How to Make Homemade Sprays for Fighting Aphids

Aphid and larvae on a rosebud

The Spruce

Project Overview
  • Working Time: 30 mins - 1 hr
  • Total Time: 1 - 2 days
  • Skill Level: Kid-friendly
  • Estimated Cost: $5

Homemade remedies for pesky insects are a longstanding tradition among organic gardeners, who have had to be creative in finding ways to battle insects and diseases without the help of synthetic chemicals. In the case of fighting aphids, or plant lice, two homemade sprays have proven very effective: tomato leaf spray or garlic oil spray. While knowing how to make and use them is important, it's equally important to understand why they work.

Tip

Before you try anything else, try simply rinsing the aphids off the leaves of affected plants. Don't use a pressure washer, just a garden hose and nozzle with enough pressure to knock the aphids off the plants without damaging the foliage. If the infestation is small, you can just wipe the aphids away with a wet cloth.

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Click Play to Learn How to Make a Homemade Spray for Aphids

What You'll Need

Equipment / Tools

  • Bowl or bucket
  • Knife
  • Strainer or cheesecloth
  • Spray bottle
  • Glass or plastic jar with lid
  • Measuring spoons

Materials

  • Fresh tomato leaves
  • Water
  • Garlic cloves
  • Mineral oil
  • Dishwashing liquid

Instructions

Tip

Before applying either of the mixtures below, be sure the insects you are fighting are indeed aphids. They have pear-shaped bodies, are generally about 1/16 to 1/8 inch in diameter, and can sometimes have a furry appearance. They can be a variety of colors including brown, black, red, yellow, or green and if you get up really close, you will be able to see tube-like structures at the end of their abdomens. These are called cornicles.

Tomato Leaf Spray

Tomato plants, members of the nightshade family, contain toxic compounds called alkaloids in their leaves. When the leaves of tomato plants are chopped, the alkaloids are released. By suspending the alkaloids in water, they make an easy-to-use spray that is toxic to aphids, but still safe around plants and humans.

  1. Chop and Soak Leaves

    To make tomato leaf spray, simply chop enough tomato leaves to make one or two cups and combine with two cups of water in a large bowl or bucket. Let the solution steep overnight.

  2. Strain and Place in Spray Bottle

    Strain out the leaves using cheesecloth or a fine strainer. Add an additional cup of water and pour into a spray bottle. Be sure to label the bottle.

  3. Use

    To use the mixture, spray the stems and foliage of the infested plant and pay particular attention to the undersides of leaves since that is where aphids most commonly congregate.

Illustration on homemade sprays for fighting aphids
The Spruce

Garlic Oil Spray

Organic gardeners have long relied on garlic as part of their pest-fighting arsenal. Garlic contains sulfur, which, besides being harmful to pests, is also an antibacterial and antifungal agent. The dish soap in this mixture also breaks down the bodies of soft-bodied pests like aphids.

  1. Chop and Steep Garlic

    To make garlic oil spray, finely chop three to four cloves of garlic. Place in a small bowl, and add two teaspoons of mineral oil. Let this mixture sit for 24 hours.

  2. Strain and Place in Container

    Pour two cups of water into a glass or plastic bottle. Use a strainer to remove the garlic pieces and add the remaining liquid to the water. Add one teaspoon of dishwashing liquid. Label the container.

    This mixture can be stored and diluted as needed. Add to a spray bottle before using.

  3. Use

    Before using this spray on the entire plant, test it by spraying an inconspicuous part of the plant. If there are no signs of yellowing or other leaf damage after a day or two, it is safe to use. If there is leaf damage, dilute the mixture with more water and try the test again. Once you have determined that it will not harm your plant, spray the entire plant, paying particular attention to the undersides of leaves.

    Warning

    Garlic oil can be harmful to beneficial insects such as ladybugs, which are natural predators of aphids. It is best to keep as many beneficial insects around as possible. This spray should only be used if you have not seen any beneficial bugs in your garden. Otherwise, you should use the tomato leaf recipe, which will not harm beneficial bugs.

    Other Natural Methods

    • Try to attract beneficial insects like ladybugs, lacewings, parasitic wasps, or damsel bugs to your garden with plant selections. They will attack the aphids. Plant mint, fennel, dill, yarrow, and dandelions to attract these beneficial predators to your garden.
    • Avoid over-fertilizing in the garden. Too much nitrogen encourages lots of new, tender growth that aphids love.
    • Cut an aluminum pie plate to fit around the base of the plant. The reflected ultraviolet rays from the sun's light cause the aphids to move away from the plant.
Article Sources
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  1. Integrated Pest Management for Aphids. Clemson University Extension Service.

  2.  Pomilio, Alicia B., et al. Toxic Chemical Compounds of the Solanaceae. Natural Product Communications, 2008, doi:10.1177/1934578X0800300420

  3. “A Review of Bioinsecticidal Activity of Solanaceae Alkaloids.” Toxins 8, no. 3 (March 1, 2016): 60. https://doi.org/10.3390/toxins8030060.

  4. Omar, SH., Al-Wabel, NA. Organosulfur Compounds and Possible Mechanism of Garlic in CancerSaudi Pharmaceutical Journal, 18,1,51-58, 2010, doi:10.1016/j.jsps.2009.12.007

  5. Almanac, Old Farmer’s. “Aphids.” Accessed August 17, 2021. https://www.almanac.com/pest/aphids.

  6. Encouraging Beneficial Insects in Your Garden. Oregon State University.

  7. Reflective Mulches Foil Insects. University of California, Agriculture and Natural Resources.