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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.

Photo Credit
Pixabay

Preventing Aphid Infestations in Your Garden

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.

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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.

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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 website companion of The Old Farmer's Almanac. She covers gardening, plants, pest control, soil composition, seasonal and moon c...
Read More from Catherine Boeckmann

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Comments

<span>Barbi</span> Sun, 06/14/2015 - 08:47
Firstly, I'm dating this post because I dislike that I have no clue how old the existing conversation in here is. - June 14th 2015 - Garden & Zone: Containers on a 2nd floor deck, in zone 5b (Peterborough, Ontario, Canada) Plants: red & green pepper (in containers), hanging strawberry plant, strawberry mint plant (tastes like strawberry mint, does not produce berries haha), lemongrass, ivy, lobelia, fuschia hybrid, calibrachoa hybrid & green dracena and a bleeding heart plant that I pray is going to survive in a container over winter (my fave plant ever, let's see if apartment life will support bleeding heart 'captivity')! PROBLEM: green aphids found on my pepper plants this morning, along with what I had THOUGHT are maybe aphid larve (they are long and skinny white worm looking species, MAYBE a millimeter or two in length), but I have found other information that indicates they MIGHT be "aphid midge (Aphidoletes aphidimyza) larvae" which I read actually controls aphids. So, few things I want to inquire about between my problem and things noted within this thread. First, does the diatomaceous earth help control the aphids? Or just the ants? Is this just an overall generally good thing to sprinkle at the base of plants to protect from certain infestations of enemy insects? I have some bought in the gardening section (to clear up I'm not using the pool formula :D )a few years back...does age of this product affect efficacy? Next, I read a suggestion to just hose off the aphids from the plants regularly with cool water (luckily I recently bought a hose and the attachments to use it with my kitchen sink...again, 2nd floor apartment), so that is what I had done this morning. I have a funny feeling that because I am not blessed with life's solutions being the simplest ones, that those little buggers (pardon the bun) will be returning and forcing me to attempt solution #2! So taking into consideration I have a passing by dog who uses the deck to gain access to the back yard, some robins who have a nest on our deck using it for 2 rounds of offspring every summer, a cat who is indoors but sits at the screened door which my peppers are RIGHT beside the door, here are the solutions I will be looking at. Firstly, I will be adding a couple containers of nasturtium as my first line of defense, then the options are as follows; 1. mixture of soap and water 2. mixture of soap and water and alcohol 3. mixture of soap and water and cayanne 4. 'organic' pesticide 5. giving up ;) (I won't likely make this choice....I LOVE PEPPERS) So, my curiosities are this; if I use the DE, what can I expect it will do for current problem? or what can I expect it will do in general? did I just spray off aphid larvae or the aphid midge larvae which would have been there to take those aphid down? will the nasturtium survive the infestation of the aphids? or will I have a flower that looks like it went to war with the aphids and the aphids will win? do I need to attempt control of the aphids on the nasturtium or just let the flower do it's job attracting the little buggers as if it's the crack dealer and the aphids are the crack heads? (haha...sorry if you don't find that funny...I have a sick sense of humour) are there other flowers or plants one would suggest placing beside the peppers to help with insect control (be it for aphids or any other common invasive insect that might like my peppers as much as I do)? with the plants and flowers I have listed that I currently have, are any of them at high risk more than others for the aphid attack (I assume aphids will attack any plant equally...little 'buggers' are not plant prejudice!?!?!) or any other insects infestation? Remember, I am on a 2nd floor deck in zone 5b (in Ontario) and am determined I am eating peppers that I have harvested myself ;)
<span>Darla</span> Sun, 01/22/2017 - 20:09
Just a word of caution: I've known two people who eat a lot of peppers and hot spicy food all the time and both died of stomach cancer. I'd never even heard of stomach cancer. One was Asian, the other just really loved peppers in her food. Apparently the beneficial vitamin C derived from the pepper is not greater than the cancer causing factors.
<span>B.r.</span> Tue, 03/14/2017 - 21:10
Eating a lot of peppers does not cause cancer according to a google search on the topic. In fact, it actually fights cancers and has many other health benefits.
<span>Cerise</span> Mon, 06/15/2015 - 21:57
First of all, WHERE did you get the attachments to hook to your kitchen sink??????? I also live in an apartment and am tired of carrying a bucket!! Secondly, the best thing for aphids is Epsom salt!!! For a real large pot I use a half cup per pot. Just mix it up a bit with the dirt on top and then water like normal. Within two days all the aphids and white flies were gone. And they have NOT come back!!!!! I used it on my roses, tomatoes, pumpkin plant. Plus all my decorative plants. I also use it on my inside plants!! The Epsom Salt has something in it that the plants need!! ALL my plants are growing like crazy!!!! It seems like my pumpkin plant is growing about two inches a day!!! So remember, 1/2 cup of EPSOM SALT per pot!!!!!
<span>Faithfulflowers</span> Thu, 09/10/2015 - 17:55

Can I use Epsom salt that has a lavender scent? I am wondering if the lavendar would hurt the plants at all.

 <span>Patrick25</span> Wed, 04/29/2015 - 15:13
Hey all, I have started and indoor Hydroponic garden with about three pepper plants, 2 tomato plants, and 2 basil plants. I have had them for about 4 months with out any bugs or any issues. Today while adjusting some of the plants, I have noticed a ton of aphids (on all of them other than the basil). I sprayed them with a combination of 2 parts alcohol and 5 parts water and added garlic as well. Are there any other steps I can take to enure the safety of my plants. Insects are not an option due to the fact this is an indoor set up.. Thank you all.
<span>Algardener</span> Fri, 06/05/2015 - 15:09
Hi Patrick! Have you tried an organic insecticidal soap? I use to have an aphid problem on my indoor herbs and Safer Brand's Insect Killing Soap cleared it up. You can usually find it at a nursery or garden store. Hope it works for you!
<a title="View user profile." href="/author/editors">The Editors</a> Fri, 05/01/2015 - 11:20

Hi, Patrick, These are probably root aphids (they seem to be the most common in hydroponics). Root aphids spread through water, apparently. Some sources advise putting liquid pyrethrym concentrate into the water/nutrient mix. Pyrethrum is an organic pesticide, sort of. Apparently the production process is not entirely. Depending on the strength of it, Pyrethrum may kills any beneficials you have introduced. Consult a local organic vendor for information.

 <span>Rachelle Bradford</span> Wed, 04/01/2015 - 08:27
I heard that planting Marigolds is a good defense for aphids, but do not remember why. I think they attract a beneficial insect.
<span>Milkandhoney</span> Wed, 02/11/2015 - 01:18
Hey, What about pumpkins? I heard they are delicate and you have to be careful of what you put on them. So what can I use for pumpkins?