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How to Identify and Get Rid of Aphids on Plants

green aphids crawling on a plant

Aphids are pesky green bugs that can wreak havoc on your garden.

Image Credit:
Pixabay
Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

What are those little green bugs on your plants? They’re probably aphids! Here are our best tips for identifying and getting rid of aphids in your garden.

What Are Aphids?

Aphids seem to find their way into every garden. They are small, soft-bodied insects that feed by sucking the nutrient-rich liquids out of plants. In large numbers, they can weaken plants significantly, harming flowers and fruit. Aphids multiply quickly, so getting them under control before reproduction starts is important. Many generations can multiply in one season.

Lee Townsend, an Extension Entomologist at the University of Kentucky College of Agriculture, explains, “Infestations generally result from small numbers of winged aphids that fly to the plant and find it to be a suitable host. They deposit several wingless young on the most tender tissue before moving on to find a new plant. The immature aphids or nymphs that are left behind feed on plant sap and increase gradually in size. They mature in 7 to 10 days and then are ready to produce live young. Usually, all of them are females, and each is capable of producing 40 to 60 offspring. The process is repeated several times, resulting in a tremendous population explosions. Less than a dozen aphid “colonizers” can produce hundreds to thousands of aphids on a plant in a few weeks. Aphid numbers can build until conditions are so crowded, or the plant is so stressed, that winged forms are produced. These winged forms fly off in search of new hosts, and the process is repeated.”

The good news is that aphids tend to move rather slowly and, with diligent care, can be controlled.

Identification

Identifying Aphids

Aphids are tiny (adults are under 1/4 inch), and often nearly invisible to the naked eye. Various species can appear white, black, brown, gray, yellow, light green, or even pink. Some may have a waxy or woolly coating. They have pear-shaped bodies with long antennae; the nymphs (young aphids) look similar to the adults. Most species have two short tubes (called cornicles) projecting from their hind end.

Rose Aphid on a plant
A close-up view of a rose aphid.

Adults are usually wingless, but most species can develop a winged form when populations become crowded, so that when food quality suffers, the insects can travel to other plants, reproduce, and start a new colony. Aphids usually feed in large groups, although you might occasionally see them singly or in small numbers.

While aphids in general feed on a wide variety of plants, some species of aphids can be specific to certain plants—for example: bean aphids, cabbage aphids, potato aphids, green peach aphids, melon aphids, and woolly apple aphids.

dark brown aphids on a leaf with a hand holding it
Some aphids are darker colors, like brown. The potato aphid is a common brown aphid. 
Photo credit: GrowVeg.com.

What Does Aphid Damage Look Like?

Nymphs and adults feed on plant juices, attacking leaves, stems, buds, flowers, fruit, and/or roots, depending on the species. Most aphids especially like succulent new growth. Some, such as the green peach aphid, feed on a variety of plants, while others, such as the rosy apple aphid, focus on one or just a few plant hosts.

  • Look for misshapen, curling, stunted, or yellowing leaves. Be sure to check the undersides of leaves; aphids love to hide there.
  • If the leaves or stems are covered with a sticky substance, that is a sign that aphids may have been sipping sap. This “honeydew,” a sugary liquid produced by the insects as waste, can attract other insects, such as ants, which gather the substance for food. When feeding on trees, aphids’ honeydew can drop onto cars, outdoor furniture, driveways, and so on.
  • The honeydew can sometimes encourage a fungal growth called sooty mold, causing branches and leaves to appear black.
  • Flowers or fruit can become distorted or deformed due to feeding aphids.
  • Some aphid species cause galls to form on roots or leaves.
  • Aphids may transmit viruses between plants.
  • Aphids also attract other insects that prey on them, such as ladybugs.
yellow aphids on a plant leaf
Aphids can be various colors, including yellow, and produce a sticky honeydew substance. 
Photo Credit: John Obermeyer/Purdue University.

Still not sure? Use our Plant Problem ID tool to easily diagnose pests and diseases.

