The Colorado potato beetle
These insects belong to the leaf beetle family and can be recognized by the presence of 10 yellow and 10 black stripes on their curved backs.
These colors tend to drive away predators. Their wings, which allow them to fly, are hidden beneath their elytrons. Between 1 cm. and 2cms. in length, this insect has two small club-like antennae. Its chest and its head are browny-black.
The Colorado beetle originates from North America, as its name suggests. For centuries, it lived isolated in the Rocky Mountains, where it fed on a wild species of the potato plant. But with the expansion of this plant around the 1850’s, the beetle gradually colonized the American continent. Within 25 years, it spread rapidly throughout all the eastern regions of America. This invasion was so dense that it shocked the European authorities.
By the end of the 19th. Century, potato imports from America were suspended, but the damage had already been done. Germany, England, and soon after, France, were colonized. These new beetles then spread to eastern Europe. Their rapid acclimatization was made possible by their ability to resist the cold. They hibernate in the soil in winter and reappear in fine health when the weather gets warmer.
They feed exclusively on the leaves of Solanaceae, that is, potato, tomato, and aubergine plants. The larvae pose as many problems as the adult beetle. The female lays its egg – up to 2,500 – from spring to the end of summer beneath the leaves. They take between 4 to 10 days to hatch. The larvae then devour the leaves under which they are laid, then attack the surrounding leaves. After three successive mutations, the larvae transform into nymphs, who hide in the soil before reappearing as adult Colorado beetles within 15 days.
When the garden is invaded by these beetles, both the larvae and the adults must be destroyed. The insecticides used must be constantly changed, as scientists suspect that this insect is capable of developing a resistance to chemical products. If your garden is only slightly infested, the best, and most ecological, thing to do is to remove the beetle and its larvae manually.