There are many ways to keep insect pest populations at a controlled level without ever using any substances that could be harmful to you or to beneficial insects.
When planting your landscape or garden always leave a little room for "beneficial insect companion plantings." Companion planting is a practice by which you include plant types that draw or lure beneficial insects into your garden. These beneficial insects will either ward off or eat the bad bugs.
Make sure you include some of the following plants in your plantings:
Sweet Alyssum - This plant is very attractive when in bloom and provides a good nectar source for many adult beneficial insect species.
Basil - It's always a good idea to include basil in the vegetable garden at any time of year. The flowers are a rich source of pollen and nectar and you can use the leaves in the kitchen.
Dill - This is one of the best plants for luring beneficial insects into the garden. Dill flowers are very high in nectar and it is also one of the most useful of seasonings for cooking.
Mint - Any member of this family of plants is very useful in drawing beneficial insects into the garden.
Marigolds and Nasturtium - These can handle a slew of buggy challenges. They thwart bugs that can harm your tomatoes, potatoes and strawberries including tomato hornworms, squash bugs, and whiteflies. The smell of marigolds will help to also deter rabbits and squirrels.
Yarrows (Achillea) - Plant these to attract ladybugs and lacewings, both of which will kill and eat many bad bugs.
Here's a listing of beneficial insects and the plants that will attract them to your yard.
Brachonids, Chalcids and Ichneumon Wasps - These small beneficial insects destroy leaf-eating caterpillars. You can attract them to your garden by planting carrots, celery, parsley, caraway and Queen Anne's lace. These plants are easy to grow, and some should be left to flower. It's the flower that attracts the insects.
Ladybugs - These common insects consume aphids, mites, whiteflies and scale. When you see aphids around, and you also see ladybugs, there is no reason to spray a chemical when the ladybugs will do the job naturally. Ladybugs can be attracted to your garden by planting members of the daisies, tansy or yarrow plant families.
Lacewings - Lacewings are avid consumers of aphids, and their larva eat aphids and other varieties of other insect pests. They are attracted to flowers such as yarrow, goldenrod, black-eyed susan's and asters. Lacewings can also be purchased online and released directly into your garden.
Hover-flies - Hover-flies are avid consumers of aphids, and the larva of hover-flies eat aphids and other insect pests. Like the Lacewings, they are attracted to flowers, such as yarrow, goldenrod, black-eyed susan's and asters. Seeds for these flowers are available online, or at most garden centers.
Praying Mantis - These large insects have an appetite for most garden pests. Praying mantis eggs are set out in the garden where they hatch and quickly grow to adult size. The eggs are available through mail-order catalogs.
Natural Homemade Remedies
NOTE: Sprays that kill harmful insects will also kill beneficial insects. Use these homemade remedies selectively, only spraying the infected plants, and avoiding spraying on flowers. Apply them early in the morning or just before dark when butterflies and other beneficial insects aren't feeding on flowers. Re-apply after a rain.
Here's a few simple formulas:
Soft-bodied Insects (mites, aphids, mealybugs) - Mix one tablespoon canola oil and a few drops of Ivory soap into a quart of water. Shake well and pour into a spray bottle. Spray plant from above down, and from below up to get the underside of the leaves. The oil smothers the insects.
Mites & Other Insects - Mix two tablespoons of hot pepper sauce or cayenne pepper with a few drops of Ivory soap into a quart of water. Let stand overnight, then stir and pour into a spray bottle and apply as above. Shake container frequently during application.
Insects and Fungal Diseases - Combine one tablespoon of cooking oil, two tablespoons of baking soda and a few drops of Ivory soap into a quart of water. Pour into a spray container and apply as above.
Potato Starch Spray - Mix two to four tablespoons of potato flour in one quart of water. Add two to three drops of non-detergent liquid soap. This will also protect the plants from insect that feed on liquid, also called sucking insects, in the plants.
Rodale's All-purpose Spray - Chop and grind one garlic bulb and one small onion. Add one teaspoon of powdered cayenne pepper and mix with one quart of water. Let steep for one hour and strain through cheesecloth. Next add one tablespoon of liquid dishwashing soap to the strained liquid. Mix well and spray plants thoroughly. This kills the sucking insects.
