Evolution of insect is based on studies of different branches of science. For example insect morphology, molecular biology, evolution, bioinformatics, insect taxonomy and scientific computing.
Class of insect originated an earth 400 years ago the same time as terrestrial plants appeared.
Insects are known to be evolved from a group of crustaceans.
First insects were land bound in the time of Devonian period. First definitive insect fossil is Rhyniognatha hirsti which are estimated to be 396 to 407 years. old.
Insect genera which developed during Cenozoic which began about 66 million years ago. From those periods insects become preserved in amber which is often in perfect condition.