The Colorado potato beetle: how to fight without pesticides?

The Colorado beetle is a beetle which can, in the event of an invasion, reduce the yield of the potato crop by at least half. But that’s not to mention that once properly installed in the vegetable garden, it also attacks pepper, tomato or eggplant plants. It is therefore essential to react as quickly as possible to fight against the Colorado potato beetle, but the best solution is of course to opt for a alternative to pesticides. Let’s take stock of the little tips and prophylactic measures allowing to considerably reduce the population of this beetle.

Colorado potato beetle: the return of a gardener’s arch enemy

After a few years of virtual silence, the Colorado beetle (Leptinotarsa ​​decemlineata) is resurfacing in our fields and gardens, and more particularly in the regions north of the Loire. Experts believe that global warming could explain the return of the Colorado beetle.

This beetle of the family of Chrysomelidae is a voracious but also a tough one. Its lifespan is approximately 2 years, which is more than enough to ruin many cultures. Recognizable in adulthood by its yellow livery with black stripes, the Colorado beetle is most prevalent from mid-April to the end of June. It reproduces at high speed since a single female can lay nearly a thousand eggs on the underside of potato leaves (among others).

We can recognize the Colorado beetle larvae quite easily. They are colored orange and have small black dots. They are great leaf eaters. In less than 15 days, they undergo three successive moults. It is then that they leave the leaves to become embedded in the earth and not come out until July, totally metamorphosed since they have acquired their adult appearance.

It is essential to show yourself very vigilant because a Colorado beetle infestation leads to defoliation total of the entire planting of potatoes and other garden vegetables. But the leaves being essential to each plant, the harvest is therefore extremely jeopardized.

Natural fight against the Colorado beetle: little tips and prophylactic measures to adopt

The gardener has several environmentally friendly solutions so as not to see its potatoes and certain other plants undergo the attacks of the Colorado beetle.

  • Spray Bordeaux mixture in the garden because it constitutes a repellent effective against the Colorado beetle provided that the spraying is carried out two to three nights in a row,
  • From April, inspect as regularly as possible leaves potatoes.
  • Manually kill adult Colorado beetles without exception, as soon as they appear,
  • Crush all the Colorado beetle eggs as soon as they are laid in order to avoid a new risk of infestation,
  • Opt for a early planting so that the foliage of the potato plants is already adult, and therefore less tender, by the time the Colorado beetles begin to infest the crops,
  • Eliminate systematically regrowth which promote the concentration of these undesirable,
  • Prevent the Colorado beetle larvae from infiltrating the soil leaving during summer the earth harden sufficiently, which implies not to dig or hoe,
  • Get rid of plant debris and waste from the vegetable garden because they serve as food for the Colorado beetle which can therefore concentrate in large numbers,
  • Perform the potato crop rotation : once every three or four years is enough. This helps eradicate specimens that overwinter in the soil.

Do not hesitate to resort to good combinations of plants in the vegetable garden, because some are effective against Colorado beetles. This is the case of blue-flowered annual flax and thegarlic that can be sown or planted in the rows of potatoes or every other row. For a more severe fight, it is possible to plant castor and datura but be careful because these are plants whose toxicity is formidable. We are therefore content to install them at the edge of the space reserved for the cultivation of potatoes and not in the rows, and it is absolutely necessary forbid children to touch it. Colorado potato beetles are attracted to these two plants. The females lay eggs there without problems, but the larvae are then very quickly poisoned.