Caterpillars can be a big problem for organic gardeners. Depending upon the type of caterpillar, they can destroy ornamental plants, vegetables, and even shrubs and trees.
While it’s possible to knock caterpillars out with pesticides, the problem is, you also knock out beneficial insects. You run the risk of killing butterfly caterpillars along with destructive moth caterpillars.
In this article, we discuss the use of organic Neem Oil insecticide and several other natural methods to control and kill caterpillars.
How Effective Is Neem Oil For Caterpillar Control?
There are a number of available natural pesticide products containing Neem Oil. It may seem strange to think of this natural product as a pesticide. The fact is, Neem seeds contain a natural insecticidal ingredient known as Azadirachtin.
There are also money-saving neem concentrates you mix with water to create a thrifty, effective, natural spray.
Always read the label.
Used correctly, Neem Oil can be quite effective against caterpillars as part of a comprehensive pest management plan.
It is one of several natural ways to control pest insects in your garden. Here are a few ideas for using Neem oil to control and kill caterpillars.
#1 – Spray When The Sun Is Down
When using a natural Neem Oil pesticide, remember to spray at sunset. This helps avoid impacting beneficial insects, such as bees and butterflies.
Spraying after the sun goes down is also desirable because moisture on the leaves can magnify the rays of the sun and cause burned spots on delicate leaves.
#2 – Know Your Adversaries and Your Allies
Always keep in mind that whenever you spray anything in your garden, the spray impacts more than your target pest.
In some cases, this is good.
For example, Neem Oil sprays can be effective against spider mites, aphids and pest caterpillars. Take care to know the habits and habitats of your beneficial insects so that you can avoid killing them, too.
#3 – Apply The Product Thoroughly
When spraying Neem Oil to deal with caterpillars, be sure to coat the entire plant on tops and bottoms of the leaves and all along the stems.
Spray the surface of the soil for about a foot all the way around the plant to stop caterpillars from climbing up.
Make Your Own Neem Oil Spray or Drench
You can make a Neem Oil soil drench to kill off ground dwelling caterpillars and grubs. This recipe will work used both as a spray and as a soil drench:
Caterpillar Killing Simple Neem Oil Solution
This solution smothers caterpillars and other insects.
- 2 ounces of cold pressed Neem Oil
- One gallon of warm water
Mix this up and spray it in the evening while the solution is still warm. Try to use it all up in one go. If you want to reuse the solution, you may need to set the container in a warm place (not directly in the sun). Shake it up to distribute the oil evenly throughout the warm water.
Add a few drops of mild dish soap or Dr. Bronner’s liquid castile soap to act as a surfactant to help evenly distribute the oil through the water. In any event, shake the solution well before using it.
Related: Controlling Saddleback Caterpillars
Neem Oil: One Tool In Your Toolkit
Although Neem Oil is effective, it’s important to remember that it’s just one tool in your toolbox, as illustrated by the experience of the presenters in the video below.
Even though they used a Neem Oil product as directed, it doesn’t seem that they had true success.
The problem may have been that they chose an ineffective product, and/or it may have been that they didn’t use the product frequently enough.
It is just as likely that the fact that they relied on a single product contributed to the lack of effectiveness. You are far more likely to have success using Neem Oil against caterpillars when combined with other types of natural pest treatments in a complete Integrated Pest Management (IPM) system.
Mix It Up!
Alternating the types of natural sprays you use can be a helpful technique.
Use your Neem Oil spray solution on a weekly basis and use a different product, such as this Chili Spray in between Neem Oil applications.
Here’s how you make it:
- 3.5 ounces of ground chilies
- Half a gallon of boiling water
Add the chilies to the boiling water and allow the mixture to boil (covered) for five minutes. You’ll need to use a large pot to prevent the mixture boiling over. Be careful not to inhale the steam from the boiling solution.
When the five minutes is up, turn off the heat and allow the mixture to cool for (at least) several minutes. While it is cooling, mix together half a gallon of cold water and a few drops of mild dish soap or Dr. Bronner’s liquid castile soap.
You can allow the chili mixture to cool completely.
If working with the mix while it is still warm, remove the lid from the pot carefully. Open the lid away from you so the steam will not rise into your face and eyes.
Carefully pour in the cold water mixture.
Pour the mixture through a strainer or cheesecloth into a gallon bottle for storage. Keep it in a cool, dark place. Decant as needed into a one-quart spray bottle.
Spray as you would the Neem Oil solution, but before spraying entire plants, test a few leaves to make sure the solution will not damage your plants.
Wait a full day to be sure there will be no negative impact. Spray the solution as needed (even daily) in the evening.
Alternate Products To Suit The Season
For the greatest effectiveness against small caterpillars, early in the growing season, look for a spray that contains Bacillus thuringiensis var. kurstaki (Bt). This natural bacteria is deadly to very young caterpillars but does not affect other insects.
Remember not to spray this product on plants frequented by butterflies because it will kill butterfly caterpillars just as effectively as moth caterpillars.
Reapply Products After Rain
Remember that all of these sprays will be washed off by rain, so always reapply any solution you are using after a good rain.