These bugs can be defeated by aerial spray of species-specific viral infection. But that weapon has to be designed first. In 70-ies, the USSR by such means successfully combated Lymantria dispar invasion in Siberia, which devastated pine forests on unimaginable scale. Though it took about 7 years and if memory serves, 3 research institutions to make insights into immune system of this species and make effective species-specific virus. The strain is still available.