Insects (Insecta)

Insects (Insecta) belong to the Arthropoda (also known more commonly as 'arthropods')—a group of animals that also includes spiders, crustaceans, scorpions, and centipedes. Like most arthropods, insects have:

• jointed appendages
• exoskeleton
• segmented body
• compound eyes

Insects are a highly successful group of animals. The Class Insecta accounts for more species of animals than any other class of animals. Their numbers are nothing short of remarkable, both in terms of the numbers of individuals as well as the number of species. In fact, there are so many insects that no one knows quite how to count them all. The best that can be done is to make estimates.

Scientists approximate that there may be as many as 30 million species of insects alive today. To date, over one million have been identified. At any one time, the number of individual insects alive on our planet could be in the ballpark of 10 quintillion, which is equivalent to 10¹⁸ or 10,000,000,000,000,000,000.

Insects have small body sizes but are otherwise extremely variable in shape and form. In general, the body of an insect is made up of a head, thorax, abdomen, a pair of compound eyes, a pair of antennae, and a set of complex mouthparts (often specialized according to a specific type of feeding) (Source: Myers).

Classification:

• Kingdom: Animalia
• Phylum: Arthropoda
• Class: Insecta

New to animal classification? Find out more about how scientists classify animals.

Where to See: The success of insects as a group is reflected by the diversity of habitats they live in, which includes terrestrial (desert, forest, grassland, rainforest), freshwater (ponds, lakes, streams, wetlands) and marine (Source: Myers).

Members of Class Insecta: The Class Insecta is subdivided into the following orders:

• bristletails (Order Archaeognatha)
• silverfish (Order Thysanura)
• mayflies (Order Ephemeroptera)
• damselflies and dragonflies (Order Odonata)
• crickets and grasshoppers (Order Orthoptera)
• stoneflies (Order Plecoptera)
• rock crawlers (Order Grylloblattodea)
• stick and leaf insects (Order Phasmotodea)
• earwigs (Order Dermaptera)
• mantids (Order Mantodea)
• cockroaches (Order Blattodea)
• termites (Order Isoptera)
• web-spinners (Order Embioptera)
• angel insects (Order Zoraptera)
• barklice and booklice (Order Psocoptera)
• parasitic lice (Order Phthiraptera)
• bugs (Order Hemiptera)
• thrips (Order Thysanoptera)
• dobsonflies and alderflies (Order Megaloptera)
• snakeflies (Order Rapdhidioptera)
• antlions and lacewings (Order Neuroptera)
• beetles (Order Coleoptera)
• strepsipterans (Order Strepsiptera)
• scorpionflies (Order Mecoptera)
• fleas (Order Siphonaptera)
• flies (Order Diptera)
• caddisflies (Order Trichoptera)
• moths and butterflies (Order Lepidoptera)
• bees, wasps, ants, sawflies (Order Hymenoptera) (Source: Burnie and Wilson: 23)

Sources

• Burnie, D. and D.E. Wilson. Animal. Dorling Kindersley. London. 2001.
• Myers, P. 2001. 'Class Insecta' (On-line), Animal Diversity Web. Accessed September 20, 2005