An effective remedy for the Colorado potato beetle — Garden

On the spot — a remedy for the Colorado potato beetle instruction

Potatoes have always been the second bread. This tasty and healthy vegetable is present on the table of almost every person, and the dishes that can be cooked from it are difficult to count.

It grows in almost every garden plot. Therefore, it is so important that the efforts that gardeners make to grow the second bread pay off with good yields. Potatoes, like any vegetable crop, have their own diseases and pests. But the scale of the harm that can be caused to plants from the Solanaceae family of beetles that came from the state of Colorado is simply impressive.

A warning! Under favorable conditions and large numbers in one day, the larvae of the Colorado potato beetle can eat half of the potato bush.

Colorado potato beetle damage

The harm that the Colorado potato beetle inflicts on plants from the family of the nightshade is obvious.

  • The leaf mass of plants decreases, which leads to a decrease in yield.
  • Plants are under stress, which also does not improve the conditions for their development.
  • The vegetation of bushes eaten by the beetle ends ahead of time, this leads to a shortage of crops.
  • Moving through the plants, the larvae of the beetle contribute to the spread of late blight, and the wounds on various parts of the potato bushes are the gateway for infection.

How to deal with leafing pest

Ruthless pest must be fought. You can collect the larvae manually. Of course, this method is completely safe in terms of ecology, but very laborious. The collection of beetles will have to be carried out daily, but this is not a guarantee for the complete destruction of the pest. The beetle can fly over long distances, so it will appear again and again. There are many popular ways of dealing with a malicious pest. But often they are ineffective, processing has to be repeated.

Attention! The Colorado potato beetle can fly in the wind at a speed of almost 10 km / h and fly long distances.

Chemicals against beetle

When the infection with a bug is large, and even more so if there are a lot of potatoes planted, you will have to resort to the help of chemicals.

Means for protection of cultivated plants from insect pests are called insecticides. There are a lot of such preparations based on various active substances. Most often, their spectrum of action is quite wide.

One of these drugs is an effective remedy for the Colorado potato beetle. This tool copes well not only with it, but with many other pests of garden crops.

Drug on the spot

In the composition of Napoux there are 2 active ingredients at once:

  • Alpha-cypermethrin. Its content in a liter of suspension is 100 g. A substance from the group of permetroids, synthesized by analogy with a natural insecticide based on a pyrethrum plant, familiar to many chamomile. It affects the nervous system of cold-blooded animals and the Colorado potato beetle, including by destroying the cell membranes, which causes paralysis of the pest’s nervous system. The drug acts upon contact with it and when it enters the intestine of the insect. Half of the drug is decomposed into safe substances for 69 days.
  • Imidocloprid. A liter of its suspension contains 300 g. This substance belongs to the class of synthetic neonicotinoids and also acts on the nervous system of cold-blooded animals, disrupting the conductivity of nerve impulses. Fatal when hit by any part of the insect. The effectiveness of the substance is very high, only about 10% of individuals remain alive. Penetrating into the tissue of potatoes, imidacloprid, due to chemical reactions, turns into chloronicotinilic acid, it is an antidepressant for potatoes. Consequently, it has a double effect: in addition to suppressing the Colorado potato beetle, it also heals potato bushes, increasing their yield.

Mechanism of action

Imidacloprid is able to penetrate the tissues of potato plants. Moving through the vessels, it quickly penetrates the leaves, making them poisonous to both the beetle larvae and adult individuals. This effect lasts for about 3 weeks. All this time, potato plants remain a poison for beetles of any age. And even stray individuals will not be able to damage the plants. The effect of the drug will be noticeable after a few hours. And in a couple of days it will reach its peak. Pests of any age are affected. On the spot will act for almost a month. The multiplicity of treatments — 2, but not less than 3 weeks should pass before digging up the potatoes. Weather conditions do not affect the effectiveness of the drug.

Mode of application

Instructions attached to the drug, recommends diluting 3 ml or one ampoule of Napoup in water. Its maximum amount is 9 liters, when there are few pests. Minimum — 6 l with a high degree of infection by larvae and beetles. After thorough mixing, the solution is poured into a spraying device and the potatoes are processed, trying to moisten all the leaves.

