About Insects
Insects belong to a group of animals called arthropods and can be found in nearly every habitat on Earth. There are more than one million known species of insects, with another estimated 10 million unidentified. This means that insects easily comprise more than half of the known life forms on our planet. Insects occur in such great numbers that those that study insects--entomologists- -believe that in an average square mile there are more insects than there are people.
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Identification
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Insects all have six legs and a body that is composed of three distinct regions: the head, thorax and abdomen. Many insects have wings, with the legs and wings connected to the middle section--the thorax. Insects possess an outer skeleton (exoskeleton) made up of a substance known as chitin. This does not grow as the insect gets larger, meaning that they will shed this exoskeleton and grow a new one. The majority of insects have what are known as compound eyes, which means they have separate lenses, sometimes thousands in one eye. Insects use their antennae to smell. A few, such as bees and ants, even have a sense of taste in their antennae.
Types
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The insects are divided by biologists into a total of 29 orders within the family of Insecta, under three separate subclasses. The subclass Apterygota is made up of primitive flightless insects without wings, such as silverfish. The subclass Exopterygota are insects that when young closely resemble the adult of the species, but have wings that develop on the outside of the body. Dragonflies and termites belong to this subclass. Endoterygota is the subclass in which the insect will develop its wings inside its body and go through a complex metamorphosis. Some of the more commonly known insects are in this subclass; such as those in the orders Diptera (flies), Lepidoptera (moths and butterflies), Hymenoptera (ants, bees and wasps) and Coleoptera (beetles). Coleoptera comprise more than a quarter of all known animals.
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Features
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Insects have many different features to fit their niches. Grasshoppers, for instance, use their strong hind legs to jump great distances to avoid predators. Ants are social insects and are well adapted for that role. They lay down a chemical trail when finding food that the rest of the colony can follow. Also, only the reproductive ants have wings, which they use only when it is time to leave a colony to establish a new one, taking off in great swarms in search of a mate. The rest of the ants responsibilities are to protect the eggs and provide food for the reproductive ants. Praying mantises have eyes that can detect movement up to 60 feet away and coloring that lets them blend into the environment. This makes them difficult to see by potential enemies and prey (often other insects).
Benefits
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The beneficial aspect of insects cannot be understated. Wasps, ants and bees pollinate flowers and plants, essential to the plants reproduction. Bees make honey and other insects provide such things as wax and silk. Insects are used as bait for fishing and they are actually eaten on a regular basis in parts of the world. Beetles are among the myriad of insects that act as scavengers and eat dead animals and plant matter, helping to decompose matter into a reuseable form. Insects also provide food for a multitude of animal species, especially the birds. They, themselves, eat more of their kind than any other type of animal, helping control their numbers.
Effects
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Insects are also considered pests and are capable of causing disease and damaging crops and structures. Termites cause billions of dollars worth of damage in the United States alone each year by eating wood in homes and other buildings. Locusts and weevils devour crops and many other insect species inflict harm on agricultural crops around the world. Ants, bees and wasps sting or bite, sometimes resulting in serious health concerns if the individual is allergic to their venom. Mosquitoes, ticks and bedbugs can transmit diseases such as malaria, Lyme disease, encephalitis, and West Nile virus. In fact, mosquitos, through the transmission of disease to people, are responsible for more human deaths throughout history than all other species put together.
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Resources
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