Insect Control: Soaps and Detergents by W.S. Cranshaw 1 Quick Facts... Soaps can be used to control a wide range of plant pests. Small, soft-bodied arthropods such as aphids, mealybugs, psyllids and spider mites are most susceptible to soaps. The ease of use, safety and selective action of soaps appeal to many people. Limitations of soaps include the need to wet the insect during application, absence of any residual effectiveness, and potential to damage some plants. Soaps or detergents used for control of insects are applied as dilute sprays, mixed with water to produce a concentration of about 2 percent. Soaps have been used to control insects for more than 200 years. Recently, there has been increased interest in and use of these products. This change is due to a better understanding of how to use soaps most effectively and a desire to try insecticides that are easier and safer to use than many currently available alternatives. How soaps and detergents kill insects is still poorly understood. In most cases, control results from disruption of the cell membranes of the insect. Soaps and detergents may also remove the protective waxes that cover the insect, causing death through excess loss of water. Soap-Detergent Sprays Soaps and detergents act strictly as contact insecticides, with no residual effect. To be effective, sprays must be applied directly to and thoroughly cover the insect. Several insecticidal soaps are distributed for control of insects and mites. Available under a variety of trade names, the active ingredient of all is potassium salt of fatty acids. Soaps are chemically similar to liquid hand soaps. However, there are many features of commercial insecticidal soap products that distinguish them from the dishwashing liquids or soaps that are sometimes substituted. Insecticidal soaps sold for control of insects: are selected to control insects; are selected to minimize potential plant injury; and are of consistent manufacture. Some household soaps and detergents also make effective insecticides. In particular, certain brands of hand soaps and liquid dishwashing detergents can be effective for this purpose. They are also substantially less expensive. However, there is increased risk of plant injury with these products. They are not designed for use on plants. Dry dish soaps and all clothes-washing detergents are too harsh to be used on plants. Also, many soaps and detergents are poor insecticides. Identifying safe and effective soap-detergent combinations for insect control requires experimentation. Regardless of what product is used, soap-detergent sprays are always applied diluted with water, typically at a concentration of around 2 to 3 percent (Table 1). Susceptible Insects Most research with insecticidal soaps and detergents has involved control of plant pests. In general, these sprays are effective against most small, soft-bodied arthropods, such as aphids, young scales, whiteflies, psyllids, mealybugs, and spider mites. Larger insects, such as caterpillars, sawflies and beetle larvae, generally are immune to soap sprays. However, a few large insects, including boxelder bugs and Japanese beetles, are susceptible. Insecticidal soaps are considered selective insecticides because of their minimal adverse effects on other organisms. Lady beetles, green lacewings, pollinating bees and most other beneficial insects are not very susceptible to soap sprays. Predatory mites, often important in control of spider mites, are an exception: a beneficial group of organisms easily killed by soaps. Application One of the most serious potential drawbacks to the use of soap-detergent sprays is their potential to cause plant injury -- their phytotoxicity. Certain plants are sensitive to these sprays and may be seriously injured. For example, most commercial insecticidal soaps list plants such as hawthorn, sweet pea, cherries and plum as being sensitive to soaps. Portulaca and certain tomato varieties also are sometimes damaged by insecticidal soaps. The risk of plant damage is greater with homemade preparations of household soaps or detergents. When in doubt, test soap-detergent sprays for phytotoxicity problems on a small area a day or two before an extensive area is treated. Plant injury can be reduced by using sprays that are diluted more than the 2 to 3 percent suggested on label instructions. To reduce leaf injury, wash plants within a couple of hours after the application. Limiting the number of soap applications can also be important, as leaf damage can accumulate with repeated exposure. However, because of the short residual action, repeat applications may be needed at relatively short intervals (four to seven days) to control certain pests, such as spider mites and scale crawlers. Also, application must be thorough and completely wet the pest. This usually means spraying undersides of leaves and other protected sites. Insects that cannot be completely wetted, such as aphids within curled leaves, will not be controlled. Environmental factors also can affect use of soaps. In particular, soaps (but not synthetic detergents) are affected by the presence of minerals found in hard water, which results in chemical changes producing insoluble soaps (soap scum). Control decreases if hard-water sources are used. Insecticidal soaps may also be more effective if drying is not overly rapid, such as early or late in the day. Soaps and detergents can offer a relatively safe and easy means to control many insect pests. As with all pesticides, however, there are limitations and hazards associated with their use. Understand these limitations, and carefully follow all label instructions. Table 1: Approximate mix to produce various dilute soap sprays. Percent dilution desired Approximate amount of soap to add to water to produce: Gallon Quart Pint 1 2 1/2 Tbsp (-) 2 tsp (+) 1 tsp (+) 2 5 Tbsp (-) 4 tsp (+) 2 tsp (+) 3 8 Tbsp (+) 2 Tbsp (+) 1 Tbsp (+) 4 10 Tbsp (-) 2 1/2 Tbsp (+) 4 tsp (+) (+) Will produce a solution of slightly higher concentration than indicated. (-) Will produce a solution of slightly lower concentration than indicated. 1Colorado State University Extension entomologist and professor, bioagricultural sciences and pest management. 12/96. Reviewed 3/08. Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned. Go to top of this page. Updated Friday, August 03, 2012

I use an old squirt bottle filled with water. Then put a squirt of lemon joy dishwashing liquid in it and shake - The kind of dishwashing liquid for doing dishes by hand, not the dishwasher kind. Insects don't like lemon. The thing is you have to keep doing it weekly or so. It works for some stuff. Something was eating my strawberry plants and that took care of it. But now they are blooming so I stopped because I didn't want to discourage the bees. And I see 1 plant is getting eaten. So I don't know - do I spray again??? I guess I will because you can't have strawberries without a plant. I think it was white flies on my potatoes - I sprayed and I think it helped but I did it so late - who can tell the leaves are full of little holes. You have to get that stuff early and often.

