Article in English: Take a metal can with a reclosable lid, such as a large coffee can, and punch small holes in this lid. Put raw meat inside the can, close the lid, and tie a string around the can. Place this in shallow parts of water where you suspect leeches live, and they will be attracted to and enter the can. You can then pull the can out of the water and dispose of the leeches.  Leeches are most active during warm months. Lay your trap, check it daily during warm periods, and dispose of any caught leeches. Repeat this until few or no leeches appear in the trap.  The exact size of the holes you should punch in the can lid will depend on the species of leech. If no leeches are being caught in your trap, try a larger or smaller hole size until it works. Ducks may feed on leeches, which can help to keep their populations low. If you attract ducks using duck feed, however, this can increase levels of phosphorus in water and contribute to algae growth. Species of duck known to consume leeches include:  Ring-necked duck (Aythya collars)  Wood duck (Aix sponsa) Muscovy duck (Cairina moschata) These fish are natural predators of leeches and will help to control their population. This method will only work for enclosed, private waters like ponds. An overabundance of vegetation and organic debris in ponds and lakes is thought to contribute to the growth of leech populations. If possible, keep vegetation to about ten percent of a pond’s surface area. Remove or control any excess vegetation to help combat leech infestation. Methods include:  Minimizing the feeding of fish and ducks. Their waste provides nutrients that increase the growth of aquatic vegetation. Manually removing vegetation from the water. It is best to remove the whole plant, roots and all. Make sure to discard the plants out of the water so that the debris does not nourish future plant growth. Dredging or deepening the body of water. The greater depth will make it harder for plants to root. Lowering the water level. Shallower water during cold and freezing times will...

Summary in Indonesian:
Tempatkan jebakan. Pelihara atau tarik perhatian bebek ke wilayah perairan yang ditinggali lintah. Jaga populasi ikan bluegill dan largemouth bass. Kendalikan tanaman akuatik dan sisa-sisa organik. Gunakan metode pengendalian kimiawi.