Control and Prevention

How to Get Rid of Aphids: Killing Aphids

  • Try spraying infested plants with a strong stream of water; sometimes, all aphids need is a blast to dislodge them. Typically, they are unable to find their way back to the same plant.
  • Neem oil, insecticidal soaps, and horticultural oils are effective against aphids, but these substances need to come into contact with the aphids in order to work. Be sure to follow the application instructions provided on the packaging.
  • You can often control aphids by wiping or spraying the leaves of the plant with a mild solution of water and a few drops of dish soap. Soapy water should be reapplied every 2-3 days for 2 weeks.
    • One variation of this soap-water mix includes cayenne pepper: Stir together 1 quart water, 1 tsp liquid dish soap, and a pinch of cayenne pepper. Do not dilute before spraying on plants.
  • Diatomaceous earth (DE) is a nontoxic, organic material that will dehydrate aphids.
    Warning: Do not apply DE when plants are in bloom, as it will kill pollinators such as bees and butterflies if they come into contact with it.
thumb over the end of a garden hose spraying water
Hosing down your plants is one way to control the aphid population in your garden.

How to Prevent Aphids

  • For fruit or shade trees, spray dormant horticultural oil to kill overwintering aphid eggs.
  • Beneficial insects, such as ladybugs, lacewings, and parasitic wasps, will feed on aphids. Attract these insects to your garden by providing an environment that features a range of flowers and foliage plants, as well as access to water. Supplemental populations of these insects can be ordered online and should help control the aphid populations from the start.
  • Companion planting can help keep aphids away from your plants in the first place, or can draw aphids away from the plants you want to grow. For example:
    • Aphids are repelled by catnip.
    • Aphids are especially attracted to mustard and nasturtium. Plant these near more valuable plants as traps for the aphids. The aphids will likely go for these plants before your prized tomatoes. (Check your trap plants regularly to keep aphid populations from jumping to your valued plants.)
    • Nasturtiums spoil the taste of fruit tree sap for aphids and will help keep aphids off of broccoli.
    • Garlic and chives repel aphids when planted near lettuce, peas, and rose bushes.
Ladybug larva
Ladybug larvae look scary, but they are one of the top aphid predators. If you see them on your plants, leave them be! 

Using Alcohol to Control Aphids

Isopropyl alcohol (also called isopropanol or rubbing alcohol) works fine and is easy to find, but be sure it doesn’t have additives. Ethanol (grain alcohol) seems to work best. Alcohol usually comes in 70 percent strength in stores (or 95 percent strength purchased commercially). To make an insecticidal alcohol solution, mix equal parts 70 percent alcohol and water (or, if using 95 percent alcohol, mix 1 part alcohol to 1 ½ parts water). 

You can also add alcohol to a soapy emulsion to make it more effective. For example, in a spray bottle, combine 5 cups water, 2 cups isopropyl alcohol, and 1 tablespoon liquid dish soap. 

These types of solutions should NOT be sprayed over the entire plant at once. Spray or wipe down only the infested areas. It will only kill the aphids it comes into contact with, so repeated applications may be necessary.

CAUTION: When applying an alcohol or soap spray, or a combination, always test on a small area of the plant first, and apply in the morning or evening, when the Sun is not as intense. Watch the plant for a few days for any adverse reactions before applying more. Plants can be sensitive to alcohol and dish soap. Also, some soaps have additives that can damage plants—select the purest form.

Check out this video to learn more about how to get rid of aphids:

Do you have more tips for controlling aphids? Let us know in the comments below!

Garden Pests

About The Author

Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann is the Executive Digital Editor of Almanac.com, the digital home of The Old Farmer’s Almanac. She leads digital editorial strategy and publishing across a wide range of Almanac sub...

