Every mole eats 70 to 100% of its body weight in earthworms and grubs every day. Eating is so important to the mole that most of its brain is literally hard wired to its teeth and mouth.
Just to avoid starvation, a mole may need to capture as many as 2000 earthworms in its brief lifetime. The simple fact about trapping moles is that you aren’t going to get moles into your mole trap without bait. But it is not hard to find bait that moles will find hard to resist.
Where there are large numbers of earthworms, there will also be large numbers of moles. Catching an earthworm is a simple matter of turning over earth and letting worms wriggle out if you dig where you see fresh earthworm castings. These are the small pellets of soft earth that the worm has excreted after it has digested the dead leaves and stems of plants that are mixed in the soil.
You are most likely to find earthworm castings where leaves or grass has been left to decay on the surface of the soil. Earthworms prefer soil that is mostly dirt rather than organic matter. They do not care for pure compost or peat, and they usually avoid acidic soil such as can be found in bogs and under acid-loving plants such as azaleas, rhododendrons, and blueberries. Nitrogen fertilizers kill worms.
Don’t forget that you must not handle the earthworms you use for bait with your bare hands. Use gloves that you reserve for handling tools and traps you use for moles. Don’t wash your gloves aftet you handle earthworms. The worm smell will transfer to traps you use to catch moles.
Some species of earthworms are protected. The Giant Palouse earthworm of eastern Washington state in the United States is protected as endangered species. This albino worm burrows as deep as 5 meters (16 feet) in the soil and grows up to a meter (a little more than a yard) long. Moles won’t eat this worm, and it might give you a start should you happen to dig one up. If you sight a member of this species, the US Fish and Wildlife Service would appreciate your giving them a call so they can note its location.
The Oregon Giant earthworm is even larger and longer than the Giant Palouse earthworm. It can grow up to 130 cm (4 feet) long and achieves a diameter of about 25 mm (1 inch). Oregon giant earthworms are most often encountered in undisturbed forest litter underneath Douglas fir trees, although they are sometimes sited in the Williamette Valley of Oregon between Portland and Eugene.
Grubs are the larvae of beetles, bees, and wasps. Since you really don’t want to be digging around in a bee hive or a wasp’s nest, most of the grubs you will use to bait mole traps are the larvae of beetles.
Some predatory beetles have predatory larvae that travel through the ground seeking food. Other beetles lay their eggs in the plants on which they feed as adults. In much of North America and Europe, “June bugs” lay their eggs in well-tilled garden soil that is rich in humus. If you have beetles emerging every June, then May is the perfect time to turn the soil and look for the larvae of the beetles that will grow up to eat your plants.
You can also locate grubs by the damage they cause. Strips of brown lawn are often caused by grubs chewing away at the roots. Lift the dead sod to look for live grubs. Japanese beetles are especially fond of rose bushes. Japanese beetle damage begins to show up in periods of drought. Remember to handle grubs with gloved hands.
Earthworms are sold on Amazon.com. You can buy red wrigglers from Uncle Jim’s Worm Farm through Amazon.com—just be sure to get overnight or 2-day delivery, and don’t try to ship worms during the heat of US summers. In the UK, earthworms are also available from Amazon. Chapelwood Earthworms sells them by the liter. Grubs are available in pet shops as Tiny Wigglers, a supplement for turtles. Because the grubs are freeze-dried, however, most moles would pass them up for worms.
There are also earthworm-shaped mole poisons made by several North American manufacturers. Some are pre-formed in the shape of a worm. These tend to melt when they are shipped during the summer. Others are squeezed out into the shape of a worm. Both are designed to trick a mole into consuming poison.
Usually, poison baits are not a good idea. They will definitely kill a mole, but there is no guarantee that the mole will eat the bait. More often than not, moles will come up from their burrows at locations where you have not put out bait.
Dogs and cats, however, are also attracted to mole bait. You may kill your pet, or a neighbor’s pet, without killing even a single mole. And if you do kill a mole, you will never know for sure. Even if the poison bait works, a new mole may just move in from the neighbor’s to take the dead mole’s place.