Entomology(fromGreek,entomos, "that which is cut in pieces or engraved/segmented", hence "insect"; and-,-logia[1]) is thescientificstudy ofinsects, a branch ofarthropodology, which in turn is a branch ofzoology. In the past the term "insect" was more vague, and historically the definition of entomology included the study of terrestrialanimalsin otherarthropodgroups or otherphyla, such asarachnids,myriapods,earthworms,land snails, andslugs. This wider meaning may still be encountered in informal use.Like several of the other fields that are categorized withinzoology, entomology is ataxon-based category; any form of scientific study in which there is a focus on insect related inquiries is, by definition, entomology. Entomology therefore includes a cross-section of topics as diverse asmolecular genetics,behavior,biomechanics,biochemistry,systematics,physiology,developmental biology,ecology,morphology,paleontology,mathematics,anthropology,robotics,agriculture,nutrition,forensic science, and more.At some 1.3 million described species, insects account for more than two-thirds of all known organisms,[2]date back some 400 million years, and have many kinds of interactions with humans and other forms of life on earth.Most insects can easily be recognized to order such as Hymenoptera (bees, wasps, and ants) or Coleoptera (beetles). However, insects other thanLepidoptera(butterfliesandmoths) are typically identifiable to genus or species only through the use ofIdentification keysandMonographs. Because the classInsectacontains a very large number of species (over 330,000speciesofbeetlesalone) and the characteristics separating them are unfamiliar, and often subtle (or invisible without amicroscope), this is often very difficult even for a specialist. This has led to the development ofautomated species identificationsystems targeted on insects, for example,Daisy, ABIS, SPIDA and Draw-wingInsect identification is an increasingly common hobby, withbutterfliesanddragonfliesbeing the most popular.