Are tiny little insects chewing up your garden or houseplants? Are you looking for a way to destroy them without toxic pesticides? It’s time to get yourself some neem oil, STAT.
What Is Neem Oil?
Neem oil is extracted from the seeds of the neem tree (Azadirachta indica), a member of the mahogany family and a native of India and South Asia. The plant has been used for centuries in Ayurvedic medicine, especially as an antiseptic, but scientists have only been studying its potential as a pesticide since the 1960s.
How Neem Oil Kills Insects
Neem oil doesn’t actually kill bugs by poisoning them. Instead several active ingredients called limonoids repel insects while also disrupting their growth and reproduction. Azadirachtin is the most potent of these limonoids, so look for it on the ingredients list when purchasing a neem-based pesticide.
How it works: Azadirachtin is chemically similar to insects’ hormones and ingesting it can mess with metamorphosis by either preventing larva and pupa from maturing or by preventing adults from reproducing.
Additionally, neem oil kills soft-bodied insects when it is sprayed directly on them. The coating causes them to suffocate by preventing respiration the same way that insecticidal soap does.
Neem works well for aphids, mites, mealybugs, whiteflies, scale, beetles, leafhoppers, leafminers, lacebugs, caterpillars, and other chewing insects. It’s also effective at getting rid of fungi and mildews like root rot, sooty mold, and powdery mildew, likely because of its antibacterial properties.
Interesting Fact: The coolest thing about neem oil is that many plants absorb it through their roots when it’s applied to the soil. The roots deliver the neem to the stems and leaves, so when a hungry mealy bug takes a bite of leaf, it gets a mouthful of the deadly neem. This systemic effect varies from plant to plant and isn’t necessarily effective on all insects, but it’s one of the reasons neem is such a powerful tool for fighting garden pests and commercial crops.
Neem is non-toxic to humans and wildlife, including most beneficial insects like bees and ladybugs that do not feed on leaves. (Be cautious about beneficial caterpillars.) It is safe to use indoors, outdoors, and on food (just be sure to wash everything well). You can use it safely around pets provided they do not ingest the oil directly.
How to Use Neem Oil at Home
Neem oil is most often applied as a spray. Typically you will need to mix two to four tablespoons of the neem oil concentrate with one gallon of water, but check the directions on the bottle.
Neem oil might kill some plants, especially if they are young and if the oil is applied too heavily. Test a small area of the plant and wait 24 hours before applying it all over. Apply neem in the evening for outdoor plants and out of direct sunlight for indoor plants to prevent leaf burning. Spray all surfaces of the leaves, including the undersides. Reapply every seven to 14 days as needed.