Who eats the colorado potato beetle

Who eats the colorado potato beetle

Anyone who grows potatoes is familiar with the Colorado potato beetle. This insect pest is one of the best known beetles, famous for it’s ability to devour vegetables in the nightshade family: potato, tomato, eggplant and peppers. The adult beetles as well as their larvae can strip the plants of leaves and ruin an entire crop, if left to their own devices.

The rather attractive dome-shaped adults are nearly a half-inch long, yellow, with five black stripes on each wing cover. In late spring, after hibernating in the soil, usually along field edges, they emerge, with one thing on their mind: finding a food source. They walk toward this goal for a few days until they have the strength to fly about looking for potato plants or their relatives. Once they find them, the female beetles start snacking on foliage and laying clusters of 15 to 25 bright yellow-orange eggs on the undersides of the leaves. From these hatch the soft-bodied, hump-backed larvae that look a little like slugs.

They larvae start out small but grow fast, molting four times into larger stages, or instars. The last instars grow to be quite plump, and they’re the ones that eat the most foliage. Then, they crawl into the soil and pupate. From this resting stage, a second generation of adults emerges by the end of the season, ready to eat again before passing the winter underground.

It’s amazing that not long ago, this serious pest of vegetables pest was a harmless, well-behaved insect. It fed only on the buffalo bur, a tough weed that grows along the eastern foothills of the Rocky Mountains. Then, about 150 years ago, the beetles discovered a new food growing in the white man’s gardens. It adopted the cultivated potato as its favorite food, spread rapidly, and we’ve been fighting Colorado potato beetles ever since.

It happened like this: with the opening up of the West following the Mormon migration to Utah in1847 and the California gold rush of 1849, pioneers arrived by the thousands and many of them planted potatoes. By 1855 potato growing reached westward to the native home of the beetle, and the insect started to spread eastward along the routes traveled by the pioneers.

By hitchhiking and flying with the prevailing winds, the beetle migrated about 85 miles a year. It reached Nebraska in 1859, Illinois in 1864, Ohio in 1869, and the Atlantic coast in 1874. This caused great alarm overseas, and almost every European country banned the importation of American potatoes. Europe’s potato growing regions remained free of potato beetles until after World War One, when they appeared near Bordeaux, France, where there had been concentrations of American troops and supplies. Now the beetle is widespread in Europe, too.

Prior to the coming of the Colorado potato beetle as a pest, the name “potato bug” was used to describe a different beetle that is a relatively minor pest on potatoes. Now called the “old-fashioned potato bug”, this long slender beetle has two black stripes on each wing cover. The adult feeds on potatoes but lays its eggs in the ground and the predatory young feed on grasshopper eggs and the like.

There are many naturally occurring controls of Colorado potato beetle. Fungi infect them, beneficial insects attack them, and toads and birds eat them. Rarely, however, do these forces combine to offer sufficient control to protect crops. Home gardeners resort to hand picking the beetles, followed by squishing, stomping or drowning them. Over the years, farmers have unleashed an arsenal of insecticides against the potato beetle, only to find it developed resistance to many of them.

In recent years, new pesticide materials have been developed that have lower human toxicity and less environmental impact than those of the past. The most widely used of these is a strain of the B.t. bacterium that specializes in infecting potato beetles. It’s sold under several bio-insecticide brand names. However, development of resistance remains a concern if a single class of insecticide is relied upon too heavily for control.

Cultural practices play an important role in the management of Colorado potato beetle, as they help minimize the need for insecticides, protect natural predators, and prevent the development of pesticide resistance. Such practices include crop rotation, trapping, mulching, row covers, and flaming.

By changing the location of host plants, crop rotation is one way to suppress potato beetle populations because it makes it harder for them to get to their food after they emerge in the spring. The problem is, the pest is rather mobile so long distances are needed between last year’s fields of potatoes and this year’s in order to have much of an effect. A few hundred feet doesn’t do much; a few thousand feet may help; but a mile or two is better. Physical barriers like rivers or roads in the terrain between rotated fields can enhance the effectiveness of crop rotation.

