Soap has been used for centuries as an all-purpose pesticide. It disrupts insects’ cell membranes, and kills pests by dehydration. The key is not to use too much soap, or you’ll also kill the vegetation near the pests. If you follow the proportion of soap to water in the Soap Spray recipe, below, the vegetation should be fine.
Doug Harp, a graphic designer friend, first alerted me to soap as an effective all-purpose pesticide when he used Dr. Bronner’s Liquid Peppermint Pure-Castile Soap diluted with water to kill the gypsy moths that had infested his apple trees. We were working on a project together, and I’d get faxes updating me on his kill rate (this was back before e-mail!), which, much to his delight, was excellent.
Note: Buy a liquid soap and not a detergent. Health food stores have liquid soaps, such as Dr. Bronner’s Pure-Castile Soaps.
Insecticidal Soap Spray
1 to 2 tablespoons liquid soap
1 quart water
Combine ingredients in a bucket, mix, then transfer to a spray bottle as needed.
All-Purpose Pesticide Soap Spray
Strong smelling roots and spices such as garlic, onions, horseradish, ginger, rhubarb leaves, cayenne and other hot peppers, are all known to repel insects.
A handful of roots and spices
Enough boiling water to cover
Soap Spray (recipe, above)
Add the roots and spices to the bottom of a mason jar. Cover with the boiling water, screw on the top, and let set overnight. Strain, and add to the Soap Spray. Note that this will rot, so use it all up or freeze leftovers for another time.
Variation: Garlic Spray
Use 1 to 2 heads garlic. Deer and rabbits hate the smell