Homemade Organic Insect Sprays

Alcohol Sprays

The idea of using rubbing alcohol as a spray for plants pests has been around for years. Can cause leaf damage on African Violets, and Apple trees.
Protection offered:   Alcohol sprays work on aphids, mealy bugs, scale insects, thrips and whiteflies. Alcohol sprays have been used successfully on houseplants and tropical foliage plants. Most of these have heavy, waxy cuticles that are not easily burned.
How to Make:   Use only 70% isopropyl alcohol (rubbing alcohol): mix 1 to 2 cups alcohol per quart of water. Using undiluted alcohol as a spray is very risky for plants. You can also mix up an insecticidal soap spray according to the dilution on the label but substitute alcohol for half of the water required.
How to Use:  Since alcohol can damage plants always test your spray mix on a few leaves or plants first. Tests results should show up within 2 or 3 days.

Garlic Oil Sprays

Organic gardeners have long been familiar with the repellent or toxic affect of garlic oil on pests. when it is combined with mineral oil and pure soap, as it is in the recipe that follows, devised at the Henry Doubleday Research Association in England, it becomes an effective insecticide. Some studies also suggest that a garlic oil spray has fungicidal properties.
Protection Offered:   Good results, with quick kill, have been noted against aphids, cabbage loopers, earwigs, June bugs, leafhoppers, squash bugs and whiteflies. The spray does not appear to harm adult lady beetles, and some gardeners have found that is doesn’t work against the Colorado potato beetles, grape leaf skeletonizers, grasshoppers, red ants, or sow bugs.
How to Make:   Soak 3 ounces of finely minced garlic cloves in 2 teaspoons of mineral oil for at least 24 hours. Slowly add 1 pint of water that has 1/4 ounce liquid soap or commercial insecticide soap mixed into it. Stir thoroughly and strain into a glass jar for storage. use at a rate of 1 to 2 Tablespoons of mixture to a pint of water. If this is effective, try a more dilute solution in order to use as little as possible.
How to Use:   Spray plants carefully to ensure thorough coverage. To check for possible leaf damage to sensitive ornamentals from the oil and soap in the spray, do a test spray on a few leaves or plants first. If no leaf damage occurs in 2 or 3 days, go ahead and spray more.

Herbal Sprays

Many organic farmers are familiar with using sprays made from aromatic herbs to repel pests from the garden plants. Several recent studies confirm the repellent effect of such sprays. The essential oil of Sage and Thyme and the alcohol extracts such as Hyssop, Rosemary, Sage, Thyme, and White Clover can be used in this manner. They have been shown to reduce the number of eggs laid and the amount of feeding damage to cabbage by caterpillars of Diamond back moths and large white butterflies. Sprays made from Tansy have demonstrated a repellent effect on imported cabbageworm on cabbage, reducing the number of eggs laid on the plants. Teas made from Wormwood or Nasturtiums are reputed to repel aphids from fruit trees, and sprays made from ground or blended Catnip, Chives, Feverfew, Marigolds, or Rue have also been used by gardeners against pests that feed on leaves.
Protection Offered:   Try herbal sprays against any leaf-eating pests and make note of what works for future reference.
How to make:   In General, herbal sprays are made by mashing or blending 1 to 2 cups of fresh leaves with 2 to 4 cups of water and leaving them to soak overnight. Or you can make a herbal tea by pouring the same amount of boiling water over 2 to 4 cups fresh or 1 to 2 cups dry leaves and leaving them to steep until cool. Strain the water through cheesecloth before spraying and dilute further with 2 to 4 cups water. Add a very small amount of non-detergent liquid soap (1/4 teaspoon in 1 to 2 quarts of water) to help spray stick to leaves and spread better. You can also buy commercial essential herbal oils and dilute with water to make a spray. Experiment with proportions, starting with a few drops of oil per cup of water.
How to Use:   Spray plants thoroughly, especially undersides of leaves, and repeat at weekly intervals if necessary.

"Hot" Dusts

Black pepper, chili pepper, dill, ginger, paprika, and red pepper all contain capsaicin, a compound shown to repel insects. Synthetic capsaicin is also available for field use. Researchers have found that as little as 1/25 ounce of capsaicin sprinkled around an onion plant reduced the number of onion maggot eggs laid around the plant by 75%, compared to a control plant.
Protection Offered:   Capsaicin-containing dusts repel onion maggots from seedlings, as well as other root maggot flies from cabbage family plants and carrots. Pepper dusts around the base of the plants help repel ants, which is desirable in a garden where ants often protect and maintain aphid colonies on plants.
How To Make:   It can be rather expensive to buy enough packaged pepper dusts to sprinkle throughout your garden. However, if you grow and dry your own red peppers, chili peppers, or dill, you can make lots of dust at low cost. Use a mortar and pestle to grind the peppers, or dill, including the seeds, to dust. Be careful handling the hot peppers because they irritate sensitive skin.
How to Use:    Sprinkle along seeded rows of onions, cabbage, or carrots, in a band at least 6 inches wider than the row or planting bed. A fine sprinkling will suffice, but the more dust you use, the better the effect. Renew after a heavy rain or irrigation. To protect plants from ants, sprinkle around the base of plants in an area as wide as the widest leaves.

