How to Manage Pests

UC Pest Management Guidelines

Floriculture and Ornamental Nurseries

Cabbage Looper

Scientific name: Trichoplusia ni

(Reviewed 3/09, updated 5/10, corrected 5/19)

In this Guideline:

DESCRIPTION OF THE PEST

Loopers arch their backs as they crawl. Cabbage loopers are light green and usually have a narrow, white stripe along each side and several narrow lines down the back. The dome-shaped eggs are laid singly on the undersurfaces of older leaves. Adult moths have brown, mottled forewings marked in the center with a small, silver figure 8.

DAMAGE

Young cabbage looper larvae feed primarily on the underside of lower leaves, skeletonizing them. Larger cabbage loopers chew entirely through leaves and flowers.

MANAGEMENT

Biological Control
A number of parasites, both tachinid flies and parasitic wasps, attack lepidoptera larvae and reduce their population growth rate. However, most of these larvae continue feeding through to the last instar, so parasitized larvae will still damage crops. Viruses also do not usually kill the larvae until later instars. Trichogramma spp. are commercially available egg parasites that can be effective against cabbage looper. Applying insecticides other than Bacillus thuringiensis (Bt) products are likely to exclude parasites because their residue are lethal to these beneficial insects. For more information, see BIOLOGICAL CONTROL.

Cultural Control
Because these pests feed on a large variety of plant species, keep production areas free of weeds (e.g., mustards) that serve as hosts to cabbage loopers. Exclusion of winged adults can be accomplished by covering openings to the greenhouses with screens. Screens are especially important when lights are used at night in greenhouses to control flowering because lights attract adult moths. Individual seedling flats may also be covered with screens to exclude adults and larvae. Row covers can be a practical measure to exclude moths in field production as long as the mesh prevents entry of adults and the row cover is held above the plant surface to eliminate oviposition through the fabric.

Monitoring and Treatment Decisions
If Bt sprays are planned, use pheromone traps to determine adult flight activity and mating. Once adults are caught in traps, it is very likely that larvae are present and Bt should be applied as soon as possible because it is most effective against young larvae. Use regular visual inspections of plants to detect larvae and their damage.For guidelines on when to treat, see ESTABLISHING TREATMENT THRESHOLDS.

TREATMENT

Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals
Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact.

Class		Pesticide (commercial name)	Manufacturer	R.E.I.1	Mode of action2	Comments
botanical	A.	pyrethrin/PBO3 (PT Pyrethrum TR)	Whitmire MicroGen	12	3/—	An aerosol.
	B.	pyrethrin/rotenone (Pyrellin EC)	Webb Wright	12	3/21B
carbamate	A.	carbaryl* (various)	Bayer	12	1A
insect growth regulator	A.	azadirachtin (Azatin XL)	OHP	4	un	Must contact insect. Repeat applications as necessary. Label permits low-volume application.
	B.	diflubenzuron (Adept 25WP)	Chemtura	12	15
	C.	novaluron (Pedestal)	Chemtura	12	15	Use no more than twice per year and don't exceed 52 oz/acre/year. Don't use on poinsettia.
	D.	tebufenozide (Mimic, Confirm)	Dow Agro Sciences	4	18
microbial	A.	Bacillus thuringiensis ssp. Kurstaki# (various products)	Valent	4	11	Most effective against early instar larvae; pheromone trapping recommended for timing applications.
organophosphate	A.	acephate (Orthene T, T&O Spray)	Valent	24	1B	A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse only labeled for greenhouse use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses.
	B.	acephate (PT 1300 Orthene TR)	Whitmire MicroGen	24	1B	An aerosol only for greenhouse use.
pyrethroid	A.	Bifenthrin (Attain TR)	Whitmire MicroGen	12	3	Check label. A fogger for greenhouse use only.
	B.	bifenthrin* (Talstar Professional)	FMC	12	3	Label permits low-volume application.
	C.	cyfluthrin (Decathlon 20WP)	OHP	12	3	Label permits low-volume application.
	D.	deltamethrin* (DeltaGard)	Bayer	12	3
	E.	fenpropathrin* (Tame 2.4EC Spray)	Valent	24	3	Label permits low-volume application.
	F.	fluvalinate (Mavrik Aquaflow)	Wellmark	12	3	Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal.
	G.	permethrin (Astro)	FMC	12	3	Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, diffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year.
spinosyn	A.	spinosad (Conserve SC)	Dow Agro Sciences	4	5	Do not apply more than 10 times in a 12-month period. Compatible with most beneficials, but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis.

PUBLICATION

UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392

Insects and Mites

J. A. Bethke, Entomology, UC Riverside
Acknowledgment for contributions to Insects and Mites:
K. L. Robb, UC Cooperative Extension, San Diego County
H. S. Costa, Entomology, UC Riverside
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
M. P. Parrella, Entomology, UC Davis

Top of page