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
(c) A. M. Varela, icipe
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.
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.