At the Terratis facility in Montpellier, male insects grow inside large glass enclosures. In batches of 400,000, they are exposed to X-rays, making them infertile.

"After sterilization, we release them into urban areas," explained Clelia Oliva, co-founder of Terratis. "They look for females and mate, but when the females lay eggs, those eggs are empty."

The aim is to flood an area with sterile male mosquitoes until the invasive population gradually collapses.

How to overcome the growing spread, propelled significantly by climate change, of the striped creature has taxed minds across much of Europe in recent years. Not only do they sting people over the summer months, but they also carry serious diseases.

First developed 50 years ago for agriculture, the sterile insect technique is now being adapted to fight mosquitoes, as disease-carrying species continue to multiply.

The tiger mosquito (Aedes albopictus), which can transmit diseases such as dengue, the Zika virus and chikungunya, is now present across most of France.

But enhancing efforts to ramp down their numbers remains difficult. Of around 50 industrial projects being developed worldwide, Terratis—founded in 2024—is seen as one of the most promising.

The startup produces 1.5 million sterile mosquitoes per week and aims to reach 40 million within two years. "This year, we've seen a surge in orders," said Oliva, noting strong interest from cities struggling to control mosquito populations.