To those of you who have been using these "home made" detergents, are you experiencing any odor, mold or mildew issues? The reason I ask is because castile soap builds up into a gooopy, gel-like gunk if not properly rinsed. This could potentially cause problems in washers. Every home-made product I've tried - from detergent to fabric softener - has proven unsatisfactory. Either the products don't clean well, they risk building up in my machine or on my clothes or they just don't work. Price is not the only consideration, which is what appears to be driving this homemade laundry movement.

Here's 10 recipes. It's pretty forgiving as to formulations by the looks of the recipes. Some like to add water softener, OxyClean, dishwashing detergent or other additives to help with their needs. 10 Homemade Laundry Soap Detergent Recipes Recipe #1 1 quart Water (boiling) 2 cups Bar soap (grated) 2 cups Borax 2 cups Washing Soda Add finely grated bar soap to the boiling water and stir until soap is melted. You can keep on low heat until soap is melted. Pour the soap water into a large, clean pail and add the Borax and Washing Soda. Stir well until all is dissolved. Add 2 gallons of water, stir until well mixed. Cover pail and use 1/4 cup for each load of laundry. Stir the soap each time you use it (will gel). Recipe #2 Hot water 1 cup Washing Soda 1/2 cup Borax 1 Soap bar Grate the bar soap and add to a large saucepan with hot water. Stir over medium-low heat until soap dissolves and is melted. Fill a 10 gallon pail half full of hot water. Add the melted soap, Borax and Washing soda, stir well until all powder is dissolved. Top the pail up with more hot water. Use 1 cup per load, stirring soap before each use (will gel). Recipe #3 Hot water 1/2 cup Washing Soda 1/2 cup Borax 1/3 bar Soap (grated) In a large pot, heat 3 pints of water. Add the grated bar soap and stir until melted. Then add the washing soda and borax. Stir until powder is dissolved, then remove from heat. In a 2 gallon clean pail, pour 1 quart of hot water and add the heated soap mixture. Top pail with cold water and stir well. Use 1/2 cup per load, stirring soap before each use (will gel). Powdered Laundry Detergent - Recipe #4 2 cups Fels Naptha Soap (finely grated - you could also try the other bar soaps listed at the top) 1 cup Washing Soda 1 cup Borax Mix well and store in an airtight plastic container. Use 2 tablespoons per full load. Recipe #5 Hot water 1 bar (4.5 oz) Ivory Soap - grated 1 cup Washing Soda In a large saucepan add grated soap and enough hot water to cover. Heat over medium-low heat and stir until soap is melted. Fill a large pail with 2.5 gallons of hot water, add hot soap mixture. Stir until well mixed. Then add the washing soda, again stirring until well mixed. Set aside to cool. Use 1/2 cup per full load, stirring well before each use (will gel) Recipe #6 2.5 gallons Water (hot) 1 Bar soap (grated) 3/4 cup Washing Soda 3/4 cup Borax 2 TBS Glycerin Melt bar soap over medium-low heat topped with water, stir until soap is melted. In a large pail, pour 2.5 gallons of hot water, add melted soap mixture, washing soda, borax and glycerin. Mix well. Use 1/2 cup per full load. Recipe #7 2 cups Bar soap (grated) 2 cups Washing Soda 2 - 2.5 gallons hot water Melt grated soap in saucepan with water to cover. Heat over medium-low heat and stir until soap is dissolved. Pour hot water in large pail, add hot soap and washing soda. Stir very well. Use 1 cup per full load. Recipe #8 2 gallons Water (hot) 1 bar Soap (grated) 2 cups Baking soda (yes baking soda this timenot washing soda) Melt grated soap in a saucepan with enough hot water to cover. Cook on medium-low heat, stirring frequently until soap is melted. In a large pail, pour 2 gallons hot water. Add melted soap, stir well. Then add the baking soda, stir well again. Use 1/2 cup per full load, 1 cup per very soiled load. Powdered Laundry Detergent - Recipe #9 12 cups Borax 8 cups Baking Soda 8 cups Washing Soda 8 cups Bar soap (grated) Mix all ingredients well and store in a sealed tub. Use 1/8 cup of powder per full load. Recipe #10 - (Powdered) 1 cup Vinegar (white) 1 cup Baking Soda 1 cup Washing Soda 1/4 cup liquid castile soap Mix well and store in sealed container. I find it easiest to pour the liquid soap into the bowl first, stirred in the washing soda, then baking soda, then added the vinegar in small batches at a time (the recipe foams up at first). The mixture is a thick paste at first that will break down into a heavy powdered detergent, just keep stirring. There may be some hard lumps, try to break them down when stirring (it really helps to make sure the baking soda isnt clumpy when first adding). Liquid Detergents Note: Soap will be lumpy, goopy and gel-like. This is normal. Just give it a good stir before using. Make sure soap is covered with a lid when not in use. You could also pour the homemade soap in old (and cleaned) laundry detergent bottles and shake well before each use. *If you cant find Fels-Naptha locally, you can buy it online (check Amazon). Optional: You can add between 10 to 15 drops of essential oil (per 2 gallons) to your homemade soap.