Fire Ants Are Disappearing Across Texas — Scientists Found What Came Back to Hunt Them

[00:00:00]Their frenzy is deceiving.

[00:00:04]The efficiency and order of the fire ant colony is a force of nature, and it's one that's taking over Texas one mound at a time.

[00:00:13]>> Fire ants kill newborn calves in their sleep. They swarm nursing home patients who can't move out of bed.

[00:00:20]They send over 80,000 Americans to emergency rooms every year. And in Texas alone, they cause over a billion dollars in agricultural damage annually. A single queen produces 1,500 eggs per day across a 30 million acre invasion that no chemical program in 40 years has been able to reverse.

[00:00:41]Then a biologist found colonies collapsing across three pasture zones with no treatment applied. The cause was a 5-in lizard that shoots blood from its eyes. It had been gone for 40 years.

[00:00:55]It came back on its own. What fire ants did to Texas. To understand what those survey numbers were showing, you have to understand what red imported fire ants actually did to the state they invaded.

[00:01:09]Not the version people mention when they complain about getting stung in the yard.

[00:01:13]The version that plays out across 30 million acres of Texas grassland and that changed the ecology of the state's pastures in ways most Texans never realized they were watching happen. Red imported fire ants arrived in the United States through the port of Mobile, Alabama sometime in the 1930s. They reached Texas by the 1950s. They came from South America where millions of years of co-evolution had built a full community of natural enemies, parasites, pathogens, and competing species that kept their populations in check. In Texas, none of those checks existed. The ants encountered open habitat, warm soil, abundant prey, and zero effective biological resistance. A single red imported fire ant colony contains between 100,000 and 500,000 workers. In heavily invaded pasture land, colony densities reach 100 to 200 mounds per acre. Each mound is a superorganism operating with collective intelligence focused entirely on acquiring protein.

[00:02:18]And the primary protein source in a Texas pasture that fire ants are most efficient at harvesting is the exact species that another animal had depended on entirely for survival across millions of years of shared evolution.

[00:02:33]The damage extended far beyond a single prey species. Fire ants attack ground nesting birds. They swarm newborn deer and livestock.

[00:02:42]They short-circuit electrical equipment by nesting inside junction boxes attracted to the electromagnetic fields.

[00:02:50]Texas agricultural losses from fire ant damage have been estimated at over 1 billion dollars annually. The ants colonize virtually any open ground, roadsides, playgrounds, athletic fields, cemeteries, airport runways.

[00:03:05]Their mounds harden in the soil and can damage mowing equipment. In heavily infested pasture, cattle learn to avoid large sections of grazing land entirely and the economic loss compounds season after season.

[00:03:20]Every chemical approach that has been deployed against them, broadcast baiting, individual mound treatment, growth regulators, contact insecticides, has produced the same result, temporary suppression in the treated zone followed by recolonization from the surrounding landscape within one to three seasons.

[00:03:40]The fire ants' reproductive biology simply outpaces chemical intervention.

[00:03:46]A single queen can produce 1,500 eggs per day. A colony can replace its losses faster than any affordable bait program can inflict them. The animal that depended on that food source was about to lose it, and the speed at which it happened left no room for adaptation.

[00:04:03]But before we get to what disappeared from the pastures, you have to understand what the animal was that disappeared because this creature is one of the strangest and most [music] precisely engineered predators that ever evolved on the North American continent.

[00:04:18]The lizard that shoots blood from its eyes. The Texas horned lizard is the official state reptile of Texas. It is 3 to 5 in long, flat-bodied, covered in spines, and looks like something designed to survive a world far more dangerous than a hill country pasture.

[00:04:36]And it is. This animal carries one of the most bizarre defense mechanisms in the animal kingdom. When attacked by a canine predator, a coyote or a fox or a domestic dog, the horned lizard contracts muscles around the veins in its head, cutting off blood flow back to the heart while allowing arterial blood to continue flowing in.

