A tiny wasp that lays its eggs in the eggs of other insects may be just what California walnut growers need to control that crop's most damaging insect pest -- the codling moth. A team of UC farm advisors and other UC scientists have been looking for an alternative to chemical sprays, which although effective, are damaging to beneficial insects such as walnut aphids and mites. Control of the codling moth is essential, because the walnut industry can endure only a 4 percent damage rate from the moth. Now in their third year of field experiments, researchers have achieved about 70 percent control with the tiny wasp known as Trichogramma platneri. They are optimistic that different methods of releasing the wasp into walnut orchards eventually will boost that average into the commercially viable range. Some of the novel techniques under study include supplementing release of wasps with honey, and "chumming" the wasps with the scent of the codling moth.