You can find insects practically everywhere in the world. Although most of them have wings, a few of them do not have. Some of them are cute, and some are annoying. While some live in cold areas, many live in tropical regions. After all, they have some characteristics in common. Let’s delve deeper into the marvellous world of insects and explore its fascinating secrets.
Insect Definition
An insect is any member of Arthropods, the largest group that includes spiders, centipedes, and crabs. It is a small invertebrate animal with no internal skeleton or backbone. However, it has a three-part body with an external skeleton. Additionally, it has six jointed legs, zero to four wings, and two antennae.
Helpful and Harmful Insects
Although there are insects that annoy and irritate us, there are many that benefit us and other living creatures. On the one hand, some insects can be harmful as they can:
Sting or bite us, like mosquitoes and fleas.
Spread diseases to other living creatures, like mosquitoes.
Cause a nuisance, such as flies.
Eat and damage crops, like aphids.
Damage wood and clothes, like termites and clothes moths.
Why Are Insects Important?
Insects may benefit humans, animals, and the environment. Some of them may be helpful in pollination, ecological balance, medicine, agriculture, commerce and more. Here is how:
1. Pollination
Several insects help in the pollination of plants. Bees, butterflies, and others collect nectar from flowers. They carry pollen from one flower to the next. Once pollinated, the flower creates seeds to reproduce. It grows more and healthier plants and fruits in the next generation.
2. Balance of Nature
Additionally, insects help in keeping an ecological balance, which depends on the activities of parasites and predators.
Parasites are helpful because they live in or on hosts, which are pests, and get their food, causing their death.
Predators are also beneficial because they attack and eat pests. For example, ladybirds eat aphids that damage crops.
3. Agriculture
Besides pollination and eating harmful pests, insects play a vital role in agricultural ecosystems. They can improve the agricultural soil through the decomposition of manure, such as dung and carrion. They bury this organic waste and recycle nutrients that plants can use.
4. Medicine
In addition, insects may cure and protect us from major diseases. Therefore, medical and pharmaceutical industries widely use them with other insect-derived products.
5. Commerce
Moreover, some insects make a few products that humans use. Some of them are:
Honey by honeybees. Honey is used as a natural sweetener and a treatment for several diseases.
Beeswax by honeybees. It is a natural wax used for eating. Besides, it is useful for medicinal purposes.
Silk by silkworms. It is used to make clothing, upholstery, fabric and other products.
Carmine dye by cochineal bugs. Carmine dye is used to dye cosmetics, textiles, drugs, and food.
Shellac by female lac bugs. Shellac is used in floor polishing, inks, electrical insulations, and more. It also coats candies, drug tablets, and children’s furniture.
Explore the Magnificent World of Insects
Insects Life Cycle
In this magnificent world, all insects hatch from eggs. However, they have two basic life cycles. While some of them undergo complete metamorphosis, others go through incomplete metamorphosis. Keep reading to discover the difference between these two life cycles.
Incomplete Metamorphosis
Similar to a child looking like their parents, some insects hatch from their eggs with an overall form resembling their adults. Their physical form, structure, or substance does not entirely change from the moment they hatch. They have incomplete metamorphosis and go through three stages of change in their life cycle: egg, nymph, and adult.
An insect hatches from the egg.
It hatches into a nymph with a thin exoskeleton and no wings.
As it grows larger, its exoskeleton cannot grow. So, it goes through a process called “moulting”. In this process, it replaces its exoskeleton or tight skin with a new, larger version that allows it to grow.
The insect moults several times in its lifetime until it finally becomes an adult.
Cockroaches, crickets, grasshoppers, and termites go through incomplete metamorphosis.
Complete Metamorphosis
Unlike incomplete metamorphosis, insects that have complete metamorphosis go through four stages of change. They are egg, larva, pupa, and adult. Their physical form, structure, and substance change completely in each stage. Their babies do not look like their adults. Here is the process:
Life begins as an egg.
An insect hatches from the egg into a soft worm-like form called a larva. The larva has an increased appetite and eats a lot of food, thus growing very fast.
At the larval stage’s end, the larva enters a resting stage called a pupa. It occurs when it makes a hard shell and lives inside without moving and eating.
The larva’s body changes completely inside the pupa and becomes a fully grown adult. In this stage, it develops all the adult’s features, including legs and wings. Then, it leaves the pupa.
Insects that develop this way include butterflies, moths, bees and ants. Let’s watch this entertaining video about the life cycle of a butterfly.
