Amongst the thousand kinds of insects, there are some who bite us and are our great enemies. When they bite us, they inject germs of many dangerous diseases into our body. Do you know which insects are our enemies?
Dangerous among the insects which spread various diseases through bites are mosquitoes, tse tse flies, lice, rat fleas, bed bugs etc. When these insects bite any sick person, and suck the blood, the germs of the disease pass into the bodies of the insects. When these insects bite a healthy person, they pass on to him the germs of that disease along with the saliva through a needle-shaped hollow organ. These germs infect the healthy person and make him sick.
Malaria is caused by the bite of female anopheles mosquitoes which, if we exclude wars and accidents, have mainly been responsible, directly or indirectly, for 50 per cent of human deaths since the ancient times. Even today, despite major campaigns to eradicate malaria, at least 200 million people are afflicted by the disease every year throughout the world. Disease likes the dangerous ‘sleeping sickness’ is caused due to the bite of tse tse flies. Lice transmit typhoid. The rat fleas carry the germs of plague. Bed-bugs cause skin diseases. They suck our blood to keep themselves alive. You must be wondering how the germs of the diseases are passed into our body while the insects keep on sucking the blood. In fact before sucking the blood they inject a small amount of saliva into our body to prevent the blood from clotting. By doing so the germs of the disease enter our body along with the saliva.
However, there are some other insects too which sting but do not spread any disease. Among them are honey bee and wasp. Their sting causes intense pain. The strings of these insects are located at the tail end. They are connected to the poison glands. These insects use them as weapons for their self-defence. When they bite us like the doctor’s syringe, they inject some poisonous substance into our body. It causes swelling on the skin, itching and severe pain.