Read more from Catherine Boeckmann

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Comments

<span>Pam</span> Tue, 06/21/2016 - 11:26
In the one home made bug spray, you listed 2 parts alchohol to 5 parts water then you switch from parts to 1 Tbsp. dish soap and didn't give an over all measurement. I gave this recip to my dad who place it in a approximately 1 litre. He sprayed it on his plants and they wilted and some died completely. When we rinsed the wilted ones to try to save them the water running off was sudsy, and a white layer on the soil. You might want to change the recipe to give the soap measurement in parts or the whole recipe in measurements.
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 06/22/2016 - 14:34

Oh, my goodness! We are so sorry to hear about your dad's plants! We have revised the formula to: 5 cups water, 2 cups alcohol, and 1 tablespoon liquid soap.
Whenever applying an alcohol or soap spray, or a combination, to plants, always test a small area first, and apply in morning or evening, when the sun is not beating down. Watch the plant for a few days for any adverse reactions before applying more. Plants can be sensitive to alcohol and soap. Also, some soaps have additives that plants may be sensitive to -- try to use the purest form. If still wary about trying -- dilute the formula first, watch your plants for a few days, and then work up to full strength gradually if the plants seem to be able to handle it.

 <span>Virginia Kropas</span> Sun, 05/29/2016 - 20:24
This summer, for the first time aphids on my viburnum. Yes, the new growth. My neighbor had asked for advice about his bushes then I checked mine. I pruned a lot of the new stems out and used hard spray. I'm going to try the recipes above. I have confidence in them and they won't hurt anyone else. Howis the nasturtium thing supposed to work??? The 2nd year I had them in my old yard they were black with aphids so the leaves weren't very appetizing to eat. Hmmm... the aphids are probably rich in protein! They showed up the next yr. so I don't grow 'em.
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 06/01/2016 - 12:47

The nasturtium will attract aphids AWAY from other plants. The idea is that you sacrifice the nasturtium—left the aphids collect there, then discard the plant, aphids and all.
 You don't want to eat the nasturtium flower when the plant is used in this fashion.

We hope this helps!

 <span>Brooke</span> Thu, 05/19/2016 - 19:04
I have a tree in my yard that is covered in wee aphids, clumped in every wad of new/shriveled leaf growth. I also have ladybug eggs all over the same tree, and quite a few ladybugs running around eating the aphids and mating. My concern is that the ratio of aphid to ladybug is at least quadruple, and even though each ladybug can eat up to 50 aphids a day, my tree and surrounding plants may die well before the ladybugs can ramp up. Should I be patient and wait for the ladybugs to do their thing? If I treat with the above, will it kill off the ladybugs as well?
<span>Bonnie Wulff</span> Sat, 05/07/2016 - 19:13
I've never had these before and they are everywhere. Please help before I lose all my flowers. Thank you.
<span>Kas</span> Thu, 04/07/2016 - 16:16
I started plants from seed, set them outside to get them hardened only 30 mins 1st day couple hrs 2nd day inside for a day, out couple hrs 4th day, and I find afids all over my kale. How did I get them in that length of time? KAS
<a title="View user profile." href="/author/editors">The Editors</a> Fri, 04/08/2016 - 12:08

This is one of the most vexing challenges for all gardeners—there seems to be an aphid type for almost eveyr plant! There is no one reason why aphids appear, indoors or outdoors. Soil with high levels of nitrogen are said to favor aphids; do not add to soil unless nec (do a soil test).

Vegetables are susceptible at seedling stage, so some sources recommend growing plants under (row) covers. Kale, being a cool season crop, is especially vulnerable.

If the plants do not survive...there is probably still time to buy seedlings (you did not say where you are).

Wish we had better news...

 <span>Cynthia Riley</span> Sun, 03/27/2016 - 16:13
Ever year they get invaded by whiteflies and aphids. What can I do to stop the invasion? What is best way to get rid of them?
<a title="View user profile." href="/author/editors">The Editors</a> Tue, 03/29/2016 - 12:59

Try washing the aphids off the plants with a strong spray of water from a hose, and repeat if they reappear. For more controls for aphids, please see article above.

For whiteflies, you might like to go to: http://www.almanac.com/content/whiteflies for suggestions. Some gardeners actually have had success using a hand-held vacuum cleaner to pick up the adult insects; morning is best, when the adults are sluggish. Place the vacuum bag in a plastic bag, seal, then freeze to kill the insects.