Organic Neem Oil For Insect Control. How It Works

One of the easiest, and most effective organic insect controls I’ve found is Neem oil. It provides a natural alternative to many chemical and synthetic insecticides and pesticides.

Neem oil is a vegetable oil pressed from the fruits and seeds of the neem or Azadirachta, a mahogany tree which is native to India and areas in the tropics. It is an important part of the commercially available products of neem for organic insect control.

The active ingredient in neem oil is Azadirachtin, and is known to affect over 200 species of insects.  Neem oil also finds wide usage as a biopesticide for organic farming, as it repels a wide variety of pests.

It is effective on mealy bug, armyworm, aphids, thrips, whiteflies, mites, fungus gnats, beetles, moth larvae, mushroom flies, leafminers, caterpillars, locust, nematodes and the Japanese beetle.

The Neem Tree and Uses

The Neem tree, also known as Indian lilac or margosa, probably originated in India or Burma. Neem is a large, fast-growing mahogany evergreen that can reach approximately 40 to 80 feet in height. The tree is drought resistant and heat tolerant, and may live up to 200 years.  Neem oil, which is extracted from the tree’s seeds, has been used for its medicinal and insecticidal properties for more than 2,000 years.

Neem has been shown to ward off flies and mosquitoes, aiding in control of the spread of diseases such as malaria. Neem leaves placed in the pockets of woolen clothing are said to fend off moths.  It’s also added to stored grains to help keep insects out.

Components of neem oil can be found in many products today. These include toothpaste, cosmetics, soaps, and pet shampoos. Neem products do not provide absolute insect control, but  applications can reduce pest populations dramatically by repelling them and inhibiting their larval development, growth, fertility, mating and egg laying.

A solution of neem oil  has anti fungal properties as well as the oil coats the plant’s surface and prevents the germination of fungal spores.  Neem oil and some of its components are used in over 100 pesticide products. They are applied to a wide variety of crops and ornamental plants for insect control.

Neem oil can be formulated into granules, dust or concentrates.  It reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs.

Neem oil is not known to be harmful to mammals, birds, earthworms or beneficial insects such as butterflies, honeybees and ladybugs if it is not concentrated directly into their area of habitat or on their food source. It can be used as a household pesticide for ant, bedbug, cockroach, housefly, sand fly, snail, termite and mosquitoes both as repellent and larvicide.

Neem oil also controls black spot, powdery mildew, anthracnose and rust fungus.  But neem oil is also a systemic insecticide. That means you can pour it on the soil or plant leaves and it is absorbed. It also serves as an anti-feedant, which means simply spray it on and bugs stop eating!

The main thing Neem does is functions as a hormone disruptor in the insect’s body. When neem is used a caterpillar becomes a non-hungry caterpillar. Instead of being able to become a moth, lay more eggs and damage your garden forever.

Neem functions in many ways, but it kills most small soft-bodied insects and mites directly, serves as a fungicide, kills plant parasitic nematodes but is compatible with beneficial nematodes, kills algae and mosses, is not harmful to bees or earthworms. It is a broad spectrum insecticide, miticide and fungicide, and controls numerous diseases as well as insects and mites.

Lowes Neem OilGarden Safe 16-oz Neem Oil Extract Liquid. Lowes Item 86891. Model # HG-93179

Fungusrust, leaf spot, anthracnose, scab, black spot, downy mildew, botrytis, needle rust and flower, twig and tip blight, alternaria, powdery mildew

Insectsaphids, spider mites, scale, whiteflies, beetles, leafrollers, other insects

Price –  About $10.00 for 16 ounce liquid bottle

Need Oil solutions should never be applied to plants during hot weather, above 85 degrees or in direct sunlight. To prevent burning of leaves, plants should be shaded if possible until the application is dry. Horticultural oils, including neem, can also affect bees if it contacts them — once the spray has dried it is no longer harmful.  However, it does not work for all insect species.

The neem ingredients accumulate in the tissues deep inside the plant.  A tiny aphid usually feeds from the outer part of the plant, so it can not eat deep enough to get to the neem. But leaf hoppers, grass hoppers or similar chewing insects will be affected quickly.

Other Considerations
Most growers like to see insect pests drop dead right away. Although pesticides usually provide that instant gratification, their use contributes to the buildup of toxins in the environment and can affect beneficial insects. In addition, these chemicals are responsible for the accidental poisoning of humans, pets, livestock and wildlife populations.

For ecologically friendly pest management, neem is nontoxic to humans, animals and beneficial insects. It is biodegradable, does not build up resistance in pests and at around $10 for a 16 ounce bottle, is relatively inexpensive. For safety and health reasons alone, controls such as this may be the only option for indoor growers or those whose plants are in or very close to their living area.

What happens to Neem oil in the environment?

Azadirachtin, is rapidly broken down. Microbes and light break down the pesticide in soil, water and on plants. The half-life of azadirachtin in soil ranges from 3 – 44 days.  It also rapidly breaks down on plant leaves. The remaining components of neem oil are broken down by microbes in most soil and water environments.

Can Neem oil affect birds, fish, or other wildlife?

Neem oil is practically non-toxic to birds, mammals, bees and plants. Neem oil is slightly toxic to fish and other aquatic organisms. Azadirachtin, is moderately toxic to fish and other aquatic animals. It is important to remember that insects must eat the treated plant to be killed. Therefore, bees and other pollinators are not likely to be harmed.

With today’s push for more organic gardening in the home garden, it can be hard to balance natural cures for common problems and still getting a pretty display or a good harvest. While most organic pesticides are not as effective as their chemical counterparts, there is one exception, and this is neem oil. Neem oil can not only effectively control the insects and pests on your plants but it can also eliminate many fungus problems as well.

Neem oil is normally applied as a spray to the leaves of the plant. While neem oil is a good insecticide, there are some things to keep in mind when using it.  First, some plants can be killed by neem oil, especially if it is applied heavily. Before spraying a whole plant, spray a leaf on the plant and wait 24 hours to check to see if the leaf has any damage.

Neem oil should not be applied to a plant in direct sun. If the plant you want to treat is in full sun, apply the neem oil spray in the evening so that it has time to be absorbed overnight.  Also, do not apply Neem oil to plants that are stressed by drought or over watering.

How does neem oil work?

Azadirachtin, the most active,  reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Azadirachtin can also repel and reduce the feeding of nematodes. Basically, neem oil kills insects by slowing down or stopping their ability to feed.

Apply your neem oil insecticide about once a week to kill pests and keep them away. Apply like you would other oil based sprays in making sure that the leaves of the plant are coated, especially where the pest problem is the worst.  Use a neem oil solution on trees, shrubs, ornamentals and flowers. As far as I can tell, slightly higher concentrations (up to 10%) of neem oil are effective as an insect repellent too.

I think this explains why some  insects are not affected or repelled by low concentrations recommended for pest control.  It biodegrades quickly so it’s a good choice for using in and around the home.

Natural pest control is less expensive than buying and applying pesticides, and it’s safer for your garden, your family, the natural wildlife and the environment. Remember that a lot pest damage is natural.

Maintain an educated eye toward the garden and the ability to identify the pest problems and then decide what natural pest damage to allow before initiating any chemical or organic controls.  Neem oil is a great pest control method that places emphasis on prevention and organic solutions.

By Victoria Stone