author(s)
Priyankar Mondal

abstract
Since the ‘theory of natural selection’ proposed by Darwin, the study of kind and diversity of life got a whole new perspective under the light of evolution, but there is a lack of shreds for evidences regarding the origin of complicated developmental strategies among organisms. Insects are not an exception as they include a sheer number of taxa with diverse life histories. Insects having ‘caterpillar’ or ‘larva’ like immatures completely different from the adults arrived late in the evolutionary timescale, whereas their preceding ancestors had immatures almost similar to the adults, known as ‘nymphs’. This review summarizes two recently available contrasting hypotheses and evidences regarding the origin of caterpillars, did they evolve as descents with modification or as the products of distant hybridization? It also aims to provide endocrinological and molecular overview of insect metamorphosis and how it differs between insects with caterpillars and those without caterpillars.