The Life Cycle of a Butterfly
Insects Body Parts
Our Planet Earth has around 14 million species of these tiny creatures that differ in size, colour, and shape. But guess what?! All of them have a three-segment body, with a head (front segment), thorax (middle segment), and abdomen (back segment). They have an external cover called the exoskeleton that protects their bodies. They also have body systems that help them live. Now, it is time to examine each part separately.
Head
The front segment of the insect is the head. It contains the brain, simple and compound eyes, mouthparts, and two antennae.
Eyes
Many adult insects do have two kinds of eyes: simple and compound. All insects with compound eyes have simple eyes, but not all insects with simple eyes have compound eyes. The simple eyes, called ocelli, collect and focus light through a single lens. On the other hand, the compound eyes consist of thousands of hexagonal (six-sided) lenses. Each lens receives a separate image. The insect’s brain combines all these received images into a single one.
Feeler or Antenna
Between the insects’ eyes, there is a pair of antennae, sometimes referred to as feelers. They bear several sensory organs that are used for sensing.
Mouthparts
Besides eyes and antennae, the insect’s head has mouthparts adapted for chewing solid food or sucking liquid food. That is why there are two basic types of mouthparts: chewing and piercing-sucking. There are also two modifications of these two main types: sponging and siphoning (sucking). Insects with chewing mouthparts are the most basic type. They have:
An upper lip called the labrum.
Strong cutting jaws called the mandibles.
Weaker teeth called the maxillae.
A lower lip called the labium.
A tongue-like structure in the mouth’s floor called the hypopharynx.
Thorax
Let’s leave the front section and move to the middle one. The insect’s middle part is the three-segmented thorax. It usually has six jointed legs and zero to two pairs of wings (zero to four wings).
Wings
Not all insects fly or have wings. Some adult insects have two pairs of wings to fly. They are forewings and hindwings. A few insects have only one pair, forewings, and do not have hindwings.
Legs
Insects are from the Hexapoda group, which means having six legs. They have three pairs of jointed legs adapted for leaping, walking, running, burrowing, swimming, or grasping prey. They consist of five parts:
A coxa: the basal segment of the insect’s leg.
A trochanter: the small second segment of the insect’s leg.
A femur: the third segment of the insect’s leg and the thickest one.
A tibia: the fourth segment of the insect’s leg covered in hairs and spines.
A tarsus: the final segment of the insect’s leg. It ends with one or two claws with adhesive pads to enable the insect to hold onto smooth surfaces.
Abdomen
The insect’s back segment is the many-segmented abdomen. It has a maximum of 11 segments, which include:
The heart.
Reproductive organs that help the insect reproduce.
Other digestive organs that help the insect digest food.
Insects are invertebrates; they do not have a backbone or an internal skeleton like us. Instead, they have an exoskeleton, a hard external shell or cover (outside their bodies) that protects their bones and muscles.
Respiratory System (Gas Exchange System)
In our bodies, the blood carries oxygen from our lungs to our hearts. Then, it moves oxygen to our muscles and tissues. Conversely, it moves carbon dioxide from muscles and tissues to our hearts and then to our lungs to pass it out of our bodies. But guess what! Insects’ respiratory system is not combined with their circulatory system. Here is how most of them breathe:
An insect breathes through spiracles, valve-like openings in its exoskeleton along the thorax and the abdomen.
When the air enters an insect’s body through these spiracles, it travels to the trachea. The tracheal system is a complex network of tubes where oxygen and carbon dioxide exchange. These tubes are continuously connected with the cuticle of the body surface.
Other Systems in Insects
Insects have an open circulatory system that differs from our closed one. Their blood or haemolymph flows in the haemocoel, their main body cavity.
They also have a ventral nervous system that controls their bodies and processes information to ensure the effectors have rapid functioning and coordination.
Digestive System: Their midgut is responsible for most digestion in their bodies as it secretes digestive enzymes. Little digestion takes place in their hindgut.
Sensory System (Advanced Sensory Receptors).
I will leave you with this video. Enjoy!
Insects Behaviours
Scientists observed two types of behaviours in insects: innate and learned. Insects acquire learned behaviours through learning or experience, like the division of reproductive labour and care labour. However, they inherit or know by instinct innate behaviours, like flying.
Each insect species has a different behaviour in hunting, mating, locating egg-laying sites, eating prey, learning capacity, and searching for mates. For example, to avoid predators and protect themselves from enemies:
Shield bugs resort to several colours.
Grasshoppers and other insects use camouflage, also called cryptic colouration, to blend in with their surroundings, disguise their appearance and mask their movement and location.
Stink bugs produce repellant odours via specialised glands.
Some insects produce poison or toxic chemicals.
Mosquitoes, fleas, and other insects bite.
