Classification of insects

Insects are, without a doubt, one of the most diverse and surprising groups of invertebrates in nature. Its biodiversity is incalculable, since there are still many species to discover and study, especially in the ecosystems of tropical forests in humid regions, where insects coexist and multiply. It is estimated that the number of species of insects discovered to date outnumbers the number of human beings that inhabit the Earth, that is, there are more than 8,000 million species of insects.

As we can imagine, the classification of all of them, as well as the study of their anatomical characteristics and their main functions within the ecosystems in which they inhabit, is really complex and fascinating. Entomology is the science that takes care of it, but you don’t need to be expert entomologists to have some basic notions about the insects that surround us, we can always learn about them by reading an article on the subject, like this one that we published from Green Ecology, about the classification of insects .

Taxonomy or classification of insects

The taxonomy or classification of insects allows us to better understand the different groups and classes of insects that exist according to their main characteristics. The classification of this type of invertebrate animals is very broad, but in this article we will know the most common groups :

  • Odonata ( odontos, tooth): long-bodied insects with large eyes and small antennae. As their name suggests, odonates are characterized by having strong toothed mouthparts, which they use to feed and devour insects of different kinds. They have two pairs of membranous wings with numerous transverse veins. The well-known dragonflies and damselflies belong to this order of insects.
  • Blattodea: widely distributed throughout the planet, cockroaches (order Blattodea) are one of the best-known omnivorous insects. Their hardened forewings, long threadlike antennae, and strong chewing mouthparts give them one of the least appreciated appearances by humans.
  • Orthoptera ( ortho , rectum; pteron , wing): these insects are commonly known as jumpers, since they are capable (with greater or lesser force) of actively jumping using the muscles of their third pair of legs. Crickets and grasshoppers are without a doubt the best known insects of this group.
  • Phthiraptera: to this group belong those insects without wings, characterized by their way of life as ectoparasites of birds and mammals. They are small in size, some do not have eyes and their mouthparts are modified to pierce the skin and suck the blood of the animal they parasitize. Lice are perhaps the most representative insects of this order.
  • Coleoptera: those commonly known as beetles and ladybugs, are just some of the more than 370,000 species of coleoptera that exist in nature. They present their first pair of wings modified in the form of resistant elytra, under which their second pair of membranous wings with which they fly is hidden.
  • Diptera: flies and mosquitoes constitute the group of Diptera. They can be moderate or very small in size, and they have a single pair of membranous wings. Their mouthparts are clearly differentiated and adapted to suck or sting, generally forming a proboscis-like structure.
  • Lepidoptera: the majestic and surprising butterflies, as well as the nocturnal moths, are included within this order of insects. Characterized by their long tongue coiled in a spiral, transformed into a proboscis or spirit, as well as by the covering of scales with different colors and geometries that their wings present.
Physical characteristics of insects – external anatomy

The external anatomy of insects is one of the most complex and fascinating in the animal kingdom. Its structure is characterized by:


Made up of a resistant cuticle, the exoskeleton covers and protects both the intestines, the tracheas and other vulnerable organs against blows and damage. This exoskeleton of great importance for the development and survival of insects, adapts to the segmented anatomy of these organisms, which presents three well differentiated body regions: head, thorax and abdomen.


The outside of the head of insects is called the cephalic capsule. In it, both the eyes and the jaws appear, as well as different appendages as antennae and others as mouthparts (maxillae and lip).


The thorax is in turn divided into 3 well-differentiated thoracic segments, in which are the legs and wings of insects. They vary in number, morphology, and function.


Finally, the abdomen completes the complex external anatomy of insects. It is made up of a variable number of segments depending on the species (between 7 or 11 segments), among which the genital segments stand out (eighth and ninth segment in females; ninth in males).

More characteristics of insects: what they eat and their reproduction

As for the feeding of insects , it is worth noting the great variety of diets and habits that they present. There are insects that eat leaves of terrestrial or aquatic plants, predators of other insects, parasitoids, ectoparasites, bloodsucking of mammals and birds; as well as those that feed on the nectar and / or pollen of the flowers of flowering plants (angiosperms), thus contributing to the wonderful process of plant pollination. Here you can find out which are the pollinating insects .

However, another of the amazing processes that characterize insects is, without a doubt, metamorphosis . Through it, insects change their appearance and structure in various stages, from hatch to adulthood. To do this, individuals undergo the shedding of the outermost part of their “skin” (cuticle), thus allowing the growth of insect tissues that had not matured. In addition, several organs characteristic exclusively of adults (such as the reproductive system) are differentiated.

In this way, the adult individuals will be reproductively active and will be prepared to carry out copulation between adult individuals of the opposite sex, this being the most common reproductive method. Later, the females deposit the eggs and after a more or less long incubation period, an immature insect will be born from each egg. However, there are other processes of reproduction of insects , such as parthenogenesis (the eggs develop completely without being fertilized), polyembryony (two or more embryos are produced from a single egg), and viviparity (when the embryonic development is completed inside the mother’s body, which produces young larvae instead of laying eggs).

Wingless insects are grouped within the wingless , which includes species such as:

  • Silverfish (Lepisma saccharina).
  • Lice of the human scalp ( Pediculus humanus capitis ) and in cattle ( Haematopinus eurysternus).
  • Common fleas (family Pulicidae).
  • Campodea maestrazgoensis (endemic species of northern Spain, inhabits caves).
  • Anurida maritima.
  • Papirius saundersi

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