Written by HLRBO Staff|
Last updated
New World screwworm returned to the United States this summer for the first time since 2017, and as of September 19, 2026 the USDA has confirmed 50 animal cases, every one of them in livestock or pets and none in wildlife. The APHIS confirmed-detections dashboard lists 50 domestic cases alongside zero wildlife and feral cases and zero wild flies caught in traps. That dashboard is updated daily, so treat the number as a dated snapshot rather than a standing total. Deer seasons are opening on top of that record, and hunters are now part of how the country watches for the next case.
Start with what the record actually says
Two claims circulating in outdoor coverage do not survive a check against the agency.
The first is that this is the first US screwworm case in roughly sixty years. It is not. APHIS's own historical reference guide states the eradication program in the Southwest "was declared a success in 1966," and that in 2016 screwworm "re-emerged in the Florida Keys, affecting endangered Key deer," with eradication achieved by early 2017. The accurate framing is that 2026 is the first US detection since 2017, and the first on the southwestern border in decades.
The second is a case count of 47. The dashboard's own total as of September 19, 2026 was 50 animal cases, every one of them in livestock or pets and none in wildlife. Any figure below 50 is not the total the agency was publishing on that date.
The confirmed detections sit in Texas and New Mexico. Texas counties on the dashboard include Zavala, La Salle, Uvalde, Medina, Edwards, Val Verde, Terrell, Crockett, Pecos, Brewster, Presidio, Sutton, Schleicher, Tom Green, Gillespie, Starr and Jim Hogg. New Mexico's are Grant and Lea. The species are cattle, sheep, goats, dogs and horses. The first case was announced June 3, 2026 in a three-week-old calf in Zavala County, with larvae in the umbilical area.
Why this fly is not a blowfly
Most maggots a hunter finds on a carcass are eating dead tissue. Screwworm larvae do the opposite, and that single difference is the whole story.
New World screwworm is Cochliomyia hominivorax. Texas Parks and Wildlife describes the flies as laying eggs "in open wounds, genitalia or mucous membranes such as the nostrils, eyes or mouths of live warm-blooded animals," where the eggs hatch within about 24 hours into larvae "that only feed on living tissue, unlike other fly larvae that prefer dead or necrotic tissue." The larvae "burrow or 'screw' into living tissue with sharp mouth hooks." Untreated, an infested animal dies.
All warm-blooded animals are susceptible, people included, which is why USDA runs the response through screwworm.gov rather than a livestock-only channel. TPWD narrows that usefully for hunters: "While all warm-blooded mammals can be infested with NWS, white-tailed deer, jackrabbits, cottontails, small mammals and turkeys are more commonly affected."
Marcus Blum, Ph.D., AgriLife Extension statewide wildlife specialist and assistant professor in the Texas A&M Department of Rangeland, Wildlife and Fisheries Management, told AgriLife Today on August 25, 2026 that the calendar was the bad part. "The timing of these positive New World screwworm cases came at a bad time, with fawning season overlapping with the presence of screwworm. This left both fawns and does vulnerable." AgriLife reported that there have been no confirmed cases of NWS in wildlife to date, and that Blum believes there have likely been undetected ones. Blum's own account of why that gap exists is the practical one: "It's just really difficult to get your eyes on every part of each free-ranging animal regularly as you can with livestock."
What you would actually see
The adult fly is roughly housefly-sized or slightly larger, with orange eyes, a yellow face, a metallic blue or green body, and three dark stripes down the back. You are unlikely to identify one in flight. The wound is the tell.
Look where the skin is already broken. TPWD lists the common sites as the umbilical stump on newborns, mucous membranes at the genitalia, eyes, nose and mouth, and damaged skin from cuts, scrapes, stings, tick bites and antler or velvet shedding. On a buck in September, velvet shed and fighting wounds are exactly the openings that matter.
What you are looking for is an open sore holding live maggots, deeper and more inflamed than a surface strike, with the larvae packed head-down into the tissue rather than crawling loose. On a live animal, TPWD adds behavior: animals "shaking heads or acting irritated." On a game camera, the sign is a wound that keeps getting larger over successive nights instead of scabbing.
What to do, and who to call
Screwworm is a reportable disease. The Association of Fish and Wildlife Agencies guidance, updated June 11, 2026, tells state agencies to route any suspicion to the State Animal Health Official or the USDA Area Veterinarian in Charge and the state wildlife health lead.
