The New World screwworm was eradicated in the US in 1966, until this year. Recently, they have been found in Texas as of th spring of 2026. This is certainly alarming for all of us who raise livestock in Texas and the Lower 48. This screwworm wreaked havoc the last time it was around.

This got me to thinking about why it has returned?

Part of the problem is the feral hog population shared between the US and Mexico. Pigs are well known to be unclean both biblically and in their own physicality. They carry many parasites and diseases. This is one of the many that carry and spread.

The feral pig population exploded in Texas. See the headline below:

Texas farmers battle $119 million annual loss from feral hogs, seek coordinated control efforts

“Texas farmers face ongoing challenges from feral hogs, causing $119 million in annual losses. Control methods include trapping, hunting, and toxins, but success requires coordinated efforts.”(1) Matthew Ablon and CBS

According to the CBS article by Matthew Ablon, the pigs are not native to America and were introduced by the Spanish. My Great-grandmother Hank said that during the 1930s, the market for pigs dropped, and the farmers turned out their domestic herds because they could no longer afford to feed them at the rate of return they were getting. Most likely, this happened repeatedly, exacerbating the problem.

Gestation Period of Hogs

The other problem with them is the short gestation period, as documented below:

“Pigs have the highest reproductive rate of any ungulate; but like reproductive maturity, it is highly variable among populations. Females (sows) have multiple estrous cycles annually and can breed throughout the year with an average litter size of 4-6 young per litter . The average gestation period for a sow is approximately 115 days and they can breed again within a week of weaning their young, which can occur approximately one month after birth.”(2)

John C. Kinsey, and TWD

As a result, the population of feral pigs has skyrocketed. They have little to no apex predators, and they have increasingly become a problem that Texas has had a hard time eradicating.

How does the feral pig population correlate with the New World screwworm?

The term “Birds of a feather, flock together” comes to mind. Both of these issues spiral out of control quickly. The Texas hogs migrate to and fro across the Mexico border. The barriers of resistance do little to deter the pigs’ migration. They come and go as they please with no thought of the border patrol or ICE agents. The Screwworm had largely been confined to Mexico after it was eradicated in Texas using (3) Sterile flies. During the spring of 2025, we began to hear ranchers and the USDA raise alarms about what they were hearing in Mexico. That was the screw worm getting dangerously close to the Texas border. During 2025, the reports that came in documented the worm marching northward, getting closer and closer to the US border.

(4) In June of 2026, it became known that two infestations were found in Zavala and Uvalde Counties in Texas. The USDA is confident that we can curtail the spread of the New World Screw Worm using the same techniques as before.

What to Look For

• Larvae (maggots) and eggs in or around body openings such as the nose, ears, and genital areas, or the navel of newborn animals
• Draining or enlarging wounds
• Foul odor or the smell of decay
• Signs of pain such as irritated behavior, depression, not eating, or isolating from other animals or people
• Click here to report

The history of the Eridication program can be found here. (5)

See the image below for how the US eradicated the New World screwworm last time.

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Source

1. https://www.cbsnews.com/texas/news/texas-feral-hogs-invasive-species-history
2. https://tpwd.texas.gov/huntwild/wild/nuisance/feral_hogs
3. https://www.aphis.usda.gov/sites/default/files/factsheet-sit-proven-tool-nws.pdf
4. https://www.aphis.usda.gov/news/agency-announcements/usda-confirms-presence-new-world-screwworm-united-states
5. https://www.nal.usda.gov/exhibits/speccoll/exhibits/show/stop-screwworms–selections-fr/1958-1969