How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Cabbage loopers are green caterpillars with a narrow, white stripe along each side and several narrow lines down the back; they have a characteristic arch to their back as they crawl. Eggs are similar in appearance to corn earworm eggs, but flatter, and laid singly on the underside of leaves. Adult moths have brown, mottled forewings marked in the center with a small, silver figure eight.

DAMAGE

The cabbage looper can be a very damaging pest. Young larvae feed primarily on the underside of leaves, skeletonizing them. High populations may move to the fruit and feed on the fruit surface.

MANAGEMENT

Encourage biological control agents by using least-toxic pesticides to control other pests. Treatments may be warranted if loopers are numerous.

Biological Control
Cabbage looper has many natural enemies that frequently keep it below economic levels, unless they are killed by insecticide applications. Important parasitic wasps include the tiny egg parasite, Trichogramma pretiosum, and three wasps that attack the caterpillars (Hyposoter exiguae, Copidosoma truncatellum, and Microplitis brassicae). The tachinid fly, Voria ruralis, also attacks the caterpillar. In some areas, the nuclear polyhedrosis virus, an important biological control agent, occurs naturally in fields and kills loopers that it infects.

Organically Acceptable Methods
Biological control and sprays of Bacillus thuringiensis are acceptable to use in an organically certified crop.

Monitoring and Treatment Decisions
Treatments are generally warranted if there are sufficient numbrers of loopers feeding on leaves so that they are easily found. Monitor adult flights with pheromone traps and observe egg laying to time treatments.

Common name		Amount/Acre	P.H.I.+
(trade name)			(days)
When choosing a pesticide, consider information relating to water quality and impact on natural enemies and honey bees.
A.	METHOXYFENOZIDE
	(Intrepid) 2F	4–10 fl oz	3
	MODE OF ACTION: An insect growth regulator (Group 18)1 insecticide.
	COMMENTS: Time spray to target eggs and small larvae. Do not apply more than 4 applications/acre/season or spray at less than 7 day intervals. Use allowed under a supplemental label.
B.	SPINOSAD
	(Entrust)#	1.25–2.5 oz	1–cucumbers 3–other cucurbits
	(Success)	4–8 fl oz	1–cucumbers 3–other cucurbits
	MODE OF ACTION: A microbial (Group 5)1 insecticide.
	COMMENTS: Time spray to target eggs at hatch or small larvae. Do not apply more than 9 oz Entrust or 29 fl oz of Success/acre/season.
C.	BACILLUS THURINGIENSIS ssp. KURSTAKI#
	(various products)	Label rates	0
	MODE OF ACTION: A microbial (Group 11.B2)1 insecticide.
	COMMENTS: Apply when eggs start to hatch and larvae are small (early instars) and before significant crop damage occurs. To be effective, Bacillus thuringiensis must be applied to young larva in the 1st or 2nd instar. Choose one of the other materials listed if larger larvae are present. Larvae must be actively feeding to be affected. Repeat as necessary to maintain control.
D.	CRYOLITE
	(Kryocide) 96W	8–12 lb	Summer squash: 7
			Winter squash, cucumber, melons, pumpkins: 14
	MODE OF ACTION: An inorganic (Group 9A)1 insecticide.
	COMMENTS: Labeled for use on cucumber, squash, melons, and pumpkins. Can be applied as a spray or dust. Thorough coverage using ground equipment is necessary for adequate control. Do not apply immediately before harvest. Remove excess residues on edible portions by washing, brushing, or other effective means. Effectiveness of this material is lower than materials listed above.
	...OR...
	(Prokil Cryolite 96)	10–16 lb	Summer squash: 7
			Cantaloupe, watermelon, winter squash: 14
	COMMENTS: Labeled for use on cantaloupe, squash, and watermelon. Applied as a spray. Thorough coverage using ground equipment is necessary for adequate control. Do not apply immediately before harvest. Remove excess residues on edible portions by washing, brushing, or other effective means. Effectiveness of this material is lower than materials listed above.
E.	METHOMYL*
	(Lannate) 90	0.5–1.0 lb	1 (less than 0.5 lb)
			3 (0.5 lb or higher)
	(Lannate) LV	1.5–3 pt	1 (less than 1.5 pt)
			3 (1.5 pt or higher)
	MODE OF ACTION: A carbamate (Group 1A)1 insecticide.
	COMMENTS: Labeled for use on cucumbers, melons, and summer squash. Highly toxic to bees.
F.	ESFENVALERATE*
	(Asana XL)	5.8–9.6 oz	3
	MODE OF ACTION: A pyrethroid (Group 3)1 insecticide.
	COMMENTS: Repeat as necessary to maintain control. Do not exceed 0.25 lb a.i./acre/season. Highly toxic to honey bees and use of this chemical will increase mite populations.
+	Preharvest interval. Do not apply within this many days of harvest.
1	Modes of action are important in preventing the development of resistance to pesticides. Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season. For example, the organophosphates have a group number of 1B; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode of action is assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
*	Permit required from county agricultural commissioner for purchase or use.
#	Acceptable for organically grown produce.

PUBLICATION

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
R. L. Coviello, UC Cooperative Extension, Fresno Co.
E. T. Natwick, UC Cooperative Extension, Imperial Co.
L. D. Godfrey, Entomology, UC Davis
C. B. Fouche, UC Cooperative Extension, San Joaquin Co.
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
Acknowledgment for contributions to the insect and mite section:
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties

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