Here is something I found on the net on getting rid of leeches w/o using chemicals:
Making A Leech Trap - The Search For Safe Leech Control
Avoiding Dangerous Chemicals And Using Safe Methods
Hmmmm.... how to kill leeches in pond..... If you want to go down the chemical route it is complex and dangerous. It is also expensive to buy pond chemicals in the quantities needed. It involves replacing all plants, estimating exactly how much water the pond holds, mixing chemicals that could possibly harm the smaller fish - and destroying every living invertebrate in the pond. That was not something we were prepared to consider. So what is safe to use to kill leaches? I searched and searched until I found the idea of constructing a leech trap out of a coffee tin. Here coffee tins are not so easy to find, they tend to be metallic cardboard. Then I thought of fresh soup containers and the leech trap was born.
At present we are on our third trap and numbers are reducing. I was horrified at the number of leeches in the last trap.... How you dispose of them having caught them is another issue of course, but you need to remember that leeches are dangerous, but they are also living animals with a nervous system and should be disposed of humanely. Freezing them is one method, or release into a river system, if it is permitted, where larger fish may eat them.
Making the holes in the leech trap
Boring from the outside of the leech trap
Boring holes from the outside to create a burr on the leech trap makes it less likely leeches will crawl out through the holes. These holes can be made carefully with a steak knife and should vary in size from 2-5mm.
Raw Materials for the Leech Trap
And how the Leech Trap works
The leech trap works on the same principle as Winnie the Pooh and the Honey Jar. Leeches, being greedy, will gorge on blood and when they do they become so big that they get stuck in the hole. That is the principle - and it works. The main items needed are meat and a container. Liver or kidney is cheap and works well. Here you see a view of the inside of the leech trap. The holes are also burred which discourages early escape.
Sinking the leech trap
Placing the leech trap in your pond
Just use a net to lower the trap into the water. It will fill with water and float upright. This will catch many leeches as they can sense the meat and swim up to it. To sink the trap deeper, put stones in before the meat. Then just leave the trap for a few days to a week. It will soon fill if you have a bad infestation.
Garden Pond Resources.
Everything you need for a pond in your garden
If after reading about our organic method, you still feel squeamish and want to go down the more extreme chemical route, you can buy chemicals to clean your pond, or chemicals to kill leeches, in this section.
The First Leeches at the Feast
Leeches in the Trap....
Within a few hours, the first few leeches will come to the trap. They swim in through the holes and gorge happily on the meat.
The Leech Trap Works
The leech trap fills with leeches - pictures of blood sucking parasites.
Inspecting the trap after a day in the water. Leeches are on the sides and also on the meat. These small leeches would probably normally prey on water snails, but the population explosion may have destroyed all their normal food.
Inspecting the trap after a day in the water the leeches are on the sides and also on the meat. These small leeches would normally prey on water snails,but the population explosion may have destroyed all their normal food.
Leeches caught in the leech trap on the second day........As this is the third trap,there are not so many. There were hundreds caught in the second trap. The first trap was possibly emptied too soon. Leeches have very few natural predators and can wreak havoc in a small pond feeding and possibly killing frogs and fish once they have exhausted the supply of snails.
The trap is lowered back into the water and after another two days it will be emptied and replaced. This needs repeating until no further leeches are caught. After a few weeks another trap may need to be set for hatching eggs.
What is a Leech then?
Facts about leeches....
Apart from being gross, what is a leech? A leech is a water worm, it belongs to the phylum Annelida, class Hirudinea. The blood sucking leech is a parasite to animals, birds, fish, frogs and mammals - including man. Infestation by leeches produces a condition known as Hirudiniasis. Not all leeches suck blood, some are carnivores and hunt insects and snails. However about 75% of known species of Leeches are blood sucking external parasites.
Leeches secrete Hirudin, a chemical produced in their mouth glands, which stops blood coagulating. Up to the middle of the 19th century bloodletting by leeches was a common treatment. Medicinal leeches are sterile, but wild leeches can produce infection and ulceration when satiated as they drop off.
Leeches enjoy slow moving streams, ponds, lakes and marshes, and can live on on moist vegetation in jungles and other humid environments.
