Grow It Eat It: Maryland's Food Gardening Network

Cabbage Looper

Cabbage looper - Trichoplusia ni

Cabbage looper egg - Photo by Whitney Cranshaw, Colorado State University, Bugwood.org Cabbage looper larva - photo by David Cappaert, Michigan State University, Bugwood.org Cabbage looper pupa in cocoon - photo by Whitney Cranshaw, Colorado State Univerisyt, Bugwood.org
Egg Larva Pupa in cocoon
Early cabbabe looper Cabbage looper adult moth - photo by Keith Naylor, Bugwood.org Cabbage looper on collards
Early Adult moth Cabbage looper on collards
Appearance Eggs: Tiny yellowish-white to greenish half-spheres, laid singly on leaves, often in small clusters of 6-7. Larvae:  Caterpillars initially hatch off-white and become pale green with distinct white stripes down each side and 4 light stripes down the back. 5-7 instars, reaching 1½” at maturity. Typical “measuring” worm that arches its body up into a loop as it crawls.
Pupae: About 3/4" long, initially green, turning dark brown/black, contained within a white, thin, fragile silky cocoon formed on underside of foliage, in plant debris, or in loose soil.
Adults: Moderate size (up to 1½” wingspan) mottled gray-brown moth with silvery white mark near center of each forewing.
Life Cycle/Habits Moths overwinter in south and come north on storm fronts; a few may overwinter here as pupae. Moths are semi-nocturnal, being most active around dusk, overnight, and sometimes on cloudy days. Larvae population doesn't build up until May, and there are two or more overlapping generations a year. Early instar larvae feed voraciously, usually on leaf undersides; late stage larvae feed more generally and may bore into heads of vegetables.
Host Plants Cole crops (a.k.a. crucifers or brassicas), including: broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, turnips, etc. May also damage potato, tomato, pea, lettuce, and spinach, as well as some flower and field crops, and a wide range of broadleaf weeds.
Signs/Symptoms Only larval feeding causes damage; adult moths feed on nectar. Early larval instars feed on leaf undersides, creating windowpane patterns on thick-leaved plants like cabbage. Later instars chew ragged holes in leaf centers, and may bore into cabbage and broccoli heads, causing stunting or failure to form head. Serious defoliation and damage can occur. Larvae excrete many moist, brown droppings.
Monitoring
 Check leaf undersides early in season for feeding damage. Later, monitor for large larvae and droppings.
Prevention/Control
  • Inspect transplants carefully. Camouflaged larvae are hard to spot.
  • Use floating row cover, if this is a yearly pest.
  • Hand pick and destroy larvae.
  • Bacillus thuringiensis (Bt), an organic pesticide, can be used if loopers become established. Neem is also effective.
  • Early maturing plants are less damaged by this warmth-loving pest.
  • Plant resistant varieties.
Photo credits:
UGA5140052 (adult moth): Keith Naylor, Bugwood.org
UGA1455107 (egg): Whitney Cranshaw, Colorado State University, Bugwood.org
UGA2131067 (larva): David Cappaert, Michigan State University, Bugwood.org
5369941 (pupa in cocoon): Whitney Cranshaw, Colorado State University, Bugwood.org

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For more information, contact Jon Traunfeld

Last updated: 01/20/2012