All insects have 6 body regions

Wonderful world of insects

Facts, facts, facts ...

Our world is full of insects - their bright colors and the many different shapes invite us to be amazed again and again. Although the little ones couldn't look more different, they have an incredible amount in common.

Beewolf gold wasp - Photo: Frank Aeckersberg /

Whether a million or even up to 80 million - the number of insect species on earth is enormous. In Germany one assumes 33,000 insects. No other animal class has developed such an impressive biodiversity. Almost all insects can fly. They have conquered the air, the soil, the water, the plants and other animals as their habitat. They occur in all biotopes - except on the open sea and in the polar regions. And although insects are extremely different in their appearance, they all have the same “body measurement index” - what makes an insect an insect?

Body: Classic three-piece suit

Beewolf on field thistle - Photo: Helge May

The insect body always consists of three parts: head (caput), chest (thorax) and abdomen (abdomen). All insects have six legs. The three pairs of legs and the wings sit on the segments of the chest. The important organs for digestion and the sex organs of the insects are located in the abdomen. Insects do not have a skeleton like humans. Your body is protected by a thin layer of chitin. This special protective cover is called the exoskeleton. Chitin means shell or shell. The horny substance protects the small animals from moisture and makes the insect body very stable and flexible at the same time. The insects' breathing works via a branched system of tubes (trachea) that run through the entire body. Insects have a simple nervous system and an open blood vessel system. This means that the internal organs are located inside the body and are bathed in blood.

Head: super senses and toolbox

The sensory organs such as eyes and antennae are located on the head. The eyes of the insects consist of thousands of individual eyes. They are therefore called compound or complex eyes. Likewise here are the mouthparts. These can vary depending on the species and food specialization. Butterflies have long trunks that can be rolled out to absorb liquid food from fruit juice to minerals from puddle water. Beetles and bedbugs have short, sharp kicks to stab into bowls or other animals and suck them out.

Development: small artists among themselves

Pupae of the scale insect ladybird (= kidney-spotted ball ladybug) on ​​a pea cone fruit - Photo: Helge May

Insects are quick-change artists. A distinction is made between insects with an imperfect or a complete metamorphosis. Bugs, dragonflies and grasshoppers hatch from the egg and look almost like the later adults. With each moult, their appearance more closely resembles the fully developed animal. This step-by-step transformation is called imperfect metamorphosis. Grasshoppers and bed bugs are examples of these animals. How often and how long such a larval stage lasts depends, among other things, on the temperature and the food available.

A complete metamorphosis means that the animal is completely transformed. Butterflies and beetles go through the different phases of life egg - caterpillar - pupa - butterfly or egg - grub - pupa - beetle. The larvae (maggots, caterpillars or grubs) look very different from the adults. In addition, they sometimes have completely different ways of life, occur in different habitats and prefer different sources of food. Only in the pupal stage does the insect transform and hatch out of its pupa with a completely different appearance. Flies, bees, butterflies and beetles go through this development cycle.

Diet: the crawling diet

Aurora caterpillar eats garlic mustard - Photo: Helge May

Plant and animal foods are on the menu of insects. But there are also omnivores like earwigs. Often, however, insects only feed on plants or only on meat. In the case of herbivores, wood, dung and dung are also part of the animal's diet. Insects are also able to extract usable nutrients for their development from these. Among the carnivores there are predators, parasites and scavengers. Depending on the stage of development, insects can also change their type of diet. From specialists who only use a very specific plant, there are also all-rounders and generalists who make their diet flexible.

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