Insects

Insects

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Introduction

Insects are the most prolific of animal types. They exist in unimaginable numbers, in every corner of the world. The estimate of the number of insect species range from 30 to 50 million species, of which nearly half are beetles.

I look forward to having you all join me on this journey of writing on this abundant group of animals.

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What is an insect?

The word ‘insect’ is often used wrongly to describe different types of creep-crawlies. In actual fact, in order to be an insect, a creature must fit several requirements. All insects have six legs and most also have ‘feelers’, called antennae, and wings. Their bodies are split into three sections: the head, where the eyes, jaws and antennae are found the thorax, which holds the legs, wings and the abdomen, which contains internal organs. Insects are invertebrates, as they have no backbone.

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How does the eye of an insect work?

Insects have compound eyes, made up of hundreds of small individual sections. Each of these sections is called an ommatidium, at the top of which is lens, or facet, on the outer surface of the eye. Every facet faces a separate way and can only see a short distance in front of it. Only one ommatidium picks up the whole image of whatever the insect is looking at.

The others around it see only part of it. Because of the way insects’ eyes are constructed, the image they see is often depicted as hundreds of small images. This is like saying that we see two images of everything because we have two eyes. Such an image would be of little use to an insect as its view of the world would be too confusing. Instead, just like our brain combines the image from our two eyes, the insects’ brain puts together the different images from each section to create one whole picture. Although short-sighted, insects are very good at picking up movement, so can move away quickly from any sign of attack.

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Which is the most destructive insect?

The desert locust is extremely destructive when it comes together with millions of other locusts in enormous swarms. A single locust is able to eat its own body weight in food each day, so in huge swarms they devastate entire areas. In a day, one tonne of these insects, just a small part of the swarm, can eat the same amount as 2,500 people. A plague of desert locusts, occurring mainly in Africa and Asia, can damage the livelihood of millions of people. A swarm can range in size from under 1km2 to 100s of km2, with between 40 million and 80 million locusts in each km2.

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High-speed insects?

Insect are fast movers, even those without wings. However, the fastest movers are flyers and some of them are very fast indeed, particularly considering their small size.

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What happens in a beehive?

In a beehive, each bee has a specific role that determines which job they do. They are divided into queens, workers and drones. In a colony, there is only one queen who lays eggs. She has a longer body than all other bees and can lay up to 2,000 eggs a day. Workers are female bees, who do all the various jobs within the colony: take care of the queen, look after the babies, guard the colony, collect food and build the hive. Drones are male bees. Their only purpose is to mate with the queen to produce eggs. This ensures there is a continual supply of bees to live in the hive.

Female bees gather nectar from flowers which they turn into honey. This honey is useful food source and beekeepers keep many bees in order to collect and sell the honey. These bees live in wooden hives with sliding sections to make collection of the honey easier.

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Why do bees and wasps sting?

Bees use their sting to defend their colony. If they sense the hive is under attack, they will use their sting to warn off an intruder. A bee’s sting is like a needle with barbs on it. When it is inserted into the skin, the barbs prevent it from coming out, so it stays pumping poison into the victim.

Unfortunately, for the bee, this means that the sting is ripped from its body when it flies away and this causes the bee to die soon afterwards. Wasps, on the other hand, can sting many times. They sting in self-defence or to protect the nest, but they also use their sting to kill prey. Dead insects are fed to the young hatchlings, which are called larvae.

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Which are the largest insects in the world?

Insects are limited in how large they can become by the system they use to breathe. Without lungs, they use breathing holes called spirocetes along the side of their bodies and absorb oxygen they need directly into their tissues. This system is very inefficient and only works at all smaller on smaller creatures. If it grew over a certain size, an insect would simply suffocate.

The goliath beetles from Africa have the largest body mass in the insect world. They can grow up to 15cm long and weigh over 100g. The Longhorn beetle can grow even longer.

The Queen Alexandra Birdwing butterfly from New Guinea has the largest wingspan – about 30cm.

