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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>Colleen Vanniel</span> Tue, 05/16/2017 - 15:33
Planting Marigolds will take care of aphids. We have a 10 x 16 "Rose Garden" that has approximately 8 - 10 plants that keep them at bay. We plant them at each corner and one on each side. Sometimes I place a few among the plants to make sure they are protected. And.... Geraniums in containers at each door (larger spaces, i.e. garage door and slider) I may have additional pots for wider openings. Since we started this we have had no (I repeat NO flies in the house!!! My husband - a biologist - thinks it is the leaves and not the blooms. Sometimes the garage door is open for hours. We do not use any harmful chemicals on the lawn and garden so our beautiful little Maltese has the run of the yard!
<span>Stephan R</span> Tue, 05/16/2017 - 15:16
I'm in Johannesburg, South Africa. What can I use on these trees ?
<span>Ned Quick</span> Sat, 06/03/2017 - 19:52
Wetable sulphur, neem oil. Organic materials. If you are badly infested, it is a lot of work to stay organic. Bad infestations, I use malathion, but the bees do not like it. Nor do humans. With any insect problem, you need to repeat many times to stop the reproductive cycle. Be steadfast, and re apply after much rain. University of California Davis is an ag school and publishes on the web. My Hawaii farm has your same troubles. Repeat applications to stop the reproductive cycle. Also spray the ground around the trees. Then the critters do not have a home anymore. Good luck
<span>Vickie Morgan</span> Fri, 10/06/2017 - 11:49
There is a GREAT!! Product, that I never see mentioned on any site, that is considered to be, and can be used as organic! It's made from the Chrysanthemum Daisy flower. Its called, "Hi Yield Garden, Pets, and and Livestock Dust", and I swear by it!! It knocked out my aphids AND the fungus gnats in my potted indoor pepper plants!? Totally! To control aphids, spray plants well, with water stream to knock them off. Then, I sprinkled on soil AND plant leaves both, and started bottom watering too. Before applying dust, I also watered potted plants with peroxide (5 percent), and water, as a soil soak to kill any larvae in soil, first.( One part peroxide to 4parts water.) Reapply dust every few days and carefully follow directions, AND read ENTIRE label BEFORE using! Take precautions as some people could be allergic or have breathing problems like asthma! Always wear dust mask! Reapply until you haven't seen your target pest(s) for 2 weeks or so. Yes. It is used on pets, and Livestock to control flies, fleas, etc. It's THAT safe! And it works! Please try, esp. if you want to stay organic! Check label if you buy a diff. brand of a pyrethrum based product, as it may contain butoxyl, which is NOT organic and unsafe! Hope this helps someone else. Good luck!
<span>Kandy Kisses</span> Sat, 12/16/2017 - 12:48
did you snort this dust? it clearly says on all high yield products that they are insecticide and not flower products..and they kill bees, which we are losing too quickly as it is!
<span>Mark</span> Tue, 05/16/2017 - 13:27
Over the last couple years, I've had aphids wipe out these flourishing crops. Once they get started, there is no stopping them. Insecticidal soap, neem oil, hand picking, shop vacuum and blowing them off with the hose only delays the inevitable. I prune off the most invested leaves but I cannot stop them. By mid-season I have to pull the plants. I will try flour dusting and adding alcohol to the soap solution but I'm skeptical. Is there some way to stop them before they get started?
<a title="View user profile." href="/author/editors">The Editors</a> Tue, 05/16/2017 - 15:40

How frustrating! Have you tried to attract beneficials to your garden? These may help to keep the populations down a bit. Try planting some flowering groundcovers around the perimeter of the garden and order some beneficials such as lady beetles and release them in the area. Silver-colored reflective mulch helps to repel aphids, and using row covers early in the season helps to protect seedlings. Good luck!

 <span>Magia Santo</span> Wed, 05/24/2017 - 20:07
The *easiest* thing to do is grow a bait plant or plants that will draw aphids out of your valuable crop. Depending on the size of your grow, either line the perimeter of your garden with the bait plants or keep one or two in the corner of your growing area. I don't know what you're using as far ar fertilizer and/or additives but I don't use ANY nitrates in my garden. Still, feed your bait plants with Blood Meal: they'll grow really tall, really fast yet have really thin cell walls (sending off infrared struts to insects). I also root drench and foliar with chitin found in crab and shrimp shell. Doing this could prevent insects all together, Chitin provides a bulletproof vest for your plants, you'll definitely notice...so will the bugs, they'll be on the hunt for an easier meal (infrared). They'll head straight for the bait plant(s) and leave the rest of the crop alone. Seriously.
<span>Peggyc</span> Tue, 05/16/2017 - 13:10
The soapy mixture with hot sauce plus some salad oil (spray adheres to plants) also works not only for aphid, but as a deer repellant. North Carolina US
<span>Karen Horne</span> Tue, 02/21/2017 - 17:11
For the first time, in early January I found black aphids all over a small area of garlic. I fought with insecticidal soap and eventually that plus snow seemed to stop them. But they have now moved to a larger bed and are covering the garlic there. Insecticidal soap hasn't touched them there. I've switched to Neem oil but it doesn't seem to be slowing them down. I'm thinking of adding alcohol to the Neem and water to try that but am running out of options. Any other thoughts?