Some good tips for getting rid of chipmunks in a garage include sealing their access points, baiting the pests with a trap, removing any food material stored in the garage, and cleaning any bird feeders. In addition, use repellents, and remove excess foliage from around the garage.
To seal entry points, caulk all the holes in the area, and cover the gaps between the door and the floor using hardware cloth. To discourage the pests from entering the garage, remove any piles of wood, bird seed and pet food stored inside.
In addition, remove shrubs and plants that run from the woods to the house, and place gravel around the garage. Protect bulbs of flowering plants with plastic or wire meshes, or plant only bulbs that the chipmunks are likely to avoid. Clean bird feeders regularly, use thistle for bird seed, and position the feeder 15 to 30 feet away from the garage.
When using a rat or mesh trap, put some sunflower seeds or corn kernels inside, and allow the chipmunks to feed on them for a couple of days. Then, set the chipmunk trap, conceal it using a cloth or piece of cardboard, and place it perpendicular to the route taken by the chipmunk. Keep two traps next to each other with their triggers facing in opposite directions. Release the trapped animals several miles away from the garage.
Some good chipmunk repellents include moth balls, and a solution of 3 ounces of Epsom salt and 1 teaspoon of Lysol in 1 gallon of water. Alternatively, apply chemicals such as bitrex, thiram, polybutene and nicotine sulfate on the bark, stem and bulbs of inedible plants.