Garlic Spray - Blend 1/4-pound of strong garlic for five to 10 minutes with a quart of water and one tablespoon of liquid dishwashing soap. Strain the mixture through cheesecloth and collect the liquid. Next dilute the solution with one part per 10 parts water before spraying. This solution will last about one month if refrigerated. It will repel ants, mole crickets and sucking insects.
Hot Dust - Grind dried homegrown red or chili peppers or dill weed (including seeds) to dust. Sprinkle along seeded rows of vegetables to repel ants. Store-bought black pepper, chili pepper, dill, ginger, paprika and red pepper all contain capsaicin, which repels ants. Note: when using red peppers or chili peppers take care not to get the dust in your eyes or on your hands!
Safe Products For Insect Control
NOTE: Before spraying to kill insects, I always recommend identifying the insect you want to eliminate. You want to make sure you're not spraying a beneficial insect. Sprays that kill harmful insects will also kill beneficial insects. Use these natural insecticides selectively, only spraying the infected plants, and avoiding spraying on flowers. Apply them early in the morning or just before dark when butterflies and other beneficial insects aren't feeding on flowers.
Insecticidal Soaps and Sprays - These remedies work to safely repel many insects and are available at your local nursery and garden center.
Neem Oil - Neem Oil works to repel or kill insects and also kills many types of fungus and disease.
Milky Spore - For lawn or garden grubs, there is a natural remedy called milky spore. The granules are spread on the soil and cause the grubs to contract a disease that kills them. This natural control affects only the grubs, leaving the beneficial organisms unharmed. Milky spore multiplies over time and will sit inactive, waiting for grubs to infect. One treatment is said to last 40 years. The grubs in your garden soil are actually the larvae of Japanese beetles. So, when you kill the grubs you kill the beetle.
Diatomateuos Earth - To control earwigs, slugs and other soft-bodied insects, sprinkle diatomaceuos earth over plants and around edges of garden beds. The diatoms particles are very small and sharp - but only harmful to the small exoskeletons of insects, slugs and snails. Insects cannot become immune to its action, as it is a mechanical killer - not a chemical one.
Yellow Flypaper - Old-fashioned fly-paper is very effective in the garden for aphids and whiteflies. In fact, any board or heavy paper painted yellow and coated with a sticky substance such as tanglefoot (available at garden centers) will do the job.
Pheremones - Great for Japanese beetles! These biological mating scents attract insects to a trap which is coated with a sticky substance. Pheremone traps are effective, but remember they are "attracting" the insects - be sure to position them on your garden perimeter or you'll attract outside pests into your garden!
Floating Row Covers - Floating row covers consist of lightweight opaque material which is draped over the garden bed. Sunlight and water go through, but insects and birds are kept out. The material is so light that the growing plants simply push it up as they grow - like Jiffy Pop popcorn. The edges of the row cover need to be anchored with rocks or boards or the wind will lift it. The material is "spun" which resists tearing, but usually begins to break down after a few years. Row cover material comes in rolls so you can make a continuous cover no matter how long the garden bed. Row covers are great for protecting seedlings. They are even more useful throughout the growing season when placed over vegetables such as carrots, beets, broccoli, swiss chard and spinach because it makes an effective barrier against flying insects looking for these plants to lay their eggs on.
Barrier Paper - Scraps of waxed cardboard from milk cartons, or a scrap of roofing felt are a simple yet effective defense against cabbage moths. Cabbage moth larva kill young sprouts of broccoli, cabbage, brussel sprouts, kale and cauliflower. Cut the waxed cardboard or roofing felt into 2" squares and slit one side into the center; make another small slit crossways. Open the slit and slide the square so the seedling stem is in the center. This prevents the cabbage moth from laying eggs at the base of the sprouts. Leave in place and as the plant grows it will simply push the slit open wider. Be sure to apply as soon as the sprout appears, or the moth will beat you to it!