That is most likely webworms that you are seeing. These caterpillars have 2 or three cycles or generations per year. The simplest way to deal with webworms is to take a long pole and destroy their protective webs. Repeat this every time you see that they have built more webbing. Without the protection, they are sitting duck for paper wasps and other predators.
An effective, organic spray option is to apply a spray containing B.t. to the leaves after disturbing the webs. B.t. is sold under many brand names including Dipel and Thuricide, and is most effective on young caterpillars. When they eat the leaves sprayed with B.t. the caterpillars will soon get sick, stop eating and die. B.t. works best on young webworms (smaller than your thumbnail in length. Larger ones may need to be treated with pyrethrins or another of the stronger insecticide products.
Thanks for the question. Please stop in again soon!
Q&A Library Searching Tips