Light Brown Apple Moth

(View field identification guide)

Light brown apple moth (LBAM) is an exotic pest native to Australia that has been detected in coastal California from Los Angeles to Sonoma counties.

In both appearance and behavior, the light brown apple moth is similar to other leafroller species in the tortricid family. The mature larvae are pale to medium green with a light yellow-tan head. The first segment behind the head (prothoracic shield) is greenish with no dark markings. Full-grown larvae are about 1/2 to 3/4 inch (10 to 18 mm) long. However, larvae cannot be reliably identified using morphological characters.

There are many native tortricids that can be confused with this pest. Tortricid moths hold their wings over their abdomens in a bell shape when at rest, andhave protruding mouthparts that resemble a snout. Many moths have oblique markings on the wings.

Depending on the climate, light brown apple moth may have 2 to 4 generations a year. In its native range it does not survive well at high temperatures, but it does thrive in cooler areas with mild summers, moderate rainfall, and moderate to high humidity. Overwintering larvae do not have a winter resting stage (diapause). They pass the winter as second- to fourth-stage larvae on vegetation surrounding field. Larvae may survive for up to 2 months in the winter without feeding.

Adult moths emerge after 1 to 3 weeks of pupation and mate soon after emergence. They stay sheltered in the foliage during the day, resting on leaf undersides. Females begin to lay eggs 2 to 3 days after emerging. The eggs are laid on leaves in masses of 20 to 50 (but may contain up to 170 eggs), slightly overlapping each other like fish scales. Egg masses are covered with a greenish transparent coating when newly laid, but the eggs become darker as the embryo develops. Larvae emerge after 1 to 2 weeks and disperse widely on the plant. In spring the first stage larvae move to shoot tips and form nests by webbing together developing leaves. The larvae feed within these shelters. Later in the season, larvae may enter fruit.

For more information on scouting and field identification, see the video: Scouting and Field Identification of Light Brown Apple Moth in California Nurseries.

Overwintering larvae feed on buds; injured buds may fail to develop. During bloom, larvae feed on flower and fruit clusters. Feeding can also cause direct damage to berries.

Research on management of light brown apple moth in California has been limited due to the previous quarantines imposed wherever it was found. As a result, most recommendations for California are based on work in grapes from other countries such as Australia and New Zealand, where overwintering sanitation, biological control, and selective insecticides are the primary means of control.

General insect predators and several species of spiders can reduce leafroller numbers by feeding on eggs or larvae. High mortality has been reported during the initial dispersal of the newly hatched larvae. Several parasitic wasps, Meteorus sp. in particular, have been recorded parasitizing light brown apple moth in California.

In grapes, sanitation of mummy clusters in the dormant season can help reduce the number of overwintering leafrollers. However, the value of sanitation in blueberries is unknown.

Cultural control and sprays of Bacillus thuringiensis and the Entrust formulation of spinosadare acceptable for use on organically certified crops.

The most efficient and reliable method for monitoring the presence of moths is with the use of light brown apple moth pheromone traps, using commercially available lures.

In early spring, monitor shoots for webbing of leaves and larvae inside their nests. Look for rolled leaves that appear glued to shoots. Beginning at bloom, monitor fruit for webbing and larvae. Treatment thresholds are not yet established.