California Ag Network

Tag: Sterile Insect Technique

  • Screwworm Strain Readied for Active Duty

    American scientific ingenuity in the form of sterile fly releases helped eliminate New World screwworm from the country in the 1960s. Now, ARS researchers are combining that ingenuity with next-generation tools to counter new resurgences of the pest threatening livestock and wildlife in New Mexico and Texas.

    “Releasing sterile screwworm flies is a proven, decades-old approach to eliminating populations of this pest and preventing the harm it inflicts—physically to livestock animals and wildlife and financially to the producers who raise livestock for our milk, meat, hide and other products,” said Kim Lohmeyer, Director of ARS’s Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, TX. “Advances in genetics have now given us better tools to understand the screwworm’s population dynamics and leverage that knowledge for improved control methods, including sterile fly releases.”

    The latest example is NovoFly™, an all-male strain of screwworm developed by Lohmeyer’s team and university collaborators. With full regulatory approval of NovoFly™, critical resources can be redirected towards producing only males, essentially doubling the number available for SIT releases to eradicate established populations of the pest or isolate outbreaks of it.     

    Central to screwworm eradication is the Sterile Insect Technique (SIT). SIT is a biologically based approach to pest control that originated with the pioneering studies of ARS entomologists Edward B. Knipling and Raymond C. Bushland. That research began in the mid-1930s and continues today at the  Kerrville lab, which was posthumously named after these two entomologists.

    In January 2026, USDA Secretary Brooke Rollins and Deputy Secretary Stephen Vaden highlighted  SIT as part of a New World Screwworm Grand Challenge to counter recent U.S. incursions of the pest up through Central America.

    The SIT calls for releasing sterilized male flies near infestation areas where they can mate with wild female flies. The resulting eggs fail to hatch into flesh-eating larvae, which typically burrow into wounds or mucus-lined openings of livestock animals such as cattle—but also wildlife and, less often, pets and people.  Without larval offspring, the screwworm population eventually collapses, sparing animals further harm and reducing producers’ costs for insecticides, veterinary services, and medications.

    Despite SIT’s success in eradicating America’s indigenous screwworm population by 1966 (and eliminating subsequent resurgences of it), researchers saw room for improvement. “A sterile male can prevent a lot of wild females from reproducing, but a sterile female fly that mates only once doesn’t help with SIT,” explained Alex Arp, an ARS Research Geneticist who co-developed the all-male NovoFly™ strain.  While only sterile males are desirable, until now there has been no good way to separate them from females prior to SIT release, he added.

    Producing only male flies would increase production efficiency by doubling the number of male larvae that can be reared and male pupae that can be sterilized without major changes to production facilities. Without sterile females being released, sterile males have increased opportunities to mate with wild females, resulting in a more effective, efficient SIT program.

    Toward that goal, Arp and collaborators engineered Novofly™ with a genetic “switch” that kills female larvae during early rearing stages but doesn’t function in males. This allows for a doubling in the number of males that can be brought to maturity for release using the same amount of artificial diet and equipment.

    NovoFly™ is currently undergoing regulatory approval before the Environmental Protection Agency. Once approved, NovoFly™ will be mobilized for “active duty” at designated screwworm rearing facilities. USDA’s Animal and Plant Health Inspection Service coordinates SIT efforts in the U.S, Mexico, and Central America.

    “The research that went into creating NovoFly™ will provide the basis for the Grand Challenge project led by Max Scott of North Carolina State University together with Arp and many other collaborators,” Lohmeyer added—an effort that will set the stage for the next generation of this screwworm strain.

    To learn more about USDA’s whole-of-government approach to combatting NWS, visit “Stop Screwworm: Unified Government Response to Protect the United States”

  • New Sterile Fly Facility Contract Announced

    The U.S. Department of Agriculture (USDA) and U.S. Army Corps of Engineers (USACE) today announced a construction contract with Mortenson Construction to build a new sterile fly production facility at Moore Air Base in Edinburg, Texas. This facility is a key component in Secretary Rollins’ sweeping 5-prong strategy (PDF, 1005 KB) to fight New World Screwworm (NWS), as it will expand USDA’s domestic response capacity, bolstering protection for U.S. livestock, wildlife, and public health.

    USACE is partnering with USDA and will provide oversight for the contract, design, engineering, and construction of the facility.

    “The Army Corps of Engineers is an essential partner in bringing this facility to life and further highlights the Trump Administration’s government wide effort to fight the New World Screwworm threat in Mexico,” said U.S. Secretary of Agriculture Brooke L. Rollins. “The Army Corps is the best in the business and their engineering expertise and proven track record in delivering complex projects will help ensure we can build a modern, resilient facility that protects American agriculture from invasive pests for decades to come. This first of its kind facility on U.S. soil will ensure we are not reliant on other countries for sterile flies.”

