Q: I’ve been trapping leeches with success. Will the rest die this winter or do I need to continue next spring?
Bernie – Muskegon, MI
A: Those little bloodsuckers sure steal the fun, don’t they?
Hitching a ride with waterfowl, amphibians, small mammals—even your muck boots—leeches love living in mucky debris at the bottom of your pond. They settle in and wait for worms, snails, insect larvae, small water-loving animals and even humans to cruise by. When something looks tasty, they’ll use their suction cup-like mouths and teeth to latch on and feed on their blood.
Leeches aren’t necessarily bad for your pond or lake—in fact, they’re an important part of the food web. But they can be a nuisance, particularly if you use it for swimming or water sports.
Death by Winter Frost
During the winter, leeches don’t die. They ball up and burrow in the mud just below the frost line, nice and cozy, where they hibernate through the cold temperatures. In the spring, they’ll return to their bloodsucking ways.
If temperatures fall below freezing where you live, one wintertime leech-control trick is to manipulate the water level in your pond. Drop the water level at least 4 feet after ice has started to form on the pond. This will freeze the leeches that were living in the shallow underwater mud. It’s an effective method, but it could also kill other aquatic life burrowed in the mud.
Sure, they’re part of the ecosystem, but no one likes climbing onto the dock with their legs covered in leeches, right? There are several ways to trap and control those bloodsuckers.
- Capture them in tiny traps. Punch leech-size holes in a coffee or aluminum can with a lid, bait it with raw chicken or fish heads, and position it in a shallow area of your pond. When the leeches climb in for a meal, they can’t escape because their full bellies will prevent them from exiting. Remove the can once it’s full and repeat until the leeches are gone.
- Control them with leech-grubbing fish. Your finned friends will savor the protein-rich treats. Fall is the perfect time to add more fish to your pond—and leech control is a perfect excuse to boost your game fish population. Red-ear sunfish are particularly fond of leeches.
- Destroy their habitat. Because leeches live in the muck and detritus in the shallow areas of your pond or lake, keep up with weed maintenance so you’re not creating a hospitable habitat for them. Remove shoreline vegetation with weed removal tools, cut and rake out dead organic debris from the water and add natural bacteria to break down the muck.
Pond Talk: How do you control leeches in your lake?