The longest insect is a type of stick insect, Phobaeticus kirbyi, which is found in Borneo. This can grow up to 30com long. Another type of stick insect, heteropteryx dilitata, holds the record for the longest insect eggs of 1.3cm.

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Why do insects have skeletons on the outside of their bodies?

An insect’s hard outer armour, known as the exoskeleton, supports its body and protects its soft inner parts. It creates a waterproof coating and stops insects from drying out. The exoskeleton also allows insects to live in almost any climate, including deserts. The problem with this is that insects cannot grow any bigger inside a shell that does not move. That is why they have to shed their skin. After they have done this, their bodies are soft and can grow. But then this soft cover quickly hardens again to protect the insect. Insects are not the only creatures with exoskeletons; crustaceans also have outer shells that work in the same way.

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How does a moth find a mate?

Moths tend to fly mainly at night, so they use smell to find a mate rather than sight. Female moths release a scent to attract males. This mixture of chemicals, known as pheromones, drifts on the wind where it is picked up by the sensitive antennae of male moths. With their fantastic sense of smell, males are able to follow the source of the scent to find the female. Silk moths are able to detect the scent of a female from 10-20km away.

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What is a beetle?

Beetles are members of the insect family. What makes them different is that they only have one pair of wings. Their second pair has evolved to become a hardened shell, which they use to cover and protect the working pair. There are 4,000 species of beetle in the UK alone, while worldwide, scientists have named over 350,000 different species and many more remain unnamed. There are over six times as many beetles as the whole total of vertebrate animals. Many beetle shave developed a bewildering array of horns and other adornments which are used for display and fighting other beetles.

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Do dung beetles eat dung?

Dung beetles ae a type of beetle known as a scarab beetle. These are among the largest members of the beetle family. Large animals produce a lot of dung, and herbivores particularly are not very good at extracting all the nutrients from the plants they eat. This means that their dung is a valuable source of food and the dung beetle is happy to exploit it. The beetles make their distinctive balls of dung in order to provide a source of food for their young. The beetle slay their eggs inside these balls, known as ‘brood balls’ which they roll to a safe place. While dung beetles are most associated with Africa, they are found all over the world from Australia to America. One useful by-product of their activities is a reduction in the number of flies around the piles of animal dung.

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Are spiders insects?

Spiders look very similar to insects in many ways. They have exoskeletons, spindly legs and segmented bodies and compound eyes. However, they are not insects. Spiders belong to an order of animals called the arachnids. The arachnids have eight legs, unlike an insect’s six, and no member of the arachnid family has wings. In the wild spiders are excellent hunters and insects are definitely on the menu. Spiders spin webs of a sticky silken material in which they trap flying insects. They then kill the insect with their venom and devour.

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In what ways are insects useful to humans?

Insects, particularly bees and butterflies, have a major role in pollinating plants. This is a big benefit to humans as it means we continue to have crops to eat, such as fruits and vegetables. We also eat the honey that bees make. Some insects themselves are a source of food for people in parts of the world like Southern Africa and Thailand, where insects like locusts and beetles are eaten. Other insects such as ladybirds, are useful as they help to protect against the damage caused by other insects. They eat pests like aphids that attach crops.

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Conclusion

What an interesting world we live in with such amazing creatures! There are more insects than other kind of creature on the planet – they make up about 85 percent of the world’s known animals.

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Thank You!

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References:

• easyscienceforkids.com › Animals › Insects
• https://kids.nationalgeographic.com/animals/hubs/insects/
• www.ducksters.com/animals/bugs.php
• https://en.wikipedia.org/wiki/Antenna_(biology)
• https://en.wikipedia.org/wiki/Aphid
• https://en.wikipedia.org/wiki/Coccinellidae
• https://en.wikipedia.org/wiki/Arachnid
• https://en.wikipedia.org/wiki/Butterfly
• https://en.wikipedia.org/wiki/Beetle
• https://en.wikipedia.org/wiki/Moth
• https://en.wikipedia.org/wiki/Spider
• https://en.wikipedia.org/wiki/Exoskeleton
• https://en.wikipedia.org/wiki/Phobaeticus_kirbyi

Images linked to their sources in the description below each one.