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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>Kat D</span> Sat, 07/19/2014 - 15:26
I notice that no one is mentioning bean plants. I have black eyed peas and green beans, The ants are farming aphids harder than I am gardening! Every day I can check the peas and beans, spray with the onion/garlic/pepper/soap spray. Recipe is from organic gardening dot com. Every day they are back! I can't keep up with the activity! My pods will be almost completely covered with aphids and ants, running down the vines and under the leaves! I can't stand the ants! I already spoke with the local ag extension agent, who said spraying daily would work. However, in California we face watering restrictions at the moment, 2 times a week for watering. The ants/aphids have resisted it all. They are now spreading to some of the melons and cucumber in my garden, and possibly saw signs this morning on one of the squash. I am about to just throw up my hands and give up, let them eat the dang beans and peas. as long as they leave my heirloom tomatoes be!
<span>Mnaveaux</span> Sun, 04/12/2015 - 10:46
I have found the best solution for ants to be to track them back to their nest opening, and treat them there. You can use a commercial ant poison (Amdron is the only one that works for me), and I put a tight screen over the area so my lovely lizards and birds cannot get near the poison. There are less harmful ways to treat ants, too, if you research it, only I've not found success with any of them yet. Keep your eye on the nest as it will no doubt come to life again sometime in the future. Also, make ever widening circles around the nest to find its connected nests. I have one 100 feet away not even in my yard that connects, so I treat them both. For some reason, great big red ants inhabit the nest but don't wander far. And the teeny tiny ants track back to the nest, too, from my garden far away. I don't understand that, but there you have it.
<span>Mike Promnitz</span> Tue, 07/29/2014 - 01:35
You sound overrun with insect pests. I'm no farmer, but I use chili spray made from our own chilies, to control virtually all pests. I've never found anything nearly as effective. One may have to spray a few times over a year and spraying underneath the leaves helps a bit. Nature always has the best solutions. Just add chopped chili to water over heat and when cooled, decant into spray bottles. Avoid inhaling the fumes and avoid cheap, hyperbred chilies. No pest will return. I don't yet grow okra, but will be soon. For the flesh of produce, use a weaker solution and avoid using the spray for about 3-4 weeks before picking. Good luck
<span>James Lewing</span> Fri, 07/25/2014 - 09:37
Had the same problems. I use Cyonara insect control for aphids, hornworms, stink bugs, it kills any insest that takes a bite. My troubles are over, untill next time. Spray every two weeks. Don't worry about rain. I add a little dish soap to make it sticky
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 07/21/2014 - 12:32

The ants are there because of the aphids. They are "farming" them.  The ants are good guys. The aphids are pests. Get rid of the aphids and you'll get rid of the ants.  You an just blast those aphids with a soapy spray. Once the plants dry, just dust some DE (diatomaceous earth) on the plants and at their base.
We would ignore the ants but if they are really out of control, try boric acid. Make traps with 4 parts sugar, 1 part boric acid and put in saucers; they'll take it back to the colony.

 <span>Melissa Sillaman</span> Mon, 08/25/2014 - 01:13
I was wondering why no one had mentioned boric acid (aka Borax) before! I use it for laundry & around the outside perimeter of my house and my plants as a dry dust and haven't had any problems….. Except for this year, I have chronic pain in my lower back & am limited to what I can do. Dusting my flowers & shrubs wasn't done & I noticed my first green aphid on my new transplanted moonflower plant! I will need to get some boric acid. You can buy Borax, the brand name in the laundry aisle at your local walmart or grocery store (Meijer, Kroger,etc…)for around $3.50! Alot cheaper than buying the general name boric acid from a gardening/department store & you get a lot less!
<span>T. South</span> Wed, 05/06/2015 - 17:35
Boric acid and Borax are not the exact same thing. as far as I know. They MAY be related but I do think are 2 separate things. I use Borax for laundry and cleaning stove top etc....as well as in a DIY flea control mixed with salt, maybe one other thing. I make ant bait/killer with boric acid, sugar & water.
<span>Carol C</span> Tue, 03/17/2015 - 14:24
I have successfully used the boric acid solution to stop ants in the house... but please check the chemistry... Boric Acid and Borax are NOT the same. Boric Acid is the product to use... purchase from a pharmacy. Per Park Ranger advise, I did sprinkle Borax on California visit to surround/outline tent to prevent ant intrusion . That is used in powder form, not dissolved in water. Diatomaceous earth is excellent to surround the base of a seedling as it's sharpness cuts any crawling bug(slugs, etc). D. Earth is a product used for swimming pool filters. It is non toxic. We do eat it! It's in lots of grain based foods because lots of grains are stored with diatomaceous earth to keep the bugs from eating the grain! **Boric acid, also called hydrogen borate, boracic acid, orthoboric acid and acidum boricum, is a weak, monobasic Lewis acid of boron often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other chemical compounds. ** Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. Powdered borax is white, consisting of soft colorless crystals that dissolve easily in water.
<span>T. South</span> Wed, 05/06/2015 - 17:40
You are not supposed to use the *Diatomaceous earth that is for swimming pools, for pest control. the kind used for pools is not considered non toxic. I know people who use it* for flea control, but always it is pointed out to avoid the kind for pools. You seem to have more overall knowledge about it than I do...but I wanted to make that one point.
<span>Heathers</span> Wed, 08/13/2014 - 15:15
How can the ants be the 'good guys' if they're farming the aphids? ;) IMHO, the ants are just as guilty, maybe even more so since they farm the aphids. I've found that insecticidal soap works well on aphids. I mix my own & use castile soap diluted with water, since castile soap seems to be more potent than regular dish soap.