You’ve no doubt heard of neem oil, the all-natural plant extract that’s used in a wide range of health and beauty products.
It’s also considered by some to be one of the most effective insecticides around, while others say it’s ineffectual.
Understanding how neem oil works are one of the biggest differences between those who support it and those who hate it.
This is due to the fact that different forms of neem have slightly different applications and effects, some of which aren’t immediately visible.
How Does Neem Oil Work?
Neem oil contains a number of chemicals that can be beneficial when used in beauty products.
Other chemicals mimic natural insect hormone systems, wreaking havoc on their populations when ingested.
What Are The Active Ingredients in Neem Oil?
By far, the most famous chemical compound found in neem oil is Azadirachtin.
When ingested, the composition of Azadirachtin closely mimics hormones in many insect species that regulate hunger and growth.
An insect that consumes Azadirachtin will lose its appetite, be unable to achieve further growth stages, and/or become infertile.
Azadirachtin also functions as a somewhat effective natural repellent against some species, such as mosquitoes.
Nimbin is another important active ingredient with benefits to garden enthusiasts.
It’s a triterpenoid chemical in neem that works as a fungicide.
Salannin is a third known active insecticidal ingredient.
It regulates insect hunger and growth while being a plant metabolite.
Other Useful Ingredients
There are many ingredients found in neem oil that have no effect on pest control but make it useful in health products.
- Beta-Systerol: common phytosterol that reduces cholesterol
- Campesterol: common anti-inflammatory found in many foods
- Carotenoid: antioxidant
- Fatty acids
- Stigmasterol: common phytosterol that helps maintain cell membranes
- Vitamin E
The Two Main Forms of Neem
Neem oil is available as either crude (raw) or clarified.
When cold-pressed, raw neem oil is most commonly used as a systemic insecticide, being absorbed by the roots of plants to attack insects that ingest it.
It is also used to repel or control mosquitoes with some degree of success.
When Azadirachtin is extracted from the raw oil, the resulting clarified hydrophobic neem oil relies on its other active ingredients.
This form of neem oil is most often mixed with warm water used as a contact poison and poses less risk of causing chemical burns to plants when applied topically.
Neem is used to control a variety of pests like leafminers, thrips, whiteflies, caterpillars, mealybugs, aphids, plant scale, spider mites, whitefly, lace bugs, and beetles.
Related: What Bugs Does Neem Oil Kill?
Types of Neem Oil Products: Natural Insect Repellents and How They’re Used
Both raw and clarified neem oil pesticide products may be purchased in other forms, such as powder.
These different forms can affect pests better in specific ways.
Choose one or more types of a product based on the needs of your plant.
- Clarified Oil: Used as foliar insecticide oil sprays and leaf shine. It primarily kills soft-bodied insects through suffocation.
- Crude Oil: Raw neem oil is most often used as a soil drench or soil soak. The drench kills harmful ground insect populations when being absorbed by plants to become a systemic insecticide killing a variety of pests and insect feeding on the plant. Pest like Japanese beetles, cucumber beetles, and Mexican bean beetles.
- Crude Powder: Used in Africa and other areas, primarily against mosquitoes. It’s believed to kill through suffocation.
- Neem Cakes: The solids left over from extracting raw neem. These are used as organic compost with insecticidal properties.
- Neem Granules/Pellets: Fertilizer pellets containing neem. Provides both food for plants and insecticidal properties similar to neem cakes in a more measurable form.