Cabbage Looper Control: Information On Killing Cabbage Loopers

By: Bonnie L. Grant, Certified Urban Agriculturist

If you see green, fat-bodied caterpillars on your cabbage that move like little drunks, you probably have cabbage loopers. Cabbage looper pests are common on all cruciforms in the United States, Canada and Mexico. Killing cabbage loopers is essential to an attractive crop, free of holes and rotting spots. Learn how to get rid of cabbage loopers with chemical or mechanical means.

About Cabbage Looper Pests

Cabbage loopers have up to seven instars. The larvae mature to thick green caterpillars with a white stripe running along either side. They have five pairs of prologs and a cigar shaped body, which is thinner at the head end.

By the time the larvae reaches maturity, it may be as much as 2 inches (5 cm.) long. Once the looper pupates, it becomes a grayish brown moth. The larvae have chewing mouthparts, which damage foliage on a wide range of plants. The chewing behavior leaves foliage tattered and ragged with jagged edges.

Cabbage looper control and management helps ensure the vitality of your plants. Leaf damage minimizes the ability of a plant to gather solar energy.

How to Get Rid of Cabbage Loopers

The easiest, most accessible and safest way to get rid of cabbage looper pests is by manual removal. The caterpillars are big enough that you can easily spot them. Look in the morning and late evening when temperatures are cool. Pull off the icky little things and dispose of them. (I leave the details up to you, but see to it that they don’t reach adulthood.)

Look for eggs on the underside of plant leaves and scrape them off gently. Eggs are ridged and laid in rows along the undersides of leaves. Preventing the next generation is a great way of killing cabbage loopers.

Avoid the use of broad range pesticides, which will also kill beneficial predators. Whenever possible, use organic cabbage looper pesticides if you wish to use chemical warfare.

Cabbage Looper Control

It is best to use organic cabbage looper pesticides on food crops. They are safer and do not kill most beneficial insects. Bacillus thuringiensis (Bt) is an organic bacterium, which occurs naturally in soil.

Pesticides with spinosad are also effective and safe, with little impact on beneficial insects. The best results are obtained by early application when larvae are small. Check the undersides of leaves every week for signs of cabbage looper pests. Visual cues, such as ragged leaves, are also a good indicator that it is time to spray with organic cabbage looper pesticides.

Consistent cabbage looper control will gradually reduce the incidence of the pests in your garden.

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How to Spot, Treat and Prevent These Pests

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Whether you are new to gardening or an experienced enthusiast, you are probably familiar with a super common insect moth: the dreaded Cabbage Looper.

They are not dangerous, but they are fierce. They love most of the plants in your botanical garden, especially the leafy greens. They will eat up your hard work and harm your plants.

Want to know how to spot them and get rid of them? This guide will help.

Identify and Get Rid of Cabbage Loopers Organically

In many parts of North America, midsummer cole-crop plantings ought to be leafing out nicely now, and it's a pretty good bet that a sizable percentage of those tasty members of the Brassica group of vegetables will—at one time or another—be attacked by cabbage loopers. This approximately 1-1/2-inch-long caterpillar (which goes by the Latin name Trichoplusia ni) earned its more common moniker as a result of its unusual method of locomotion. Rather than keeping its body level with the surface beneath it and sort of undulating along as most caterpillars do, you see, the looper arches its body while walking (as shown in the photo), thus appearing to be "looping" itself. Although this peculiar gait (which results from the fact that Trichoplusia ni lacks two of the five pairs of stubby legs common to most caterpillars) resembles that of an inchworm (Geometridae family), the two creatures are unrelated. Loopers are, instead, members of the noctuid moth family, in which can also be found such pests as cutworms, army worms, and corn earworms.

As you'd imagine, the cabbage looper's preferred host plants include all of the coles—cabbage, broccoli, brussels sprouts, cauliflower, kale, collards, etc.—as well as lettuce, spinach, beans, peas, celery, parsley, parsnips, radishes, potatoes, and tomatoes. The considerable damage caused by this caterpillar typically takes the form of numerous irregularly shaped holes chewed through the leaves of the host vegetable. Mature and healthy plants can often survive minor infestations without suffering too much harm, but young seedlings or transplants may respond to an attack by developing a stunted, misshapen appearance and providing a poor yield.

