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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

<a title="View user profile." href="/author/editors">The Editors</a> Wed, 05/23/2018 - 14:19

It has been suggested that pyrethrum (made from chyrsanthemums) could be effective on catnip.

 <span>Kathleen O Ben…</span> Sun, 05/20/2018 - 08:23
I have been struggling with aphids in my kitchen primarily for a long time. Brought in on some flowers they seem to be around my windows. I have no house plants so they seem to be living independent from that. I've tried the soap and water thing but to no avail. They are many in number and are now moving to other windows in my home. Help!
<span>Chevette Girl</span> Mon, 05/21/2018 - 12:23
If you think you have aphids hiding out in your house somewhere, try dusting what you think to be the affected areas with diatomaceous earth (which is totally pet-safe and should make a border the aphids can't cross without dying) or spraying the affected areas every few days with a neem oil solution if you can get it and don't mind the smell.
<span>Shiralee Calway</span> Sun, 05/20/2018 - 05:15
Hi I have a very large tree in my back garden and it is full of aphids , never hard this before you can't sit outside without them crawling all over you how can I get rid of them please help me they are driving me mad , they are all over the paving and my outdoor setting they are everywhere help
<span>Carolyn</span> Mon, 05/14/2018 - 17:32
I'm a new gardener and am struggling to get rid of the aphids. My kale and other leafy green veggies have had a very bad infestation. Do I need to throw away the soil? Also, though I have treated the kale, it's no longer really growing even though it's still green and edible. Do I need to get rid of the affected plants if their growth is stunted?
<span>Chevette Girl</span> Mon, 05/21/2018 - 12:36
I've tried the dish soap and neem oil tricks but what I'm finding is that regular attention is the biggest key, one or two aphid mudering sprees don't do it. I have a spray bottle of soapy water and a spray bottle of clean water and what I'm finding pretty helpful for keeping aphid populations on my seedlings and my outdoor-become-indoor plants is a few days of spraying the plants down daily with soapy water and gently going over the leaves and stems with the fingers on my non-spraybottle hand to make sure I loosen them up and coat undersides of leaves with soapy water, wait five minutes, then use the clean water spray to wash the soapy water (and most of the aphids) off. I do this every day till I'm seeing no aphids (usually about 4 days) then I do it a few more times every other day or so just in case there are hatchlings I can't see. My potted perpetual spinach ended up with curly deformed leaves when I left the soapy water on, and the new growth on beet greens in my bunny's indoor garden have not deformed since I've started rinsing the soap off, just make sure the soap gets a good few minutes to suffocate your aphids. For a really bad infestation, I soak the heck out of the soil too with my soapy water, to make sure any of the little buggers hiding down there also get dead. I've used this method for other kinds of pests and never had problems with just leaving mildly soapy water in any plant's soil (just enough to make suds) but if you're concerned, you can also rinse the soil after letting it be soapy for half an hour or so. I found aphids on my pepper, eggplant and cabbage seedlings last week just as I was starting to put them outisde to harden off, so I've been giving them their bath and rinse and allowing them to dry before I put them outside to play. So far so good, every time I soap them up, there are fewer and fewer aphids. I'm a bit hesitant to use neem oil on my seedlings while I'm hardening them off (I'm also unsure how safe it is to use around my rabbit, googling it gave me conflicting information) but if the aphids are still a problem by the time I take the seedlings to the garden I will neem oil them once they're established in the garden. Hope that helps!
<span>Marilyn</span> Mon, 05/14/2018 - 16:12
or it will clog up everything in your sprayer...been there, cussed that!
<span>Susan Dunn</span> Mon, 05/14/2018 - 15:45
YES, just save your banana peels, cut them into a few pieces, and place the peels, outside peel side UP, beneath your roses or any other plants that get aphids. The outside banana peel gives off some kind of a gas that will make your aphids get lost. I have used this for a few years and now I never have aphid troubles. And the tree next door to us is an aphid nursery. So we are really lucky with this banana trick. No pesticides, sprays or anything else needed. But you need to eat your bananas regularly.
<span>Wendy Collinson</span> Tue, 01/23/2018 - 10:29
Do aphids start multiplying in the soil? Is it best to change the soil that the plants attacked by aphids, are growing in, to successfully get rid of them ?
<a title="View user profile." href="/author/editors">The Editors</a> Tue, 04/17/2018 - 11:48

Most aphids live on or under the leaves of plants, but grey-white root aphids live in the soil. We highly recommend that you plant something that will repel the aphids next to the crops that have been infested. Marigold, catnip, and dill will all do the trick.