A phylogeny shows the history of a species and it’s evolutionary relationships with other species (described as a tree). In each of these branching lineages, a split at a node indicates a speciation event where two species (which share a common ancestor) diverged from another. Below are 3 phylogenies showing the speciation of arthropods into different groups (Tree 1), hexapods into different groups (Tree 2) and finally Insecta into different orders (Tree 3).
Tree 1: Phylogeny of the Arthropoda
Tree 2: Hexapoda phylogeny
Tree 3: Evolution of the Insecta.
For a more up-to-date phylogenetic analysis of the major insect groups, please see the recent science paper.