There are not many creatures that have the great diversity of morphology witnessed in insects. This is deeply related to their advancement into various environments where they acquired diversified lifestyles. Insects that live deep underground have stout and robust legs which are used as shovels. Cicadas that need to produce a loud mating call have greatly developed hollow abdomens. The praying mantis' front legs are perfectly designed for catching prey, evolving intomuscular and stout structures with a lot of spines. When you see some unique morphology, please try to imagine how the particular insect has survived.