This amount of solution is sufficient for processing a plot of two weave. Tip! It is better to carry out the treatment when there is no wind and rain, then the preparation will not be washed off with water, and the wind will not interfere with moistening all the leaves of the potatoes completely.

Drug toxicity and safety measures

On the spot has 3 hazard class, for humans it is dangerous moderately, but all animals can suffer greatly from its action, therefore, it is strictly prohibited to carry out treatments near water bodies or drain residues there in order not to damage fish and other aquatic inhabitants. But the drug is very toxic to bees. For them, he has the first — the highest class of danger.

A warning! It is impossible to process on the spot the potatoes if the nearest apiary is closer than 10 km.

Do not process potatoes during flowering.

There is evidence that contact with the drug may cause poisoning of domestic animals.

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It is possible to leave on the processed site for carrying out manual works not earlier than 10 days, mechanical works can be begun earlier, in 4 days.

Processing should be carried out in special clothes, you must wear gloves and a respirator.

A warning! When processing, observe safety measures, after it you need to change clothes, wash and rinse your mouth.


  • Developed recently.
  • Does not possess phytotoxicity.
  • It has high efficiency.
  • Due to the two active ingredients in the Colorado potato beetle does not arise addiction to the drug.
  • Moderately dangerous for all warm-blooded animals and humans.
  • The spectrum of pests on which it acts is very wide.
  • No weather restrictions in the application.
  • Relieves stress from plants, increasing their yield.
  • Small consumption rate.
  • Low price.

Planting potatoes need protection from such a dangerous pest as the Colorado potato beetle. This is well able to help the drug on the spot.



CPB undergo complete metamorphosis: adult, egg, larva, and pupa.

Adults are hard-shelled with a round, convex shape. Their forewings are yellow with a total of 10 black stripes running longitudinal. They are about a half an inch long. Adults eat foliage until they pupate.

Eggs are oval, yellow to bright orange. They are layed in clusters of 10 to 30 eggs on the underside of leaves.

Larvae are slug-like with a soft shell. They are red to orange to tan depending on age and they have two rows of black dots on each side. The body which is humped enlarges with time and grows in four size stages. Larvae eat foliage as they grow and this is the most destructive stage.

Pupae are small and are found in the soil .

Life Cycle

Adults overwinter four to 12 inch deep in the ground of harvested potato fields and emerge in spring around May. Adults do not migrate but will fly for several miles to find its Solanaceous hosts. Besides potato, these include weeds such as nightshades and include garden crops such as tomato and pepper. Adults then mate and lay eggs on the host plants. Egg laying may last as long as a month and may be as many as 500 eggs on a single plant. After four to 10 days depending on temperature, eggs hatch. The cooler the air temperature the longer it will take for hatching. The hatchlings are tiny larva. The larva grow in four progressive stages (instars), eating the host foliage all the while. Depending on temperature, the larval stages will last two to five weeks or when about 400 degree days have accumulated. Then, the larva will go into the ground, three to six inch deep, and pupate. The Pupa last for five to 10 days after which new adults emerge. The emerged adult travels around, looks for mates, and after seven to 10 days begins to lay eggs. The full cycle takes five to eight weeks per generation. Usually, there are two generations per season in Nebraska, early to mid June and early to mid August. In cooler States, less than two generations may occur. At the end of the season, remaining larva move into the soil and overwinter as pupa.


CPB larvae are the most damaging form but adults also feed on the foliage. Due to feeding, leaflets have holes of varying sizes usually starting around the margins. The leaf blades are eaten often leaving a skeleton of veins and petioles behind. This results in defoliation. Defoliation threshold levels are reported as 25% before tuber bulking, 10% during the first half of bulking, four to six weeks and 25% after bulking. Vine damage results in yield loss due to loss of foliage to support tuber growth and mis-shaping of tubers is also possible. Severe damage may result in plant stunting as well.


Monitoring the edges of fields, nearby gardens and surrounding weeds especially nightshades will give warning when CPB are entering the field. Since they are poor fliers, CPB enter a field along the edge usually at a corner that is closest to the previos year’s crop. Economic threshold levels have been reported.