Ants, wasps, bees, and other insects sting.
Some insects exhibit defensive behaviour, such as death feigning (pretending they are dead).
Many flying insects develop colouration patterns on their wings that resemble eyes.
Insects Societies
Most insects are solitary and live alone. On the contrary, some are social and live in well-organised colonies. The latter includes butterflies, ants, termites, and some species of bees. They share food, communicate with each other, and feed and protect their eggs and larvae. Each individual has a specific job in the group at the proper time. Each colony has:
One queen to lay hundreds or thousands of eggs.
Many soldiers or fighters to protect the queen and the colony.
Lots of workers to collect food, repair the colony, and care for the eggs and the larvae.
Males.
Where do Insects Live? (Their Habitat)
Insects are in every place in the world where food is available. They can survive in almost every type of habitat around ponds, among grasses, on trees and flowers, in water, gardens, snowy mountains, tropical rainforests, hot deserts, caves, and homes.
What Do Insects Eat? (Their Food)
With a wide range of insect species, they eat plenty of food. For example:
Half of all living insects are herbivores. Also known as plant eaters, they survive on plants only. They consume flowers, nectar, grass, leaves, seeds, roots, and wood.
Predator insects hunt smaller insects and animals and eat them. For instance, praying mantis eat crickets, beetles, and spiders. Bigger praying mantis eat small birds, frogs, and caterpillars.
Parasites, such as lice and fleas, survive on large animals. Also known as bloodsuckers, they suck the host’s blood and eat their flesh without killing them.
Flies live on soft, decaying garbage, fruits, and other organic matter. They feed on bacteria and spread it once they excrete waste.
Types of Insects (Their Species)
There are millions of insect species on our planet Earth. Modern insect classification divides insects into 30 orders, which are:
Archaeognatha (or Jumping Bristletails) includes petrobius maritimus.
Blattodea includes cockroaches and termites.
Coleoptera includes beetles and ladybugs.
Diptera includes flies and mosquitoes.
Dermaptera includes earwigs.
Embioptera includes anisembia texana.
Ephemeroptera includes mayflies.
Grylloblattodea includes grylloblatta barberi.
Hymenoptera includes wasps, bees, ants, sawflies, and Asian giant hornets.
Hemiptera includes true bugs, leafhoppers, and cicadas.
Isoptera includes termites.
Lepidoptera includes butterflies, moths, caterpillars, and silkworms.
Mantodea includes praying mantids and mantis.
Mantophasmatodea includes mantophasma zephyra.
Megaloptera includes dobsonflies.
Mecoptera includes scorpionflies.
Neuroptera includes lacewings.
Odonata includes dragonflies and damselflies.
Orthoptera includes grasshoppers, katydids, crickets, and locusts.
Phthiraptera includes lice.
Psocoptera includes book lice.
Plecoptera includes stoneflies.
Phasmatodea includes walkingsticks.
Raphidioptera includes snakeflies.
Siphonaptera includes fleas.
Strepsiptera includes stylops.
Trichoptera includes caddisflies.
Thysanura includes silverfish.
Thysanoptera includes thrips.
Zoraptera includes zorotypus newi.
Insects Facts That Will Surprise You
In the following lines, LearningMole will list some surprising facts about insects you did not know before. Did you know that:
Over 75 % of named animal species are insects. They have the highest population of all animal creatures because they have existed on Earth for millions of years. There are approximately 14 million species of insects on the planet, with an estimation of over one quintillion (1 followed by 18 zeros!) individual insects. However, the number of known species is only around one million, and scientists continuously discover new species.
All insects are invertebrates with no backbone or internal skeleton.
Insects are cold-blooded because their body temperature changes when the surrounding temperature changes.
Some insects have very short life cycles, while others have pretty long ones.
Chrysalis is the pupa of butterflies and moths.
A caterpillar is the young form of a butterfly or a moth. It has lots of legs and eats the leaves of plants. Wrapping itself in a chrysalis, it turns into an adult butterfly or moth.
A maggot is the young form of a fly. It is used as bait on a hook to catch fish.
The larva of a bee, a wasp, and a beetle is called a grub.
The scientist who studies insects is called an entomologist. They travel the world and observe insects in their natural habitats.
Facts About Bees
You can find bees on every continent except Antarctica.
Worker bees fill a honeycomb with honey, then cover each cell with wax.
A honeybee produces only one-twelfth (1/12) teaspoon of honey throughout its life.
Honeybees are the smartest insect all over the world.
Honeybees use a sophisticated communication system. They use a unique movement called the “waggle dance” to tell other bees where the food sources are.
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