Not convenient these little striped beetles. They devour the leaves of potatoes with terrifying voracity!
However, there are ways to control the Colorado beetle that are natural and environmentally friendly.
What is the Colorado beetle?
The Colorado beetle is a pest of the garden, belonging to the order Coleoptera. He is feared for his voracity of leaf eater, destroying entire cultures. Introduced accidentally in France, it has few predators and must be systematically eliminated.
How to recognize the Colorado beetle?
The Colorado beetle is easily recognizable by its bright colors. It looks like a ladybug except it has a yellow and black striped back. Measuring 1cm to 2cm long, they feature a brown torax, head and abdomen. These contrasting colors are the envy of potential predators to prey on it, making it even more difficult to take down. As for the larvae, they are rounded, orange-brown and with black spots on the sides. Attention: they look like those of ladybugs! These are recognizable by their black dots on the top.
To overcome it, it is better to know the life cycle of these harmful little beasts.
- Early spring: Colorado beetles come out of hibernation underground and start nibbling on leaves
- In spring : females lay about 800 eggs each on the back of the leaves
- 15 days later, the larvae hatch and feed on leaves
- After three moults, they go underground for pupation
- These new adult insects will then lay new eggs.
- In late summer, adults burrow underground to hibernate
It takes between a month and a month and a half to go from egg to adult insect. Thus, each year, there are 2 to 3 generations of Colorado beetle! This quick and short life cycle makes the Colorado beetle difficult to eradicate.
What plants does the Colorado beetle attack?
The Colorado beetle feasts on the leaves of nightshades. The potato is the most affected! However, it happens that tomatoes, peppers and eggplants are nibbled by this pest of the garden.
How to fight against the Colorado beetle?
Anticipation is the preferred method of the organic gardener! There are many prevention methods that don't even require treating diseases and pests.
- Crop rotation: this technique prevents diseases from continuing and pests from establishing themselves. Avoid planting nightshades in a row on the same plot. This is even more the case with the Colorado beetle which hibernates underground. If he doesn't find any host plants when he wakes up, it will be easier to get rid of them!
- Cultivation associations : some plants keep Colorado beetles away, place them near your potatoes! This is the case with garlic, hemp, flax and castor.
- Encourage the presence of ladybugs in the vegetable garden, they eat the larvae of the Colorado beetle. For this, plant nasturtiums, fennel and broad beans.
Natural and organic treatment:
- If you've had Colorado beetles in the past year and have chickens, don't hesitate to release them in the vegetable patch at the end of winter, just before the Colorado beetles come out. They will then peck the ground to extract worms and larvae.
- Remove the eggs manually. They are easy to recognize with their bright orange color on the back of the leaves.
- A treatment recommended by more and more gardener is the Doryphora 30 CH. This homeopathic treatment is diluted in water (5 granules in rainwater) and sprayed on the leaves. Repeat daily until the beetles are gone.
- Spray horseradish or tansy manure on the leaves of your nightshades.
- As a last resort, use an insecticide based on pyrethrum. Use other methods first because insecticides kill all insects and do not differentiate between pests and auxiliaries.