How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Western tussock moth has one generation a year. Overwintered eggs hatch about the time the spring growth flush is expanding. Larvae of the western tussock moth are distinctive: young larvae are black with long bristles; maturing larvae have numerous red and yellow spots and four median dorsal tufts of light gray hair. Mature larvae spin their cocoons and pupate mainly on scaffold branches and trunks. Adults emerge from late April through July and, after mating, wingless females lay 125 to 300 eggs each in a single egg mass—usually on the empty pupal case.

DAMAGE

Western tussock moth infestations are occasionally a problem in southern California and in foothill orchards in the San Joaquin Valley. A heavy infestation of this pest may destroy all new spring growth. The larva may also eat into newly set or young fruit. The damage is similar to that of katydids, grasshoppers, and citrus cutworm.

MANAGEMENT

Western tussock moth is generally managed by monitoring in spring and treating when necessary. Use selective (those listed with a narrow range of activity) insecticides to preserve populations of natural enemies.

Biological Control
A dermestid egg predator, Trogoderma sternale, is common in some areas of southern California as is a small parasitic wasp, Telenomus californicus.

Organically Acceptable Methods
Biological control and sprays of Bacillus thuringiensis are acceptable on organically certified citrus.

Monitoring and Treatment Decisions
Look for egg masses or larvae of western tussock moth in spring to determine the population level before damage occurs. If you find an average of one healthy egg mass per tree, economic loss may occur. Treat after 90% of the eggs have hatched. If you monitor larvae, about 100 larvae an hour of search warrants treatment.

Common name		Amount to Use	R.E.I.+	P.H.I.+
(trade name)		(type of coverage)**	(hours)	(days)
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
A.	BACILLUS THURINGIENSIS ssp. KURSTAKI#
	(various)	Label rates (OC)	4	0
	RANGE OF ACTIVITY: Pests: narrow (caterpillars); Natural enemies: none
	PERSISTENCE: Pests: short; Natural enemies: none
	MODE OF ACTION GROUP NUMBER1: 11.B2
	COMMENTS: Can be used during bloom. Timing is important because of short residual period. Apply only during warm weather to control young, actively feeding worms. Use reduced wind velocity and drive 3 mph.
B.	CRYOLITE
	(Prokil Cryolite) 96	8–20 lb/acre (OC)	12	15
	(Kryocide) 96 WP	8–20 lb/acre (OC)	12	15
	RANGE OF ACTIVITY: Pests: intermediate (foliage feeders such as worms, katydids, and Fuller rose beetle); Natural enemies: few, if any
	PERSISTENCE: Pests: long, unless washed off by rain; Natural enemies: none to short
	MODE OF ACTION GROUP NUMBER1: 9A
	COMMENTS: Check label for variety. Use higher rate for larger trees. Slow-acting stomach poison that may take several days of warm weather to kill worms. Use reduced wind velocity and a speed of 3 mph. Do not exceed 90 lb/acre/season.
C.	CHLORPYRIFOS*
	(Lorsban) 4E	1–2 qt/acre (OC or A)	5 days	see comments
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: short (low rates), intermediate (high rates); Natural enemies: short (low rates), intermediate (high rates)
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: For use on all varieties. Do not apply more than twice/fruit year or make applications less than 30 days apart. During the bloom period, apply from 1 hour after sunset until 2 hours before sunrise. P.H.I. is 21 days for up to 7 pt/acre and 35 days above 7 pt/acre.
D.	CARBARYL*
	(Sevin) XLR Plus	2 qt/acre (OC)	12	5
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: long; Natural enemies: long
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: For use on all varieties. During the bloom period, apply from 1 hour after sunset until 2 hours before sunrise. XLR Plus formulation is less toxic to honey bees than the 80S formulation when direct application to bees is avoided, and the spray residues have dried. Check with your local county agricultural commissioner regarding application restrictions during the bloom period.
E.	NALED
	(Dibrom) 8E	2 pt/acre (OC)	see comments	7
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: short; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: For use on grapefruit, lemons, oranges, tangerines. This material is hazardous to bees. Do not apply during bloom. R.E.I. is 2 days for 1 pt or less; 3 days for more than 1 pt.
F.	METHOMYL*
	(Lannate LV) 2.4	1.5–3 pt/acre (OC or A)	3 days	1
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: short; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: For use on grapefruit, lemons, oranges, tangerines, and tangelos. Apply as needed, except during daylight hours of the bloom period. This material is hazardous to bees. Do not apply during bloom.
G.	CARBARYL*
	(Sevin) 80S	2.5 lb/acre (OC)	12	5
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: long; Natural enemies: long
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: For use on all varieties. This material is hazardous to bees. Do not apply during bloom.
**	A - Aircraft applications 5-20 gal water/acre.
	OC - Outside coverage uses 100–250 gal water/acre.
+	Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
*	Permit required from county agricultural commissioner for purchase or use.
#	Acceptable for use on organically grown produce.
1	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 to help prevent the development of resistance. 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 Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

PUBLICATION

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Insects, Mites, and Snails
E. E. Grafton-Cardwell, Kearney Agricultural Center, Parlier
J. G. Morse, Entomology, UC Riverside
N. V. O‘Connell, UC Cooperative Extension, Tulare County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
C. E. Kallsen, UC Cooperative Extension, Kern County
D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgments for contributions to Insect, Mites, and Snails:
J. Barcinas, E. S. I., Corona, CA
R. Dunn, Badger Farming County, Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
H. Griffiths, E. S. I., Corona, CA
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
T. Roberts, E. S. I., Corona, CA
J. Stewart, Pest Management Associates, Exeter, CA
P. Washburn, Washburn & Sons Citrus Pest Control, Riverside, CA
K. Godfrey, USDA Biological Control, Sacramento
D. Headrick, California Polytechnic State University, San Luis Obispo
B. Faber, UC Cooperative Extension, Ventura County
J. Kabashima, UC Cooperative Extension, South Coast Research and Extension Center

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