The pests can destroy entire potato crops. We reveal what remedies help against the Colorado potato beetle and how to combat it naturally.
Potato beetles can become a real plague, it is not for nothing that many parents and grandparents were sentenced to “collect potato beetles” as children in order to save the harvest. Therefore, it is important to recognize the pest early and to prevent it. If it is already too late for that, there are various ways of combating this, ranging from home remedies and biological agents to chemical sprays.
Potato beetle: origin and characteristics
The Colorado potato beetle (Leptinotarsa decemlineata) is a leaf beetle and originally comes from North America. It was introduced to Europe at the end of the 19th century and it didn't take long for the Colorado potato beetle to become a pest. At that time there were no effective pesticides and so people had no choice but to collect the beetles from the potato fields. Only with the advent of modern pesticides could the Colorado potato beetle be combated effectively. However, the early pesticides were so toxic that the potatoes would probably never have made it onto the market today.
In order to combat the beetle as effectively as possible, it is helpful to understand its life cycle. In spring, when the first potatoes sprout, the Colorado potato beetle wakes up and leaves its winter quarters. After the beetles have left the soil, they begin to feed on the small potato shoots and lay their eggs on the underside of the potato leaves. Depending on the weather, the larvae hatch from the eggs after three to twelve days and begin to eat the plants much more than the adults. The larvae go through four developmental stages before becoming adult beetles.
In the first two larval stages, the larvae are very sensitive to pesticides and are not very hungry. isHowever, when the 3rd larval stage is reached, the big eating starts and biological insecticides are also less effective. For this reason the larvae should always be fought at an early stage of development. In dry weather, up to two generations of Colorado potato beetles are possible within a year. If the first generation is effectively controlled, the number of Colorado potato beetles in the following generations will be lower and almost negligible.
Tip: You can find an overview of other potato diseases and pests in our special article.
Detect potato beetle and larvae
Adult Colorado potato beetles are about one centimeter long and stand out because of their very characteristic appearance: they are yellow and have black longitudinal stripes on their back. In addition to identifying the adult beetle, you should pay special attention to the larvae. The compact, red larvae are also easy to recognize by their black dots on the sides. If you have particularly good eyesight, you may also be able to spot the bright orange-yellow eggs on the underside of the leaf. The eggs are arranged in a round clutch.
The harmful picture of the potato beetle
Infestation by the Colorado potato beetle is relatively easy to recognize. Already from the first sprouting of the potatoes, you have to expect signs of eating. Since the potato plant is despised by many pests because of its toxic ingredients, Colorado potato beetles are often the culprit if there are clear signs of feeding. To be more precise: the older larvae of the beetle are responsible for the eaten leaves. If there are enough larvae, they can eat a potato plant down to the thick veins of the leaves. This usually means a total failure of the harvest.
How to tell if it is an infestation of Colorado potato beetles:
- Potato beetles are about one centimeter in size and strikingly yellow in color with black vertical stripes on their backs
- Potato beetle larvae are red in color and show black spots on the side
- There are signs of feeding on the leaves and shoot tips immediately after they have budded
Tip: We recommend that you use a biological control agent as soon as the first signs of larvae are eaten. Our purely plant-based Plantura organic pest-free neem is based onhighly effective neem oil and ensures that you stop eating quickly.
Prevent the Colorado potato beetle
Since the Colorado potato beetle comes out of the ground with the sprouting potatoes in spring, nets or the like are useless. Cultivation breaks only have an effect if no potatoes are grown in the entire garden for years, since Colorado potato beetles easily cover distances of up to 500 m in search of food. But there are ways and means to reduce the likelihood of a threatening Colorado potato beetle infestation.
It is very effective to recognize the first potato beetle in spring and to act quickly. We therefore recommend that you keep an eye out for the adult animals from the beginning of May. The first larvae can then be expected in June.
Timing when growing potatoes can also prevent an infestation. If you push your potatoes underground, they will have a head start on the growth of the Colorado potato beetle. The Colorado potato beetle and its larvae cause less damage to the potato plants and you may be able to avoid combating them. In addition, and especially if you often have problems with Colorado potato beetles, it is worth using early-ripening potato varieties. Here, too, the common potato beetle can no longer exploit its full damage potential.
