If you grow plants you’ve heard people raving about the benefits of using neem oil. It’s used as a pesticide and for general plant care, such as neem cake fertilizing or neem leaf shine.
But natural remedies are often considered less effective than chemical pesticide products. You might wonder if neem oil is really effective for insect control or if it’s another organic garden fad.
The good news is, neem oil is far more effective on insect pests when used properly than many chemical insecticides. Neem even works against fungal diseases like powdery mildew and many bacterial plant diseases.
The purest form of neem oil comes from crushing various parts of the neem tree – Azadirachta indica.
Pure neem extract contains five natural chemical compounds that disrupt various insects’ bodily functions. The main component being Azadirachtin, which is found in the seeds.
Clarified hydrophobic neem oil is the byproduct of extracting Azadirachtin for artificial insecticides. The oil still contains trace amounts of the chemical (usually between .5 and 3% percent). The oil has different effects on insects making it perfect for topical applications.
Neem cakes, the solids left over from extracting pure neem, contain residual amounts of the horticultural oil. They are useful for applying neem to the soil around a plant.
What Bugs Does Neem Oil Kill
Neem oil insecticide is known to affect between 200 and 600 different species of harmful insects and plant pests.
Neem may prove harmful to some beneficial insects when misapplied. But, species such as ladybugs and honeybees are not included in these numbers.
Some Common Pests Neem Oil Kills
With literally hundreds of species vulnerable to neem oil, it would take forever to list them all.
Natural neem pesticide provides effective control against these common pests found in the home and garden:
- Aphids and Neem (including hibiscus aphids, root aphids, and rose aphids)
- Bed bugs
- Black-headed caterpillars
- Blister beetles
- Boll worms
- Cabbage worms
- Caterpillar worms
- Colorado potato beetles
- Corn earworms
- Cotton stainers
- Cucumber beetle
- Eriophyid mites (Aloe mite)
- Flea beetle
- Fruit flies
- Fruit sucking moths
- Fungus gnats
- Gypsy moths
- Japanese beetle grubs
- Japanese beetles
- Lace bugs and Neem pesticide
- Leaf Footed bug
- Leaf miners
- Leaf webbers
- Lawn and root grubs
- Mealybugs (more on using Neem oil to kill mealy bugs)
- Mexican bean beetles
- Moths and moth larvae
- Mushroom flies
- Pod bug
- Pulse beetle
- Red palm weevil
- Root weevil adults
- Scale bugs on plants
- Semi loopers
- Spider mites (details on spider mites and Neem oil)
- Spindle bugs
- Spotted beetles
- Squash bugs (more on Neem oil and Squash Bugs)
- Tea mosquito
- Tomato hornworm
- Various boring insects
- White grubs
NOTE: There is no concrete evidence that any form of neem trees’ extracts will control slugs or snails.
Research has concluded that birds and other predatory animals or insects which prey on pests “poisoned” with neem oil are not at any significant risks themselves.
But, improper application of topical neem products, such as neem leaf shines or foliar sprays, can be harmful to beneficial insects such as:
- Parasitic wasps
… if they come into direct contact with the neem oil.
Is Neem Effective? – A Footnote on How Neem Kills Pests
When discussing what pests neem oil kills, it’s important to point out how neem oil kills.
Individuals often complain about the effectiveness of neem oil.
Many times these users have not applied neem correctly or are fighting an infestation that has all but killed their plant.
Neem isn’t an overnight solution. Depending on the type of oil used, it works in two different ways: internally and externally.
Internal Neem Treatment
100% percent cold-pressed raw neem is present in both neem cakes and as pure oil.
The oil is harmless to earthworms and beneficial insects such as honeybees.
It can kill grubs and other ground-based pests and any insect feeding on the plant through chewing or piercing.
Raw neem doesn’t kill the pest immediately. Instead, it works as an insect growth regulators. Neem mimics natural insect hormones that regulate hunger, growth stages, and reproduction.
This causes a population to starve or die due to an inability to produce offspring or react to the adult stage.
External Neem Treatment
Due to the limited amount of Azadirachtin present, topical applications use clarified neem oil spray.
Direct application of the oil as a foliar spray on pests can cause their airways to become clogged, suffocating them.
It’s most effective against soft-bodied insects – aphid, mealybug, and plant scale. It can also kill beetles, stinkbugs, and other armored species.
This form of neem oil dissipates fast, leaving behind no residue.
As a result, it is important to use it when beneficial insects are least active. This allows neem to kill garden pests without harming your plant’s allies.
Patience is Essential
Because it’s all-natural, insects haven’t developed a resistance to neem oil.
But, always remember – neem kills over time. It may take up to two weeks before your infestation shows visible signs of diminishing.
Its continued effectiveness makes neem oil a better alternative to fast but easily adapted to synthetic pesticides. Use neem oil as a preventative to stop insect pest infestations before they begin.