The majority of insects are herbivores, and they need greenery for their feed. Due to climate change, as more water vapor goes up & forms clouds, the same water has got to come down & drenches all types of lands. This is conducive to increasing greenery & such a condition is taken advantage of for insect population explosion.
Cutting down trees does happen, but most of it is in forest areas & in such cases, it doesn't matter much, because there are still other trees available.