Cereal bedbugs invade the houses near Toulouse

“It was teeming!” There were millions, maybe billions! It was only ten days ago. Jacques Beauville, retired farmer de Saubens, south of Toulouse, saw on his old plots, a cloud of … Bedbugs of cereals. This year, those who took over, cultivated rapeseed. Not without consequences, since the mother of Saubens, Jean-Marc Bergiawas alerted to a real invasion in his commune. And he is not the only one. “It concerns the entire Occitanie region. We have received several alerts in Haute-Garonne, especially in the Lauragais where market gardeners are affected, but also on the side of Buzet-sur-Tarn, Gragnague or Roquettes, “said the Chamber of Agriculture contacted by Toulouse news. Never or very rarely seen. But what is this mini-Bestiole and why does it proliferate so much this summer?

“The whole facade was covered!” »»

Everywhere around Toulouse, the questions arise. Because the case that could only have concerned the farmersaffects the entire population. “After the harvests, a resident of rockets, whose garden is on the Saubens side, found himself Bug invaded. The whole facade was covered! On all the walls that are hot and in the garden, ”reports the mayor of Saubens.

At the beginning, the phenomenon only affected the houses adjoining the fields of corn and rapeseed*. “But now, the subdivision inside the village, which is the opposite of the inhabitant who manifested himself first, is affected!” “Says Jean-Marc Bergia. If these dwellings are recent, the first infested houses date “at least 20 years”, assures the mayor.

However, in as many years, “we had never seen that! », Ensure the elected official and the farmer of the town questioned by Toulouse news.

Other episodes in Haute-Garonne in the past

However, the story shows that those nicknamed “bedbugs of rapeseed” pointed out their nose twice, in 2016, in 2019 and in 2020, in Haute-Garonne, but also in the center of France and the Loire-Atlantique. In the Lauragais, the village of Sainte-Julia had also been the victim, as reported La Voix du Midi Lauragais In 2022. But the appearance of cereal bedbugs (of their real name), however, remains “infrequent”, said, therefore, Laboratory Land Inovia of Baziège. And above all: it was observed more at the time of seeds “in hot and dry conditions”.

However, this year, the swarming of cereal bedbugs dates back to mid-July, well after the harvests that date from the end of June, and in a rather fresh environment compared to the heat wave in June. So how to explain their sudden arrival?

The warmth sought and non-training floors

The mystery has not yet been entirely elucidated, but several hypotheses come together. We know that These bedbugs “like hot temperatures and dry environments”, explain Nathalie Eychenne, agricultural engineer in the plant field. And that when these climatic conditions meet during the summer, invasions can be observed in months of July, August and Septemberin rapeseed cultures essentially (hence his other name “false bug of cereals”, rapeseed not being a cereal, editor’s note) but also other species, such as cabbage, soy, tomato, sunflowers, olivier, clover, etc.

To this, we must add, according to Jacques Beauville, the lack of work of the soils “because of the drought”.

This year, and this is a notable difference from other years, farmers have not worked on the soils after harvesting. If they had unleashed 5 to 10 cm of soil, many larvae would have been killed

But why did these small insects migrate to neighboring dwellings and are not confined to agricultural land?

Baby bugs looking for food?

The bedbugs of cereals currently observed are at juvenile stadium, and only measure 1 mm. It is therefore only a question of “babies” eating with vegetation. According to the study of the Terres Inovia laboratory, the larvae are looking for rapeseed (wall or upwards) or rapeseed regrowth. The latter appear following the harvests “because seeds stand out from the harvester and as soon as it rains a little, they germinate easily and create a carpet of rapeseed”, explains Aymeric Desarnauts, large cultures advisor to the Haute-Garonne Chamber of Agriculture.

However, this year, according to this advisor, there are not too many regrowths in the fields.

I think they have nothing to snack and that is perhaps why they migrate in the gardens of the inhabitants: to seek enough to eat.

The insect cycle at its peak

A hypothesis not shared by the former farmer of Saubens, also an agricultural engineer. According to his observation, the larvae have found refuge in dry weeds stuck between the collars. “We call it Ray-Grass. It is a grass, which therefore belongs to the cereal family. It is here, according to his theory joined by engineer Nathalie Eychenne, that the bedbugs would have arrived, before, simply, to follow their insect cycle…

From an egg is born a larva, then an insect which will then mate, lay, then die. “What is happening today could correspond to Reproduction stage “, Advises Jacques Beauville. By reaching their adult size(about 2.5 mm), the bedbugs develop ailes. It was at this time that the bedbugs would go, like a nuptial flight. “Given the peasant common sense, we say that they will disappear as they have arrived. »»

But it is only a supposition. Because the farmer concedes: “We don’t really have any explanations …”

Rain or water, failing that, as the only remedy

“We feel helpless. We have very few solutions » says the mayor of Saubens, like many others. No insecticide was not effective in the treatment of cereal bedbugs. “Only irrigation or the return of rains calm the phenomenon by allowing the dispersion of larvae,” explains the laboratory lands inovia.

It is the only thing that remains certain at this stage: The bedbugs do not like water. In 2022, in Sainte-Julia, they disappeared after two to three weeks of existence, following thunderstorms.

So, while waiting for the precious rain drops, it is recommended toSpray the exterior walls with a jet of waterhigh pressure, while respecting the restrictions to fight against drought. And possibly spray black soap so that the “patina” insects.

No health danger

But the best is still to wait while keeping the good news in mind: cereal bedbugs are harmlessneither dangerous for animals, nor dangerous for humans. Facts confirmed by theRegional Health Agency.

*NB: Haute-Garonne has 10,000 hectares of rapeseed this year.

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