Home Breaking Vegetable patch: Fighting Colorado potato beetles: How to protect your nightshade plants

Vegetable patch: Fighting Colorado potato beetles: How to protect your nightshade plants


Once they were a plague, today they no longer pose a major threat – but they are still annoying fellows: Colorado potato beetles can skeletonize entire plants. You can find out how to recognize an infestation and what to do about it here.

We are writing the 19th century when the Colorado potato beetle swept across Europe like a hurricane, destroying entire harvests in many places. A life-threatening situation for the people at that time, since potatoes were one of their staple foods. The beetle originally came from central Mexico – but since it was sighted in large numbers in Colorado (a US state), the insect is still called the “Colorado potato beetle”. There are now a number of successful control agents that can prevent a renewed plague. Nevertheless, you should still take a possible infestation seriously. The sooner you act, the less damage will be done to your potato plants.

Eating marks: This is how you recognize an infestation

Fully grown Colorado potato beetles are one centimeter long and wear a colorful robe, so they are very easy to spot with the naked eye: their yellow carapace is characterized by black vertical stripes, while the head is somewhat darker and black memorized. Be on the lookout not only for the beetles, but also for their voracious red larvae, which have little black spots on the side. If you want to know for sure, you can also examine the undersides of the leaves of your potato plants – if there are orange oval eggs sticking tightly together, your vegetables have been infested.

Since the Colorado potato beetle and its larvae have a big appetite, their binge eating does not go unnoticed for long. They attack the leaves of the plants, so that the first holes or indentations on the edges indicate a possible infestation. At the latest, however, when only the thicker leaf veins or only the stalks can be seen, the finding is clear – unfortunately this applies not only to potato plants, but also to other nightshade plants such as aubergines, tomatoes and peppers. And since the females begin laying eggs as early as June, you need to fight the Colorado potato beetle. As early as possible.

This is how you can fight the Colorado potato beetle

While the beetles, larvae and eggs used to be collected by hand, there are now much more modern methods. These are not only used in local agriculture on large fields, but are also suitable for private (small) gardens: In principle, you do not have to fight the adult Colorado potato beetle, but the first larvae generation to avoid larger populations. In other words, in the spring when the first potatoes sprout. However, if it is already too late for this, biological control agents and home remedies are the best choice – in order not to harm other livestock such as bees.

NeemHere are preparations based on neem oil, which are intended to ensure a quick stop to eating. The biological pesticides primarily combat the voracious larvae of the Colorado potato beetle, as they cause the greatest damage. Derived from the tropical neem tree, the active ingredient is available as a spray and garden oil.

Tip: Chemical pesticides (insecticides) are not recommended, as the beetles have become resistant to them.


It is nature’s miracle cure against Colorado potato beetles: peppermint. For a proper brew you need at least two full hands of loose mint leaves, which you pour over three to five liters of hot water in a bucket. Allow the broth to steep for 30 minutes before filtering out the coarse residue with a sieve. The whole thing is then diluted with water (ratio 1:10) and placed in a pressure sprayer – with which you spray the leaves from above and below.


Colorado potato beetles can also be fought with this root: For the liquid manure you need ten liters of water and a kilo of fresh horseradish (alternatively, 200 grams of dried radish also work) – after you have mixed both components together in a bucket, leave the contents in a sunny place Place to rest in the garden for several days. Spread the horseradish manure on the plants with a squirt bottle and repeat this process a few days later.

bedrock meal

This is finely ground rock that is rich in silica and nutrients. It is simply sprinkled thinly over the leaves of the potato plant like a powder and has two advantages: Firstly, it removes moisture from the larvae so that they gradually dry out. On the other hand, the rock dust acts as a kind of fertilizer that makes the plants more resistant to pests.

coffee grounds

In principle, the same applies to coffee grounds, which are often used as fertilizer in the garden. However, neither the Colorado potato beetle nor the larvae like the smell or taste of ground coffee – so you can sprinkle some on the leaves. It is best in the early morning when the leaves are still slightly damp, then the sentence will stick to them better. Repeat the process again after a few weeks.

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