The cultivated hazelnut was introduced to the west coast of the US during the late 1800s. Oregon’s hazelnut orchards account for 99% of US production and 5% of world production. The filbertworm, which is a native insect generally found on acorns and oaks, is the most severe pest of hazelnuts in Oregon. The females lay eggs on leaves and the new worms penetrate the nut and feed voraciously inside. Consumers prefer hazelnuts free of insect damage – insecticide sprays are necessary.

“In untreated orchards, 20-50% of nuts can become infested with filbertworm larvae. Filbertworm larvae attack hazelnuts in Oregon from June through October, when neonates bore into developing nuts and feed on kernels. … Current filbertworm management relies heavily on synthetic insecticides targeting adults, eggs, and neonate larvae. Growers often apply between one and three sprays per season to keep infestation levels below the economically acceptable threshold of 1%.”

“No effective biological control methods are currently available for this pest.”

Authors: Chambers, U.¹, D.J. Bruck², J. Olsen³ and V.M. Walton¹.
Affiliation: ¹Department of Horticulture, Oregon State University; ²USDA-ARS Horticultural Crops Research Laboratory, Corvallis, OR; ³Yamhill County Extension Service, Oregon State University.
Title: Control of overwintering filbertworm( Lepidoptera: Tortricidae) larvae with Steinernema carpocapsae.
Publication: Journal of Economic Entomology. 2010. 103(2):416-422.