Key to Insect Orders - Revised

Insects make up the vast bulk of species diversity, with just over a million described species organized into about thirty major subgroups called orders. Orders are in turn divided into families, families are divided into genera, and genera are divided into species. Properly defined; orders, families and genera are each groups of species that have descended from a unique common ancestor, as a result of which they share similar structural characteristics and have certain biological attributes in common. Not all insect orders are equal in species number; some have just a few hundred species while the larger orders have hundreds of thousands of species. Most insects are in just four large orders: Diptera, Coleoptera, Lepidoptera and Hymenoptera. The range of structural characteristics and biological features tends to be broader in the more species-rich orders. Predictions about the…