Mulching the potato crop with straw after an early-season hilling may also reduce the Colorado potato beetle’s ability to locate potato fields, and the mulch creates an environment that favors beetle predators. Growers using this system note that the straw should be spread so it’s touching the potato plants, but only a light layer of straw mulch is needed. Another way to protect plants is to place lightweight floating row covers over them and then seal the edges, well before the beetles arrive.

Plastic-lined trenches have been used to trap beetles as they head toward a field of potatoes in the spring. A plow or heavy disk can be used to form a shallow trench around a field or along the edge of a field by a hedgerow or previous potato field where new beetles are likely to come from. Then black plastic is placed in the trenches, sort of like an ‘upside down’ raised bed. Since the beetles can’t fly when they first emerge, they walk toward their food and fall into these shallow trenches. The dust keeps them from getting enough of a grip to get out, and as the black plastic gets hot the beetles get roasted.

Flaming of the early-season adults is another practice that’s employed to roast beetles. As they start to colonize field a tractor-mounted or hand-held flamer can be used to create a very quick pass of intense heat directed at the plants while they are still small. This needs to be done when weather conditions are right for the beetles to be active on top of the foliage. The potato plant can recover from this brief exposure to intense heat, but the beetles are injured, and fall to the ground, unable to recover.


Colorado Potato Beetle Management

ENTFACT-312: Colorado Potato Beetle Management | Download PDF

Ric Bessin, Extension Entomologist
University of Kentucky College of Agriculture

The common black and yellow-striped “potato bug”, a very familiar insect to home gardeners, is the most serious insect pest of potatoes. Both the striped beetle and the black-spotted, red larva feed on potato leaves. Their damage can greatly reduce yield and even kill plants. In addition to potato, Colorado potato beetle can be a serious pest of tomato, eggplant, and pepper.

The Colorado potato beetle is notorious for its ability to rapidly develop resistance to insecticides that are used repeatedly for control. This has been a serious problem on the east coast for some time, and is becoming more of a problem in Kentucky. With a limited number of insecticides available, some homeowners feel they have exhausted their control options when it becomes resistant to one or more insecticides.

Colorado potato beetles overwinter in the soil as adults. They become active in the spring as temperatures rise and begin to feed on weeds and volunteer or early planted potatoes, even entering the soil to attack emerging foliage. Female beetles lay orange-yellow eggs in batches of about two dozen or so on the underside of the leaves. Each female can lay 500 or more eggs over a four to five week period. Eggs hatch in four to nine days and the larvae begin to feed on potato foliage.

The larvae are humpbacked with two rows of black spots on each side. They usually feed in groups and damage can be severe. The larval stage lasts two to three weeks.

Full grown larvae burrow in the ground to pupate. In five to 10 days, the adult beetle emerges. This insect can go from egg to adult in as little as 21 days. The newly emerged adult female feeds for a few days before egg laying begins. There are two full and occasionally a partial third generation each year. If foliar sprays are used, an effort should be made to treat just after most eggs have hatched but before serious plant damage occurs.

Resistance Management

Insecticides in the same chemical class usually have the same mode of action, the same method of killing the insect. Resistance develops more rapidly to an insecticide when that insecticide is used repeatedly as the only control measure. Repeated use of one class kills susceptible beetles, leaving those that are resistant. Overuse of one insecticide may favor the development of resistance to other insecticides in the same chemical class. Consequently, to delay or prevent resistance it is important to avoid repeated usage of one particular insecticide by rotating the insecticides used.

Rotation needs to be among different classes of insecticides (see table below). For example, rotation between Warrior and Asana would not be as effective as a Platinum, Asana rotation. Because Warrior and Asana are in the same class of chemicals and have the same mode of action, little is gained with this type of rotation. Note that the insecticides marked with an asterisk in the table are available to homeowners.

Table 1. Availability of Insecticides to Control Colorado Potato Beetle on Different Crops

Bacillius thuringiensis var tenebrionis (Bt) is effective against small larvae (less than 1/4 inch) and should be applied at egg hatch or when larvae are first seen. A premature treatment may lose much of its effectiveness before the eggs hatch. Larger larvae are more difficult to control with Bt. Azatin, an extract of the neem seed, prevents the larvae from developing normally.

