# Cabbage looper (Trichoplusia ni) > A common green inchworm caterpillar that feeds on brassicas and many other crops; a widespread agricultural pest but harmless to people. Source: https://insectscanner.com/species/cabbage-looper/ (updated 2026-10-10) ## Is it dangerous? **Non-toxic.** Cabbage loopers are not dangerous to people. They do not bite or sting. Handling caterpillars may cause minor skin irritation in very sensitive individuals, but they are not venomous. **Pets:** Not toxic to pets. As with any insect, large numbers eaten by a pet could cause mild stomach upset. ## Quick facts - Scientific name: Trichoplusia ni - Also called: Green looper - Order: Lepidoptera (Moths and butterflies) - Family: Noctuidae (Owlet moths) - Size: 30-38 mm wingspan - Colours: Brown, Pale silver, Green (larva), Cream (underside/larval stripe) - Habitat: Agricultural fields, vegetable gardens, weedy margins, greenhouse interiors - Range: Widespread across much of the world, including North America, Europe, Africa and Asia, in temperate and subtropical regions - Active: Multiple generations per year; active spring through fall in temperate zones and year-round in warm regions; nocturnal adults, larvae feed day and night but often hide on undersides of leaves - Lifespan: Adults live about 1-3 weeks; the full life cycle is 3-6 weeks depending on temperature - Effect on plants: Garden pest - Pest: yes ## Overview Trichoplusia ni is a moth in the family Noctuidae whose larvae (loopers) are important chewing pests of cabbages, broccoli, lettuce and many other vegetable and field crops. The caterpillars move in a characteristic looping or 'inchworm' fashion because they lack some mid-abdominal prolegs. Adults are medium-sized brownish moths with a distinctive silvery marking on each forewing. In warm regions they produce multiple generations per year and can be present year-round; in cooler climates populations build over the growing season. ## How to identify it Adult moths have a wingspan around 30-38 mm and are mottled brown with a pale silvery or metallic figure (often described as Y- or omega-shaped) on each forewing. Forewings show variable darker and lighter mottling. Larvae are smooth, elongated caterpillars typically green but sometimes brownish; they have three pairs of true legs near the head and only three pairs of prolegs near the rear (none in the middle of the body), producing the looping gait. Mature larvae reach about 25-38 mm long and often show a thin pale dorsal stripe and faint lateral striping. - Larvae move with a characteristic looping 'inchworm' gait due to fewer mid-body prolegs. - Mature caterpillars are smooth, usually bright green with a thin pale dorsal stripe and reach about 25-38 mm. - Adult moths have a mottled brown forewing with a distinct pale silvery Y- or omega-shaped mark. - Compare leaf damage: large irregular holes and ragged edges on brassica leaves are typical of looper feeding. ## Lookalikes - **Imported cabbage worm (cabbage white caterpillar)** (Pieris rapae (larva)): Imported cabbage worm is a velvety green caterpillar with a faint yellow line down the back and a full set of prolegs, so it crawls rather than loops; its damage tends to be smaller holes and surface scraping. - **Soybean looper** (Chrysodeixis includens): Soybean looper is similar in appearance and habit; identification often requires close inspection of wing pattern on adults or expert confirmation. - **Common inchworm (various geometrid larvae)** (Multiple Geometridae species): Geometrid inchworms also loop but are usually associated with woody plants and often differ in coloration and proleg arrangement; habitat and host plant help distinguish them. ## Life cycle - **Egg:** Tiny pale eggs are laid singly or in small clusters on the underside of leaves; hatch in about 3-7 days depending on temperature. - **Larva (caterpillar):** Green or sometimes brown caterpillars grow through several instars over 2-3 weeks, feeding heavily on leaves and showing the characteristic looping movement. - **Pupa:** Full-grown larvae pupate in folded leaves or in debris near the soil surface; pupal stage lasts about 8-14 days. - **Adult (moth):** Nocturnal moths emerge, mate and lay eggs; adults live 1-3 weeks and may produce many generations per year in warm climates. ## Diet and predators - Young eat: Chew leaves of a wide range of herbaceous plants, especially brassicas, lettuce, tomato, soybean and many weeds - Adults eat: Adults feed on nectar from flowers but feeding is limited compared with larval consumption - Predators of the young: Parasitoid wasps and flies, predatory bugs, lacewings, lady beetles, birds and spiders - Predators of adults: Bats, nocturnal insectivorous birds, spiders and predatory insects ## Effect on plants and gardens Larvae chew holes and ragged edges in leaves of brassicas (cabbage, broccoli, kale), lettuce, tomato, soybean and many other vegetable and field crops; heavy infestations reduce yield and marketability. ### How to get rid of it Hand-pick caterpillars and remove eggs from the undersides of leaves. Cover young brassicas with fine row covers to keep moths from laying eggs. Encourage natural enemies such as parasitic wasps, lacewings and birds. Bacillus thuringiensis (Bt) sprays are effective on young larvae and safe for people and pets when used as labelled. For heavy infestations, use an insecticide labelled for loopers on the crop and follow label directions; loopers have developed resistance to some products, so rotate methods. Remove crop debris after harvest. ## Where and when to find it Look for eggs and larvae on the undersides of leaves of brassicas and other host plants; pupae are often in leaf folds or debris at the plant base; adults fly at night and may be found near lights. - Best time: Spring through fall in temperate areas; night or dusk for adults, daytime for larvae hidden under leaves. - Tips: Turn over leaves to inspect larvae and fresh feeding damage. Early detection of small larvae makes biological controls like Bt most effective. ## Fun facts - The 'looper' movement is caused by missing middle prolegs; the caterpillar anchors with the rear and reaches forward, forming a loop. - Cabbage loopers are highly polyphagous — they feed on many unrelated plant families, which helps them persist in varied habitats. - Because they are a major pest, cabbage loopers have been extensively studied for biological control and insecticide resistance. ## Frequently asked questions ### Do cabbage loopers bite humans? No. They do not bite or sting and are not harmful to people. ### Are cabbage loopers harmful to my vegetable garden? Yes. Larvae chew leaves and can severely damage brassicas, lettuce and other crops; young plants are most vulnerable. ### How do I get rid of cabbage loopers? Use integrated methods: hand-pick caterpillars, remove and destroy infested leaves, encourage natural enemies, apply Bacillus thuringiensis (Bt) to young larvae, use row covers to exclude moths, and rotate crops. Chemical insecticides are available but check labels and resistance issues. ### Why are they in my house or greenhouse? Moths are attracted to lights and may enter buildings; greenhouses and indoor vegetable setups provide food and warm conditions allowing larvae to survive and multiply. ### When will I see cabbage loopers? In temperate regions they appear from spring through fall with several generations; in warm climates they can be present year-round. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/202789), [Wikipedia](https://en.wikipedia.org/wiki/Cabbage_looper). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.