Sometimes fighting dangerous pests like screwworms and mosquitoes means sterilizing bugs

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Sometimes fighting dangerous pests like screwworms and mosquitoes means sterilizing bugs

Agriculture

Public Health

Science

Technology

A technician spreads sterilized screwworm flies for release as part of the Mexican government's fight to stop the spread of the New World Screwworm that poses a threat to livestock in Metapa de Domínguez, Mexico, Oct. 17, 2025. (AP)

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Scientists sometimes release sterilized male insects to breed with females in the wild, which produces no viable offspring. By interrupting harmful pests’ reproduction, these projects aim to reduce insect populations and the havoc they can wreak.

This technique has been used for over 50 years to combat harmful agricultural pests. More recently, researchers have explored using it to combat infectious disease spread.

The technique can be costly, it isn’t a one-time solution and it’s not a useful tool for all  problematic insects.

Even if you’re not typically averse to bugs, the idea of raising and then releasing thousands of insects into the wild might give you the heebie-jeebies.

But if it helps you rest easier, the mass release of sterile male insects is a long-standing means of insect population control, and it’s now being used to slow the spread of vector-borne diseases, including those carried by mosquitoes.

Screwworm — a harmful parasite once largely eradicated with the help of a successful sterile insect program — is back . Multiple reported U.S. cases have drawn news coverage, as has a request from researchers with Google’s Debug project asking to release millions of mosquitoes in Florida and California.

The concept raises questions: How does it work? Is it typically successful? Is it ecologically safe? Here’s what scientists want you to know.

How the sterile insect technique works

Let’s take the New World screwworm and the Aedes aegypti mosquito — two insect populations in the news.

Screwworm infestations are most common among livestock, but they can occur in humans and pets. The parasites lay eggs in warm-blooded animals’ open wounds or orifices, including the eyes, noses and mouths. After hatching, screwworm larvae burrow into skin and eat live flesh for about five to seven days, before falling off their host and burrowing underground to mature into adult flies. Left untreated, infestations can be deadly.

Aedes aegypti mosquitoes spread infectious diseases including dengue, chikungunya, yellow fever and Zika. Google’s Debug project, launched in 2016 to slow mosquito-borne disease spread, estimates 40% of people on Earth are at risk of contracting a disease spread by this species of mosquito, which is invasive outside of Africa . That’s in line with figures from the U.S. Centers for Disease Control and Prevention and the World Mosquito Program , which also hopes to reduce infectious disease spread by introducing wolbachia bacteria to weaken local mosquitoes’ ability to transmit diseases.

To thwart screwworm infestations, researchers typically raise a large group of screwworm flies and then expose the males to enough radiation to render them infertile, but not so much that it kills or hinders their ability to mate. These sterilized flies are released into an area with a screwworm infestation. When wild female screwworm flies mate with the sterilized males, the resulting eggs will never hatch .

Meanwhile, Google says it is testing ways to raise sterile male mosquitoes. One method includes using mosquitoes infected with wolbachia, a bacteria that prevents them from successfully breeding with wild mosquitoes. It’s different from the sterile insect technique’s typical radiation sterilization, but the result is the same: Mosquitoes that can’t produce viable offspring. The result is the same as radiation sterilization : Mosquitoes that can’t produce viable offspring. Google wants to then release millions of sterilized males so that when wild females mate with them, their eggs won’t hatch — just like the screwworms. The goal is to reduce each successive generation’s size as more sterilized males are released.

It can be difficult to raise mosquitoes in the massive quantities needed to actually decrease overall populations. They’re fragile, but Google says it is developing new technology to make that easier.

Is this an effective way to manage harmful pests or disease-spreading insects?

History and research show that it can be.

We’ve successfully combated agriculture pests such as screwworm for decades using sterile insects, said Greg Simmons, a retired entomologist in the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.

The technique was first developed in the U.S. , and North America is among six continents that have successfully used radiation-induced sterile insects for more than 60 years. Scientists began studying the m…