Crop Value Control Cost

* Values are numbers of larval-infested plants per 100 feet of row. Do not apply products unless the average infestation level is greater than these values.

Bechinski, E.J., Sandvol, L.E., and Stoltz, R.L. 1994. Integrated Pest Management Guide to Colorado Potato Beetles. Univ Idaho Coop Ext Circ #757.


The trench method is a semi-successful mechanical control of CPB mostly applicable to small acreage. In areas where close rotations are used or potatoes are grown adjacent to last years potato fields, this method may help to alleviate first generation CPB damage. A trench is plowed between overwintering sites and this year’s potato field. The trench should be at least 12 inches deep with sides sloping 45 to 90o. Emerging beetles walk to find their early season hosts and become trapped in the trench. A fine coating of dirt on the plastic prevents the beetles from being able to get out of the trench. Note some CPB adults may fly over the trench; however, this method can be surprisingly effective at trapping beetles.

Using a flamer is another mechanical method for controlling CPB. Its best fit is also in areas where trap crops are used to congregate immigrating beetles for easier control. Flaming is used on plants that are up to 8 inches tall with little adverse effects on them. Larger plants will provide more protection for the beetles and effectiveness is reduced. Flaming involves using two propane-powered flame jets that are directed in an offset manner toward the row. A single unit can be bought for under $3,o00 or constructed. Propane usage is about 3½ to 5½ gallons per acre. Speed is also an advantage. As might be suspected, you don’t want to go too slow with this type of machine. A speed of 4 to 6 mph is recommended. Control with the flamer should be done on a clear warm day so the beetles are up on the plants. Data for early-season control have been as high as 90% with this method.

Moyer, D.D. 1992. Fabrication and operation of a propane flamer for Colorado potato beetle control. Cornell Coop Ext Bull. pp. 7.

Olkowski, W., Saiki, N. and Daar, S. 1992. IPM options for Colorado potato beetle. The IPM Practitioner 14:1-21.


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Several common beneficial insects, predators, are good agents for devouring CPB eggs and even attacking larva; see lady beetles and others. Since CPB overwinter in potato fields, rotating crops is key and the following season’s potato fields should be planted a few miles away from the previous season’s potato fields. Since CPB will develop on weeds in the same family as potato, controlling these especially the various night shades is an important part of the management program. Bt products such as Dipel have been used to kill young CPB larvae but timing is crucial for efficacy. In the 1990s, potato clones began to be engineered (GMO) with Bt genes to protect plants from CPB. This technology is very successful in doing that but due to uninformed political pressure this GMO technology has been slowed on potato although common in corn and soybean.


Most systemic insecticides applied at planting will kill the CPB’s first generation. Most foliar insecticides will take care of later invasions by CPB. The key is not to let the population de-synchronize. If this happens, weekly applications of foliar insecticides could be needed. The best application stage is on the young larvae, first and second instar, because they have most of their eating ahead of them. Older larvae have less eating to do and also are less sensitive. Killing adults works but the result may be so/so because they may have already laid eggs and you may be killing their predators such as lady beetles as well. These predators would devour the CPB egg masses. Since CPB enter fields along the edges and gradually move inwardly, with good scouting, often only the field’s perimeter needs to be treated.

It is very important to note that the CPB is highly capable to develop resistance to insecticide products. On the East Coast and Great Lakes region, the CPB has developed resistance to combinations of products, multiple-resistance or “super” bugs. Therefore, management needs to be an integrated program of biological and chemical methods, at least until the consumer market allows resistant potato lines to return.

Home Gardens

To control CPB in garden potatoes as well as peppers and tomatoes, apply carbaryl (Sevin) to plants when the adults or young larvae are present. But be aware not to treat around flower areas to avoid killing honey bees needed for pollination.

