How to Make a 'White Oil' Smothering Oil Insect Garden DIY Spray: Perfect for Insect Eggs and Soft Bodied Insects

Smothering oil sprays have been used in gardens for centuries. The fine coat of oil covers eggs and soft bodied insects. The oil blocks the movement oxygen, and the eggs or insects basically suffocate. The oil is the main ingredient but the soap can also damage the eggs and insects, however, it is primarily being used to disperse the oil throughout the water. Without soap, the oil just floats, and you can't evenly coat eggs, insects, and leaves. 

Please follow my blog, as I will be doing an entire series on DIY sprays for pests and diseases. A 'soapy water' spray article is coming soon and that is used for damaging soft bodied and hard bodied insects by using more soap or stronger soaps in the spray. Different plants and insects can require different sprays.

How to Make Smothering Oil Insect Spray

Rather than lugging out vegetable oil, soap, and measuring spoons every time you want to make this spray, make a jar full of  'white oil'.  This is how you can make a concentrate of oil and soap and use it as you wash to make as little or as much of the spray as needed. Sometimes you need a quart and sometimes you need a gallon. 

It is really important to understand that the terms soap, detergents, and degreasers are used interchangeably and the ingredients for hand soaps, dish soaps, and dish detergents are hard to easily identify. The bottom line is some soaps are pure and mild and other soap are harsh and loaded with degreasers. In theory, they can all be used but you want to use less of the harsher soaps and detergents in your oil mix.

 

Soap Selection

Pure Soap: like castile types (no added ingredients).

This is the safest soap you can use and I use it a lot in my garden. I am not using it in this recipe. if I were, I would increase the amount of soap from 1/2 cup to 3/4 of a cup. Maybe even a full cup.

Mild/Strong Soaps: like very basic dish soaps with some added ingredients for grease. 

I am using Ivory as seen in the photo and video. I chose this, because this dish soap is often easier to get.

Harsh Soap: often called detergent soaps.

We commonly call them soap, but they are detergents for cleaning dishes and the often contain stronger degreasers as ingredients. They often come as concentrates in a bottle.  A little goes a long way for dishes but too much in sprays can damage plants.

I do recommend using something that falls into the first two soap groupings. I also recommend using the same type of soap every time you make the 'white oil".  The ratios I provide vary, when adding the mix to water. I give you a range, because of the above soap concerns, and it is best to start with the lower ratios when using this spray for the first time.

'White Oil" Smothering Insect Oil Spray

This is how you make a 3:1 ratio of oil to soap or 75%-25% 'white oil" spray. Ratios are made be using equal measures. I am using 1/2 cup as my measure. I find that makes plenty of smothering oil spray. The premade mix will last a year in the jar, if not longer.

Ingredients and Materials

Any Vegetable Oil

Soap 

Mason Jar or Repurposed Jar

Measuring Cup

Mix 1 and 1/2 cups of vegetable oil with 1/2 cup of soap in a jar. That is it. Shake well and also shake well each time you go to use it to make your spray. This is a base mix and other thing can be added to it as you wish.

I do recommend making a quart of this spray with 1or 2 teaspoon of the "white oil" and test spraying. Wait 48 hours and look for damage. If you don't see any damage, make a mix with 2 or 3 teaspoons of the oil, in a quart of water, and test spray again. If there is no damage, you have a mix that you can use in your garden. Here is my video from my YouTube channel that shows you how to make it.

Making the Actual Spray

2 to 3 teaspoons of the oil mix per quart of water

1.5 to 3 tablespoons of oil mix per gallon of water

Spraying Frequency

Maintenance and Prevention - Every 10-14 days

Only target plants that have had issues in the past. There is no need to spray every plant in your garden.

Outbreaks and Infestations - Every 3-5 days for 3 cycles

I would use this every 3 days for whiteflies and every 5 days for aphids. Each garden varies on the pests it gets.

Generally speaking, the best time to spray is in the morning or evening when temperatures are cooler. Spraying any spray on fully sunny days when temperatures are in the 90's, can lead to leaf damage even when you have been using the same spray for years.

Final word.... Yep... Test spray all new sprays you introduce to your garden.

"A Garden Wants to Give"

Cheers!

Gary (The Rusted Garden)

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