For daily wit & wisdom, get the Almanac newsletter.

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

More Like This

Comments

<span>Katie</span> Sun, 08/15/2021 - 17:24
I read that it's the azadirachtin in neem oil (only in cold pressed, not processed) that really works, but you have to treat early with a soil drench so the plant can take it up into the leaves and mess with the aphids' hormone receptors. The pure neem oil that I have solidifies at cold temperatures (basically below like 80, I think), and I'm wondering if it is possible to crumble up the solidified oil into pellets and add that to the soil in the spring before planting?
<span>Scott Lewis</span> Mon, 06/07/2021 - 09:09
I would like to know where the scientific studies are that demonstrate catnip, mint, or other Lamiaceae repel aphids. I read this some years ago and I have tested it thoroughly in my own garden and it does not appear to work. Against control plants, I tested a)growing tomatoes in a bed with mint; b)hanging mint from the tomato plants; c) spraying the plants with mint oil. In no case were the number of aphids statistically different from the controls.
<a title="View user profile." href="/author/editors">The Editors</a> Thu, 03/10/2022 - 11:13

Yes, there is scientific evidence that mint repels aphids. Refer to Common Sense Pest Control by William and Helga Olkowski and Shiela Daar, Rodales Encyclopedia of Organic Gardening, Cornell University. It is rather a long read. For catnip, I do know there's good evidence it does repel potato beetles. Here's one of many edu articles about catnip deterring aphids: https://aggie-horticulture.tamu.edu/galveston/weekly_Q&A/p&dc_5.htm 

 <span>Debra</span> Thu, 04/22/2021 - 14:47
Wanted to share my experiences with these awful (kinda cute) insects. My strawberry tree was almost killed by aphids last year as I had noticed too late. When I did notice, the tree’s leaves were black and shiny, many fell off, new leaves were stunted, curled and infested. Then I started to spray with a neem mixture until I saw ladybug larvae all over the tree. They procreated and soon I had about a dozen or more ladybugs working on the tree. So ladybugs do come but in my case, too late. This year, since aphids mostly come in the spring, I was on alert. When the strawberry tree started to grow new leaves, I went to work right away. The key is that you MUST start early. Once they multiply to the point where your plant is shiny with their sticky sweet stuff, and is visibly suffering, it’s too late. You can do what you can but you have to wash your plant (with a bit of dawn in the water to remove sticky aphid stuff), get rid of the ants that will come to farm, and solve your secondary problem of fungus and mold from the sugars. So what I am doing this year is every other day (you must be on it!) I take a gallon sprayer, fill it with water, add a bit of dish soap and a bit of fungicide (to be exact, Zerotol HC) I spray ALL the new leaf areas. Even if I do not see aphids. I check the older leaves as well. So far the plant is growing very good and new leaves are coming in strong. When the leaves are mature, I will slow down the application but for now, I’m out there EVERY OTHER DAY— not more than two days. I’m doing this with all my roses and redbud tree, beans and Swiss chard. Also- Garlic Barrier works ok for aphids but it smells SO strong and the smell will stay in your gallon sprayer. You also must apply frequently. It ruins edible plant taste so don’t spray garlic on Swiss chard for example. Recommending the water, soap, fungicide route. Hope this helps some. Aphids may be easy to kill, but their strength is in numbers and rate of procreation!! Good luck in your war!
<span>Paula Cain Lerner</span> Fri, 08/02/2024 - 13:44
How much fungicide ? Please.
<span>A Rockwell</span> Wed, 04/21/2021 - 10:45
Monarchs are attracted to Milkwed for Pollen + as a place to lay the monarch caterpillar eggs; she lays the egg on the underside Milkweed leaf; the caterpillars hatch to eat Milkweek; Milkweed leaves are the best known food for Monarch Butterflies + young; I found moisture contributes to Aphids; if I grow Milkweed in a dry environment or garden; I get less aphids; Milkweed like a natural dry meadow type environment; back yard full sun; I read;
<span>Tom Chase</span> Wed, 04/21/2021 - 09:52
This is for Submitted by sdek on June 13, 2020 - 9:03pm Contrary to what you posted, Monarchs are NOT attracted to aphids on milkweed and seek aphids instead of the plant.. Milkweed is Monarch food source and seek the milkweed. The feet of the Monarch has plant sensors and when landing on a plant it knows if it's milkweed or not. The female lays it's eggs on the underside of the leaves, not on aphids. The feet have two forked "toes" that are like spikes and attach to anything, even your skin. It's hard to lift them off and care should be taken not to jerk them to release, the feet can be damaged. Wish you had more knowledge about Monarchs. I've photographed, gave lectures to Audubons, school kids in NE for over 20 years. I cane tell what a Monarch is doing in their life cycle from the mating, egg laying, hatching, development and feeding. All aspects, so I know aphids don't attract Monarchs. I've seen Milkweed loaded with aphids and if no cat's or eggs I cut and destroy the plant. I have fields full of milkweed in VT.
<span>Yvonne</span> Mon, 04/19/2021 - 19:37
I've bought praying mantis eggs, but whenever they hatch the praying mantises disappear. We've had horrible winds, and it appears that they just blow away. I've gotten ladybugs, but they're gone now too. I've read that I should be misting my plants every morning, but I live in the desert and the leaves dry almost as quickly as I spray them. I found that one of my praying mantis egg cases hatched, but I see not a single praying mantis. I doubt that they've moved to greener pastures, because I have a buffet of aphids waiting for them. They're not eating them, they're just disappearing. I don't get it.
<span>Lawrence C Davis</span> Sat, 04/10/2021 - 12:13
It doesn't work. They come back the next day. We've tried everything but commercial pesticides
<span>Tonia</span> Wed, 02/03/2021 - 07:42
Aphids are destroying my Dama de Noche (cestrum nocturnum). Last year it was so bad the leaves were coated in honeydew. The tree is 7 years old with a well established trunk so I cut all the green back in the fall and sprayed the trunk with neem oil and did a soil drench for the Winter dormant period. It's an indoor/balcony tree. During the Summer months I've tried catnip, dishsoap/cayenne pepper mix, commercial aphid sprays, Sevin dustand flour and alcohol/water mix. I've also planted various herbs next to the tree that are supposed to repel the aphids. I just looked at it today and there are aphids on it again. As soon as any new green leaves start to appear they attack and the leaves start to curl and fall off. Any suggestions of what else I can try? I can't even pinpoint where they are coming from since I have several other plants of different types and none of them are or have ever been affected by these insidious pests. I'm at the end of my rope and really don't want to lose this tree. Thanks.