more Images
Cabbage looper
Scientific name:
Trichoplusia ni
Order/Family:
Lepidoptera: Noctuidae
Type:
pest (insect/mite)
Common names:
semi-looper, cabbage semilooper
Host plants:
Cabbage/Kale, Brassicas  Tomato  Crucifers  
General Information on Pest and Damage
Geographical distribution
Geographical Distribution of the Cabbage looper in Africa (red marked)
Introduction
The cabbage looper is widely distributed in the tropics and subtropics. It is a serious pest of cruciferous crops, but it also attacks other important crops such as tomato, lettuce, potatoes, sweet potatoes, cotton, cucurbits, etc. The cabbage looper is somewhat erratic in occurrence, typically very abundant one year, and then scarce for two to three years.

Damage caused by cabbage looper on kales
© A. M. Varela, icipe
Damage
Caterpillars feed primarily on leaves and cause irregular holes. Young caterpillars eat small holes, but older caterpillars feed on the tissue between the veins skelotinising the leaves (leaving only the midribs and veins) or giving them a ragged appearance. Plants can be severely defoliated and stunted, producing no heads or becoming unfit for consumption. They may also bore into the heads of lettuce and cabbage, contaminating them with frass. The presence of caterpillars and contamination of marketable plant parts with frass reduce the market value of the produce. Thus, large amounts of dark green pellets excreted by the feeding looper may stain cauliflower heads. The presence of cabbage looper caterpillars in broccoli heads renders them unmarketable.

Host range
The cabbage looper has a wide host range that includes crucifers, beans, cotton and various vegetable crops. It is listed as feeding on over 160 species of plants in 36 families, but cultivated crucifers are preferred.

Affected plant stages
Vegetative growing stage.

Affected plant parts
Leaves and whole plant.

Symptoms by affected plant part
Leaves: external feeding; internal feeding; webbing; frass visible; shredding.
Whole plant: plant death; dieback; dwarfing; internal feeding; external feeding; frass visible.

back to Index
Biology and Ecology of the Cabbage Looper
The eggs are round or slightly dome-shaped with ridges, and about the size of a pinhead. They are pearly or silvery white and darken when they age. Eggs are laid singly usually on the undersides of leaves. A female moth can lay from 300 to 1600 eggs. Caterpillars hatch in 2 to 6 days after the eggs were laid.

Young cabbage looper feeding on a kale leaf. Mature caterpillar reaches 3 to 4 cm in length.
© A. M. Varela, icipe
The caterpillars go through five instars during development. Very young caterpillars are white and almost clear with a black head capsule. Older caterpillars are green with a thin white line on each side just above the spiracles and two other white lines on the dorsum. Caterpillars have three pairs of legs near the head and three sets of prolegs (false legs) near its rear. They move in a "looping" manner, arching the middle portion of the body as they move forward. Fully-grown caterpillars reach 3 to 4 cm in length.

Pupa of the cabbage looper. During its last larval stage the caterpillar spins a cocoon.
© A. M. Varela, icipe
Pupa. Caterpillars pupate in white loose cocoons attached to the underside of leaves, or in a folded webbed leaf or between two webbed leaves. The pupae are light green when young and gradually turn dark brown when mature. The moths are light green when young and gradually turn dark brown when mature. The moths emerge from the pupae 10 to 16 days after pupation.

Moth of the cabbage looper. Real size: ca 2.5 cm in length, wingspan is ca. 4 cm
© A. M. Varela, icipe
The adult is a mottle, greyish-brown moth, about 2.5 cm long and with a wingspan of 4 cm. The front wings have two small silvery spots, one small and round, the other U-shaped (resembling an '8'), near the middle part of the wing. The hindwings are pale brown. Cabbage looper moths are strong fliers and are primarily nocturnal. During the day the moths can be found resting in foliage or in crop debris.

Development from egg to adult takes about 4 to 6 weeks.
back to Index
Pest and Disease Management
Pest and disease Management: General illustration of the concept of infonet-biovision
This illustration shows the methods promoted on infonet-biovision. The methods shown at the top have a long-term effect, while methods shown at the bottom have a short-term effect. In organic farming systems, methods with a long-term effect are the basis of crop production and should be of preference. On the other hand methods with a short-term effect should be used in emergencies only. On infonet we do not promote synthetic pesticides.

Further below you find concrete preventive and curative methods against Cabbage looper.
back to Index
Cultural practices

Monitoring
Inspect plant regularly for the presence of caterpillars, leaf damage and the presence of frass. Caterpillars can be detected by scouting the crop, while adults can be monitored by using light- or pheromone-baited traps.

Monitor the presence of natural enemies. They play an important role in controlling the cabbage looper. Check plants twice a week once seedling emergence begins. When populations appear to be increasing, check more often.

Treatment thresholds vary depending on the crop and location. Normally, spraying should not occur when there is less than 1 caterpillar per 5 plants (CABI, 2000). A control measure is not necessary unless you find more than 9 small to medium-sized caterpillars per plant.


Management options
1. Plant resistant varieties, if available. Some resistant varieties are "Mammoth Red Rock", "Chieftan Savoy", and "Savoy Perfection Drumhead". Ask for assistance from local agriculture office to obtain cabbage looper resistant cultivars that are available in the local markets.
2. Remove and destroy all the plant debris after harvest. The pupae might still be present in the plants. Plough and harrow the field after harvest.
3. Clear the surrounding area of weeds, which may serve as alternative hosts for the pests.

back to Index
Biological pest control

Natural enemies

Natural enemies usually keep the pest populations at low levels and control measures are not often needed. Therefore, their conservation is very important. Avoid using broad-spectrum pesticides for the control of this or other pests. Cabbage looper infestations often increase after use of broad-spectrum pesticides due to elimination of natural enemies.

