The threat of the New World screwworm (NWS) is real and knocking at our door. Impacts to the cattle industry have been making the news, but in reality, this pest affects all warm-blooded animals – large or small.
NWS was last eradicated from the U.S. in 1966 and as far south as Panama in 2000. From there, it started to make a northernly comeback in 2022 and has been on the move in Central America and southern Mexico.
In the last year, the fly has crossed two biological borders in southern Mexico, which is why U.S. Secretary of Agriculture Brooke Rollins has stopped all livestock from Mexico from entering the U.S.
Recently, NWS was detected only 370 miles from the U.S. border, which is one of the reasons why the U.S. Department of Agriculture (USDA) is so nervous, as we all know the pest poses a risk to human health, animal health and food security in the U.S.
But remember, in southern Texas and other places, there are no fences at the border, so cattle and wildlife can cross over from Mexico as they please.
I’ve also read NWS can travel up to 12 miles to find new animal hosts.
Those living in northern states have an advantage as NWS larvae can’t survive in temperatures below 46 degrees Fahrenheit, but it sounds like the pest could be troublesome in the summer.
From an economic standpoint, NWS could stop all movement of cattle from affected areas of the country.
The fly got its name because it lays its eggs in or near wounds of warm-blooded animals.
When the eggs hatch, the larvae burrow into the wound and eat the flesh around the wound. If not treated, the animal will die of infection.
The best way to eradicate the fly is to utilize the Sterile Insect Technique, a process where mass-produced sterile male flies are released in affected areas. Male flies then mate with wild females, resulting in unfertilized eggs.
Since female flies only mate once, numbers shrink until the population is eradicated.
Currently, the biggest problem is the only place producing sterile flies is located in Panama. USDA has come up with $8.5 million to build a facility in Texas, but it will take time.
U.S. cattle numbers are at long-time lows, and an infestation would be costly to southern livestock producers, especially those in Texas, where the estimated cost of an outbreak is nearly $1.9 billion annually.
Eradicating or even reducing NWS would take years, maybe even decades.
Simply stopping it at the U.S. border is not going to get the job done. The U.S. is going to need to take the lead in eradicating NWS from Mexico, all of Central America and Cuba to fully stop the threat.
This would mean applying political pressure to countries where livestock producers live with the issue every day and have no plans to control the fly.
Dennis Sun is the publisher of the Wyoming Livestock Roundup, a weekly agriculture newspaper available in print and online.
