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Identifying Insects

Identifying Insects

Identifying insects may prove beneficial in various circumstances. This article provides a brief overview about classification of insects and their features.
Sonia Nair
Last Updated: Apr 26, 2018
Insects are among the most diverse group of living organisms on the Earth. These small creatures belong to the class Insecta  in the phylum Arthropoda. The characteristic features of insects include exoskeleton, three pairs of jointed legs, compound eyes, body with three parts (head, abdomen and thorax), and two antennae. While most of the insects have all these physical features, some have modified body parts that help them adapt to their environment. Some insects develop wings during specific stages, but some others have this appendage throughout their adult life. While some insects walk, others jump, fly, swim, or walk over water. However, studies show that, there are over eight million species of insects on the Earth, and these creatures amount to about half the number of total living organisms.
Insects and Humans
Like any other living organism, insects are necessary for proper functioning of the ecosystem. These creatures play a vital role in pollinating flowers, aerating soil, controlling pests, and decomposing dead materials. In short, some types of insects are harmful for humans, but there are numerous beneficial insects, like bees and silk moths. In large numbers, certain insects can be harmful for humans in many ways. While some insects damage crops; insect bites and stings can also prove dangerous in some cases. Insects, like mosquitoes and fleas can transmit diseases to humans, pets and livestock. Termites can cause damage to the constructions made by humans.

So a basic understanding about insects can prove beneficial in various ways. Most of the pest control measures are targeted at specific insects. Treatment for insect bites may vary with different species of insects. For example, the stings inflicted by jack jumper ant of Australia can be life-threatening, and a specific antivenin has been developed for treating such stings. In short, identifying insects may prove beneficial in some situations, like the one discussed above. Otherwise too, you may develop a fancy for insects and start studying about these fascinating creatures.
How to Identify Insects
Insects in one region may or may not be present in another. While there are insects, which can be found in almost all parts of the world, some are endemic to specific regions. So you must have a basic idea about the commonly found insects in your area. They include the seasonal insects too. The first step in identifying insects is to determine whether it is an insect or not. Check the basic characteristics of an insect, like six legs, one pair of antennae, body with three parts, and compound eyes. There are various types of insects with different characteristics. If the organism has more than one of these characteristics, it is an insect. If you want to know further, it will be better to conduct an in-depth study about insects and their characteristics.
Insect Classification
Insects are basically divided into two subclasses - Apterygota (wingless insects) and Pterygota (winged insects). While Apterygota  consists of four orders (Thysanura, Diplura, Protura and Collembola), Pterygota  has two subdivisions - Exopterygota  and Endopterygota. Exopterygota  consists of sixteen orders and Endopterygota  has nine orders. The following are some of the insects that comes under the above said orders.