Frequently, control failures with Colorado potato beetle are due to other factors besides just insecticide resistance alone. Timing of sprays is critical for control. Overwintering beetles are attracted to fields over a period of several weeks; spraying an insecticide too early may only control a portion of those beetles. However, waiting until larvae are nearly full grown also increases the chances of control failure. Small larvae are much easier to control with an insecticide than large ones. Using the correct amount of insecticide as well as obtaining complete coverage of the plants is important.

Insecticides should only be used when needed. Potato plants can withstand considerable defoliation without yield loss. Plants can loss up to 30% of their foliage without yield loss. Generally, insecticides do not need to be applied unless there is more than an average of one beetle or larva per plant. Additionally, some beneficial insects such as birds, predatory stink bugs, and parasitic flies will help to reduce Colorado potato beetle numbers somewhat.

Other non-chemical control measures such as hand picking of adult beetles and immature stages is encouraged as this will aid to delay the development of resistance. Hand picking can be particularly effective in reducing the numbers of overwintering beetles coming to the young plants in the spring. Resistance by Colorado potato beetles should be managed on a field to field basis. While they may be resistant to one insecticide in a particular location, those in other areas within the same county may not have developed resistance to that insecticide.

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.



Colorado potato beetles

Quick facts

The Colorado potato beetle is a major potato pest throughout North America.

  • It also feeds on eggplant, tomato, pepper and other plants in the nightshade family (Solanaceae).
  • They become active in spring when the potatoes emerge.
  • Larvae and adults feed on leaves and can completely defoliate plants.
  • Most pesticides are ineffective against them.
  • A combination of pest management tactics can reduce Colorado potato beetle numbers.

How to >(Leptinotarsa decemlineata)

Active June through September.

Oval in shape and 3/8 inch long.

  • Have a yellow-orange prothorax (the area behind the head) and yellowish white wing covers with 10 narrow black stripes.
  • Females lay clusters of bright yellowish-orange oval eggs on the unders > Colorado potato beetle larva
    • When young larvae first hatch, they are brick red with black heads.
    • Older larvae are pink to salmon colored with black heads.
    • All larvae have two rows of dark spots on each s >Colorado potato beetle adults live through the winter in potato fields, field margins, windbreaks and gardens.

    Egg mass on underside of leaf

      Adults feed for a short time in the spring, and then begin to mate and lay clusters of 10-30 eggs on the unders >In southern and central Minnesota there is generally a second generation. By midsummer, all stages of Colorado potato beetles, eggs, larvae and adults can be present in a potato field.

    Damage caused by Colorado potato beetles

    How to protect your plants from Colorado potato beetles

    Treatment of Colorado potato beetles in home gardens can be challenging.

    Keep your garden clean

    When Colorado potato beetles first emerge in the spring, they will look for other hosts in the absence of potato plants.

    Clean up weeds like nightshade and ground cherry near your garden, as these weeds can act as a possible food source.

    Plant early maturing varieties

    • Plant an early maturing variety to escape much of the damage caused by adults emerging in m >Growing potatoes only every other year may help reduce beetle populations if
    • no potatoes are being grown within a radius of ¼ to ½ mile away, and
    • temperatures are not excessively warm.

    Pick beetles off plants

    Handpicking in small gardens can be effective.

    • Drop adults and larvae in a pail filled with soapy water.
    • Remove or crush the yellowish orange eggs on the unders >Bacillus thuringiensis var. tenebrionis, a naturally occurring bacterial disease, can control young Colorado potato beetle larvae (1st and 2nd instars).

    It is not as effective on larger larvae and adults.

    • Apply the product every few days, beginning when egg masses begin to hatch.
    • If you wait to apply this material when larvae are in the 4th instar, this method will not be effective.

    Using pestic >Colorado potato beetles are resistant to synthetic pesticides like carbaryl and permethrin, so don’t use them.

    Anytime you use a pesticide and it does not seem to kill Colorado potato beetles, switch to a different active ingredient.

      Esfenvalerate – relatively new synthetic pestic >Colorado potato beetles are not resistant to azadirachtin or spinosad. These products are also “soft” on natural enemies.

    Azadirachtin needs to be reapplied frequently and provides poorer control of large larvae and adults.

    CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Remember, the label is the law.

    Be sure that the vegetable you wish to treat is listed on the label of the pesticide you intend to use. Also be sure to observe the number of days between pesticide application and when you can harvest your crop.

