The first rule of protecting trees from Cicada Larvae is to keep adult Cicadas away from your trees. However, if trees are contaminated with larvae, there is still methods that can be employed to deal with this threat.
First rule is to treat all the trees in vicinity. By protecting one tree, you don’t stop Cicadas from spreading its eggs all over the place only comprehensive protection will stop larvae from eating your greenery. Larvae not only affects branches of leaves it also damages roots of the tree especially during its hibernation period when it spends most of the time underground eating roots and sacking tree juices.
One of chemicals that deal with larvae is “Bifen Granules”, which is very toxic to fish and should not be applied to the areas close to water. Granules must be planted directly under the trees and renewed after 2 months. In order to achieve best results, you need to put granules before Cicadas start laying eggs, which is usually late June and Early July. Make sure you treat soil with “Bifen Granules” in late May.