Quick Review


Adult — round with yellow and black stripping, 1/2 inch long
Larva — slug-like, pinkish with two rows of black dots on each side, four instars from 1/10 to 1/2 inch
Egg — small yellow to orange in masses under leaflets

Life Cycle:

Overwinters as an adult in soil of previous year’s crop
One to two generations which can de-synchronize easily
Can appear from April to September


Defoliation; tuber yield loss


Crop Rotation
Beneficial Insects
Systemic Insecticides
Foliar Insecticides but beware of resistance
Bt products
GMO potato engineered with Bt gene

Control Colorado Potato Beetle with a Mix of Strategies

The Colorado potato beetle has become resistant to a number of commercial pesticides.

  • Unchecked, the Colorado potato beetle can munch its way through your potato, eggplant, and tomato plants.

by Helga Olkowski
April 2000
from issue #26

The pretty yellow-and-black-striped Colorado potato beetle is native to wild Solanaceous plants of the semi-arid western United States. Our problem with it began when the beetle broadened its gustatory interests to include cultivated plants in the same family, such as potato, eggplant, and tomato. It has since expanded its range to include most of North America and Europe.

Because the Colorado potato beetle has become resistant to a large number of conventional pesticides, researchers have pursued alternative methods of control. As a kitchen gardener, you can choose from physical, horticultural, or biological controls. Most likely, a mix of strategies will be your best policy.

Rotation—the old standby
In spring, adult Colorado potato beetles emerge from hibernation in the soil and search out food plants for feeding and egg-laying. The feeding beetles lay yellow-orange eggs clustered in groups, usually on the undersides of leaves. The larvae, which look like fat, globular, slow-moving caterpillars, change from brown to pink as they grow, developing two rows of black spots along each side of their abdomen (top right photo, below). When fully grown, in 20 to 24 days, the larvae burrow into the soil to pupate near the plants on which they were feeding. Emerging as adults, a week to two weeks later (depending on the temperature), they start the process again. The second generation of adults remains in the soil until the next spring.

Colorado potato beetle eggs are laid on the underside of leaves. Fortunately, they’re food to lady beetles. The larva of the Colorado potato beetle is preyed upon by the two-spotted stink bug.
The yellow and black striped Colorado potato beetle overwinters near plantings it infested the previous year, so rotating crops may provide some protection against it.

The adult beetles are poor flyers and cannot easily travel far. For this reason, the rotation of crops away from where Solanaceous plants have been planted before is a traditional means of controlling Colorado potato beetle. Unfortunately for the kitchen gardener, the new plantings ideally should be at least 200 feet away from the old site. Even in small gardens, however, it’s still a good idea to rotate each piece of ground to a different plant family, because other pests, including soil-borne pathogens, remain behind from each year’s plantings.

Handpick, vacuum, or trap
Physical controls satisfy the urge for immediate revenge on a pest for the damage it causes, and against the Colorado potato beetle, you have several choices. Handpicking may be all you need to protect a small plot of potatoes. Picking is easiest early in the day when the beetles are cold and slow to move. Collect the beetles in a wide-mouth jar, coffee can, or deep baking pan, half full of soapy water. Place the container below leaves with beetles or larvae and shake the plant. The insects will fall into the container and drown. Larvae and egg masses also can be squished on the leaves. Gloves make the job easier.

Another physical control option is to vacuum up the beetles. Small, rechargeable hand-held vacuums can be quite
effective with Colorado potato beetles and other large insect pests. We have also used a water vacuum, which sucks the beetles into a cylinder of soapy water, although its long power cord carries the danger of tripping us or decapitating a plant or two.

To prevent the beetles from reaching early-sprouting tubers, especially in large plantings, you might want to dig a barrier ditch around your potato bed. The early colonizers walk to their first food sources. A near-vertical-sided, plastic-lined, dry ditch 4 to 6 inches deep and 4 inches wide cutting across their line of movement can trap these migrants and prevent early colonization.

Timing and trap crops
Planting dates turn out to be important for the control of Colorado potato beetle. A standard recommendation is to plant potatoes very early (early April in Ohio, for instance), so that the plants bloom before June, and the beetle damage occurs too late to affect yield. To advance the season, place plastic sheets on the soil to warm it up.

Shifting planting dates at the other end is also a possibility. If your season length permits it, delay planting altogether until a month or more past May.

