Several naturally derived products can help control insects on vegetables, fruit trees, and ornamental plants. They include plant extracts, microorganisms, soaps, oils, and mineral products.
However, natural does not mean harmless. Even natural insecticides can affect pollinators and beneficial insects when used incorrectly. Always identify the pest first and follow the product label. This article contains affiliate links. We may earn a commission from qualifying purchases.
Insecticidal soap
Insecticidal soaps are usually based on potassium salts of fatty acids. They work by direct contact and are particularly useful against aphids, whiteflies, mites, and other soft-bodied insects.
They leave little residual activity, but good coverage is essential and repeated applications may be necessary.
Horticultural oils
Horticultural oils can control aphids, scales, mealybugs, whiteflies, mites, and several other small pests.
They work mainly through physical contact. Avoid applying oils during very hot weather or to severely stressed plants, because some plants may develop phytotoxicity.
Neem and azadirachtin
Neem products originate from Azadirachta indica. Azadirachtin can reduce feeding and interfere with insect growth and reproduction, while neem oil also has contact activity.
They can be useful against aphids, whiteflies, thrips, mites, and other pests, particularly when infestations are still relatively small.
Bacillus thuringiensis (Bt)
Bacillus thuringiensis is a microbial insecticide. Different strains control different insects.
Btk is particularly useful against young caterpillars. The larvae must normally eat treated plant material, making early application important.
Spinosad
Spinosad originates from compounds produced by a soil bacterium and can control caterpillars, thrips, leafminers, and some beetles.
It is very effective, but it can also harm bees when they are directly exposed to fresh spray. Avoid treating flowering plants while pollinators are active.
Pyrethrins
Pyrethrins are natural insecticides derived from chrysanthemum flowers. They act quickly and control a broad range of insects.
Their natural origin should not be confused with selectivity: pyrethrins can also kill beneficial insects and are toxic to aquatic organisms.
Beauveria bassiana
Beauveria bassiana is a naturally occurring fungus that infects insects. Products containing it can be used against whiteflies, aphids, thrips, and some beetles.
It acts more slowly than conventional contact insecticides, and its effectiveness depends strongly on coverage and environmental conditions.
Diatomaceous earth
Diatomaceous earth is a mineral powder made from fossilized diatoms. It damages the protective outer layer of insects, causing them to lose water.
It is mainly useful against crawling insects and works best when dry. Always use a product labeled for pest control and avoid inhaling the dust.
Zeolite
Natural zeolite can form a fine mineral particle film on plants. Research suggests that these films can interfere with insect movement, feeding, and egg laying, producing both physical and repellent effects. Studies have demonstrated activity against pests including tomato leafminer and olive fruit fly.
Its effectiveness depends on maintaining good coverage, and rain can remove the protective layer. For U.S. gardeners, use only products whose labels permit the intended pest-control use.
Silicone-based insecticides
Silicone polymers are not natural insecticides, but some products use them as physical-action pest controls. They can coat insects, restrict movement and feeding, and provide useful contact activity against pests such as aphids.
Their major advantage is the lack of prolonged residual insecticidal activity after the spray dries. However, direct spray can also kill beneficial insects, so targeted application is important. Recent research found significant aphid control but also high mortality of directly exposed parasitoids and lacewing larvae.
Their legal classification and approved uses can vary between products, particularly in the United States, so always check the label before use. EPA considers a substance intended to prevent, destroy, repel, or mitigate a pest to be a pesticide unless a specific exemption applies.
Which insecticide should you choose?
There is no single natural insecticide for every pest. Soap and oils are useful against many soft-bodied insects, Bt is particularly selective for caterpillars, spinosad provides stronger activity against several difficult pests, and microbial products such as Beauveria can provide biological control.
Mineral products such as diatomaceous earth and zeolite work mainly through physical mechanisms, while silicone polymers provide another non-conventional contact option.
Useful products
- Neem oil https://amzn.to/4yYGjwr
- Horticulture oil: https://amzn.to/4yhMuLY
- Pyrethrum: https://amzn.to/3T7nOH1
- Bacillus thuringiensis: https://amzn.to/4jsm7OV
- Spinosad: https://amzn.to/3TPv22B
- Beauveria bassiana: https://amzn.to/3TrNu16
- Diatomaceous Earth: https://amzn.to/4ypQ4UI
- Insecticidal soap: https://amzn.to/46NYjgZ
Natural insecticides are part of IPM
The best strategy is not to spray automatically whenever an insect appears.
Identify the pest, monitor its population, preserve predators and pollinators, remove heavily infested plant material when practical, and choose the most selective treatment available.
Natural pest control works best when insecticides are used as one part of an integrated pest management strategy, not as the only solution.