Nicotine

One of the top three insecticides in the 1880s, nicotine in several forms is still widely used. Nicotine comes from the tobacco plant and is extremely toxic to insects. The great advantage of home-made nicotine tea is that it is very short lived, retaining its toxicity for only a few hours after spraying. It is relatively nonhazardous to bees and lady beetles because of its short persistence.
Protection Offered:   Nicotine is effective against ground and soil pests, especially root aphids and fungus gnats, and on many leaf-chewing insects, such as aphids, immature scales, leafhoppers, thrips, leaf miners, pear psylla, and asparagus beetle larvae.
How To Make:   You can brew your own batch of nicotine tea by soaking tobacco leaves or cigarette butts in water to make a spray. Soak 1 cup of dried, crushed tobacco leaves, or an equivalent amount of cigarette butts, in one gallon of warm water with 1/4 teaspoon pure soap added. Strain the mixture through cheesecloth after it has soaked for 1/2 hour. The solution will keep for several weeks if stored in a tightly closed container.
How to Use:    For soil pests, pour the spray mixture onto the soil in the area of the stem base and root zone. for leaf pests, spray leaves thoroughly, especially the undersides. Nicotine can be absorbed by plant leaves and remain there for several weeks. to be safe, use nicotine only on young plants and only up to one month before harvest. It's probably safest not to spray nicotine on eggplant, peppers or tomatoes. While most tobacco cultivars now grown are resistant to tobacco mosaic virus, nicotine sprays could contain the pathogen, which will infect nightshade family crops.

Pyrethrin

The dried, powdered flowers of the pyrethrum daisy, Tanacetum cinerarifolium, were used as early as 1880 to control mosquitoes. The popularity of pyrethrum insecticides waned when synthetic insecticides were introduced, but they are now enjoying a commercial comeback. Many new products formulated with natural pyrethrums are available. Pyrethrins are the insecticidal chemicals extracted from the pyrethrum daisy. Do not confuse them with pyrethroids, the term for a new class of synthetic pesticides. Pyrethrums, which are mainly concentrated in the seeds of the flower head, are a contact insecticide, meaning the insect only has to touch the substance to be affected. Pyrthrins have a quick knockdown effect on insects: Flying insects are paralyzed. pyrethrins can be applied up to one day before harvest because they are quickly destroyed by light and heat and are not persistent in the environment. Pyrthrins will kill lady beetles but do not appear to be harmful to bees. They are toxic to fish and to the aqautic insects and other small animals that fish eat. Pyrethrins do not seem to be toxic to birds or mammals.
Protection Offered:   Pyrethrins are cataloged for flowers, fruits, and vegetables, including greenhouse crops. they are effective on many chewing and sucking insects, including most aphids, cabbage loopers, celery leaftiers, codling moth, Colorado potato beetles, leafhoppers, Mexican bean beetles, spider mites, stink bugs, several species of thrips, tomato pinworms, and whiteflies. they are especially good against flies, gnats, mosquitoes, and stored products pests. Flea beetles are not affected, nor are imported cabbageworms, diamondback moths, pear psylla, and tarnished plant bugs.
How to Make:   If you grow your own pyrethrum daisies, you'll have the main ingredient for a make-it-yourself spray. The concentration of pyrethrums is at its peak when the flowers are in full bloom, from the time the first row of florets open on the central disk opens too the time all the florets are open. pick flowers in full bloom and hang them in a sheltered, dark spot to dry. Once the flowers have dried thoroughly, grind them to a fine powder, using a mortar and pestle, old blender or small hammer mill. Mix with water and add a few drops of liquid soap. Store in a glass jar and keep the lid tightly closed, because the mixture looses activity if left open. You'll have to experiment with the amount of water to add, because the concentration of pyrethins in the flowers is an unknown variable. If the spray you make does not seem to kill insects, use less water the next time you make the concentrated spray. Also keep in mind whole flower heads stay potent longer so do not grind until ready to use.
How to Use:    Pyrethrins are more effective at lower temperatures, so for best results, apply in early evening when temperatures are lower. Spray both the upper and lower surfaces of the leaves, because spray must directly contact the insects such as thrips that hide in leaf sheaths and crevices. The first spray will excite them and bring them out of hiding, the second will kill them. Never use pyrethrin products around waterways and ponds.

Tomato Leaf

Nightshade family plants, such as Tomato, potatoes and tobacco, have toxic compounds called alkaloids in their leaves. These toxins are water soluble and can be soaked from chopped leaves and made into home-made sprays. These sprays also work by attracting natural pest enemies. The good bugs follow the smell of the spray in looking for prey.
Protection Offered:   Tomato leaf sprays have been used to protect plants from aphids. Also, spraying Tomato leaf spray on corn may reduce corn earworm damage. The corn earworm is also called the Tomato fruit worm, as it also attacks Tomato plants. A scientific study has shown that corn plants sprayed with Tomato leaf spray attracted significantly more Trichogramma wasps to parasitize the corn earworm eggs than the unsprayed did.
How to Make:   Soak 1 to 2 cups of chopped or mashed Tomato leaves in 2 cups of water overnight. Strain through cheesecloth or fine mesh, add about 2 more cups of water to the strained liquid, and spray. For aphid control, be sure to thoroughly cover the leaf undersides, especially of lower leaves and growing tips of plants where aphids congregate.
How to Use:   Spray plants thoroughly, particularly undersides of lower leaves and growing tips where aphids congregate. while this spray is not poisonous to humans on contact, use care in handling, especially if you are allergic to the nightshade family.

Resources: Rodale's Chemical-Free Yard and Garden