We have noted the presence of rusty tussock moth (Orgyia antiqua) feeding in our hazelnut plots for the last two seasons. This insect seems not to be a pest, only an incidental feeder that causes minor defoliation.
The larvae are quite colorful and showy, with clumps of bristles (setae) on their backs. These bristles are used to convey defensive toxins to predators. The adult moths are interesting. Similar to winter moth, which is another pest of hazelnuts from a different family of moths, the adult female is flightless. The females do not stray from their cocoons, rather they wait for males to locate them by flying along pheromone trails and then they lay their eggs (several hundred) on the cocoon after mating.
This species is exotic to Oregon and it is unclear when it was naturalized. In the UK it is known as the Vapourer moth. We have yet to see an adult moth in the orchard.