The monarch butterfly could soon disappear.
This insect with orange wings ribbed with black, which lives mainly in North America, has seen its population decline sharply since the 1980s, according to the International Union for Conservation of Nature (IUCN).
To closely monitor and quantify monarch populations over the years, scientists have gotten into the habit of measuring the surface area (in hectares) of these immense clusters that these insects form when they cluster around tree trunks. .
Between 1996 and 1997, the IUCN counted 18.2 hectares of monarchs.
This winter, scientists counted... 0.9.
Or 20 times less.
In total, monarchs will have lost 99.9% of their individuals between the 1980s and 2021. To explain such a decline, scientists have looked at their complex migratory journey.
The monarch butterfly can in fact travel up to 5,000 kilometers each year.
It mainly spends the summer in North America before spending the winter in the high forests of the state of Michoacan in Mexico.
And therein lies the trap.
To reach these forests, these butterflies go through a migratory route strewn with more and more pitfalls.
Deforestation (which reduces their potential habitats along the road), repeated periods of drought, increasingly frequent floods, insecticides and other pesticides which water the crops they cross... In short, this road is becoming dangerous for their survival.
The announced disappearance of these butterflies is not without consequences.
Like other insects, the butterfly's place in the ecosystem is essential.
The species, at the base of the food chain, is eaten by other insects, birds and some small animals.
If the base of the chain were to disappear, all the other species would find themselves threatened.
Insects are also used for pollination.
And when we know that a third of food agriculture in the world and three quarters of flowering plants depend on insects... “No insects, no food, no humans”, sums up Dino Martins simply. , entomologist, in an article in National Geographic.