[00:04:57]Pressure builds inside the sinus cavities behind its eyes until the thin tissue membranes rupture, and the lizard fires a jet of blood from its eye sockets up to 4 ft in distance. The blood contains a noxious chemical compound that tastes so foul to canine predators that coyotes tested in controlled studies exhibited immediate avoidance responses, >> [music] >> gagging, head shaking, and in some cases refused to approach horned lizards again afterward. USDA researchers confirmed that the aversive effects are mediated through oral and nasal receptors, and that horned lizard blood triggered significantly stronger rejection responses in coyotes than blood from other lizard species. The defense is so precisely calibrated that the lizard won't trigger it in response to a a approaching. Researchers spent years trying to study the behavior and kept failing because the lizards wouldn't fire.

[00:05:52]They eventually had to train a dog to gently paw and nibble the animals before the mechanism activated. The lizard can distinguish between canine predation and other types of threat by touch receptor patterns on its skin. It only deploys its most costly defense against the predator it was specifically designed to deter, but blood squirting is the backup plan.

[00:06:14]The horned lizard's primary survival strategy is its diet, and its diet is where the entire story pivots.

[00:06:22]An adult Texas horned lizard requires between 60 and 100 harvester ants per day to meet its caloric needs. Some studies put the number above 100.

[00:06:32]Harvester ants are large, slow-moving, seed-collecting ants whose colonies carpet the rocky limestone soils of the Edwards Plateau. They follow predictable foraging trails. They provide meaningful nutrition per individual prey item. The entire foraging biology of the Texas horned lizard was built around the harvester ant as a food source so reliable that no alternative feeding strategy ever needed to develop. The lizard even evolved a specialized resistance to harvester ant venom.

[00:07:02]Laboratory tests showed that horned lizards survived intraperitoneal doses of harvester ant venom that rapidly killed laboratory mice and other lizard species of comparable size.

[00:07:13]They produce copious mucus in the pharynx and esophagus that embeds and immobilizes swallowed ants before the stingers can cause damage. High-speed video research published in 2021 revealed that horned lizards strike ants specifically at the mesosoma, the thorax region, deliberately avoiding the head and the venomous gaster even when those body parts are closer to the lizard's tongue. They capture and orient the ant headfirst during retraction so the mandibles get coated in mucus immediately. This is not an animal that eats ants casually. This is a predator so deeply specialized that it evolved venom resistance, mucus production, and strike targeting precision across millions of years. All to consume a single prey type with maximum efficiency and minimum self-damage. And then fire ants arrived and dismantled the food supply that entire system was built on.

[00:08:09]The collapse.

[00:08:10]Red imported fire ants do not coexist with harvester ants. They eliminate them. Fire ant workers locate harvester ant colonies, overwhelm them through numerical superiority, kill the queens, and convert the territory to fire ant occupation within a single season.

[00:08:30]In the decades following fire ant establishment across the Edwards Plateau, harvester ant populations in invaded pasture zones collapsed to levels that could not sustain horned lizard foraging. The lizards did not adapt. They had no adaptation to offer.

[00:08:46]Their biology was locked into a dietary dependency that had never needed a backup plan because no competitor capable of removing harvester ants at landscape scale had existed in North America before. They stopped reproducing in zones where harvester ants were gone.

[00:09:02]The population contracted corridor by corridor, pasture by pasture across the same decades that millions of Texans remember as the years the horned lizards vanished. Children who caught them in their yards in the 1950s and 60s grew up and had grandchildren who had never seen one outside a photograph. The disappearance was so gradual that most people didn't notice it happening until it was already complete. There was no single year when the horned lizard stopped being present. They just became less frequent, then rare, then absent.

[00:09:36]Texans who had grown up handling them as casually as they picked up rocks slowly realized that no one in their family had seen one in years, then decades. The state reptile of Texas had become functionally invisible across most of the state that had named it as its icon.

[00:09:54]But fire ants weren't the only force.

[00:09:57]Pesticide use across the same period compounded the damage. Broadcast baiting programs designed to target fire ants killed native ant species indiscriminately, including the harvester ants that horned lizards needed. People who believed they were fighting fire ants were accidentally destroying the food web that the state reptile of Texas [music] depended on to survive. Some landowners mistakenly identified native Texas red harvester ants as imported fire ants and poisoned their own properties, eliminating exactly the species the landscape needed to retain. Agricultural practices added another layer. Shredding and clearing weeds eliminated the seed sources that harvester ants depended on for food. No seeds meant no harvester ants. No harvester ants meant no lizards. The collapse cascaded through the food web in a sequence [music] that was invisible from the surface but devastating at every level below it. The horned lizard disappeared not because anyone targeted it but because the food web it had been built to occupy was disassembled beneath it faster than biology could respond.

