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Cabbage Looper

Trichoplusia ni

Cabbage Looper

Trichoplusia ni cabbage looper

Trichoplusia ni.01

by Dumi. CC BY-SA 3.0

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Trichoplusia ni, the Cabbage Looper, is a medium-sized moth targeting plants in the Brassicaceae family. They get the common name 'looper' after the way the caterpillar walks, forming a semi-circular loop with the extended body. They possess an extensive host range, being able to survive on over 120 species of plant. Although, compared with other pests, their damage isn't too severe. It can sometimes be challenging to get rid of them due to their growing resistance to pesticides. Luckily, they have a whole range of natural predators which can help control them, including wasps, birds, bats and spiders.
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Has many natural predators to help control populations.
Can ruin yields making vegetables inedible.


Adults: They're a medium-sized insect with a mixture of light, dark brown and grey mottling, with a white distinctive 'U' marking on the forewings. Wingspan: 2.5cm / 1 and a half inches. Larvae: They're pale green like the vegetables they attack, this is how they remain camouflaged until the damage is severe. Faint white lines run the length of the body, with two bold lateral stripes. They possess 2 pairs of prolegs and 3 pairs of legs near the head. Pupae: The cocoons are green and attached to the undersides of foliage with masses of stretched silk. Eggs: Are pale creamy yellow with ridges, laid singly by the female under leaves of hosts.


Chew leaves of plants. Can defoliate plants. Older larvae tunnel heads of vegetables.











North America and some parts of South America

Biological treatment

Unfortunately, some species of owlet moth give rise to caterpillars that can be highly destructive. Collectively known as Cutworms, these larvae can severely damage plants, particularly in agriculture. By regularly monitoring the high-risk plants in your garden (see below) you might be able to catch these pests before damage is made irreversible. If damage has already been done, not to worry, we've put together some tips and tricks that will help prevent another infestation in the following years. Always try to scarify and plough the soil before doing any planting. This will hopefully reveal any pupae or larvae hiding in the topsoil. Weeds and plant debris should be cleared two weeks to ten days before planting. Plant checks should be undertaken during the nighttime using a torch, or at dawn, this is when caterpillars will be most active. A range of insects and animals eat cutworms. Sometimes it's worth waiting for other insects to take care of your pests if the infestation is considered average. Parasitic wasps and flies use these caterpillars to feed their larvae. Likewise, ground beetles, lacewings, praying mantis, ants, and birds will all eat these insects. Before you sow your seeds, let your chickens loose on your veg patch. They will clear the area of grubs, caterpillars or any overwintering pupae. If available, you can purchase beneficial predatory nematodes from some commercial retailers. Watering these into the soil should eliminate the caterpillars hiding beneath the topsoil. Soil temperatures need to be between 12-20ºC for the treatment to be effective. Diluted neem seed and leaf sprayed onto potato in regular intervals is proposed an effective treatment. Baits are most effective when other resources are limited. These can be purchased online or from garden retailers. If available, pheromone traps are a brilliant way to catch male moths in search of females. Not only do you reduce the reproductive success of the males in the area, but you can also use traps to monitor the infestation level of your garden. Installing protective collars, made from plastic cups, bottles, or paper tubes, etc., can help protect the stems of young plants. Sticky substances are another barrier that can be effective at preventing caterpillars from reaching stems. Diatomite earth, sawdust, or crushed eggshells are substances disliked by caterpillars.

Chemical treatment

Lastly, there is a whole range of chemical products varying in persistence and toxicity, that can be purchased from a local garden centre. It's always best to check the products active components before using them. They're frequently undergoing restrictions and bans. Follow label instructions carefully and always double-check if you are feeling unsure. Be sure you're using the correct volumes of product to water ratio, using the proper nozzle. It's essential to assess whether the crop is worth saving or not because treatments can result in some resistance build-up in the pest population. Likewise, if you intend to eat your crop, be sure it's listed on the bottle label. Contact insecticides containing natural plant oils can be more environmentally benign than synthetic pesticides. Look out for products containing natural pyrethrums, fatty acids and plant oils. Synthetic pyrethroids that are available for home use include ingredients: Deltamethrin, lambda-cyhalothrin and cypermethrin.


A close up of a green Brassica rapa var. chinensis plant

Pak Choi

Brassica rapa var. chinensis

Chinese Cabbage

Brassica rapa (Pekinensis Group)

A close up of a green Brassica oleracea var. italica (Italica Group) broccoli plant


Brassica oleracea var. italica (Italica Group)

A close up of a green Brassica oleracea var. botrytis plant in a garden


Brassica oleracea (Botrytis Group) 'Cauliflowers'


Brassica oleracea (Capitata Group) 'Cabbages'


Spinacia oleracea


Pisum spp.

A close up of some white Nasturtium flowers and green leaves


Nasturtium spp.

A close up of a white and yellow Solanum tuberosum flower


Solanum tuberosum


Dianthus spp.


Wasps, spiders, centipedes, bats, birds and rodents.
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