FOOD SECURITYWhat to Know About Screwworm in Texas
The first case of New World screwworm in 60 years has been confirmed in Zavala County, near the Mexican border. The flesh-eating fly poses a threat to the state’s $15 billion cattle industry.
An infestation of the flesh-eating flies has been confirmed in South Texas, setting off alarm bells for the state’s cattle industry.
A sample from a 3-week-old calf from La Pryor in Zavala County tested positive for the country’s first case of New World screwworm, the U.S Department of Agriculture Secretary Brooke Rollins said during a June 3 news conference about the case.
There have been no other detections so far.
The USDA said in a social media post earlier that it had already activated personnel on the ground and was working with local partners. The federal agency also said that issues with screwworms shouldn’t immediately cause food supply chain issues, as screwworms do not infect meat, fruits or vegetables.
However, an outbreak of screwworm threatens to do $1.8 billion in damage to Texas’ economy alone, according to a U.S. Department of Agriculture estimate. This potential fly pandemic could also increase already record-high beef prices nationwide, given the state’s importance to the cattle industry.
Here is a breakdown of why the cattle industry and government leaders are concerned about a parasitic fly:
What Is a Screwworm?
The New World screwworm is a type of blowfly that lays its eggs in the flesh of living animals rather than dead ones. Cuts as small as a tick bite may attract a female fly to lay her eggs. One female can lay 200 – 300 eggs at a time and may lay up to 3,000 eggs during her 10- to 30-day lifespan.
The eggs hatch into maggots that burrow into the wound to feed on the living flesh. The larvae in their final stage develop little hooks and dig deeper into the flesh, hence the name screwworm. After feeding for about seven days, larvae drop to the ground, burrow into the soil, and emerge as adult screwworm flies, repeating the cycle of infestations.
Multiple infestations are common with multiple stages of larva in one wound, sometimes leading to a “feeding frenzy” resulting in rapid tissue damage.
New World screwworm is typically found in South America and parts of the Caribbean. However, the fly has steadily moved northward from South America, through every country in Central America, and into Mexico, since 2023. Federal and Texas officials started monitoring cases the following year.
Can the Screwworm Infect Humans and Pets?
Most screwworm infestations occur in mammals, like cattle, pets, and wildlife, but they can also occur in people.