[00:11:04]Protection legislation in the 1970s and formal listing as a threatened species in Texas in 1977 ended direct persecution. But legal protection doesn't feed an animal whose food is gone. The question became whether anything could bring the harvester ants back and the answer required a zoo in Fort Worth to do something that had never been done before.

[00:11:28]2,000 lizards. The Fort Worth Zoo began its Texas horned lizard conservation program in 2011 in partnership with Texas Parks and Wildlife [music] and Texas Christian University. It was the first zoo to successfully breed the species in captivity. Nobody had ever managed it before, partly because the species had been in decline for so long that basic husbandry protocols didn't exist.

[00:11:54]Senior curator of ectotherms Diane Barber led the effort to develop breeding and rearing methodologies from scratch. Most of the reptiles and amphibians she works with, Barber has noted, are animals people struggle to care about because they can't form an emotional connection to them the way they can with mammals. The horned lizard was different.

[00:12:14]Texans loved this animal. Ranchers across the state were calling the zoo asking for lizards to be reintroduced to their properties. The early attempts at reintroduction failed. The program initially released adult lizards into the wild at Mason Mountain Wildlife Management Area in Mason County, roughly 4 hours southwest of Fort Worth. Adult lizards dropped into unfamiliar territory were immediately vulnerable to predation and survival rates were too low to sustain a population. The program pivoted. They started releasing hatchlings instead, animals small enough to find cover quickly and establish themselves before predators could locate them.

[00:12:53]The survival trajectory improved. TCU biology professor Dean Williams led genetics research that identified three distinct genetic populations of [music] Texas horned lizards across the state.

[00:13:05]One in the western deserts, one in the northern plains, and one in the southern plains. That finding mattered enormously because it meant releasing the wrong genetic population into the wrong habitat could undermine the entire effort. A lizard from the western desert population wouldn't carry the genetic adaptations suited to northern plains conditions. The Fort Worth Zoo focused on the northern population. Williams' lab at TCU sent 15 undergraduates through the program over the years, generating genetic data from wild and captive populations, analyzing habitat use through photographic surveys, and identifying the ants and insects in the lizard's diet through DNA barcoding. One undergraduate project investigated whether [music] a clutch of horned lizard eggs, typically 20 to 30 per nest, comes from a single father or multiple fathers. The answer matters because it determines how much genetic diversity each clutch contributes to the recovering population. By 2021, the program reached a milestone. Hatchlings released at Mason Mountain in 2019 became the first reintroduced horned lizards to breed and reproduce in the wild on their own. That had never happened before in any horned lizard reintroduction program anywhere. In 2024, the zoo set a record by releasing 617 lizards in a single season, collaborating with Dallas Zoo, Caldwell Zoo, Fossil Rim Wildlife Center, and Pearland Nature Center. 301 of those hatchlings came from Fort Worth's own breeding colony.

[00:14:42]By 2025, the zoo had hatched its 2,000th lizard. The work required more than breeding animals. It required preparing the habitat to receive them. That meant sustained fire ant suppression at the release sites using targeted poisoning methods designed specifically to reduce fire ant populations while minimizing damage to native ant species.

[00:15:05]Researchers at Mason Mountain developed application protocols that used smaller, more precise bait deployments >> [music] >> to avoid the broadcast approach that had historically killed harvester ants along with fire ants.

[00:15:18]Harvester ant colonies began recovering in the treated zones. horned lizard numbers stabilized. The trajectory was encouraging, but slow. And the treated zones were small. While conservationists were rebuilding the lizards food web from the ground up in these protected corridors, the United States government had been waging a parallel war against fire ants using a weapon so bizarre it sounds invented. Decapitating flies from South America that turn fire ants into zombies before killing them.

[00:15:48]The flies that came from South America.