Another option is to plant an early potato crop as a trap crop. When the early crop is attacked, you can kill the beetles with a flamer. For a small garden, an ordinary hand-held propane torch will work as well as a long-handled weed flamer. Potato sprouts are fairly resistant to heat damage, and early sprouts attacked by the beetles will re-grow even if they’ve been damaged by fire. Or you can plant a main crop directly after flaming. Keep in mind that flaming cannot be used with a straw mulch or other inflammable mulch materials.

Mulches and row covers
Planting potatoes in, or just beneath, a thick straw mulch has been shown to reduce damage from a number of potato pests, including aphids and flea beetles, as well as Colorado potato beetles. Mulches attract predators, such as carabid ground beetles and hunting spiders, which feed at night. But mulches may not be successful in damp cold areas where slugs are a problem.

As is the case with so many pest problems in small vegetable gardens, preventing migrating insects from reaching the plants by using row covers is a useful tactic. Anchor the covers securely into the soil because Colorado potato beetles are strong walkers and could move in under unburied row cover edges.

Nematodes and parasites
The deliberate introduction of biological controls can be effective against the Colorado potato beetle. The cost of these predators and parasites may make it desirable for you to split the purchase with friends and neighbors. But releasing just one batch can help restore natural enemies of the beetles to areas depleted by years of spraying or habitat destruction.

Before planting, you can introduce purchased beneficial nematodes into the beds. Be sure the soil is moist, and carefully follow the package instructions. We water in nematodes late in the day to prevent them from drying out before moving into the soil. The nematodes are most effective in light, well-drained soils, since they move within the soil and water solution. Heavy clay soils discourage their distribution below ground. Beneficial nematodes attack the overwintering beetles as they lie buried in the soil. They will help reduce flea beetle and click beetle larvae as well.

The tiny parasitic mini-wasp Edovum puttleri is also commercially available. Research has shown that it may parasitize up to 50 percent of the Colorado potato beetle egg masses on potatoes and an even higher percentage on eggplant (up to 91 percent). If you grow both potatoes and eggplant where Colorado potato beetle is a problem, you may find it worthwhile to release Edovum puttleri. Many garden catalogs include this species. Release the wasps when you see the first yellow egg masses. Release them again on the second batch of eggs in early summer. In many areas this second batch of eggs is the start of the heavy damage period.

There are also a number of predatory insects that feed heavily on Colorado potato beetles. Soldier bugs are one such predator, and there is now a commercially available attractant to increase their numbers in the garden. At first glance, soldier bugs look like stink bugs, but by watching you may see them attack other insects. Among your vegetables, include plantings that bring in the natural predators and parasites of a wide variety of pests. Coriander, dill, fennel, and sweet alyssum will sustain many beneficial insects, including some that prey on Colorado potato beetles.

Insect diseases
In general, a good way to reduce insect pest numbers is with a pathogen that causes disease in the insect, is specific to it, but does not kill its natural enemies. A number of new Btt (Bacillus thuringiensis tenebrionis) products have high selectivity for Colorado potato beetles and virtually no mammalian toxicity. Btt works best against the early larval stages, so must be timed properly. Wait until all the egg masses have hatched. You can tell because only the shells will be left, and little larvae will be crawling nearby. The larvae have to eat the Btt from the leaf, so coat the leaves thoroughly, especially the undersides.

This Btt is different from the better-known Bt pathogen used to control caterpillars. Be careful to get the right product. Like all live biological products, Btt can be damaged by long storage and high heat, so purchase it from a reliable source. Follow the directions carefully, since mixing with soft water (low pH) is essential. The directions will tell you how to do this and what remedy to follow if your water is hard (i.e., it contains calcium and other minerals).

Beauveria bassiana is a commercially available fungal pathogen that is effective against Colorado potato beetles. Beauveria bassiana has a wider host range than Btt and works best under moist conditions. As with the Btt, it is most effective against the young larvae. However, it can also be sprayed directly on the beetles.

With so many methods available for preventing intolerable damage, you can keep a few Colorado potato beetles in the garden as appreciated wildlife rather than as overwhelming pests.

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