UC Management Guidelines for Saltmarsh Caterpillar on Sugarbeet

UC Pest Management Guidelines

Sugarbeet

Saltmarsh Caterpillar

Scientific name: Estigmene acrea

(Reviewed 11/05, updated 1/10)

In this Guideline:

Description of the pest
Damage
Management

Saltmarsh caterpillar is one of the woollybear caterpillars that has long hairs covering the entire body. Their hairs are generally of sufficient density as to completely hide the skin. They are typically black at each end with a median band in between of brown or reddish brown hairs. They also exhibit yellowish spots on the sides. The hairs are called urticarial hairs and may produce a stinging dermatitis (rash) on the skin of sensitive individuals.

Caterpillars eat leaves. Young caterpillars skeletonize leaves while large, older caterpillars consume all of the leaf except the major veins. Small larvae are usually found feeding in groups on the underside of the leaves.

Biological Control
The eggs are attacked by a number of predators and parasites. While the dense body hairs on the larvae effectively deter some of the potential predators and parasites, larvae are attacked by several diseases.

Monitoring and Treatment Decisions
No economic thresholds have been developed for saltmarsh caterpillars, which tend to be somewhat cyclic in their nature with damaging populations occurring every 3 to 4 years. While present in other years, numbers are generally low, and severe injury rarely occurs.

Common name

R.E.I.+

P.H.I.+

(trade name)

Amount/Acre

(hours)

(days)

When choosing a pesticide, consider information relating to natural enemies and honey bees as well as the environmental impact. Not all registered pesticides are listed. Always read label of product being used.

BACILLUS THURINGIENSIS ssp. KURSTAKI#

(various products)

Label rates

MODE OF ACTION GROUP NUMBER¹: 11

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.

Acceptable for use on organically grown produce.

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/.

UC IPM Pest Management Guidelines: Sugarbeet
UC ANR Publication 3469
Insects and Mites
E.T. Natwick, UC Cooperative Extension Imperial Co.
Acknowledgement for contributions to Insects and Mites:
C. G. Summers, Entomology, Kearney Agricultural Center, Parlier
D. R. Haviland, UC IPM Program, Kern Co.
L. D. Godfrey, Entomology, UC Davis

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How to Manage Pests

UC Pest Management Guidelines

Sugarbeet

Saltmarsh Caterpillar

Scientific name: Estigmene acrea

DESCRIPTION OF THE PEST

DAMAGE

MANAGEMENT

PUBLICATION