Question
I am in the St. Louis, MO area. I planted a knockout rose about 1 1/2 years ago.  Last summer the leaves started looking like something was eating them and lacy looking.  This year they have bloomed and the new leaves are beginning to look the same.  My neighbor is also having the same problem.  What can we use to stop this.

Answer

Saw flies or rose slug Lacey leaves are caused by a rose saw fly or rose slug. They work under the leaves and suck out the nutrients until the leaf finally dies. It would be a wisdom to check and see if you can find what looks like a tiny dark brown slug. If you find even one then that is what is causing the problem. Any rose insecticide will solve the problem for you but make sure you also spray on the undersides of the leaves as well  as all around the base of the rose bush because they can hide there. The leaves will renew themselves as roses can put out three sets of leaves. before they weakened the bush.