Worm farms provide compost enthusiasts and gardeners with a prime source of nutrient-dense "super food" for healthier plants and better conditioned soil. Maintaining a pest-free worm farm can be a challenge, especially if you have an outdoor worm bin. Although they're often little more than an annoyance, keeping ants out of your worm bin helps provide more food for your worms, which, in turn, ensures that the worms will be in top physical condition, an important consideration if you're planning on selling some as bait for fishermen.
Monitor the moisture level of your worm farm daily, especially during hot weather. According to Santa Cruz County Department of Public Works, ants are more likely to invade dry worm bins. Spray water on the bedding in your worm bin with a spray bottle until the bedding is about as moist as a wrung-out sponge.
Wipe your worm bin periodically with a lemon- or ammonia-based window cleanser to remove any scent trails left by wandering scout ants in search of food. Spray the cleanser across the entire outside surface of your wooden worm bin and wipe it away with a paper towel. Spray the cleanser directly on the paper towel if your worm bin has ventilation holes in it. Avoid wiping the top edge of your worm bin to keep from causing toxic effects by exposing your worms directly to the cleaner.
Elevate your worm bin to make it more difficult for the ants to access the food scraps. Cut four 6-inch long legs from 4-by-4-inch cedar posts with a general-purpose blade on a jigsaw. Position the cedar blocks vertically on the ground and rest your worm bin on them. Rub a generous coating of Vaseline across the bottom 2 inches of each post to discourage ants from climbing the legs.
Submerge the legs of your worm compost bin in water to discourage the ants. Recycle 1 gallon, plastic ice cream tubs or milk jugs instead of using glass containers that could break. If you use milk jugs, remove the narrow top portion with your jigsaw to allow enough room for the legs of your worm bin to enter the jugs without touching the plastic sides. Fill the four empty plastic containers with 3 to 5 inches of water and position the legs of your worm farm in the water. Keep the water containers free of floating objects that the ants might use to get to your worm food.