The pest is common to the United States and to southern Canada. Its larvae hatch from minute, pale green eggs that the adult—a small, mottled brown nocturnal moth with an irregularly shaped silvery marking on each front wing—lays on the upper surface of the infested plant's leaves. In the moth's northernmost range, two generations are usually completed in a single year, while in its warmer southern realm, four (or more) generations may be produced annually.

Fortunately, options are available to those gardeners who are faced with a cabbage looper problem but would rather not resort to broad-spectrum insecticides in solving the crisis. If the infestation is still in its early stages, it should be fairly easy to remove the loopers by hand (chickens seem to savor the pests!). A better approach, if your eyesight and patience are up to it, would be to spy—and stop—an "attack" before the bugs hatch.

When a more serious infestation occurs, though, it might be time to get out the big guns, in this case the bacterium, Bacillus thuringiensis. Sold in both powder and liquid form under such names as Dipel and Thuricide, this bacterial agent can—in a gardening emergency—really save the day. Do use it only as a last measure, sparingly, and with a great deal of caution in application, though, because the substance will kill the larvae of beautiful and harmless butterflies and moths as readily as it destroys loopers.

Finally, should you find your cabbage patch slowly disappearing down the maws of a horde of wormlike chewers, remember that the pests might actually be imported cabbageworms (Pieris rapae), diamondback moth larvae (Plutella xylostella), or even garden webworms (Achyra rantalis) rather than loopers. Fortunately, the differences among these larvae are relatively unimportant, because the pests prey on the same plants, and can be controlled with identical techniques!

Garlic Water

Garlic water works as a repellent for cabbage worms. You can use a commercial product such as Garlic Barrier, or you can make your own garlic water. Mix one1percent pure garlic juice with 1 percent fish oil and 98 percent water. Put the mixture in a pump sprayer and saturate the leaves and head of the cabbage. A study conducted at the Alabama Agricultural Experiment Station showed that garlic water worked better than a synthetic insecticide to minimize both cabbage worms and their damage.


Cabbage loopers are found throughout the US, although they only overwinter in warmer climates.

According to experts from the Entomology Department at the University of Florida, these pests can complete between two and seven life cycles each year.

Warmer temperatures lead to the completion of more life cycles, which means you’ll be dealing with them for most of the growing season.

In the south, this pest overwinters as an adult and some of these adults migrate north in the spring.

John L. Capinera from the University of Florida Department of Entomology and Nematology notes that it has been estimated that adult cabbage looper moths have a flight range of up to 125 miles.


How to Identify Cabbage Worms

Cabbage worms are velvety green larvae. They have a few faint yellow stripes. They are not to be confused with cabbage loopers, which are yellow-green caterpillars. Unlike cabbageworms, cabbage loopers raise and lower their bodies as they move because they have no middle legs. Cabbage worms become cabbage white butterflies, which are mostly white with a few black markings. Cabbage white butterflies might seem like a pretty addition to the garden, but they are probably laying eggs on the undersides of leaves.

Where you find cabbage worms and cabbage loopers, you also might find the eggs and larvae of the diamondback moth and the zebra caterpillar. The camouflage of these creatures is excellent, so you will often see the frass, or fecal matter, that they leave behind before you see them.

Photo Credit: Cabbageworm eggs like the one in this picture are absolutely tiny, so you might not see them before it’s too late.

Cabbage Worm Damage

Cabbage worms can happily eat away at the bases of cabbage, cauliflower, or the heads of broccoli without being noticed. They feed on foliage, and eventually they can leave plants only with stems and large veins. If left to their own devices, cabbage worms can devour your crops. Their fecal matter can also stain and contaminate the produce.

Photo Credit: Purdue University. Imported cabbageworms feed on the flesh of foliage and often hide on the undersides of leaves.

More Advice on Organic Cabbage Worm Control

Red-leafed varieties of cabbage and kohlrabi are less preferred by cabbage worms, probably because they provide poor camouflage.

You can increase the number of paper wasps that patrol your garden by hanging bottomless birdhouses nearby, or simply use small wooden boxes with no bottoms. They make excellent nesting sites.

Grow plenty of flowers and blooming herbs to provide a continuous supply of nectar for beneficial insects. Provide perches to increase how many cabbage pests are snapped up by birds.

More information on organic cabbage worm control is available from Ohio State, University of California, University of Maryland.

Watch the video: Foolproof Way to Kill Cabbage Worms and Cabbage Loopers!

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