![\"\"](\"https:\/\/missouriindependent.com\/wp-content\/uploads\/2025\/12\/screwworm-1024x683.jpeg\")
<\/p>\n<\/p>\n
The New World screwworm fly. The insect that produces flesh-eating larva, eradicated in the United States, has broken containment and presents a threat to livestock. (U.S. Department of Agriculture photo)<\/p>\n
State and federal officials are gearing up to stop the advance of a parasitic fly that is less than 70 miles from the United States border with Mexico.<\/p>\n<\/div>\n
Since Nov. 25, at least 10 new cases of incidents involving the New World screwworm fly have been confirmed within 400 miles of the border. The flies have been inching their way to the U.S. since they broke the biological barrier created by Panama\u2019s narrow geography in 2022.<\/p>\n
\u201cThere is a threat of it maybe getting into the southern United States, and then it would most likely end up in Missouri, too, at least maybe some isolated cases,\u201d State Veterinarian Steve Strubberg said. \u201cIt\u2019s conceivable that it could happen in the coming year or two.\u201d<\/p>\n<\/div>\n
Deb Hudman, Missouri Department of Conservation health section chief, added that \u201ctransportation of infected animals is most likely how it would enter.\u201d<\/p>\n<\/div>\n
Experts are hoping for a long winter and cold spring to help keep the flies from crossing the border.<\/p>\n<\/div>\n
\u201cThe cold weather is good,\u201d Hudman said. \u201cAnything as low as 48 degrees Fahrenheit stops the larvae and pupae development, and anything below 59 degrees significantly drops the activity of adult flies.\u201d<\/p>\n<\/div>\n
Local and federal agencies are working to take advantage of the weather and keep New World screwworm flies out of the U.S. Last month the U.S. Department of Agriculture launched a\u00a0website<\/a>\u00a0hoping to centralize information about the flesh-eating fly.<\/p>\n<\/div>\n \u201cThe USDA remains focused on implementing our sweeping five-pronged plan to combat New World screwworm. As part of these critical efforts, USDA is working on both sides of the border to ensure a comprehensive response,\u201d said Lyndsay Cole, a USDA spokesperson, in an email.<\/p>\n That\u00a0five-pronged<\/span>\u00a0plan includes a total of $29.5 million in investments to renovate an existing fruit fly production facility in Metapa, Mexico, and to build a sterile insect dispersal facility at Moore Air Base in south Texas. The Mexico facility is expected to open as early as next summer. Planning is also underway to build a new production facility at Moore Air Base, according to the USDA website.<\/p>\n<\/div>\n \u201cUnfortunately there won\u2019t be enough of those sterile flies available to us for a few years. It takes a long time to ramp up those production facilities, so we are hoping it stays in Mexico,\u201d Strubberg said.<\/p>\n According to the plan, sterile screwworm flies are among the primary tools the government can use to fight the New World screwworm, but only one plant exists in Panama; it produces 100 million flies a week. A separate plant in Mexico that produced 500 million flies a week was shut down in 2012 for economic reasons.<\/p>\n The goal of producing sterile flies is to have them mate with female flies, which usually mate only once in their lifespan. Using this method, over time the population is reduced back down to zero. The sterile insect technique is what allowed the U.S. to eradicate the flies in the 1960s.<\/p>\n<\/div>\n The U.S. government has worked closely with Panama since the now-broken biological barrier was formed.<\/p>\n <\/strong><\/p>\n \t<\/p>\n<\/div>\n Screwworm was eradicated in the U.S. in 1966 at the cost of around $750 million. This time around, the USDA\u2019s Economic Research Service says it could cost the Texas economy alone $1.8 billion over the next year if the fly gets into the United States.<\/p>\n<\/div>\n Losses of $730 million are predicted to fall onto cattle producers. Nine of the last 10 confirmed cases of screwworm within 400 miles of the U.S. have come from bovines, according to data collected by the USDA.<\/p>\n<\/div>\n \u201cIf it would come in, we would have such a great expense of eliminating it,\u201d Strubberg said. \u201cThere are just so many different areas of added expense for individual producers.\u201d<\/p>\n<\/div>\n The impacts it would have on consumers are harder to predict, Strubberg said. But potential spikes from a dip in supply and increased expenses from dealing with screwworm could add to shelf costs.<\/p>\n<\/div>\n To help the government contact producers in a potential infested zone, Strubberg urges people to register their premises through the Missouri Department of Agriculture if they have animals. The premises registration form can be found\u00a0here<\/a>.<\/p>\n <\/strong><\/p>\n \t<\/p>\n<\/div>\n The flies can infest all living warm-blooded animals. This includes humans, pets, livestock and wild animals. Some signs to look out for in infected animals include an open wound or navel that looks infected, decreased activity and animals isolating themselves.