Cabbage Looper

Trichoplusia ni

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Insect Profile

Beneficial Rating

-4 Pest

Active Months

JanFebMarAprMayJunJulAugSepOctNovDec

US Distribution

NortheastSoutheastMidwestSouthwestWestPacific Northwest

Habitat Preferences

gardensagricultural fields

Taxonomic Group

Caterpillar

Order

Lepidoptera

Family

Noctuidae

Lifecycle

The cabbage looper undergoes a complete metamorphosis with four distinct stages: egg, larva, pupa, and adult. The cycle begins when the adult female moth lays single, dome-shaped, whitish-yellow eggs on the underside of host plant leaves. These eggs typically hatch in about three days. The larval stage, which is the primary pest stage, lasts for 9 to 14 days and consists of four to seven instars. The larva is a green caterpillar with a distinctive looping motion. Following the larval stage, the insect pupates in a silken cocoon attached to the underside of a leaf, a stage which can last from 4 to 13 days depending on temperature. Finally, the adult moth emerges. The entire life cycle from egg to adult can be completed in 24 to 33 days, allowing for multiple generations per year.

Overwintering Strategy

Pupae overwinter in crop debris or soil. In warmer climates, such as the southern United States and Mexico, they may continue to develop throughout the winter.

Native Range

North America

Attracted By

cabbagebroccolibok choyand over 160 other plants

Repelled By

marigoldsonionsgarlicthymewormwoodtomatoestansypepperminthyssopnasturtiums

Organic Control Methods

Organic control of cabbage loopers focuses on prevention and biological methods. One of the most effective methods is the application of Bacillus thuringiensis (Bt), a naturally occurring bacterium that is toxic to caterpillars when ingested. Spinosad-based sprays are another organically acceptable option. Encouraging natural enemies is also crucial; parasitic wasps such as Trichogramma pretiosum, Copidosoma truncatellum, Hyposoter exiguae, and Microplitis brassicae, as well as the tachinid fly Voria ruralis, are important predators. Planting insectary plants can help attract and sustain these beneficial insects. Hand-picking the caterpillars off plants can be effective in small gardens. Floating row covers can be used to prevent adult moths from laying eggs on the crops.

Companion Planting

Companion planting can be an effective strategy to deter cabbage loopers. Aromatic herbs such as thyme, peppermint, hyssop, and tansy can help mask the scent of susceptible plants. Marigolds, nasturtiums, and onions are also known to repel the adult moths, preventing them from laying eggs on host plants. Planting these companions interspersed with cabbage-family crops can create a less attractive environment for the pests.