[00:15:52]In 1994, two independent research teams began studying phorid flies as biological control agents against imported fire ants. One team was based at the USDA Agricultural Research Service Laboratory in Gainesville, Florida. The other was at the University of Texas at Austin. Both were working from the same premise.

[00:16:13]The reason fire ants are so devastating in the United States is because they arrived without their natural enemies.

[00:16:20]If you could import those enemies, you could tip the ecological balance back toward native species.

[00:16:26]Phorid flies in the genus Pseudacteon are parasitoids that specialize in fire ants.

[00:16:33]The female fly is roughly 1 to 2 mm long, smaller than the ants she hunts.

[00:16:39]She hovers above fire ant foraging trails or disturbed mounds, identifies a target worker, and swoops in to inject a single egg into the ant's body in a fraction of a second.

[00:16:50]The ant doesn't die immediately.

[00:16:52]What happens next is slower and considerably worse.

[00:16:56]The larva hatches inside the ant's body and migrates into its head, where it feeds on the contents of the head capsule, the muscles, the neural tissue over the course of roughly 2 [music] weeks. During this period, the parasitized ant enters what researchers describe as a zombie phase.

[00:17:14]The ant wanders aimlessly, leaving the colony's organized foraging patterns, exhibiting disoriented behavior that serves no purpose except to carry the developing larva to a location suitable for pupation.

[00:17:27]The ant is still alive. It is being operated from the inside.

[00:17:33]Eventually, the larva releases an enzyme that dissolves the membrane connecting the ant's head to its body.

[00:17:40]The head detaches and falls to the ground.

[00:17:43]The fly pupates [music] inside the severed head and emerges as an adult roughly 2 weeks later, ready to begin the cycle again.

[00:17:51]The USDA began releasing phorid flies across the southeastern United States in the early 2000s. Before any releases were approved, APHIS produced a formal environmental assessment confirming the flies were sufficiently host-specific that they would target imported fire ants and leave native ant species alone.

[00:18:11]Six species have been established on red imported fire ants in the US to date.

[00:18:17]Two species, Pseudacteon tricuspis and Pseudacteon curvatus, are now widely distributed across the southeast.

[00:18:24]Curvatus densities are roughly tenfold higher than tricuspis, likely because fire ant colonies contain more of the smaller workers that curvatus prefers.

[00:18:34]In Texas, releases were made near Austin and Vidor, and established populations have been expanding their range at roughly 10 to 15 miles per year.

[00:18:44]The direct kill rate is modest.

[00:18:46]Studies show phorid flies parasitize up to 5% [music] of colony workers, and the population impact of a single fly species doesn't consistently rise above the 10 to 30% background variability in fire ant numbers. But the indirect effects are significant. When phorid flies are present, fire ant workers stop foraging. They retreat underground.

[00:19:08]Their above-ground activity drops measurably, which gives native ant species, including harvester ants, competitive breathing [music] room to maintain territory they would otherwise lose.

[00:19:19]The phorid fly program was never designed to eliminate fire ants. It was designed to level the playing field. To restore enough of the competitive balance that native ecosystems had a chance to push back.

[00:19:33]And in some of the same hill country corridors where the flies were establishing themselves, something else was pushing back, too, in ways that nobody had been measuring until a wildlife biologist's survey data stopped making sense.

[00:19:48]The numbers that didn't make sense.

[00:19:50]The wildlife biologist had been running fire ant colony density surveys across a monitoring grid on the Edwards Plateau outside Kerrville for 9 years. She knew what fire ant activity was supposed to look like on this landscape before she walked the first transect of any season.

[00:20:08]She knew the mound distribution patterns. She knew the foraging corridor signatures.

[00:20:14]She knew the colony density indices that had defined every data cycle since her first year.

[00:20:20]Then, the data from three specific pasture zones stopped matching anything her 9 years of monitoring had ever produced.

[00:20:28]Fire ant colony density across those zones was declining, not sharply, not from a single cause she could identify from the truck, consistently, measurably, in the same direction across three consecutive survey seasons in the exact [music] pasture corridors where something else had been quietly returning to the landscape for the first time in 40 years. She called the research station before she drove back. She told them something out there was eating them. She drove to the first anomalous pasture and spent 2 days on hands and knees at the mound sites.

