Why is the presence of insects in a rain forest ecosystem important?

Although Insects are a very important part of daily life, Insects are probably one of the most important things in a rain forest ecosystem,
they contribute by decomposing old and weak trees (or just said as killing them as they feed),
Many provide pollination for other flowers,
Make new habitats by destroying old and weak trees,
Things like Leaf and Needle eating insects regulate nutrients in the forest,
and they overall improve the forests health.