Organic pesticides are commonly available at garden shops and large retailers and can offer a safe, more earth-friendly alternative to standard pesticides. Organic pesticides come in spray and dust forms and though they are made of all-natural ingredients, some may be toxic to humans or animals, particularly house pets. These insecticides may burn plants, so read labels carefully to see if the insecticide you choose is appropriate for the plants you will be treating.
Considered the safest of all organic pesticides, insecticidal soap is composed of either potassium or sodium salts mixed with fatty acids. The mixture should be applied directly to the plant at the first sign of infestation, as it is only effective when wet. Insecticidal soap, which may be made at home with dish soaps, is nontoxic to animals but can damage some plants by burning the leaves. A broad spectrum insecticide, insecticidal soap may be used on fruits and vegetables up until harvest, though both should be washed before eating.
This well-known, powdery insecticide is widely used but does have some drawbacks. Bt, which is short for bacillus thuringiensis, should be dusted onto plants, and insects must consume the bacteria for it to be effective. This insecticide, which breaks down quickly, is effective against beetles, caterpillars and gypsy moths. Bt may be a skin irritant and can kill so-called "good" insects, including butterflies and ladybugs. Bt is available under several trade names.
Available under different trade names, potassium bicarbonate can also be purchased and mixed at home with horticultural oil (petroleum oil) to make an effective insecticide. In either case, a potassium bicarbonate insecticide should be sprayed on to plant foliage and may be used on fruits and vegetables until harvest, though both should be washed before consuming. Potassium bicarbonate has a longer life than many other insecticides and can work as a preventative for several weeks. Avoid using this product in full sun, as it may burn leaves.
Made of neem seed oil and sold under several trade names, this insecticide should be sprayed on plants at the first sign of infestation and is a broad-spectrum product. The seeds come from the neem tree, which is native to India. Neem seed oil is a slow-acting insecticide that may be harmful to house pets. This type of insecticide should be used during overcast, but not rainy times, as it breaks down in direct sun and washes away in rain.