[00:21:03]She documented mound activity levels.

[00:21:05]She measured foraging trail density. She checked soil conditions and rainfall records to rule out environmental explanations. She reviewed whether any adjacent landowner had deployed commercial fire ant bait without notifying her program.

[00:21:21]Every explanation she tested came back negative.

[00:21:25]The suppression signal in the data was real, and it was not coming from any human source.

[00:21:31]Then she called the wildlife monitoring office.

[00:21:34]What she had found was not a reintroduced animal from any program she had access to.

[00:21:39]It was a resident population established, reproducing, foraging across the pasture zones adjacent to a protected limestone outcrop corridor that had been under predator and livestock exclusion management for 11 years for reasons that had nothing to do with fire ants. When she mapped documented horned lizard activity against the fire ant colony density data across the same pasture grid, the correlation was not ambiguous. The zones with the highest lizard density and the zones showing the steepest fire ant colony suppression occupied the same ground.

[00:22:13]The mechanism behind that correlation is the part of this story that changes how you think about what a single species can do to a landscape.

[00:22:21]The mechanism nobody designed.

[00:22:24]An adult Texas horned lizard positions itself at the entrance of a harvester ant foraging trail and feeds with a precision and consistency that constitutes systematic predation pressure on the fire ants most vulnerable competitor. The intuitive assumption is that the lizard suppresses fire ants by eating them directly. It doesn't. Texas horned lizards do not actively consume fire ants. Research suggests they are unable to effectively neutralize fire ant venom the way they neutralize harvester [music] ant venom.

[00:22:57]The horned lizard's venom resistance is specific to its evolved prey.

[00:23:02]Fire ants are not part of its system.

[00:23:04]The mechanism is indirect, and it operates at the colony territory level in a way that took researchers months to fully understand after the initial data anomaly was identified. A single adult horned lizard consuming 60 to 100 harvester ants per day at the trail entrance is not applying meaningful fire ant suppression on its own, but a lizard foraging consistently at harvester ant trail entrances creates something unexpected. It creates territorial stability for the native ant colony by relieving competitive pressure at the perimeter.

[00:23:37]Here is how that works in practice.

[00:23:40]Harvester ant colonies maintain territories through active defense of their foraging grounds against encroaching fire ant colonies.

[00:23:48]A harvester ant colony with a large active territory is constantly expending energy defending the edges of that territory against fire ant scouts probing for weaknesses. When a horned lizard systematically harvests from the trail entrance, it reduces the harvester colony's outward expansion. That sounds counterproductive until you understand what happens to the energy budget of the colony.

[00:24:12]The energy the colony would have spent defending an overextended perimeter is now available for internal colony maintenance, queen nutrition, and brood production.

[00:24:22]The colony gets smaller but denser, more workers per unit of territory, more defensive capacity per mound entrance. A smaller, more concentrated harvester ant territory resists fire ant encroachment more effectively than a larger, thinly defended one. The lizard is essentially pruning the colony into a more defensible shape.

[00:24:43]At the pasture scale, across multiple harvester ant colonies being maintained by resident horned lizard foraging, the competitive dynamic between native and invasive ant species shifts measurably.

[00:24:55]Harvester ant [music] territories become more defensible. Fire ant expansion encounters resistance at points where it previously met none. Colony density declines in the consistent pattern that the transect data was recording with a precision nobody had designed an instrument to capture until the numbers stopped making sense.

[00:25:15]The horned lizard was not just eating.

[00:25:17]It was restructuring the competitive architecture between two ant species at the landscape level in real time.

[00:25:25]40 years of chemical intervention had never touched that [music] architecture.

[00:25:29]A lizard the size of a human palm was modifying it by showing up to the same trail entrance every morning and eating breakfast.

[00:25:37]This is the part of the story that surprised every researcher who reviewed the corridor data.

[00:25:42]The lizard wasn't doing anything new.

[00:25:44]It was doing what it had always done across millions of years of Edwards Plateau ecology.

[00:25:50]The only thing that had changed was that the landscape had finally given it enough space to do it again.

