Inside the French factory breeding 1.5 million sterile mosquitoes a week

Two years after it was founded, the Montpellier-based firm Terratis is producing 1.5 million sterile male tiger mosquitoes every week. Its two-year target is 40 million a week. It is, by some distance, the most aggressive industrial scaling of the sterile insect technique (SIT) against Aedes albopictus in Europe, and one of only about 50 such projects worldwide.

The single most useful quote of the week came from Frederic Simard, an entomologist at France's IRD (Institut de Recherche pour le Développement) in Montpellier. Asked where the technique stands, Simard said it is at "iPhone 1.0 stage." It works. It is not yet finished.

The company and the technique

Terratis was founded in 2024 by Clelia Oliva, who remains its public face. Its product is simple to describe: male Aedes albopictus pupae, irradiated with X-rays in batches of about 400,000, sorted, and shipped to French cities that want to flood their local tiger-mosquito populations with males that cannot father offspring. The sterile males are released in urban areas; wild females mate with them; the eggs fail to hatch. Within a few generations, the local population collapses.

The technique itself is older than most readers. The IAEA has been funding SIT programmes since the 1960s, originally against agricultural pests. Adapting it to mosquitoes required new industrial engineering: mosquitoes are smaller, more fragile, and harder to rear in factory quantities than fruit flies, and the engineering has only recently caught up with the biology.

The data, in order

Drawn from AFP coverage carried by Phys.org on 16 June and by France 24 the same day, with follow-up detail in Midi Libre and Euronews:

• Weekly output, current: 1.5 million sterile male Aedes albopictus.
• Target within two years: 40 million a week.
• Sterilisation method: X-ray ionising radiation, applied in batches of about 400,000.
• Cost example (Malbosc district, Montpellier): roughly €70,000 ($81,000) for 100,000 males released twice weekly across 31 locations.
• Trial duration in Malbosc: ongoing since August 2025.
• Comparator trial (Brive-la-Gaillarde, May 2025): 11 million sterile males released; per Oliva, half of the spring eggs were sterile, with 90% projected by the end of summer 2026.
• Comparator output (Brazil, Wolbachia facility): one facility produces 100 million Wolbachia-infected eggs per week, a different technique, on a different continent, at a different scale.
• Number of comparable industrial projects worldwide: approximately 50.

The 40-million-a-week target is the line to remember. It would put Terratis in the same industrial league as the Brazilian Wolbachia facility, but using a different mechanism.

The honest quote

Simard's "iPhone 1.0 stage" line is the most quotable framing in the brief, and the most useful for a general reader. It is honest in three directions at once.

It is honest about the technique, which has been demonstrated in contained trials (including the Brive-la-Gaillarde numbers above) but is now being asked to perform at city scale for the first time. It is honest about the regulatory environment, where the technique sits in a "grey area" (neither biocide nor GMO, in Simard's framing) and where neither French nor European regulators have produced a clean approval pathway. And it is honest about the politics: Simard also noted that the technique must be "combined" with others, and called Wolbachia an "emergency response" rather than a long-term strategy.

The two techniques are not interchangeable. Wolbachia-infected males carry a bacterium that either kills the offspring or renders them incapable of transmitting dengue; X-ray-sterilised males simply do not produce viable offspring. Both reduce mosquito populations; both have advocates; both have technical and regulatory wrinkles. The Montpellier story is, in part, a test of which one scales first.

What the local press is adding

The Midi Libre follow-up of 17 June is the most useful data point for French readers. Eight in ten tiger mosquitoes, the paper reports, originate in private gardens. The entomologist Julien Mocq, of the firm Altopictus in nearby Pérols, is leading a public meeting to walk residents through the breeding sites they cannot see. This is the most human-scaled version of the same story: a million-mosquito-a-week factory in the same department as a public meeting about a single bucket of standing water.

Both are right. Both are the same answer.

The municipal funding gap

The one detail the AFP coverage surfaces that the press release language usually buries is money. Stephane Jouault, deputy mayor of Montpellier, told AFP: "We don't have the means to finance releases on the scale of an entire city." The Malbosc trial runs at roughly €70,000 for 100,000 males twice a week across 31 locations. Scaling that to the city, and to a season, implies a budget that no French municipality is currently writing.

That is the same constraint that came up in the 14 June Toulouse coverage: the mayor's office pays, the regional health agency (ARS) does not. If France is going to run a national SIT programme, somebody is going to have to write a national cheque.

What this means for an ordinary reader

For a person living in Montpellier, Toulouse, Brive-la-Gaillarde, or La Verpillière this summer, the Terratis factory is, in the short term, a story about their town council and a referendum on its mosquito budget. In the medium term, it is a story about whether a single industrial firm can hold the line on a species that, per Le Parisien's count on 16 June, is now present in 83 of France's 96 metropolitan departments.