For a hunter, the practical version is shorter. In Texas, native wildlife goes to a local TPWD biologist or 512-389-4505; livestock and exotic wildlife go to the Texas Animal Health Commission at 800-550-8242; a human wound goes to a healthcare provider. Outside Texas, APHIS directs reports of live or recently dead wild animals to USDA Wildlife Services at 866-487-3297, and livestock or pet concerns to a veterinarian, who reports upward. General questions go to [email protected]. Before you call, note the date, GPS location and species, and take close photos of the wound and larvae.
If you harvested the animal, TPWD's Hunter and Landowner Guide is specific. Put the carcass on a tarp, plastic sheeting or a hard surface so larvae cannot reach soil. Remove every larva or cut out the affected area. Put collected larvae in a sealed container fully submerged in 70 percent isopropyl alcohol, double-bag and freeze excised parts, and hand the samples to a TPWD biologist. Suspect carcasses get burned, frozen solid, or buried at least four feet deep in tightly compacted soil on the property of harvest, and infested carcasses are not to leave that property. TPWD does not recommend eating apparently sick or infested wildlife, and encourages deboning meat taken from inside an infested area.
The last outbreak, and the number worth doing yourself
The Florida Keys is the honest benchmark, because it was a deer outbreak. APHIS's final report, dated May 30, 2017, counted "145 cases: 128 presumptive cases and 17 confirmed cases of NWS in the Florida Keys, with the majority, or 135, of those positive cases observed in Key deer." No production livestock was affected. It took about 188 million sterile flies, roughly $3.2 million in APHIS spending, and 174 days from laboratory confirmation on September 30, 2016 to the eradication declaration on March 23, 2017.
Put the two outbreaks side by side. In Florida, 135 of 145 cases were deer, which is 93 percent. In 2026, as of September 19, 0 of 50 confirmed cases were wildlife of any kind. The outbreak had run 106 days from the June 3, 2026 announcement to the last reported detection on September 17, 2026, about one confirmed case every two days, and the wildlife column had not moved off zero. Set that against a Texas white-tailed deer herd that TPWD's published season forecast puts at 5 million animals.
That is the right-sized version of this risk. Screwworm in American deer is a documented, expensive, solvable event that has happened once in the last sixty years and is not, on the present record, happening now. Blum's caution stands alongside it: no confirmed wildlife cases does not mean no wildlife cases, because nobody inspects most deer.
What a lease should say about it
Most hunting leases were written without a word about parasites, and most do not need rewriting. What they do need is one paragraph on carcass handling, because the TPWD guidance imposes obligations on the property, not just the hunter.
Three things belong in writing. First, that suspected infestations get reported to the landowner and to the state wildlife agency the same day, with photos. Second, that carcass disposal happens on the premises of harvest by burning, freezing or burial at four feet or deeper, and that suspect carcasses do not leave the property. Third, who pays for that, because burial at depth means equipment.
A landowner inside an active infested zone has one more item to track: whether the state has released the zone. APHIS approved its first Texas infested-zone releases on August 31, 2026, and has modified zones several times since. Zone status governs animal movement, so confirm it with the Texas Animal Health Commission or your own state animal health official before opening day, not after.
Wherever you hunt
Texas and New Mexico carry every confirmed case so far. Neighboring states have stood up guidance without a detection of their own. The Oklahoma Department of Agriculture, Food and Forestry, in a June 4, 2026 alert, tells hunters to report suspicious wounds on recently harvested wildlife to a local game warden or the state veterinarian at 405-522-6141 "prior to removal of wildlife," which is a stricter sequence than most hunters expect. Louisiana routes reports through the state wildlife and agriculture departments or an LSU AgCenter office, and Florida's wildlife agency has kept its own screwworm page since 2016. Other states differ, and none of this substitutes for what your agency or your lease says. Check your state wildlife agency's disease page before the opener, and read the carcass-movement rules for any animal you plan to haul across a county line.
The useful mindset is not fear. It is the same one that made hunters the backbone of chronic wasting disease surveillance: you are already out there, already looking at wounds, and already handling more deer than any biologist will this fall. As APHIS's own wildlife surveillance guidance puts it, animals harvested by hunters "offer a valuable surveillance strategy." Learn the wound, carry a phone, and make the call.
Landowners running leases carry the carcass-handling burden whether or not the lease mentions it, which is a good argument for getting it in the document before the season rather than after a bad find. HLRBO's guidance for owners putting ground up for lease is at lease your land, and the reporting behind pieces like this one lives on the HLRBO blog.