    Jeffrey Hahn, Extension entomologist; Suzanne Burkness, College of Food, Agricultural & Natural Resource Sciences; Dave Ragsdale and Edward Radcliffe


    7 Ways: How To Control Colorado Potato Bugs and Beetles

    If you’re trying to grow potatoes (or any member of the hemlock family or solanaceous crops) one of the most often encountered problems is the Colorado potato bug or beetle.

    Larva and adults beetles prey upon potato plants by eating both the blossoms and the leaves.

    In addition to potato plants, these voracious little beetles also lay waste to other members of the hemlock family, such as peppers, eggplant and not to mention creates tomato plant problems.

    When plants loses a great number of leaves, its vigor and ability to produce fruit are hampered. All of these plants will suffer reduced production levels if potato beetles continue to consume your plants.

    Potato Bugs – These Beetles Are Very Flashy!

    Colorado potato beetles (leptinotarsa decemlineata) are most commonly found in the southwestern areas of the United States. You will begin to see the adults emerge late in the spring time when you’re potatoes are just beginning to establish themselves and grow well.

    Adult potato beetles, potato bugs or Jerusalem crickets are easy to spot because they are quite dramatically marked. Their wings are black and striped with a yellow-orange color, and their heads are orange with black spots.

    You’ll find the adults amongst the foliage of your potato plants. Unless you intervene you will soon see clusters of reddish potato beetle larvae on the tips of your potato plant branches.

    If you are growing eggplant, the potato beetle larvae will be gray. As they get larger, you will notice the potato beetle larvae beginning to sport black dots on their sides.

    How To Recognize Potato Beetle Damage

    During the potato beetle larval stage these bugs are hungry little critters.

    They first go for the tastiest and most tender parts of plants. You can find them infesting gardens with solanaceous plants or those that are from nightshade family.

    For this reason, they will usually eat the flower buds from potato plants before eating the leaves.

    They move very quickly, and if interfered with they will strip all foliage from your potato plants.

    It is important to note that this is more likely to happen when you plant a mono crop.

    In other words, if you have all potatoes, tomatoes or other hemlock type plants you are more likely to lose your whole crop.

    Crop Diversity Is Key

    If you have a mixed crop, potato beetle larvae may ignore some plants and focus on others, so it’s a good idea to keep a diversified organic garden.

    This type of garden is more likely to attract beneficial insects which are natural predators of potato beetles.

    When you have a good assortment of beneficial fauna in your garden, you can be sure that potato beetle eggs, larvae and even adult beetles will be consumed.

    You want to have a good mix of ladybugs, ground beetles and small wasps. In this way you can be certain that eggs, larvae and beetles will have to fight to survive.

    The Lifecycle Of The Colorado Potato Beetle

    Adult potato beetles can live through the winter by hiding under the bark of trees or other cover to protect them from freezing.

    When the weather warms up in the middle of the spring time, they come out of hiding and seek out potato plants or other hemlock type plants.

    Once they find the type of plants they need, they eat, mate and lay eggs.

    Within a couple of weeks, the eggs hatch and the larvae will begin feeding on the plants. This goes on for another couple of weeks until the larvae become pupa.

    From the laying of eggs to the time the pupa become adults can take 30-45 days.

    The amount of time is dependent upon the weather. In cooler weather, this transformation takes longer. In warm weather the entire process usually takes about 30 days.

    When you live in a warm climate, you may get a double dose of potato beetles every year!

    When the cycle of metamorphosis takes only 30 days, it is entirely possible for it to be completed twice in a growing season.

    How To Keep Your Potato Plants, Eggplants, Peppers & Tomatoes Relatively Free Of Potato Beetles

    Organic control is most effective for pest management. You might think spraying pesticide would be a good idea, but you’d be wrong.

    You will have far more success fighting off potato beetles with an arsenal of natural weapons.

    There are a number of organic ways of controlling potato beetles and maybe some other pests such as tomato fruitworm, aphids, and others. Among them include:

    • Pick the potato beetles off from the soil or plant as you see them.
    • Attract beneficial insects to your garden.
    • Line trenches between rows with plastic.
    • Mulch the soil and plants heavily with straw.
    • Practice crop rotation

    These natural solutions are far better than chemical insecticides because as time has passed, the Colorado potato beetle has developed commercial insecticide resistance from a vast majority of brands.

