I've been doing mechanical control as well - cutting off the infected branch and burning it. We are not as hard-hit as Camano Island, and the caterpillars seem to enjoy the native alders as much as my fruit trees. Rick, I was in north Everett yesterday (Sorticulture) and noticed a lot of webs on some shrubs by the roadside, but not so many in trees. So, perhaps Camano is the epicenter and it gradually lessens the further away you get.