How to Manage Pests
UC Pest Management Guidelines
Monitoring Caterpillars and their Natural Enemies
(Reviewed 9/16, updated 9/16)
In this Guideline:
Caterpillars are the larvae of moths and butterflies (order Lepidoptera). Omnivorous looper, western avocado leafroller (amorbia), and (least frequently) orange tortrix are sporadic pests in avocado. Healthy trees can tolerate some loss of chewed foliage and blossoms. Extensive defoliation can result in sunburn to fruit and twigs. Economic damage occurs primarily when caterpillars chew and scar fruit. Conserve natural enemies, as caterpillars are usually under effective biological control.
IDENTIFYING CATERPILLARS AND NATURAL ENEMIES
SAMPLING CATERPILLARS AND THEIR NATURAL ENEMIES
Using the Shake Method
Shake foliage to sample avocado looper:
Using the Timed Method
Make timed counts for amorbia (western avocado leafroller), avocado looper, and orange tortrix.
MONITORING ADULT MOTHS
Adult moths are nocturnal and consume only liquids and pollen. During the day they rest on the underside of leaves or on shady bark.
Deploy pheromone-baited sticky traps for adults to identify the species in groves and indicate peaks in flights of egg-laying adults. Each trap is baited with a separate pheromone to attract adult male amorbia, omnivorous looper, or orange tortrix. For amorbia, two different pheromones are used:
Unless other methods are recommended, deploy traps at a density of about one trap per ten acres when adult moths are expected to be present. Check with suppliers for recommended pheromones and the type and number of traps to use.
Trapping moths can indicate that foliage monitoring is warranted and helps to time management actions such as release of Trichogramma egg parasites. Adult traps generally are not useful for determining need for treatment, partly because caterpillars are the damaging stage and natural enemies kill many eggs and larvae relative to the moth population that is trapped earlier in the season.
UC IPM Pest Management Guidelines: Avocado
Acknowledgment for contributions to General Information:M. L. Arpaia, Botany and Plant Sciences, UC Riverside
M. L. Bianchi, UC Cooperative Extension, San Luis Obispo County
C. J. Lovatt, Botany and Plant Sciences, UC Riverside
P. Mauk, UC Cooperative Extension, Riverside County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
G. W. Witney, California Avocado Commission, Irvine, CA
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