People who are looking for an organic, non-pesticide way to keep pests from their garden might get good results using diatomaceous earth. Diatomaceous earth is a powder made of 100-percent organic ground fossils of diatoms that came from fresh water. It kills many pests, including ants, snails, cockroaches and other insects.
Understand how diatomaceous earth works. While it seems like a harmless powder to us, it is actually quite sharp and hazardous to insects. It must come in contact with the pest to be effective. It will scratch and puncture the exoskeleton of soft-bodied insects, thereby causing them to dehydrate and die. Hard-bodied insects will absorb the diatomaceous earth into their spiracles, eyes and other entry points into the body.
Look for agricultural or horticultural grade, rather than pool grade. You may be able to find it at a feed store. However, if you cannot find diatomaceous earth locally, there are plenty of online retailers from which you can purchase it.
Make a shaker out of an old coffee can and an extra lid to make application a little easier, and reduce waste,. Punch holes in the bottom of the can with a nail. Cover this end of the can with your extra lid. Fill the can and cover the top with your other lid. Place a lid from a second can on the other end for storage. Simply remove the lid covering the holes when you are ready to sprinkle diatomaceous earth on your garden.
Apply the diatomaceous earth when you don't expect rain in the next few days. If it does rain, reapply the powder as soon as the plants and ground dry out.
Dust plants with a layer of the diatomaceous earth. In addition, coat the ground around the plants. Look for anthills and other insect nests. Apply the powder directly to these nests.