    For this reason, it is more effective to use a variety of organic methods to catch potato beetles off-guard.

    One example is making use of essential oils such as a neem oil, which is known as an effective solution against garden pests.

    Diatomaceous earth also does a great job of eliminating insects and other harmful insect pests in your potato fields.

    Attract Helper Beneficials

    The best beneficial fauna or natural enemy to help you in your fight against potato beetles include:

    • Predatory Stink bugs (hemiptera pentatomidae)
    • Double eyed soldier bugs (perillus bioculatus)
    • Parasitic Wasps
    • Domestic Fowl
    • Ground Beetles
    • Box Turtles
    • Ladybugs
    • Spotted lady beetles (coleomegilla maculata)
    • Birds
    • Toads

    You can attract a lot of beneficial insects for biological control by planting flowers amongst your potato crops.

    In addition to insects that will help you fight potato beetles, planting flowers will also attract pollinators such as butterflies and bees so it’s a win-win all around.

    Taking A Proactive Stand: 10 Ways To Combat Potato Bugs

    Along with forming an alliance with beneficial fauna, there are a number of steps that you can take to keep potato beetles at bay. Among them are:

    1. Rotate your crops. This is a very effective way to baffle potato beetles and to prevent them from being able to find your crops. It’s a good idea to alternate grains with tubers to prevent having potato beetles establish themselves.

    2. Dig trenches between your rows of potato plants. These trenches should be a foot wide and dug at a 45 degree angle. Line each trench with black plastic. When the potato beetles fall into the trench, they will be trapped.

    3. When your young potato plants have emerged and are growing well, mulch around them with straw or hay. Be sure to do this early enough that potato beetles have not yet found your plants. When they come looking and make their way across the straw or hay, they are very likely to encounter the one of the natural predators you have cultivated.

    4. Use floating row covers to protect your potatoes once you have mulched them. Open them up once a week and examine your plants to be sure that potato beetle larvae or adults are not present. If they are, remove them by hand.

    5. Keep chickens, ducks, geese and/or guineas. Once your potato plants are fairly mature (one foot tall) you can let your flock wander through them from time-to-time to pick off potato beetles.

    6. Carry a bucket of warm soapy water with you when you examine your potato plants. It’s also a good idea to carry a little mirror with you so that you can easily examine the undersides of your potato leaves.

    If you see larvae or adult beetles, remove them and drop them in the soapy water. Doing this every day will greatly reduce the number of potato beetles in your garden. Using an insecticidal soap will make killing pill bugs, sow bugs and potato bugs easier.

    7. Plant potato beetle resistant varieties of potato such as “King Harry”. This type of potato plant has a great many leaf hairs, making them undesirable to potato beetles.

    8. Mix buckwheat plants into your garden. Potato beetles don’t like them, but predatory wasps do. The blooms of the buckwheat plants will attract these beneficial garden insects at just the right time to help you battle potato beetles.

    9. If you see lots of larvae on your plants, you may want to spray with organic spinosad insecticide. This organic pesticide is produced using fermentation.

    It is save for indoor and outdoor plants, fruit trees, flower gardens, lawns and veggie gardens. It is listed as safe for use in organic food production by the USDA National Organic Program.

    10. Throughout the growing season, continue to add coarse mulch around your potato plants. This can be straw or hay or even grass clippings or leaves. This type of mulch provides habitat for natural potato beetle predators.

    Potato Beetles Are Garden Enemy #1

    Because they are so adaptable, reproduce so prolifically and wreak havoc with all kinds of hemlock crops, potato beetles are the scourge of many a gardener’s existence.

    The challenge of coping with their notorious ways has spurred many a scientist into action.

    You can find lots of interesting information at the websites of several major universities. Additionally, there is even a website dedicated entirely to the contemplation of the potato beetle problem.

    It is Potatobeetle.org where you will find articles, tips, studies, anecdotal information and even potato beetle haiku and artwork submitted by young organic gardeners in the making.

    The main thing you should remember when battling potato beetles is that you will probably never overcome them.

    However, if you adopt a Wile E. Coyote sort of approach to them and keep devising one fiendish plan of attack after another, you have a good chance of keeping them at bay and having a bit of fun doing it!

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