There are two leafrollers commonly found in Washington orchards: Pandemis leafroller (PLR) and Obliquebanded leafroller (OBLR). The phenology of the two species is quite different and you need to be sure which species you have for proper management and use the correct model on DAS. PLR used to be more common, but in the past 10 years, OBLR has displaced PLR from many of the production areas.
Both Pandemis (PLR) and obliquebanded (OBLR) leafroller overwinter as small larvae in hibernaculum in protected areas on the tree.
Most PLR have emerged the half-inch green stage of apple bud development, OBLR emerge later, by the pink stage of flower development. The prolonged emergence of OBLR from their hibernacula results in decreased residual control from the delayed-dormant Lorsban application.
DAS provides development models for both species that help to improve timing for insecticide applications and for sampling to determine population densities and efficacy of control programs.