The adult, flying form of most insects lasts for just a few weeks or months but this is only a small fraction of the insect’s total life span. The adults are generally adapted only for mating and eat little or not at all. The larval form will have spent a year or two hiding away in a pond, underground or inside a tree/rotting log, eating and growing. The Magicicadas of eastern USA are a genus of cicada that spend 13 or 17 years underground (depending on the location) before they all emerge as adults in a single, synchronised wave lasting a couple of months. This is nothing compared to termites though. Although the smaller workers are only around for a year or two, a termite queen can live for up to half a century!
Answered by Luis Villazon.