In the American state of Texas, larvae of the screwworm fly, a parasite that was eradicated in the area last century, have been found for the first time in years. Coincidentally, the US announced this week that it would allocate tens of millions to combat the flesh-eating insect.

The larvae were discovered in the umbilical region of a three-week-old calf. The fly (or ) lays its eggs in cavities of warm-blooded animals, such as noses, ears or open wounds. Unlike many other flies, these larvae do not eat dead carcasses, but live flesh.

If animals affected are not treated, such an infection can lead to death in as little as two weeks. In the past, the fly has caused tens of millions of dollars in damage to American livestock. In rare cases, humans can also be affected.

Midway through the last century, the fly was successfully controlled in several American countries by releasing sterile males into the habitat. These screwworm flies are still exposed to radioactive radiation in their eggs, which means they cannot produce offspring. The eggs they fertilize do not hatch and the population therefore declines rapidly.

In the 1950s, this method cleared the island of Curaçao of the screwworm fly within a few months. This removed a major threat to the goat population there.

Later, eggs were also released on a large scale in the United States, with the result that the fly has been exterminated there since the 1970s. In recent years, there have been only a handful of reports in the country, such as an infection in a traveler from El Salvador and an outbreak among wild deer in Florida. Those cases were always easy to manage.

Yet the fly has threatened to return more and more in recent years. The animal advanced from Central America and had already been spotted just across the border with Mexico. Last year the US stopped livestock imports from that country to prevent the spread, but now a case has emerged in LaPryor in Texas, 80 kilometers from the border.

The US had scaled down its capacity to combat the fly in recent years, but the country announced this week – even before the new case – that it was freeing up millions again for this purpose. 21 million dollars have been allocated to convert a breeding plant in Mexico, a new control center in Texas itself will cost another 8 million.

There are also plans to set up a fly factory on American soil. That plan will cost several hundred million. “We have defeated this pest before and will do so again,” the Ministry of Agriculture promises.

Now that a case has been discovered in Texas, a 20-kilometer quarantine area has been declared, where mammals such as livestock and pets are only allowed to leave after a check. Sterile flies are also being released in a targeted manner and surveillance in the area is being stepped up.

The Ministry of Agriculture is convinced that the danger can be averted. “There is no reason to believe that this case will lead to the return of this pest in our country.”