How to Manage Pests
UC Pest Management Guidelines
Scientific name: Schizura concinna
In this Guideline:
caterpillar is easily
recognized because of its striking appearance: the main body color is yellow
and is marked by longitudinal reddish and white stripes; the head is bright
red; and the fourth abdominal segment is red and enlarged. Redhumped
caterpillars pass the winter as full-grown larvae in cocoons on the ground. In
spring and early summer, moths lay egg masses on the undersides of leaves. Eggs hatch into larvae that begin feeding on leaves. There are at least three
generations each year in northern California.
Redhumped caterpillars generally skeletonize leaves,
leaving behind only leaf veins. They do not web leaves.
Redhumped caterpillar can be a pest of plum orchards in the Central
Valley. Biological control and pruning is often sufficient to manage the pest;
use the monitoring guidelines below to determine need for treatment.
A number of
natural enemies attack redhumped caterpillars, frequently preventing them from
becoming destructive pests. Most common are two parasitic wasps: Hyposoter fugitivus, which forms a single pupal case that is white
with a black band around the middle, and a species of Apanteles, which forms a fluffy white mass of pupal cases.
Several general predators, including spiders,
lacewings, bigeyed bugs, and damsel bugs, occasionally feed
on caterpillar eggs and small larvae.
trees, cut out and destroy infested twigs.
Organically Acceptable Methods
and cultural control and Bacillus thuringiensis (Bt) sprays are
acceptable for use in an organically certified crop.
Monitoring and Treatment Decisions
looking for redhumped caterpillars in May, when eggs or larvae of the first
generation may be present. Check trees throughout the orchard, looking at the
undersides of leaves for egg masses or groups of small larvae. Skeletonized
leaves that turn brown may indicate the presence of redhumped caterpillars. If
you find larvae of the first generation, do not treat. Prune out and destroy
localized infestations. Monitor again in July for second-generation larvae and
for the presence of parasites before you make a treatment decision. Look for
parasite pupae among larval colonies. If 80% or more of the larval population
is parasitized, no treatment is needed. If parasitization is very low, prune
out and destroy infestations or treat infested trees. Infestations tend to be
very localized; so spot treatments usually suffice. Formulations of Bt are
effective against the larvae.
||Amount to Use**
choosing a pesticide, consider information relating to impact on natural enemies and honey bees, impact of timing on beneficials, and environmental impact Not all registered pesticides are listed. Always read label of product being used.
||BACILLUS THURINGIENSIS ssp. KURSTAKI#
||MODE OF ACTION GROUP NUMBER1: 11.B2
||COMMENTS: Most effective on small caterpillars. Does not destroy natural enemies.
UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462
Insects and Mites
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier
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