Additionally, beneficial insects can reduce the number of Colorado potato beetles. So make sure you have plenty of retreat areas so that as many beneficial insects as possible “work” for you in your garden. Insects that are useful against Colorado potato beetles include, above all, predatory bedbugs and ground beetles.
Summary: How to prevent Colorado potato beetle infestation
- Keep cultivation breaks within a radius of 500 m
- Keep an eye out: from May onward for adult Colorado potato beetles; from June after larvae
- Forcing potatoes to give your potatoes a head start on growth
- Early ripening varieties help reduce yield loss
- Promote beneficial insects such as predatory bugs and ground beetles
Tip: With a blooming flower meadow you not only conjure up an eye-catcher in your garden or in a pot on the balcony, but also promote beneficial insects against the Colorado potato beetle. Our Plantura beneficial insect magnet is a seed mix with over 20 different plants that allows you to create such a beneficial insect paradise.
Fight potato beetle
When controlling the Colorado potato beetle, not only choosing the right agent but also the time of control is of crucial importance. Since the adult Colorado potato beetle, in principle, does not cause any significant damage, combating it is of secondary importance. Much more important is control of the first generation of larvae in spring. If this generation of larvae is effectively combated, a large population of Colorado potato beetles can no longer build up over the course of the year. Under normal conditions, you then have peace of mind from the Colorado potato beetle and can relax and wait for the potato harvest.
In the event of an infestation in spring, we recommend using a biological agent immediately. Neem oil-based supplements are a great way to use herbal methods to control Colorado potato beetles. Our Plantura organic pest-free neem is based on this valuable neem oil. The herbal remedy ensures a quick feeding stop and is not dangerous to bees. To use on the potato, simply mix 2.5 milliliters of Plantura organic pest-free neem with 300-700 milliliters of water. About ten square meters of potatoes can then be treated with this emulsion. Since the active ingredient is absorbed by the plant, hidden insects are also reached. An important point: the larvae of the Colorado potato beetle are becoming more and more resistant to pesticides as they develop. It is therefore best to apply the pesticide shortly after the eggs hatch in spring. As with any plant protection product, it is also important to use organic pest-free neem correctly in order to achieve maximum treatment success and to protect the environment and user - always read the package insert before use.
Tip: Our organic pest-free neem can also be used outdoors or indoors against other biting, leaf-mining or sucking insects such as aphids.
Fight potato beetles naturally with beneficial insects
At this point in time there are no beneficial insects available that are able to fight the Colorado potato beetle really well. At this point we can only refer to the preventive measures. By encouraging naturally occurring enemies, such as ground beetles or predatory bugs, you reduce the likelihood of mass reproduction. In this way, you may be able to avoid a plant protection measure with plant protection products.
Fighting potato beetles biologically: home remedies and more
The oldest and at the same time most laborious method is collecting the Colorado potato beetle. forHowever, for good control, the larvae should also be collected and the eggs should also be crushed or scraped off. With individual potato plants on the balcony or terrace, this may not be a problem. However, if you are the proud owner of a larger potato patch, collecting them is an almost impossible task. It just takes a lot of time. If you do decide to use this remedy, we recommend collecting it in the morning. Other home remedies, which are often mentioned in connection with Colorado potato beetles, are almost ineffective. These remedies include:
- rock flour
- Wood Ash
- Sprays made from fern or mint
For biological control of the Colorado potato beetle, a bacterial protein that acts selectively on the pest is available for organic farming. This protein from the bacterium Bacillus thuringiensis ssp. tenebrionis is not allowed for private users. The protein from Bacillus thuringiensis ssp. aizawai works well against caterpillars but not against the Colorado potato beetle. Our Plantura Zünslerfrei XenTari® contains this effective protein and enables you to control free-eating caterpillars on box trees, cabbage plants and fruit trees.
Fighting potato beetles with chemical agents
Pesticides are often harmful to beneficial insects and other insects in your garden. We therefore always recommend biological measures for the private garden. The Colorado potato beetle is largely resistant to one of the most popular agents in chemical control, pyrethroids, simply because this agent has been widely used in the past. Most Colorado potato beetles are also resistant to the similar biological agent pyrethrum from the chrysanthemum. We strongly advise against controlling the Colorado potato beetle with these two active ingredients, as this will further promote resistance.
With these tips, nothing stands in the way of a successful potato harvest. By the way: Potatoes don't always have to be yellow. There is a colorful variety of potatoes from which you can choose exciting varieties.