The technique works. The factory scales. The regulators are a year or two behind. And until the city is covered, the garden, the gutter and the screen are still the dependable layer. Clelia Oliva's stated goal is "not to eradicate the species entirely, but to significantly and sustainably reduce their numbers." That is also a fair description of what one well-tended garden at a time can do.

What we know

• Terratis, founded in Montpellier in 2024, now produces 1.5 million sterile male Aedes albopictus per week and targets 40 million within two years. (Phys.org / AFP, 16 June 2026)
• Sterilisation is by X-ray irradiation, in batches of about 400,000. (Phys.org / AFP, 16 June 2026)
• The Montpellier Malbosc trial has run since August 2025, releasing 100,000 sterile males twice weekly across 31 locations, at a cost of roughly €70,000. (Phys.org / AFP, 16 June 2026)
• Brive-la-Gaillarde's 11-million release (May 2025) yielded 50% sterile spring eggs; 90% is projected by end of summer 2026. (Phys.org / AFP, 16 June 2026)
• IRD entomologist Frederic Simard described the technology as "iPhone 1.0 stage" and said the sterile-insect approach "needs to be combined" with other techniques. (Phys.org / AFP, 16 June 2026)
• Sterile mosquitoes fall in a regulatory "grey area", neither biocides nor GMOs. (Phys.org / AFP, 16 June 2026)
• 80% of tiger mosquitoes in France originate in private gardens. (Midi Libre, 17 June 2026)
• One Brazilian facility produces 100 million Wolbachia-infected eggs per week. (Phys.org / AFP, 16 June 2026)
• Of approximately 50 industrial SIT projects worldwide, Terratis is among the most-advanced. (Phys.org / AFP, 16 June 2026)

What to do

• For residents of the 83 French metropolitan departments where the tiger mosquito is now established: the technique is real but it is not yet at city scale. Personal protection (DEET- or picaridin-based repellent at peak biting times, long sleeves at dusk, screens on windows and doors) remains the dependable layer. The tiger mosquito's active window has expanded to May to November, so the protection is a five-month layer, not a one-week layer.
• For residents of Montpellier, Toulouse, Brive-la-Gaillarde, or La Verpillière: the SIT pilot in your city is real, but it is funded at the municipal level and is running at cemetery- or district-scale, not city-scale. Your garden, your gutters, and your screens still do the work. The 80%-in-private-gardens statistic (Midi Libre) is the one to remember.
• For anyone in France attending a public meeting about tiger mosquitoes (such as the one Julien Mocq is leading in Pérols): the question to ask your mairie is not "is the release coming?" but "what is the release schedule, what is the published reduction target, and what is the budget line?". A genuine release publishes all three. A press release that does not is not yet a release.
• For anyone reading from outside France: the same logic applies anywhere the tiger mosquito is established. The technique is portable, but no city in the world has yet replaced household protection with sterile-mosquito releases at city scale. Industrial sterile-mosquito releases and personal protection are complements, not substitutes.

Sources cited

1. AFP via Phys.org — "Scaling up: Key French firm now breeds 1.5 million sterile mosquitoes a week" (16 June 2026). https://phys.org/news/2026-06-scaling-key-french-firm-sterile.html
2. France 24 — "Stériliser le moustique tigre : le pari incertain d'une protection industrielle" (16 June 2026). https://www.france24.com/fr/info-en-continu/20260616-st%C3%A9riliser-le-moustique-tigre-le-pari-incertain-d-une-protection-industrielle
3. Midi Libre — "Environ 80% des moustiques tigres proviennent de jardins privés : un expert explique comment limiter leur prolifération" (17 June 2026). https://www.midilibre.fr/2026/06/17/environ-80-des-moustiques-tigres-proviennent-de-jardins-prives-un-expert-explique-comment-limiter-leur-proliferation-13424067.php
4. Euronews via MSN — "France is releasing millions of sterile insects to fight tiger mosquitoes" (17 June 2026). https://www.msn.com/en-in/science/biology/france-is-releasing-millions-of-sterile-insects-to-fight-tiger-mosquitoes/vi-AA25Qwgv
5. Ogilvy (2026-06-14) — "Toulouse bets five million sterile mosquitoes on a two-year clean-out." https://github.com/Mosticare/content/blob/main/blog/science/2026-06-14-toulouse-five-million-sterile-tiger-mosquitoes.md
6. Ogilvy (2026-06-12) — "Google / Debug: 64 million Wolbachia mosquitoes in California and Florida." https://github.com/Mosticare/content/blob/main/blog/science/2026-06-12-google-debug-64-million-wolbachia-mosquitoes-california-florida.md