Q: My pond has leeches! How do I get rid of them?
Tana – West Allis, WI
A: Leeches. They’re not for the squeamish. These little bloodsuckers – which are actually segmented worms related to earthworms – use their suction cup-like mouths and teeth to latch on to vertebrate and invertebrate animals, feeding on their blood.
The majority of leeches thrive in freshwater environments, though some species can be found on land and in the sea, too. Of the 700 different species of leeches, 100 are marine, 90 are terrestrial and the remaining 510 prefer habitats like your lake or pond.
One of the more common leeches found in North America is the Freshwater Leech or North American Leech. This brownish-green worm with black and red spots grows to about 2 inches long and lives in lakes, marshes and slow-moving streams.
Harmless – and Healthy
Historically, leeches have been used medicinally on humans to improve and restore blood circulation. The practice of leeching, or leech therapy, can be traced to India and Greece and has been done in both Europe and North America up until the 18th and 19th centuries. Though the practice waned for a time – likely a combination of the yuck factor and modern medicine – it’s slowing coming back into favor.
If a leech latches onto you, don’t worry. In most cases, it won’t do any harm. In fact, you might not even feel it as the tiny critter injects the spot with anesthetic-anticoagulant combo while attaching itself with its suckers. You can remove a leech by breaking its suction seal with your fingernail or another blunt object, causing the worm to detach its jaws.
The leeches in your pond have probably hitched a ride from visiting birds or plants that you’ve purchased and placed in your pond. Leeches will attach themselves to their host – like a duck or heron – and take in their fill of blood. Once they’re satiated, they’ll drop off and establish themselves in their new home. Leeches will also hide in plant roots and on the bottom of pots, and when you place them in your lake, they’ll happily move right in.
Fish love to gobble down leeches. A healthy fish population will, in most cases, keep leech numbers under control. Among game and lake fish, red ear sunfish do a great job of eating these worms. Other natural leech predators include turtles, crayfish and water fowl.
Besides using your finned friends to control the leeches in your lake or pond, you can also try some of these recommendations:
•Control the muck on the bottom of your pond – which is where they lay their eggs and spend their off time – with a product like MuckAway™.
•Remove debris, cattails and phragmites from shallow areas of your pond.
•Add more leech-eating fish.
•Set a leech trap. Punch leech-size holes in a coffee or aluminum can, bait it with raw chicken and position it in a shallow area of your pond. When the worms go for the grub, they can get in – but not out. The burrs from the whole punch will prevent them from escaping. Remove the can once it’s full and repeat until the leeches are gone.
Pond Talk: What did you do the first time you found a leech locked onto your leg?