    “For more than 250 years, USACE has helped secure America by engineering solutions to our nation’s toughest challenges. We are proud to be partnering with USDA in the construction of the Sterile Fly Facility, a critical investment in our nation’s future agricultural, public and economic health. Combining our engineering expertise with USDA’s mission expertise brings us one step closer to alleviating this biological threat,” said Lt. Gen. William H. “Butch” Graham, U.S. Army Corps of Engineers commanding general.

    A sterile fly production facility is a specialized biosecure complex where New World Screwworm flies are raised and sterilized using irradiation and then released into targeted areas. Female New World Screwworm flies only mate once in their lives, so if they mate with a sterile male, they lay unfertilized eggs that don’t hatch. This method, known as the Sterile Insect Technique, has been a cornerstone of proven screwworm eradication efforts for decades and is recognized worldwide as a highly effective, environmentally responsible approach to insect control. Sterile Insect Technique, when paired with surveillance, animal movement restrictions, and education and outreach, is a proven and effective tool for controlling and eradicating New World Screwworm.

    USDA currently produces about 100 million sterile flies per week at the COPEG facility in Panama and disperses them within and just north of affected areas in Mexico. In addition to the COPEG facility in Panama, USDA invested $21 million to support Mexico’s renovation of an existing fruit fly facility in Metapa, which will double NWS production capacity once complete. With ongoing support from APHIS technical experts, Mexico anticipates sterile fly production will begin at this facility in summer 2026. The new facility at Moore Air Base will be the only U.S.-based sterile fly production facility and will work in tandem with facilities in Panama and Mexico to help eradicate the pest and protect American agriculture.

    USDA and USACE will break ground on this new facility later this spring, after initial planning and development meetings with the new contractor. By November 2027, the production facility at Moore Air Base is expected to reach its initial goal of producing 100 million sterile flies per week. After that, construction will continue at the facility to increase production with the long-term goal of producing 300 million sterile flies per week.

    The New World Screwworm is a parasitic fly whose larvae feed on warm blooded animals, causing severe animal health impacts and significant economic losses if not controlled. The United States eliminated the pest in 1966 and has maintained that freedom through the ongoing sterile fly program and international partnerships.

    USACE, a command within the U.S. Army, is one of the world’s premier public engineering, design, and construction management organizations. With more than 35,000 employees worldwide, USACE delivers engineering solutions in support of military construction, water resources infrastructure, environmental stewardship, and federal agency partnerships. USACE provides engineering expertise to strengthen national security, energize the economy, and reduce disaster risk.

    For more information about NWS and USDA’s efforts, visit Screwworm.gov. — By the United States Department of Agriculture

  • USDA Completes Sterile Fly Dispersal Facility

    U.S. Secretary of Agriculture Brooke L. Rollins and Governor of Texas Greg Abbott visited Moore Air Base to  celebrate a significant achievement in the fight against New World Screwworm (NWS) with the completion of a U.S.-based sterile fly dispersal facility in Edinburg, Texas. This facility expands USDA’s ability to disperse sterile flies along the border and into the United States, if necessary.

    “The Trump Administration continues to bring the full force of the federal government to fight New World Screwworm,” said Secretary Brooke Rollins. “This sterile fly dispersal facility was a high priority project, and our team delivered it in record time. This new facility is a monumental achievement for our domestic preparedness efforts, but we are also diligently working to stop the spread of screwworm in Mexico, conduct extensive trapping and surveillance along the border, increase U.S. response capacity, and encourage innovative solutions. We will never stop fighting to protect American agriculture. USDA, through a whole-of-government approach, will continue to hold Mexico accountable to mitigating the spread of this dangerous pest.”

    “America is going to take care of ourselves, including dealing with the approach of screwworm as it gets closer to our border,” said Governor Abbott. “We put together the resources necessary for Texas to provide a Texas-size response to this. We thank Secretary Rollins and President Trump for stepping forward to provide the stop gap effort essential to protecting our ranchers and our wildlife.”

    Trump Administration NWS Response

    In June 2025, Secretary Rollins announced a sweeping five-pronged plan(PDF, 1005 KB) to enhance USDA’s already robust ability to detect, control, and eliminate NWS. As part of that announcement, she also shared plans to build this sterile NWS fly dispersal facility in South Texas. The completion of the facility further expands the network of dispersal facilities through Central America and Mexico and solidifies the increased preparedness offered by having a U.S.-based facility.

