Leech, commonly known as leech, grows and breeds in inland freshwater areas. There are three semicircular jaws in the mouth to form a Y-shape. When sucking animals, the lower jaw is drilled into the skin to suck blood, and the blood is stored in the whole digestive tract and blind sac from pharynx to esophagus. All parts of the body have drainage holes, which open on the ventral side. (Excerpted from Baidu Encyclopedia). Because it can suck blood stasis under the skin, it has medicinal value. Leech mummy can drive away evil blood, blood stasis, moon closure and blood stasis (suitable for eating and using), and it is also used in modern times. Medical leeches are disposable. If you are sucked by leeches, you can't pull them out. Don't pull out leeches, the more the straw is pulled out, the tighter it will stay in the wound, which will easily cause infection and ulceration. You can gently pat the top of the bite with your hand, or gently bulge around the leech to loosen the sucker. You can also use cool oil, that is, water and salt soaked in cigarettes, which is extremely important in outdoor activities. No matter where you go, you'd better take a small bag of strong vinegar, alcohol or white wine with you. Drop pepper, lime, etc. on the insects to make the sucker loose.