Light Brown Apple Moth

Light brown apple moth, also known as 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 that occur in grapevines. The mature larval stages are pale-to-medium green with a light yellow-tan head. The first segment behind the head (prothoracic shield) is greenish brown with no dark markings. Full-grown larvae are about ½ to ¾ inch (10 to 18 mm) long. However, larvae cannot be reliably identified using morphological characters. Take captured, suspect larvae (preferably alive) to the county agricultural commissioner's office for proper identification.

The most efficient and reliable method for trapping male adults is with the use of light brown apple moth pheromone traps. 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 and have protruding mouthparts that resemble a snout. Many moths have oblique markings on the wings. If you find a tortricid moth in a light brown apple moth pheromone trap, take it to your county agricultural commissioner's office for positive identification.

Depending on the climate, this pest may have from 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). During the winter second- to fourth-stage larvae can be found on vegetation surrounding vineyards, on weeds or in grape mummies on the vine. 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, depositing them at night on the upper side of leaves. On grapevines, eggs are normally found on fully developed leaves near the edge of the leaf blade. The eggs are typically laid 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 vine. In spring the first stage larvae move to shoot tips where they web together developing leaves to form nests. The larvae feed within these shelters. Larvae may enter fruit clusters as early as bloomtime. They produce webbing along the cluster stem tying flower parts together and feed on developing berries in a manner similar to omnivorous leafroller and orange tortrix.

Overwintering larvae may feed on buds; injured buds may fail to develop further. During bloom, larvae may feed on flower clusters. After veraison, feeding damage to the berries may allow rot organisms to infect fruit.

Removing mummified fruit and overwintering sites under the vines can reduce populations of these leafrollers. Well-timed spray treatments with a selective insecticide may be warranted if moths are caught in pheromone traps placed inside the vineyard and light brown apple moth larvae are seen feeding on grape clusters.

General insect predators and several species of spiders may influence these leafroller populations 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.

Appropriate sanitation practices during the dormant season can help prevent a buildup of these leafrollers. Mow broad-leaved weeds in and around the vineyard before bud break. Remove mummified clusters when pruning and place them in the row middles to be chopped.

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

Pheromone lures are commercially available and may be used to monitor the presence of these moths in the vineyard.

In early spring, monitor shoots for webbing of leaves and larvae inside their nests. Follow the monitoring procedures in MONITORING CATERPILLARS, which have been developed for other vineyard leafrollers. Look for rolled leaves that appear glued to shoots. Beginning at bloom, monitor bunches for webbing and larvae. If insecticide applications are warranted, they must be applied before bunch closure.