<\/p>\n<\/div>\n \u201cThe larvae are basically maggots,\u201d Strubberg said. \u201cThey are much more aggressive than the normal maggots of the common flies we have around Missouri right now, and so they will cause a lot more damage.\u201d<\/p>\n<\/div>\n If an animal gets infected, there are a few treatment options. If treated, animals can make full recoveries, but untreated it is \u201cvery devastating,\u201d Strubberg said.<\/p>\n<\/div>\n \u201cIf you catch it early enough and treat it, you would do some surgical procedures to remove the larvae and hopefully treat them so they don\u2019t mature,\u201d Strubberg said. \u201cThere are systemic treatments of infested animals also; some of the larvae are so deep that you can\u2019t remove them all surgically.\u201d<\/p>\n<\/div>\n The FDA conditionally approved a new topical solution for the prevention and treatment of New World screwworm in cattle over 2 months old, Exzolt Cattle-CA1. The drug is in the same family as Bravecto, an oral drug used for flea and tick prevention in dogs and cats.<\/p>\n<\/div>\n \u201cExzolt Cattle-CA1 is eligible for conditional approval because it is intended to prevent and treat serious or life-threatening diseases in cattle, it addresses unmet animal health needs, and demonstrating effectiveness of the drug requires complex or particularly difficult studies,\u201d the Food and Drug Administration said in a news release.<\/p>\n<\/div>\n \u201cPets are also an easy way for screwworm to be transported,\u201d Strubberg said. \u201cWe are working with every entity we can to try and get pet owners and all animal owners aware.\u201d<\/p>\n<\/div>\n He says to monitor pets to make sure they don\u2019t have any open wounds and are feeling well. Strubberg added it\u2019s important to be especially vigilant if you recently traveled to a place with an active screwworm population like Central and South America.<\/p>\n<\/div>\n \u201cIf anyone is purchasing pets from outside the state, you definitely want the veterinarian to take a good look at it,\u201d Hudman said.<\/p>\n<\/div>\n Missouri\u2019s wild animal populations would be at risk as well.<\/p>\n<\/div>\n \u201cDeer would be something to keep an eye on because they have lots of wounds from running, vehicle strikes and fences,\u201d Hudman said. \u201cIt could certainly be present in raccoons, opossums, coyotes and rabbits. Really any warm-blooded species with an open wound.\u201d<\/p>\n<\/div>\n Wild populations would be next to impossible to contain and treat because they aren\u2019t behind a fence or in a barn, Hudman said.<\/p>\n<\/div>\n \u201cYou would have to trap all of them, and then you would have to treat them, then the first treatment might not take,\u201d she said. \u201cI just don\u2019t see how that would be very viable.\u201d<\/p>\n<\/div>\n The only wild populations that might be possible to protect are ones with small, localized populations. Hudman pointed to Missouri\u2019s elk population as an example.<\/p>\n<\/div>\n The Missouri Department of Conservation is working closely with the Missouri Department of Agriculture and the USDA to develop a plan to combat the potential arrival of screwworm. A plan is currently not finalized.<\/p>\n<\/div>\n \u201cWe\u2019re setting up and making sure there are microscopes all around the state with people who can identify the larvae so we can have a local or regional way to approach it,\u201d Hudman said.<\/p>\n <\/strong><\/p>\n \t<\/p>\n<\/div>\n Another challenge Missouri faces in identifying potential screwworm infestations is a different species of blowfly that looks like the screwworm fly. That species of blowfly feeds off dead tissue instead of living tissue.<\/p>\n<\/div>\n \u201cIt\u2019s going to be very tricky for the general public to tell the difference between the two, and the one that feeds off of dead tissue is very prevalent,\u201d Hudman said.<\/p>\n<\/div>\n While the New World screwworm fly hasn\u2019t been detected in the U.S., Hudman advises caution toward the potential presence of the fly in the coming years.<\/p>\n This article<\/a> was originally published in the Columbia Missourian<\/a> and is republished with permission.<\/em><\/p>\n<\/div>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":" The New World screwworm fly. The insect that produces flesh-eating larva, eradicated in the United States, has broken containment and presents a threat to livestock. (U.S. Department of Agriculture photo) State and federal officials are gearing up to stop the advance of a parasitic fly that is less than 70 miles from the United States…<\/p>\n","protected":false},"author":2,"featured_media":8391,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-8390","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"yoast_head":"\n\n![\"\"](\"https:\/\/missouriindependent.com\/wp-content\/uploads\/2025\/12\/Screwworm-map-296x300.jpeg\")
<\/p>\n<\/div>\n\n\n\nA costly wipeout<\/h4>\n
\n\n\n\n\nCows and wildlife: easy targets<\/h4>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nScrewworm fly impostor<\/h4>\n
\n\n\n