A wide range of natural enemies attacks the cabbage looper: predators, egg and larval parasitoids (parasitic wasps) and pathogens (Bt and viruses).

Egg predators and parasitoids are important since they kill eggs preventing any subsequent damage by caterpillars.

The nuclear polyhedrosis virus is particularly important in controlling this pest. The virus occurs naturally in the soil or on plants in most crop areas. Virus-infected insects can be reintroduced into the field by collecting diseased insects, mixing them in a blender, filtering out large tissue masses and then spraying the virus particles back onto the field.
back to Index
Biopesticides and physical methods

Bt (Bacillus thuringiensis)
Bt products give good control of the cabbage looper, and do not harm natural enemies. For optimum control, treatments should be applied when caterpillars are small. Frequent crop monitoring is helpful to know the optimal time to apply Bt and other insecticides.
For more information on Bt click here

Neem
Neem-based pesticides are reported to control the cabbage looper by interfering with the growth of young caterpillars. Fairly good control of this pest has been obtained with a 2% ethanolic extract of neem seeds (Ostermann and Dreyer, 2000). For more information on neem click here.

Physical control methods
1. Handpick the caterpillars and egg masses.
2. Use fine nylon nets as row covers to protect seedlings from egg-laying moths.

back to Index
Information Source Links
  • CABI (2005). Crop Protection Compendium, 2005 Edition. © CAB International Publishing. Wallingford, UK. www.cabi.org
  • Hill, D. (1983). Agricultural insect pests of the tropics and their control. 2nd edition. Cambridge University Press. ISBN: 0-521-24638-5.
  • Hutchison, W.D., Hoch, H., Bolin, P.C., Hines, R.L. and Wold-Burkness, S.J. (2007). The Cabbage looper. Department of Entomology, University of Minnesota. Last Revised November, 2007. www.vegedge.umn.edu
  • Kranz, J., Schumutterer, H. and Koch, W. (1977). Diseases, pests and weeds in tropical crops. Verlag Paul Parey. ISBN: 3-489-68626-8.
  • OISAT: Organisation for Non-Chemical Pest Management in the Tropics. www.oisat.org
  • Ostermann, H. and Dreyer, M. (1995). Vegetables and grain legumes. In "The Neem tree Azadirachta indica A. Juss. and other meliaceous plants sources of unique natural products for integrated pest management, industry and other purposes". Edited by H. Schmutterer in collaboration with K. R. S. Ascher, M. B. Isman, M. Jacobson, C. M. Ketkar, W. Kraus, H. Rembolt, and R.C. Saxena. VCH. pp. 392-403. ISBN: 3-527-30054-6
  • Varela, A. M., Seif, A., Löhr, B. (2003). A Guide to IPM in Brassicas Production in Eastern and Southern Africa. ICIPE www.icipe.org
back to Index
Cabbage looper on cabbage - The first instar is white and almost clear with a black head capsule. Later instars are green with a thin white line on each side. Mature larvae reach 3 to 4 cm in length.
© A.M. Varela, icipe
Instar
Growth stages.
Cucurbits
Cucurbitaceae is a plant family commonly known as melons, gourds or cucurbits and includes crops like cucumbers, squashes (including pumpkins), luffas, melons and watermelons. The family is predominantly distributed around the tropics, where those with edible fruits were amongst the earliest cultivated plants in both the Old and New Worlds.
Brassicaceae
Brassicaceae or Cruciferae, also known as the crucifers, the mustard family or cabbage family is a family of flowering plants. The name Brassicaceae is derived from the included genus Brassica. The family contains well-known species such as Brassica oleracea (cabbage, cauliflower...), Brassica rapa (turnip, Chinese cabbage...), Brassica napus (rapeseed...) and many more.
Synthetic
Manufactured by chemical and industrial processes. May include products not found in nature, or simulation of products from natural sources (but not extracted from natural raw materials).
IPM
A combination of chemical and biological control methods, based on the concept of economic tresholds. Pest management in organic farming uses many biological control methods developed as par of IPM.
organic
Refers to the farming system and products described in the IFOAM standard and not to 'organic chemistry'.
Cruciferae
Cruciferae or Brassicaceae, also known as the crucifers, the mustard family or cabbage family is a family of flowering plants. The name Brassicaceae is derived from the included genus Brassica. The family contains well-known species such as Brassica oleracea (cabbage, cauliflower...), Brassica rapa (turnip, Chinese cabbage...), Brassica napus (rapeseed...) and many more.
Predator
Animal that attacks and feeds on other animals, such as an insect (e.g. ladybird beetle), bird or spider feeding on pest insects.
Biopesticides
Biopesticides include microbiological pesticides (based on fungi, bacteria and virus) but also botanicals (plant extracts), since they are extracted from or are products of living organisms (plants)
Cultivar
Cultivar is a plant variety. It is a group of similar plants which through their structural features and performance can be identified from other varieties within the same species.
Instar
Growth stages.
Contamination
Pollution of organic product or land; or contact with any material that would render the product unsuitable for organic certification.
IPM
A combination of chemical and biological control methods, based on the concept of economic tresholds. Pest management in organic farming uses many biological control methods developed as par of IPM.
Pheromone
Substance emitted by female insects in order to attract males. Synthetic pheromones are used to disorient male insects and thus to prevent mating.