Vegetable Insect Note 40
The cabbage looper feeds on a variety of crops consuming foliage and is one of the most
destructive insect pests of vegetables. Annual losses and cost of control make the cabbage looper
an economic pest. As control is difficult, detection and surveillance of cabbage looper
populations is recommended.
Cabbage and related plants such as collards, broccoli, and cauliflower are host plants as are potato, spinach, lettuce, parsley, tomato, and cucumber. Field crops which may be attacked are cotton and soybean. Collard and cotton are preferred hosts for egg laying.
Larvae feed on undersides of leaves, moving toward the center of the plant, or on cabbage, into the head, as they develop. However, most
feeding damage occurs between the leaf veins.
Cabbage loopers overwinter in Florida and adjacent states, and adults migrate into North
Carolina each year, beginning in May. Small round greenish-white eggs are deposited singly on
the upper and lower surfaces of leaves and several days later larvae hatch. Larvae are green with
white stripes running the length of the body. This larva has three (3) pairs of prolegs
(see drawing).
and moves or rests with its body humped or "looped". Larvae feed and develop for 2 to 4
weeks, reaching a length of about 1-1/4 inches. They spin cocoons on the host plant and pupate.
The insect remains in the pupal stage for 10 days to 2 weeks before adults emerge. There are
three (3) or more generations/year in North Carolina.
Cabbage looper adults are night flying moths which are attracted to black light insect traps.
Pheromone traps, which are more effective than light traps in attracting looper moths, can be
used to monitor cabbage looper adult occurrence in N. C. and detect the beginning of each
succeeding generation. Knowing when cabbage looper moths move into N.C. (usually early May
to mid-June) and into specific fields and when another cycle occurs will help ensure insect
control through proper timing of sprays. In N. C., at least four looper species are attracted to the
pheromone. [Syngrapha falcifera (Kirby) Celery Looper also is collected occasionally.]
Only two are of economic importance and on cabbage only the cabbage looper is
important. Hence, one must be able to separate cabbage loopers from the other three species.
The following key is designed to separate them. (This key will only work if the specimens are in
reasonably good condition). Refer to the drawings of wings to help you with the key.
Plants should be examined for the presence of immature stages of the looper. Round, greenish-white eggs about the size of a pin head may be attached to the surface of older leaves. Larval stages may also be observed on the undersides of leaves. The looping motion of this worm following a simple probe with a finger, knife or twig, will confirm that the insect is a cabbage looper. A green or brown pupa encased in a loosely woven cocoon also can be found attached to older leaves.
For more information, including more color photos and line drawings, see Vegetable Insect Note 12: Cabbage Worm Complex.
Some cabbage varieties are attacked by cabbage looper than others. These varieties include Mammoth Red Rock, Chieftan, Savoy, and Savoy Perfection Drumhead cabbage.
About 20 species (8 fungi, 6 protozoans, 4 viruses, 2 bacteria) of insect pathogens have been reported from larvae of the cabbage looper. Under some conditions these pathogens are natural regulators of populations.
Some 70 different parasitoids have been recovered from the cabbage looper, but only a few are abundant. Parasitism occurs in the egg, larval and pupal stages. Obviously, egg and larval parasites are most important with larval parasites being more effective under most field conditions. A number of predators exist and include lady beetles, spiders, bugs, flies and wasps.
Natural enemies do play in important role in wide scale pest control. However in most circumstances the impact of natural enemies is too little control too late. The conservation and introduction of natural enemies is encouraged in IPM programs and may be acceptable in special conditions. Even though there are several natural enemies of cabbage looper, chemical control in most situations is usually needed.
On cabbage, broccoli, cauliflower, Brussel sprouts, and collards in home gardens, use Dibrom 60 EC (naled) at a rate of two (2) teaspoons of formulation/gallon of spray. On collards, there is a four (4) day waiting period between the day of last application and harvest; on the other crops there is a one (1) day interval. On these crops and kale and mustard greens, Bacillus thuringiensis, a bacterial insecticide, may be used as follows:
| Formulation* | Amount of formulation per gallon of spray | Days to harvest | ||
|---|---|---|---|---|
| Dipel WP | 1 Tbsp. | 0 | ||
| Dipel 4L | 2 Tsp. | 0 | ||
| Javelin WG | 2 Tsp. | 0 | ||
| Biobit FC | 1 to 3 Tsp. | 0 | ||
| Xentari WDG | 2 Tsp. | 0 | ||
| MVP L | 2 Tsp. | 0 | ||
| Agree WP | 2 Tsp. | 0 | ||
| *Other formulations of B.t. may be available. | ||||
For commercial plantings, refer to the North Carolina Agricultural Chemicals Manual.
Insecticides for control of the cabbage looper are most effective on young and exposed larvae. Thorough coverage to both leaf surfaces will be enhanced with the use of a spreader/sticker and a high pressure (200-400 psi) sprayer with hollow cone nozzles (3 to the row) on drops. A 7-day spray schedule or one based on damage threshold insect assessment is advised. Be alert for looper resistance to insecticides and alternate chemical classes to restrict resistance development.
Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. Because environmental conditions and methods of application by growers may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data.
Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance, contact your county North Carolina Cooperative Extension Service agent.
For assistance with a specific problem, contact your local North Carolina Cooperative Extension Service personnel.
Published by North Carolina Cooperative Extension Service
Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Web page last updated by M.J. Munster on 09 May 1996