A leaf roller, Platynota stultana Walsingham, has become an important pest of grapes in the San Joaquin Valley, California. It infested a large acreage during 1969-70 and 1970-71 growing seasons and caused serious economic losses. There were 5 overlapping generations during 1970. Unpicked grape bunches, decayed bunches on the ground, dried grape “mummies” left in the vineyards, and dried leaves underneath vines provide ideal overwintering sites and a reservoir of overwintering larvae for reinfesting vineyards. Larvae feed on leaves, flowers, and fruit; feeding early in the season causes cavities and scars on the berries, later in the season feeding breaks the berry’s skin and allows yeast and fungi to initiate bunch rot which causes substantial reduction in yield.