[00:25:56]The race?

[00:25:57]The wildlife biologist went back to the three anomalous pasture zones four times across the following survey season.

[00:26:05]On her third visit to the largest corridor zone, she positioned herself at a limestone outcrop edge at first light and watched the pasture floor for two hours without moving.

[00:26:15]She counted seven individual horned lizards across the visible transect section from that single position. Seven animals in a zone where her monitoring records from the program's first three years had logged zero confirmed residents.

[00:26:30]She watched one individual position itself at a harvester ant trail entrance and hold that position for 40 minutes of continuous foraging.

[00:26:39]The lizard's tongue fired with mechanical consistency, striking ant after ant at the thorax, orienting each one head first during retraction, mucus coating the mandibles before they could bite. She was watching a predator do something it had evolved to do across millions of years on ground where it hadn't been seen in her lifetime. She noted the fire ant mound density in the surrounding 50 meter radius. Then she noted the same measurement from her baseline records [music] for that specific location from 5 years earlier.

[00:27:10]She sat with both numbers written side by side in her field log for a long time before she wrote anything else.

[00:27:17]The question is whether the horned lizard recovery can expand across enough of the Edwards Plateau protected corridor network to apply sustained competitive pressure on fire ant colony density at the landscape scale. Because outside those corridors in the unprotected pastures and rangelands where fire ants face no biological resistance, harvester ant populations are still declining.

[00:27:43]The food web the lizard needs to survive is still being dismantled in every zone where the lizard has not yet returned.

[00:27:50]The Fort Worth Zoo is hatching lizards by the hundreds.

[00:27:54]Phorid flies are spreading across the southeast at 15 miles a year.

[00:27:59]Targeted fire ant suppression protocols at Mason Mountain are holding territory for recovering harvester ant colonies.

[00:28:06]Gene drive research published in 2025 by a team at Peking University and Cornell is modeling new genetic approaches to fire ant population suppression that could complement existing biological controls. The tools exist. The biology works.

[00:28:25]But the invaded landscape is 30 million acres.

[00:28:29]The protected corridors are measured in hundreds. The question is speed.

[00:28:34]Whether the animal can expand fast enough through the connected limestone corridor systems of the Edwards Plateau to matter at the scale the fire ant invasion demands. Whether the phorid flies spreading from Austin and Vidor, can reach the Hill Country corridors in time to compound the pressure the lizards are already applying. Whether the genetic diversity in the recovering populations is sufficient to sustain long-term viability across a fragmented landscape.

[00:29:03]Nobody is claiming the horned lizard alone can solve the fire ant problem across Texas. 30 million acres of invasion cannot be reversed by a reptile that weighs less than 2 oz.

[00:29:14]The protected corridors where the recovery is documented are measured in hundreds of acres.

[00:29:20]The invaded landscape surrounding them stretches from the Gulf Coast to the Red River.

[00:29:26]The math does not favor the lizard.

[00:29:29]Not yet.

[00:29:30]But what the corridor data is showing is that biology, left alone long enough in the right conditions, can accomplish things that decades of industrial chemistry could not. Every bait program deployed across the state over the last 40 years produced the same result.

[00:29:47]Temporary suppression followed by recolonization within one to three seasons.

[00:29:52]The horned lizard is producing something different.

[00:29:56]Sustained, compounding, directional pressure on fire ant colony density that does not reset when the treatment schedule ends.

[00:30:05]Because the treatment never stops.

[00:30:08]The lizard shows up to the same trail entrance every morning. It doesn't run out of funding. It doesn't need reapplication. It reproduces.

[00:30:17]The lizard is already there in those three pasture corridors. It is already restructuring something that [music] 40 years of human intervention never managed to touch. The biology that was disassembled beneath it is being reassembled. Not by a program, not by a bait station, not by a committee, but by an animal the size of a credit card that has has doing this work for millions of years, and just needed the space to come back and do it again.

[00:30:46]The Texas horned lizard was gone from most of the Hill Country for 40 years.

[00:30:52]It came back on its own, and what it did when it got there is something no eradication program ever replicated. If you liked this, hit like and subscribe, and make sure to check out our other videos.