Aug 3, 2026 by Robert Herrington, INFB Marketing
Cochliomyia hominivorax, commonly known as New World screwworm (NWS), is a species of parasitic blowfly whose larvae feed on living tissue of warm-blooded animals. At press time, there have been more than 30+ confirmed NWS cases across Texas and New Mexico.
The growing number of detections has heightened concern among livestock producers and animal health officials, who are working to contain the pest before it becomes established across larger portions of the United States – or here in Indiana.
“It's certainly a huge concern, but I think we're better prepared to handle it at this time,” said Brian Shuter, executive director of the Indiana Beef Cattle Association. “One thing we want to stress is this is an animal health issue. It is not a food safety issue. The Food Safety Inspection Service is there to help make sure that this doesn't become a food safety issue.”
Shuter said the most important thing producers can do is keep an eye on their animals.
“Be out there, check over those animals. If you see an animal with an open wound, make sure you get it in and check it out, especially if you happen to see something in that wound. Maintain a good relationship with your vet as they’re going to be critical in this process,” he said. “Be vigilant, especially if you're moving from the southern part of the country or made a trip to junior nationals. When you get home, make sure you go over those animals really well.”
Kyle Shipman, Indiana state veterinarian with the Board of Animal Health, said the last time NWS was in the United States was in the 1960s with a brief stint in the Florida Keys in early 2016.
“This is a pest that is commonly found in South and Central America, which is why it hasn't been in our news for quite a while as it has been controlled down to those parts,” he said. “Generally, these can be caught early and it doesn't necessarily mean that we're going to see a high mortality or death rate from this fly. However, flies can be quite burdensome throughout the summer months.”
Shipman said that while beef cattle are susceptible to NWS, any warm-blooded animal can be at risk.
“It can be beef cattle, swine, farm-raised deer, wildlife, as well as pets. The other thing we want to urge caution is humans are susceptible as well,” he said, adding NWS is not contagious and does not spread between animals or from animals to people. “We are not unique or different in that aspect. If we look at the data coming out of Central and South America as well as Mexico, we're seeing over 150,000 livestock cases, but also over 1,500 human cases of being impacted by this screwworm. It doesn't differentiate very well between species.”
Shipman said companion pets like dogs and cats are typically safer since these animals are on monthly heartworm or flea and tick preventative and some of those products have been either emergency-use authorized or conditionally approved to help prevent and treat NWS in those species specifically.
“That's not to say there's no products on the livestock side, but it can be restrictive in how often they are applied,” he said.
Mass production and targeted dispersal of sterile flies is part of the USDA’s response to combat NWS.
“Using sterile flies are critically important in tamping down the forward progression of this wild pest. Unsuccessful pairing helps break the NWS’s grooming life cycle and decreases the local population of those flies,” Shipman said.
Shipman said the short-term risk for Indiana is low, but not zero.
“The real risk to Indiana is not fly movement of thousands of miles from Texas, it’s actually the movement of an animal that has an impacted wound with pupa form already in it that then can complete their life cycle in Indiana and lead to the flies being present in the state,” he said. “To date, we have not had detection in Indiana. We don't anticipate having that detection, but we ultimately want producers to be prepared and vigilant, especially on animals that are moving.”
If you see suspicious wounds or maggots on animals, contact your veterinarian immediately.
“If you see something, say something. Your vet is your partner in this and so please don't hesitate to reach out,” said Shipman. “It is quite literally our job, and we will work with you and your veterinarian through that process and see our producers across the state as our first line of defense.”
For more information, visit screwworm.gov, which has a dashboard with confirmed cases.
(317) 692-7871
P.O. Box 1290 Indianapolis, IN 46206
