Organic insect killers are useful alternatives to commercial pesticides. Many natural products found in your home can be used in the garden to kill insects. It is wise to test a small area of your garden when using these particular natural alternatives. If they cause damage to your plants, dilute the mixture with more water and test again.
Dilute 1 to 2 cups of 70 percent isopropyl alcohol (rubbing alcohol) in 1 quart of water. This method works well on scale infestations and helps control a large number of common pests.
In a spray bottle mix 1/2 cup ammonia with 1 quart of water. This works well on fleas, scales, aphids, beetles, thrips, and whiteflies. For a stronger solution mix 1 part ammonia with 7 parts water.
Heat a pot of water to a simmer then add shavings of Fels Naptha soap. Let it simmer for 20 to 30 minutes. Let the mixture cool and strain the solution with a cheesecloth. Pour the solution into a spray bottle. This spray works well on chiggers, earwigs, scales, aphids, whiteflies, mites and flies.
Nicotine, which comes from tobacco, is very poisonous. Depending on the concentration used, it can kill most soft-bodied insects. Place one cigarette in one quart of water and allow it to stand overnight. Use a cheesecloth to strain the nicotine solution. To make a stronger poison, mix the nicotine solution with the soap spray. Nicotine works well to kill ants, aphids, scales, mealybugs, fungus gnats and spider mites. Be sure to wear gloves when handling nicotine since it can enter the body through the skin. It is also very harmful to animals so be careful if you have pets or children in your garden.
This abrasive dust is great to use for killing common pests. It is composed of fossilized silica shells of specific algae. Diatomaceous earth has sharp needle-like projections that penetrate the insect's outer shell and kill it by dehydrating it. A light dusting is very effective in controlling caterpillars, aphids, leaf-hoppers, slugs, snails, and thrips. Be safe by wearing a dust mask when using diatomaceous earth. One of the drawbacks is that it will cause irritation to all animals and will kill beneficial insects as well as harmful ones.
Bacillus Thuringiensis (Bt)
Bacillus thuringiensis is a bacterial pathogen that is used to control pest larvae. It has been proven to be safe with humans, animals, plants, and trees. It is marketed under the names Thuricide, Biotrol, and Dipel. These are sold as a wettable dust or as and emulsion. It is stable when stored but will lose potency in sunlight. It is carried in most garden supply stores. Pellet bait is also available and sold under the names of Soilserv and Bacillus Bait.