I live in Wilton and last year I planted Knockout Roses hoping they would be low maintenance. Each year they have been heavily attacked by sawfly larvae on the underside of the leaves. I’m trying to avoid chemical pesticides. Last year I tried a spray with Spinosad to control them with minimal success. This year I am trying RoseRx with Neem based on discussion with the Hewitt’s staff.Should I expect to contend with the sawflies each year, and could it be something site-specific? I have very sandy soil if that makes any difference.Thanks.