    On January 30, USDA announced a shift in its 100 million per week sterile fly dispersal efforts to reinforce coverage along the U.S.-Mexico border. While the sterile flies for this effort will initially be dispersed from the Tampico, Mexico facility, USDA is prepared to quickly and strategically shift operations to the new Texas facility should there be a change in the location or new concentration of NWS cases in northern Mexico.

    About Sterile Fly

    Sterile insect technique, when paired with surveillance, animal movement restrictions, and education and outreach, is a proven and effective tool for controlling and eradicating NWS. Female NWS flies only mate once in their lives, so if they mate with a sterile male, they lay unfertilized eggs that don’t hatch. Releasing sterile flies just outside of affected areas helps ensure flies traveling to new areas will only encounter sterile mates and will not be able to reproduce.

    Sterile insects are dispersed through aerial dispersal or ground release. Aerial operations are preferred because they allow for dispersal at a steady rate through a large area and also because sterile insects may be dispersed in areas that are unreachable from the ground. Ground release is used when there is a need to quickly deploy sterile insects outside of the dispersal facility range. Mass production and targeted dispersal of sterile flies remain critical components of an effective response.

    USDA currently produces sterile flies for dispersal at the COPEG facility in Panama. USDA is also investing $21 million to support Mexico’s renovation of an existing fruit fly facility in Metapa—which will double NWS production capacity once complete. With ongoing support from technical experts in USDA’s Animal and Plant Health Inspection Service (APHIS), Mexico anticipates this sterile fly production to begin as soon as summer 2026.

    To continue to expand USDA’s domestic response capacity, the Department is building a sterile fly production facility at Moore Air Base in Edinburg, Texas, with a targeted maximum capacity of 300 million sterile flies per week. USDA expects to break ground on that facility later this spring. With existing and planned production facilities fully operational, USDA will have up to 500 million sterile files per week in its arsenal to fight this pest all the way back to the Darién Gap. The international network of facilities will produce 100 million sterile flies per week at COPEG in Panama, 100 million at Metapa in Mexico, and 300 million at Moore Air Base.

    What You Can Do

    Even though there have been no detections of NWS inside the U.S. and the northernmost active case of NWS is still about 200 miles away from the border, USDA is asking Americans to continue to remain vigilant by checking their livestock and pets for signs of NWS. Look for draining or enlarging wounds and signs of discomfort. Also look for NWS larvae (maggots) and eggs in or around body openings, such as the nose, ears, and genitalia or the navel of newborn animals. If you suspect your animal is infested with NWS, immediately report it to your state animal health official or USDA area veterinarian in charge.

    NWS maggots can infest livestock and other warm-blooded animals, including people. They most often enter an animal through an open wound and feed on the animal’s living flesh. While not common in people, if you notice a suspicious lesion on your body or suspect you may have contracted NWS, seek immediate medical attention. — USDA

  • USDA Shifts Fly Dispersal Efforts to U.S. Border

    The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) is announcing a shift in its 100 million per week sterile fly dispersal efforts to stop the northern spread of New World screwworm (NWS). USDA will reallocate aircraft and sterile insects to reinforce coverage along the U.S.-Mexico border. The new dispersal area, or polygon, will include operations about 50 miles into Texas, along the U.S. border with the state of Tamaulipas, Mexico. Mass production and targeted dispersal of sterile insects are critical components of an effective strategy to fight NWS. Other tools including import protocols and surveillance continue to support these robust efforts to keep NWS out of the United States.

    “At Secretary Rollins’ direction, our highest priority is protecting the United States from screwworm,” said Dudley Hoskins, Under Secretary of Marketing and Regulatory Programs for USDA. “The northernmost active case of NWS in Mexico is still about 200 miles away from the border, but we’ve seen cases continue to spread in Tamaulipas and further south in Mexico, so we are proactively shifting our polygon as we make every effort to prevent NWS from reaching our border.”

    Sterile Fly Dispersal

    Sterile insect technique, when paired with surveillance, movement restrictions, and education and outreach, is an effective tool for controlling and eradicating New World screwworm. Female New World screwworm flies only mate once in their lives, so if they mate with a sterile male, they lay unfertilized eggs that don’t hatch. Releasing sterile flies just outside of affected areas helps ensure flies traveling to new areas will only encounter sterile mates and will not be able to reproduce. In this instance, USDA will release sterile flies north of the current active NWS cases in Mexico in a proactive effort to create a sterile reproduction buffer zone if the fly moves north from Mexico.

