Help! My Knockout roses were lush and healthy until about the middle of May. Almost overnight, the leaves were devoured between the veins. Some of my bushes sported leaves so riddled with holes that it's a wonder they could photosynthesize!
I tried spraying with soapy water, but it did no good. Little worms (lime green to medium gray in color and 1/4th to 1/2 inch in length) continued to live on the underside of the leaves. I picked off what I could, but they were rampant. I finally resorted to a pesticide, but hate using anything with warnings longer than my income tax return. Any thoughts on what these little worms might be and how they might be routed without toxins?