Order Common Name Characteristics
Thysanura Bristletails (600 species - e.g.: silverfish and firebrat) Small insects; compound eyes, very long and thread-like antennae, wingless.
Diplura Two-pronged bristletails (400 species - e.g.: Campodea staphylinus and Japyx) Small insects; compound eyes, very long and thread-like antennae with many segments, wingless, biting mouthparts.
Protura No common name (70 species - e.g.: Acerentomon doderoi) Minute wingless insects; lack eyes and antennae, piercing or sucking mouthparts.
Collembola Springtails (2000 species - e.g.: green springtail) Small wingless insects with 4 to 6 antennal segments, biting mouthparts, dense hair or scales covering the body.
Ephemeroptera Mayflies (2100 species - e.g.: Ephemera danica and Cloeon dipterum) Soft body with large eyes, very short antennae, atrophied mouthparts, membranous wings with many veins, hind pair small or absent.
Odonata Dragonflies and Damselflies (4500 species - e.g.: large red damselfly, southern hawker dragonfly) Large winged brightly colored insects; elongated bodies, large and prominent eyes, small and filamentous antennae, biting mouthparts, two pairs of narrow and shiny wings.
Plecoptera Stoneflies (3000 species - e.g.: Perla burmeisteriana) Soft body, long thread-like antennae, weak biting mouthparts, membranous wings, hind wings larger than front ones.
Grylloblattodea No common name (6 species - e.g.: Grylloblatta chirurgica) Wingless with eyes reduced or absent, long and filamentous antennae, biting mouthparts.
Orthoptera Crickets, Grasshoppers and Locusts (17000 species - e.g.: field cricket, Jerusalem cricket, desert locust ) Biting mouthparts, enlarged hind legs modified for jumping, two pairs of wings, and the front pair tough and leathery. Some members are wingless.
Phasmida Stick Insects and Leaf Insects (2000 species - e.g.: walking stick, Javanese leaf insect) Large, wingless insects; very slender and twig-like body; some members are flattened and leaf-like; long and filamentous antennae that resemble twigs; flat species have short antennae, biting mouthparts.
Dermaptera Earwigs (1000 species - e.g.: common earwig) Elongated insects, biting mouthparts, long and slender antennae, large, membranous semi-circular hind wings with fore wings modified into short, leathery wing-cases.
Embioptera Web-spinners (170 species - e.g.: Haploembia solieri) Long, segmented and filamentous antennae, biting mouthparts, two pairs of wings; some species with reduced or flat wings; long spiny legs.
Isoptera Termites or White Ants (2000 species - e.g.: Yellow-necked termite) Social insects living in large communities that consist of several forms, soft-bodied, pale-colored, biting mouthparts, powerful jaws.
Zoroaster No common name (16 Zorotypus species - e.g.: Zorotypus swezeyi) Very minute insects (less than 3 mm in length); live under bark, in decaying wood and humus; thick antennae with large, distinct segments; biting and chewing mouthparts; both winged and wingless species.
Psocoptera Psocids or Book lice (2000 species - e.g.: book louse or dust louse, bark louse) Small, soft-bodied insects; two pairs of membranous wings or wingless; broad head, long filamentous antennae and biting mouthparts; large, protruding eyes.
Mallophaga Biting Lice (3000 species - e.g.: bird louse) Small, wingless insects; usually live as external parasites on birds or mammals; broad head, flat body, very small eyes, short and concealed antennae, and modified biting type mouthparts.
Siphunculata or Anoplura Sucking lice (500 species - e.g.: human louse, human crab louse) Small, wingless insects; live as external parasites on mammals; narrow head, very minute or no eyes, short antennae, modified mouthparts for piercing and blood-sucking, and flat bodies.
Hemiptera True Bugs (70000 species - e.g.: white flies, scale insects, capsid bugs, bed bugs) Small to large-sized insects; different shapes and habits; piercing mouthparts adapted for sucking the juices of plants or animals; long antennae, two pairs or wings or wingless.
Thysanoptera Thrips (5000 species - e.g.: pea thrips) Minute insects with slender bodies; mostly found in flowers; short antennae, piercing and sucking mouthparts, a pair of very narrow wings, and many species are wingless.
Neuroptera Lacewings, Alder Flies and Snake Flies (5000 species - e.g.: ant-lion, lacewing, snake fly) Small to large and soft-bodied insects; two pairs of similar wings, long and thread-like antennae, biting mouthparts; carnivorous larvae.
Coleoptera Beetles (350000 species - e.g.: Colorado beetle, diving beetle, rove beetle) Minute to large insects; forewings modified into hard wing-cases membranous hind wings (vestigial or absent in many species); biting type mouth parts; complex metamorphosis; diverse larval stages with biting jaws.
Strepsiptera Stylopids or Stylops (400 species - e.g.: Elenchus tenuicornis) Minute insects (less than 5 mm in length); parasitic females and young ones, which live inside the bodies of other insects; females have no eyes, antennae or legs,
Mecoptera Scorpion Flies (300 species - e.g.: common scorpion fly, winter scorpion fly) Soft-bodied insects; head is elongated downwards into a beak; biting jaws at the lower end of the head; long and thread-like antennae, large eyes, two similar pairs of wings (there are wingless species too).
Siphonaptera Fleas (1800 species - e.g.: dog flea) Very small, wingless insects; adults live as external parasites of warm-blooded animals (birds and mammals). Body flattened at both sides, inconspicuous eyes and antennae; skin piercing and blood-sucking mouthparts, long hind legs for jumping; complex metamorphosis.
Diptera True Flies (90000 species - e.g.: crane-fly, hover-fly) Small to moderate-sized insects; hind wings serve as balancing organs or halteres, one pair of membranous wings (some are wingless and parasitic); large eyes, mouth parts like a proboscis for sucking liquid food and for piercing.
Lepidoptera Butterflies and Moths (2500 species - e.g.: small white butterfly, peacock butterfly, death's head hawk moth) Small to very large insects; two pairs of brightly-colored wings, large eyes, long antennae; long and coiled mouth parts, like sucking tubes (called the proboscis); complex metamorphosis.
Trichoptera Caddis Flies (6000 species - e.g.: limnephilid caddis fly) Moth-like insects; two pairs of wings densely covered with tiny hair; dull brownish or grayish insects, flying at dusk; very long and thread-like antennae, biting mouthparts; a complex metamorphosis; aquatic young stages.
Hymenoptera Sawflies, wasps, ants and bees (6500 species - e.g.: horntail, pine sawfly, common wasp, yellow garden ant, hive bee) Minute to moderate-sized insects; two pairs of membranous wings, larger front wings, wings attached by a row of small hooks on the front edge of the hind wing; large eyes, thread-like antennae, biting mouthparts, and powerful jaws.
Identifying insects can be a very difficult task, as there are millions of species with different physical features. Once you are sure that, what you have found is an insect, study its physical features. Search relevant and authentic books and websites, to find the type of insect with those features.