Q.What is wrong with my tall phlox?
My tall phlox has done well for years. However, this year the leaves are light in color and are curling up. I believe I might have an insect infestation and have seen little black beetles on the leaves. I am going to spray with neem oil but I want to make sure this is the problem. Thanks!

Yes, treat the insects with Neem OIl. This is a good choice as it acts as both an insecticide and fungicide.
The yellowing leaf patter can indicate an iron deficiency in the soil.
Here is a link with more information.
https://www.gardeningknowhow.com/plant-problems/environmental/leaf-chlorosis-and-iron.htm