Ants, files, bees, butterflies, mosquitoes and the grasshopper that make a shrill noise are all commonly seen insects.
An insect body has three parts, the head, the thorax and the abdomen.
An insect has two eyes and feelers. The feelers help the insect to find any obstacles in its way.
Some insects are useful and some are harmful.
Useful insects
Insects like the butterflies and honey bees, help a flower to become a fruit, flower contains a powdery substance called pollen grains.
When an insect sits on a flower the pollen grains stick to its body. Next the insect flies away and sits on another flower. The pollen sticking to the body of the insect falls on other flowers. These pollen grains help the flower to bear a fruit. This transferring of pollen from one flower to another is called pollination. Insects help in pollination.
Bees give us honey. Bee wax is used in cosmetics. Larva of a certain moth is used to produce silk. Some insects like ants, eat up the dead plants and animals, thereby keeping the environment clean.
Harmful insects
Locusts destroy our food crops. Mosquitoes, mites, bed-bugs and lice suck our blood. One variety of mosquitos spreads malaria. A variety of fly in Africa causes a disease called sleeping sickness. You might have seen insects like cloth moth destroying cloth by making holes. Termites destroy wood.
Cockroaches and houseflies do not bite. But they are a nuisance. Cockroaches stay in the dark corners and the drains. They come out in the night in search of food. They carry lot of germs and dirt on their body. Houseflies come from outside the house. They sit dirty places like garbage etc., and pickup all types of diseases causing germs. They come inside the house and sit on food. The germ contaminates the food, when this food is consumed it causes intestinal and other serious diseases.
Protection against harmful insects
Fixing nets to the doors and widows prevents the flying insects from entering the house. Food items should be kept covered. Surroundings of the house should keep clean and garbage should be disposed off suitably.