboard (updated daily at 5 p.m. Central).

Confirmed Date

County

Species

Status

16 August 2026

Val Verde

Sheep

Active

Active cases are those that involve ongoing disease mitigation efforts, including treatment and wound management of the infested animal until all wounds have healed.

Inactive animal cases refer to situations where mitigation activities are no longer required. Either the animal has fully recovered—with wounds healed and treatment completed—or, in cases where treatment was not performed, appropriate measures have been taken to prevent the spread of NWS, such as appropriate carcass management of a deceased infested animal.

News from this week
TWA Best Practices now online
We are proud to share Best Practices for Screwworm Detection & Reporting in Wildlife. This 12-page booklet is designed to serve as an NWS resource for TWA members, hunters, ranchers, landowners and managers, and anyone who enjoys time outdoors. We plan to print the document and have it available at future TWA events across the state.

Sterile fly release stats
During the Aug. 18 TPWD Commission meeting, Alan Cain, TPWD wildlife division director, provided an update on the status of NWS in Texas and the department’s response efforts that include outreach, wildlife surveillance and movement requirements for live native wildlife. He noted that approximately 80 million sterile flies per week are currently being released in Texas. View his entire presentation here beginning at the 38:20 mark.

——————

What to look for

Identification
NWS are parasitic flies that lay eggs in open wounds, genitalia or mucous membranes such as the umbilical cords of newborns, the nostrils, eyes or mouths of live warm-blooded animals. These eggs hatch into parasitic larvae (maggots) that only feed on living tissue, unlike other fly larvae that prefer dead or necrotic tissue. NWS larvae only burrow or “screw” into living tissue with sharp mouth hooks, giving them a screw-like appearance. Infested wounds quickly become infected and, if left untreated, will kill infested animals.

What you can do
Regularly reviewing game cameras, observations of wildlife while hunting or viewing animals, and inspection of hunter-harvested wildlife are important tools that can be used for NWS surveillance. While all warm-blooded mammals can be infested with NWS, white-tailed deer, jackrabbits, cottontails, small mammals and turkeys are more commonly affected. Instances of live or just-harvested animals with live maggots should be reported immediately.

Texas Parks and Wildlife Department (TPWD) has established procedures for the take of certain wildlife suspected to be infested with NWS.

Inspect all harvested wild game. If a harvested animal has a suspected infection, utilize a tarp or other barrier to keep larvae from coming into contact with the soil. Report the animal to your TPWD biologist, and follow guidelines for carcass treatment and disposal. Carcasses with no sign of infestation can be disposed of through normal processes.

How to report and who to report to

Pesticides for NWS
For a list of currently registered products that meet the U.S. Environmental Protection Agency’s (EPA) efficacy data, please visit Pesticides for Control of New World Screwworm.

The EPA has approved Fyfanon® ULV AG (Malathion) for treating the ground around dead wildlife when NWS larvae have already exited the carcass to pupate in the soil.

What is being done
Sterile flies are a proven technique to eliminate this pest. It is estimated that to push the screwworms back out of the United States, 500 million flies per week will need to be produced and dispersed. The following actions are in place, or under development, to expand our sterile fly resources:

TWA statement on potential feed-through treatment for wildlife
The  Texas Wildlife Association continues to work with our state and federal partners to identify and share tools that Texas landowners can use in the prevention and treatment of NWS.

We are encouraged by the recent announcement of collaborative field trials involving the United States Department of Agriculture, the Food and Drug Administration, and the Texas Parks and Wildlife Department to evaluate the use of a feed-through treatment for wildlife applications. This research represents an important step toward developing science-based management options to protect Texas wildlife resources as the construction of vital sterile insect infrastructure moves forward.

We look forward to the results of these trials and are hopeful they will determine whether this treatment can be demonstrated to be both safe and effective in preventing NWS infestation in wildlife.

Stay updated by visiting these sites

Additional online resources