    Because it is important to continue ongoing surveillance efforts while releasing sterile insects, it is possible that sterile NWS flies could be caught and/or reported within Texas. To ensure officials can tell the difference between sterile and wild NWS flies, USDA will dye the sterile pupae, and the dye will transfer to the sterile flies when they hatch. The fluorescent dye will glow under UV light and may also be visible to the naked eye. If a sterile fly is captured in a trap, this dye will allow animal health officials to quickly rule the fly out as a threat.

    USDA will continue to deploy its intensive NWS response efforts including implementing import protocols, ongoing surveillance and trapping efforts along the border, investing in NWS innovation, and supporting robust response activities in Mexico and Central America.

    Import Requirements and Protocols

    Sterile insects are an important tool, but USDA’s import requirements and protocols add another line of defense for NWS and other foreign animal diseases that threaten U.S. livestock. Earlier this week, the importance of those protocols was highlighted when a horse from Argentina was presented for routine importation at an equine import quarantine facility in Florida. Upon examination, APHIS identified an open wound with larvae on the animal and promptly collected and shipped samples to the National Veterinary Services Laboratories (NVSL) in Iowa. The horse was immediately treated with medication to kill any larvae in accordance with standard, long-standing import protocols. This morning, NVSL confirmed that the larvae were New World screwworm larvae. Accordingly, the animal will remain in quarantine until it has been reexamined and determined to be free of NWS.

    This is an example of these long-standing import protocols working as designed. While this situation does not appear to be associated with the NWS outbreak in Mexico that USDA is currently fighting, it underscores the need for vigilance in all of USDA’s coordinated efforts to fight NWS.

    Surveillance, Monitoring, and Reporting

    USDA continues to lead intensive surveillance and monitoring systems along the U.S. border. Teams continue to check 121 NWS-specific traps across high-risk areas of border states and leverage thousands of fruit fly/insect traps aligned all along the Southern border. To date, more than 42,000 flies from traps in all locations have been submitted to APHIS NVSL for identification, with no NWS detections to date. APHIS Wildlife Services is also leading a coordinated effort to inspect wildlife for signs of NWS infestation. To date, they’ve inspected more than 9,300 wild animals across 39 different species and 131 U.S. counties and found no signs of NWS infestations.

    Even though there has been no detection of NWS inside the U.S. and the northernmost active case of NWS is still about 200 miles away from the border, USDA is asking U.S. animal owners to continue to remain vigilant by checking their pets and livestock for signs of NWS and immediately reporting anything suspicious to their state animal health officials or USDA area veterinarian in charge. Signs of NWS infestation include draining or enlarging wounds and signs of discomfort. Also look for screwworm larvae (maggots) and eggs in or around body openings, such as the nose, ears, and genitalia or the navel of newborn animals.

    Adult screwworm flies are about the size of a common housefly or slightly larger, with a metallic green or blue body, orange eyes, and three dark stripes down its back. NWS maggots can infest livestock and other warm-blooded animals, including people. They most often enter an animal through an open wound and feed on the animal’s living flesh.

    While NWS is not common in people, if you notice a suspicious lesion on your body or suspect you may have contracted screwworm, seek immediate medical attention.

    For more information on NWS and USDA’s efforts, visit Screwworm.gov. — USDA Animal and Plant Health Inspection Service

  • Congressman John Duarte Shares Legislative Priorities for California Ag in Crisis

    In November 2022, the newly realigned 13th Congressional District of California elected to send a farmer to represent them in congress. Representative John Duarte has been at the job for about a year in a half and has been working on a number of bills to support California’s specialty crop industries, which are in desperate need of recovery from many challenges brought on by the pandemic and drought, among other global trade, inflation, and invasive pest pressures. Watch his brief interview with Matthew Malcolm from California Ag Network to learn more.

    Please thank this video’s sponsor Southern California Gas Company for their industry support.

  • Recent Successes & Challenges on the Legislative Front with APG’s Cadee Condit

    Growers finally got to meet American Pistachio Growers’ (APG) new Director of Government Relations, Cadee Condit in-person at the recent APG Summer Luncheon in Visalia, CA. Watch this brief interview with Cadee as she introduces herself and talks about APG’s current priorities on the legislative front. Read more about it in Pacific Nut Producer Magazine.
    Please thank this video’s sponsor Suterra for their industry support.

  • Federal Government Invests $6 Million to Combat Formidable Tree Nut Pest

    California tree nut growers received a ‘holiday gift’ from the Federal Government last week — to the sum of $6 Million in appropriation funds to combat the formidable pest of the tree nut industry, Navel Orangeworm.  Watch this brief video with the Executive Director of American Pistachio Growers Richard Matoian for more details.

    Please thank our sponsor Duarte Nursery for their industry support with an email of gratitude this holiday season.