Insects
Science Four
An Indroduction
Animals having six legs are called insects. There are millions of insect present on the earth. Insects have different types of shapes and sizes. Generally insects crawl but some of them can fly such as, butterfly, housefly, mosquitoes, cockroaches, honey bee, etc.
The body of insect consists of three parts: head, thorax and abdomen. Insects usually have two pairs of wings. Most of the insects have a pair of antennae that helps them to smell, feel and taste.
How insects help in Pollination
Some insects like butterfly, bumble-bee and honey-bee are found in the garden where fresh and colourful flowers are found. They collect nectar from the flower. Flowers produce sweet liquid called nectar. When insects sit on flowers, pollen grains get stuck to their legs or wings which are transferred to another flower when insects sit on another flower. Doing this way insects help in pollination. The process of shifting of pollen grains from one place to another is called pollination.
Types of insects
There are different types of insects. Some insects are useful while some are harmful.
Useful insects
Some insects are very useful for us, such as honey bee, lac insects, silk moth, etc.
Honey bee
Honey bees are social insects as they live collectively in hives, you may call hive as a colony. Honey bees make hives in which they collect nectar and make honey. There are thousands of bees in a beehive. Bees live in colonies. A colony of bees in a hive has about 50,000 to 80,000 worker bees. Worker bees collect nectar. In bee hives a few hundred male bees live and are called drones. There is only one queen bee in a colony. Queen bee lays legs. The rest of the bees in the colony are worker bees. Worker bees collect food for the colony. Honey bees suck nectar from flowers and carry it to a hive where they live. A beehive consists of six sided chambers called combs. Honeybees store nectar in these combs. Nectar is changed into honey. The honey collectors collect the hive and remove the honey from it.
Apiculture:
Rearing and breeding of honeybees for collection of honey is called apiculture.
Silk moth
Silk cloth is one of the beautiful cloths. We get silk from silk moths. Silk moths live and grow on mulberry leaves. A liquid is secreted from the body of silk moth which changes into fine thread. Silk moth weaves a cover around itself with this thread, this cover is called cocoons. These cocoons are collect and silk thread is obtained from it. Silk thread is very soft and very costly. Silk thread was discovered in the country of China.
Sericulture:
Rearing of silk worms for getting silk is called sericulture.
Lac insect
Lac insect gives Lac. Lac is used in making of printing ink, paints, varnishes and bangles. Lac insects are grown on Baniyaan tree. Lac insects secrete semi solid substances called Lac.
Lady bird beetle
Insects called lady bird beetle are useful for farmer. Lady bird beetles eat all harmful insects which live on plants and destroy them.
Harmful Insects
There are many dangerous and harmful insects for us. Such insects are responsible for spread many diseases.
Disease spreading insects
Mosquitoes
Mosquitoes are very dangerous insects. Mosquitoes spread malaria, dengue, chicken-gunia, etc. When mosquitoes bite sick person, it sucks infected blood and when this mosquito bites a healthy person the germs of disease transfer into the blood of healthy person. Only some type of mosquitoes spread diseases. Malaria is spread by female Anopheles mosquitoes and dengue is spread by Aedes female mosquitoes.
Stinging insects
Some insects like bee and wasp sting. Sting is located at the back of the insects. Sting is poisonous and caused pain and swollen red spot on the skin.
Housefly
Housefly spread diseases. Housefly gathers germs of diseases by sitting on garbage or animal excreta. After that those houseflies sit on the food item. Germs stuck with their legs are passed on the food and get infected. Person who eats those infected food gets sick. Housefly spread diseases like diarrhoea, cholera and jaundice etc.
Spider
Spider is not an insect. Insects have six legs but spider has eight legs. It catches various insects for food. Spider makes web to trapped insects. Spiders secrete a liquid from its mouth which changes into threads. Spider weaves this thread into web. You can see spiders and their web in old houses.
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