It can be helpful to have an insect spray that uses natural plant-based ingredients, or ingredients not having a chemical origin, to repel insects from the garden or home. Natural insect sprays are often used by people who are concerned chemical pesticides may cause harm to their health and the environment.
Garlic oil is an ingredient commonly found in natural insect sprays and is obtained by crushing garlic bulbs. It is most often used as an insect repellent or barrier rather than a product to kill insects. Garlic oil also repels beneficial insects, which may be a drawback for some organic gardeners.
Capsaicin is the oil inside chili peppers that make them hot. It is an irritant and is highly effective in repelling certain insects, such as aphids, and some wild animals, such as rabbits and squirrels. Capsaicin levels vary by variety of pepper and only the hottest peppers, such as the habanero pepper, are used to make natural insect repellent sprays.
Spinosad is an insecticide derived from a naturally occurring spore that grows in the soil. In its concentrated from, it is deadly when ingested by insects. It is highly effective against worms, caterpillars and some ants.
Neem oil is an oil derived from the Neem tree. Although it does not kill insects, it stops them from feeding and reproducing. Neem oil is effective against aphids, mealybugs, whiteflies, leaf miners and many other insects. It is also used to control powdery mildew.
Pyrethrum is made from finely crushing a certain type of chrysanthemum flower that has insecticidal properties. It kills all insects on contact, including beneficial insects, so it should not be used while bees are active. Pyrethrum is one of the safest natural insecticides to use and can be used up to the day of harvest in the vegetable garden.
Bacillus thuringiensis is commonly called Bt and a naturally occurring fungus found in the soil. It is used to control caterpillars, worms and some beetles. Once it is ingested by the pest, Bt causes an interruption in the digestive process, causing the pest to stop feeding.