Engineering the End of Pest Problems

By Joshua Yan April 3, 2025

Millions of flesh-eating flies blot out the sun as they rain down on Panama’s forest canopy. Their kind have scourged the land for millenia, giving birth to worms that feast on the living flesh of local animals until they are nothing but walking skeletons. Though it may sound like a grisly visage of biological warfare, this grotesque horrorscape is actually part of a decades-long eradication effort against the unwelcome insects.  

The New World Screwworm (NWS), or Cattle Borer Worm, is a parasite that lays its eggs in open wounds where its larvae hatch and slowly eat the host organism alive. The worm was responsible for multimillion-dollar losses in cattle every year—until the 1950s when the United States Department of Agriculture (USDA) began eradicating NWS from the U.S. and Central America. Today, it maintains an invisible barrier against the pest along the Panama-Colombia border, where 14.7 million sterile screwworms are dropped every week to keep the population from growing.  

The barrier is maintained by the Panama-United States Commission for the Eradication and Prevention of the Cattle Borer Worm (COPEG), a joint initiative between the U.S. and Panama. At the COPEG hatching facility in Panama’s Darién province, male larvae are sterilized through radiation doses of cobalt 60 and then raised to adulthood. Over 100 employees work at the plant 24/7, raising 20 million sterile flies every week. The flies are then loaded onto repurposed military planes and dropped over Darién, where they mate with the existing population. Since screwworms can only mate once in their lifetimes, this process effectively reduces NWS populations to the few females who can find the now-outnumbered natural males. 

“The screwworm barrier is a very innovative way of dealing with pests. Sterilization represents a more natural way of eradication, which is less harmful than chemical alternatives like pesticides,” Sophomore Abhishal Kocchal said. 

The screwworm barrier is not the only eradication effort of its kind. When the pink bollworm, native to Asia, appeared in North America in 1917, it quickly wreaked havoc on the cotton industry. The larvae chew through cotton bolls, greatly reducing lint quality; According to Entomology Today, this cost Arizona farmers $32 million in 1990 alone. To combat the pest, scientists genetically engineered Bt cotton in 1996, which produces Bacillus thuringiensis, a protein lethal to insects. This, combined with sterilization efforts similar to those of the screwworm, led to the official eradication of pink bollworm in 2018. 

A similar case is that of the tsetse fly, an African fly that transmits sleeping sickness to humans. Like NWS and the pink bollworm, releasing sterilized flies has proven successful, completely eradicating populations already lowered by conventional methods like pesticides. 

Another example is the Asian Citrus Psyllid (ACP), an invasive insect to California that spreads citrus greening, a disease that attacks citrus trees and reduces the quality of their fruit. One way the USDA is fighting ACP is through biological control, the method of releasing a pest’s natural predators. The USDA released millions of Tamarixia radiata, a parasitoid wasp that only targets ACP, to properties with citrus trees across the state. Studies conducted by the Florida Department of Agriculture and Consumer Services show that in their mere 28-day lifespans, each radiata wasp can kill over 500 ACP. 

These biological barriers are essential to American agriculture—the screwworm program alone saves farmers $1.3 billion a year at a monetary expense of only $15 million, according to USDA estimates. However, maintaining them often demands costs other than money, namely food waste. For example, U.S. Customs and Border Protection (CBP), which inspects produce for diseases and invasive species, reported seizing nearly 80,000 agricultural items last year, much of which was simply thrown away.  

But when animal barriers fail, they come at a tremendous price. In 2016, an NWS infestation in the Florida Keys killed 135 endangered Key deer, reducing the population to around 740, according to the American Veterinary Medical Association (AVMA). The eradication effort, which took three years, saw 154 million sterile fly releases, 17,000 animal inspections, and 700 hours of surveillance. More recently, An AVMA report from November confirmed an NWS breakout near the Mexico-Guatemala border, prompting USDA to authorize $165 million in emergency protection funding. 

“While tampering with nature is generally questionable—even moreso when it comes with a great financial toll—animal barriers are an exception because they better nature as a whole, instead of simply furthering human interests. There is no cost too great when it comes to protecting other animals, especially endangered species,” Senior Linus Awyong said. 

Animal barriers prove themselves an effective means of keeping dangerous pests at bay in spite of their infrequent shortcomings. While they may not be as well-known as pesticide sprays, animal barriers are proof of the breadth of solutions that science can provide. 

---

About the Contributor

Joshua Yan is a Senior at Leland High School. This is his second year as a staff writer for the school newspaper. He likes playing piano, playing games with friends, and pen spinning.