Ant's nests in trees are mineral gold mines for epiphytes in an otherwise aerial desert. Nests on the ground are an oasis of vital minerals for young tree saplings. See how a fallen tree is vital to the health of a rainforest. Most of these insects prey on other insects. Only a few attack other animals.
Insects alone process more flesh than all the large carnivores put together.
Major predatory arthropods include parasitic wasps, spiders, scorpions. Many insect larvae are also formidable predators. We only notice how important insect predators are when they are absent. Many plants have evolved intricate relationships with insect pollinators. Without insects, many plants would not be able to reproduce and there would be no fruits to start off food chains in the habitat.