Insects are the most diverse group of animals on the planet, with the amount of species available today estimated to be up to 10 million! These six-legged creatures come in all sorts of amazing forms and sizes which never fail at awing people. The sheer amount and diversity also means that insects play a huge role in the ecosystem- keeping food-chains in balance, pollinating plants and spreading diversity; apart from producing a wide range of products that are useful to mankind. It is safe to save that should insects perish from Earth, we humans will never be able to continue surviving!
Here at Wildlife Malaysia, we believe that knowledge is the key to understanding and appreciation. So now, just how much do you know about your insects?
Anatomy (Body Structure)
Insects are arthropods- Invertebrates (animals without a backbone) with a protective, external skeleton (exoskeleton), segmented body and jointed appendages.
Although insects may come in an extensive range of form and appearances, they all share some characters unique to them, as follows:
chitinous exoskeleton, three body segments (head, thorax and abdomen), six jointed legs, compound eyes and a pair of antennae, as follows:
1. Chitinous exoskeleton covering the entire body.
An Adrama fruitfly. Like all insects, this one has a protective skeleton made out of polymer called chitin. This shell also serves as a support as well as attachment sites for the internals of the body.
2. Three body segments- head, thorax and abdomen. In some insects these parts may not be that obvious.
A male damselfly (Prodasineura laidlawii). All insects have a head, thorax and abdomen which may not always be the same in terms of size and appearance across all insects.
3. Three pairs of jointed legs, usuually used for locomotion.
An ant collecting “Honey Dew” from a planthoppper- Both are insects. All insects have 6 legs that are jointed.
4. Compound eyes which are made up of thousands of smaller eye units.
The coloured, compound eyes of a White-barred Duskhawk (Tholymis tillarga). These eyes are made up of a lot of tinier “eyes” which altogether offer a very wide field of view and also hypersensitivity to movements.
5. A pair of antennae which helps the insect “smell” humidit, odour and pheromones (sex hormones).
A Golden Tortoise Beetle (Aspidomorpha sp.; Cassidinae). Insects have a pair of antennae which may occur in a wide range of shapes and sizes.
Senses
Most insects have specialized, perceptive organs for vision, smell and sound.
This allows them to communicate, avoid predators, hunt down preys, search for food etc.
[VISION] A Robberfly. Armed with two sharp compound eyes plus three simple eyes (ocelli), robberflies are able to see precisely the location and distance of the flying prey before lifting off and piercing them in mid-air! Imagine catching a flying Frisbee with your mouth XD
[VISION] A common honey bee (Apis mellifera) Bees have special eyes that can “see” ultraviolet, and studies have shown that many flowers glow obviously under UV light as well, allowing bees (natural pollinators) to see them easily even if the flower is surrounded by thick foliages.
[SMELL] A Giant Uraniid Moth (Lyssa zampa docile). Moths rely on olfactory (smell) to find mates, and can pick up a scent from as far as a kilometre away!
[SOUND] An male Asian Bush Cricket (Nisitrus vittatus). Crickets (usually males) make really loud chirping sounds during the night. This sound can be used to attract females or repel males.
Reproduction
A huge majority of insects rely on fertilization to reproduce, though some minorities can give birth on their own.
Mating between two grasshoppers. After a series of courtship “songs” and “poses”, a male grasshopper (top) mates with a female (bottom) by inserting a packet of sperm (spermatophore) into the female’s vagina.
An Aphid (bottom) and a ladybird for size comparison. In countries with four seasons, female aphids are actually capable of “deciding” whether they would like to give birth with or without mating, allowing apahid populations to bloom with immense rapidness!
Development
The development and growth of insects varies tremendously from one group of insects to another. But since all insects have a chitinous exoskeleton which restricts further growth in size, insects have to undergo special biological development processes called metamorphosis to growth further.
There are two types of metamorphosis, namely complete and incomplete metamorphosis.
Complete metamorphosis–
A Ladybug life cycle. Ladybirds undergo complete metamorphosis which consists of four stages i.e. Egg, Larva, Pupa and Adult. This unique developmental process is unique to certain groups of flies, butterflies and bees.
Incomplete metamorphosis–
A grasshopper fresh out of its moulted skin. Grasshopper undergo Incomplete Metamorphosis which is composed of three stages: Eggs, nymphs and adult. These insects develop in size and function through a series of moult (called ecdysis).
Locomotion (Movement)
Having six legs can really come in handy, and this has allowed insects to travel to virtually all corners of the world via walking, flying and even swimming!
A Moss Mantis Nymph (Haania sp.) is well camouflaged by the surrounding moss, where it travels by foot to look for food or shelter. The mantis will develop wings after maturing into an adult.
A wasp in flight. Insects are successful mainly because of their wings which enable them to travel far and colonize new areas. The ability to fly also make easy the hunt for food and the escape from predators.
A Water Strider. The specialized legs of this unique hunter allows it to overcome the surface tension of water and “walk” freely on water.
Defence and Predation
Most insects rely on camouflage and mimicry to deter predators.
This bizarre-looking stick insect (Pylaemenes cf. mitratus) camouflage itself like fallen tree branches and are very hard to detect.
It is believed that Bactrocera fruitflies mimic the bright colour and banded patterns of wasps so as to deter predators- humans included!
Some develop hard shells for protection.
A Ladybird (Cheilomenes sexmaculata) unconcerned about the ant biting it thanks to its hard shell. .
Some may even resort to using chemicals to protect themselves.
On the other hand, predatory insects usually have well developed appendages for immobilizing and killing prey.
A Praying Mantis cleaning its “blade”. Mantises evolved highly effective forelegs with strong hooks and sharp spines that makes catching and killing prey a piece of cake.
A Robberfly feasting on a mosquito. Robberflies developed a keen eyesight and sharp mouthpart (proboscis) that allows puncturing of preys in mid-air.
Relationship with Humans
Most insects are indirectly beneficial to humans as they keep the ecosystem in check.
Serving as very efficient pollinators, many insects facilitates the fertilization and spread of flowering plants. Insects also act as a main food source for many larger organisms in the food chain, including humans.
A Great Mormon Butterfly (Papilio memnon). Butterflies and bees are efficient pollinators of flowering plants.
However, there are many insects that have a more direct bond with humans, some of them bringing huge benefits to mankind, whereas others are outright nasty pests.
Humans rely heavily on some insects for the products they produce, for example honey from honey bees, and silk from the larvae of silkmoth (Bombyx mori) etc..
On the other hand, some of the most notorious insect pests include mosquitoes that spread many dreadful diseases, fruitfly infestations that ruin entire plantations and common houseflies that causes food poisoning etc.
A Full Mosquito (Aedes sp.). Mosquitoes are known to transmit serious diseases including dengue fever and Malaria.
An army of Blowflies perching on a tree branch. Flies are one of the main cause of household food poisoning as they carry harmful bacteria and germs on their feet.
That’s it for our brief introduction on insects! To be frank, there are countless more to write about as there are different and unique stories to tell for each species of insects!
The insect world is humongous, with many more exciting species of insects just waiting to be discovered!
However, here at Wildlife Malaysia we believe that it is more interesting to learn through pictures rather than words, so without further ado, we would like to welcome you to visit our Insect Pages!
* All photos in this article were taken by Tan Ji and are not to be used or copied without permission. For more details, please read Image- Terms of Use.
*For more info and guides on taking these type of Macro shots, please visit PixelsDimension.
* The authors attempted to make this article as simple as possible. Advanced topics will be included in the future.
