One of the most common plant pests you’ve probably never heard of is thrips. Thrips can be every bit as destructive as aphids infestations or mealybugs.
Thrips are tiny, elongated insects that feed off of plant sap and comprise over 6,000 different species worldwide.
Adults measure only 1/25” inch and can be black, brown, or yellow, while the nymphs are most often pale green or yellow.
These pests inject their eggs into a plant and, despite a life cycle of only 45 days, can have as many as 15 generations living together in a single growing season.
Even worse, thrips will take up residence in flowers and under leaves or bark and overwinter underground.
Thrips can do a lot of damage, stunting growth or causing deformity in plants, as well as discoloration and killing blooms. Produce may fail to mature, rendering them inedible.
But how can you get rid of them without resorting to harsh chemicals?
Will neem, the garden go-to, be effective against these nasty pests? Read on to find out.
Can You Use Neem Oil to Get Rid of Thrips?
The good news is that Neem oil can indeed kill thrips.
The bad news is you might have to use a little extra caution since the thrips will infest flowers such as azaleas and rhododendrons.
What Neem Oil Does
Neem oil is the natural extract of Azadirachta indica, produced by cold-pressing parts of the plant, especially the leaves and seeds.
Raw neem oil contains five insecticidal chemicals, chief of which is Azadirachtin.
Azadirachtin has a chemical composition similar to insect hormones and damages when ingested through several possible effects.
It can prevent nymphs from reaching the next instar, effectively causing them to die without ever achieving adulthood.
In adults, it can cause infertility, and in many species, it will also cause a loss of appetite, which results in the insect starving itself.
When the Azadirachtin is removed for use in commercial pesticides, the resulting clarified hydrophobic neem oil turns into a topical killer.
These forms of neem insecticidal soaps clogs the airways of insects it comes in contact with, causing them to suffocate.
The Risks of Treating Flower Blooms
There are three common methods for using neem:
- Foliar sprays
- Soil soaks
- Neem cakes
The most popular of these methods is the foliar spray, but it does have a major drawback on outdoor plants.
Because neem oil can kill beneficial insects, including bees and ladybugs, you have to spray at dusk or dawn when these garden friends are least active.
Additionally, it’s usually advised to avoid spraying blooms to reduce the risk of harming bees, and you can’t spray near beehives.
Related: Is Neem Safe For Use Around Bees?
As a result, try to only use the foliar spray indoors when fighting thrips, allowing you to safely treat the flowers as well as the rest of the plant.
Neem Foliar Sprays
As mentioned, neem foliar sprays are the most popular method of using neem, although they’re the least efficient.
You must coat the entire plant for the spray to work, including the undersides of leaves and any cracks or crevasses.
Generally, you’ll also want to avoid spraying the blooms on flowering plants.
However, for indoor plants and vegetable gardens or plants not currently in bloom, this can be a useful method of attack.
Blend 1 teaspoon of Dawn dish soap or pure castile soap into a gallon of water to make an emulsion.
Mix in 2 tablespoons of clarified hydrophobic neem oil (recommend 1% percent for most infestations or 2% percent for heavy infestations) and pour into a spray bottle.
Spray the entire plant at dusk or dawn, getting every little crack.
The neem will dissipate without leaving residue in about 45 minutes to an hour.
Note that it may last a little longer in the crevasses or deep between the petals on thick blooms such as roses, so try to avoid spraying the blossoms when outdoors.
You will need to repeat the treatment every other day for 14 days or until the infestation is gone.
Reapply every two weeks as a preventative.
Neem Soil Soaks
Less popular but far more effective is the Neem soil soak, or drench.
This has a similar recipe to the foliar spray. Only use 100% percent cold-pressed raw neem oil instead of the clarified.
Depending on the size of the plant, you will need to pour 2 to 3 cups directly on the soil around the roots, being sure to cover a radius.
For large plants, such as trees, you might need to use the whole gallon to cover the root radius properly.
We usually recommend this method because it’s far easier to use on larger plants, won’t harm beneficial insects, and lasts far longer.
The neem will kill harmful ground pests such as grubs without harming earthworms.
When the roots absorb the Azadirachtin, it becomes a systemic insecticide, only harming insects that bite or pierce the plant’s skin.
In addition, it will even help fight some fungal and bacterial infections, including root rot.
The Azadirachtin remains potent for up to 22 days, so reapply every 2 to 3 weeks to keep your plants healthy and protected.
The least commonly used neem cakes are the solids left over from extracting neem oil.
They’re used primarily as a fertilizer and contain trace amounts of neem.
Following the directions on the package, you can use neem cakes to protect the soil from overwintering thrips, as well as feeding your plants. Neem cakes are also effective against lawn grubs and other ground-based pests year-round.