When the mosquito senses one of the stimuli such as heat, gas, moisture and chemical secretions, it heads straight for its prey. The mosquito lands on its prey so gently that in most cases it is not even felt. Then it finds the most appropriate place to pierce using a pair of devices located in the mouthpart, which are called "palpi."

The first incision is made with the upper and lower jaw. The four cutters in the sucking tube cut deep into the skin. The sensory organs of heat, smell, taste and touch play an important role in establishing where the capillaries are concentrated under the skin. After a few attempts the mosquito finds the vein.

The mosquito sucks the blood by sticking the tube into the hole it has opened in the skin. Thanks to this tube it can penetrate a small vein and drink blood directly. Or it can drink the blood that accumulates in the surrounding tissue when the skin is cut.

Usually the piercing needles go into the skin vertically. The most important characteristic of the mosquito's needle is that it can bend at a certain depth. Thanks to this remarkable feature, the needle can easily move around under the skin, even to the point of being able to extend parallel to the skin. In this way the needle is able to get to the places where there is the highest concentration of veins.

However, here a serious problem awaits the mosquito. As soon as a mosquito bites, a kind of defence system goes into operation in the human body. An enzyme that prevents microbes from entering the body and stops the bleeding is secreted in the region of the wound. This enzyme enables the blood to clot. Once the blood starts clotting it is impossible for the mosquito to drink any blood. (Coagulation is caused by the transformation of fibrinogen, one of the plasma proteins, into fibrin.)

But the mosquito acts as if it is aware of this and injects an anti-coagulant secretion into the wound from within one of its sharp knives. Thus the enzyme in the blood is rendered ineffective and the clotting stops.

What's more, with this secretion the mosquito even gives a local anaesthetic to its victim, numbing the area it cuts into. Accordingly the victim is not aware that its skin has been cut and its blood sucked. It is this secretion that causes an allergic reaction in the skin and causes the skin to itch.

In the few seconds in which the above takes place, a person cannot even realise that he has been bitten by a mosquito.

A female sucks about 2.8 mg (0.0001 ounce) of blood in one go, and this takes about 2.5 minutes. When the sucking finishes, the blood is sent to the midgut by suction pumps located in the fore-section of the digestive system. The abdomen fills with blood as far as the digestive system. It takes 3-4 days to digest the blood and then the sucking process is repeated.

In a mosquito’s sucking tube there is a cutting mechanism consisting of 6 knives. 4 of these knives cut into the skin and the other 2 join to form a hollow tube, which the mosquito sticks into the tissue it has cut and sucks out the blood.

If we stop and think for a while about all these processes, we will come to some important conclusions.