Entomology is the science that studies insects, their morphology, physiology, ecology and natural history. Insects are one of the most successful groups of animals on Earth, inhabiting almost every environment and playing important roles in many food chains. They are also major pests of crops and humans, and vector diseases such as malaria and dengue fever.
The word “entomology” comes from the Greek ἔντομος (éntomos), meaning “that which is cut in pieces” or “segmented”, referring to the segmented body of insects. The branch of zoology that deals with insects is called entomology. Entomologists use a variety of techniques to study insects, including microscopy, genetics, rearing methods and field work.
Insects can be divided into two broad groups: winged (or true) insects, which include beetles, flies and moths; and wingless (or false) insects, such as ants, wasps and bees. Insects are further classified into orders based on their similarity of form or function. For example, the order Coleoptera includes all beetles; the order Diptera includes all flies; and the order Hymenoptera includes wasps, bees and ants. There are about 30 orders of insect altogether.
Most adult insects have four wings – two pairs arranged in a characteristic pattern unique to each group. The hind wings are smaller than the forewings and may be absent altogether in some groups (such as many True Bugs). The front pair of wings has evolved into hard plates (elytra) that protect the hind wings when at rest – this arrangement is unique to beetles. In other groups (such as cockroaches), both pairs of wings are used for flight but differ in structure – these are said to be heteromerous wings. In yet other groups (such as mayflies), only one pair of wings is used for flight while the other pair is vestigial or absent – these are said to be homomerous wings. Wings vary greatly in shape between different insect groups but all have a network of veins that support them structurally
Insects undergo complete metamorphosis during their life cycle – this means that they have distinct egg , larval , pupal stages , separated by molts . The larvae stage typically consists mostly of feeding , while pupae do not feed at all . Many species build cocoons around themselves during pupation for extra protection . Some terrestrial insects dig burrows underground during this stage . Upon emerging from their pupal stage , adult insects must mate before they can start laying eggs themselves Most species only live for a few weeks or months as adults males die soon after mating while females often survive long enough to lay multiple batches Development times vary between species but generally take longer in colder climates faster development times allow more generations per year This contributes to higher population densities possible under warmer conditions Life cycles can be synchronized with seasonal climatic changes by using environmental cues such as day length or temperature