Aphids are pesky green bugs that can wreak havoc on your garden.
Preventing Aphid Infestations in Your Garden
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.
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.
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.
Photo Credit: John Obermeyer/Purdue University.
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.
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.
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!
Catherine Boeckmann
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I have hops growing in my yard that are destroyed by aphids every year. I've tried the insecticidal soaps nothing seems to work. Is there something I can do in the spring before the plants starts to grow. My black and red currants bushes next to the hops are also affected. Help
Brake-Cleaner from Autozone gets rid of them the fastest. But keep in mind, you must consider how important you consider the plant that you find them on. Your welcome!
You can also use local cow urine which is again benificial in controling aphid attack. For this purpose add 1:6 ratio of cow urine to water. Tested and easiest methord in controling aphids.
I tried to discover why aphids when I washed them off of my plants inside or outside I continued to get a worse infestation quite quickly, so I used a piece of scotch tape and picked some aphids of my plant where they were firmly stuck , I put them where I could keep an eye on them over a black background and with a magnifier was astounded to see they lived for up to 3 or 4 days, and worse than that several of the more mature ones spit out more aphids , shocked I was so I no longer blast them of , I prefer just to remove them physically if i can and squish them eliminating the possibility of recreation , I would sure like to know if any one else has discovered this, try it your self, you may be very surprised at the results.
for the soap mixture, what exactly do you mean by "do not dilute before spraying on plants"?
By this, we just mean that it’s not necessary to dilute the solution before using it on your plants! Though it’s always wise to test it on a leaf first and dilute it if any adverse reaction occurs.
I use banana peels. Cut them into long strips and drape them over the center of collards, cabbage etc. Also tie them around the base of plants. My sister ties them below favorite rose blooms to keep them off. IT DOESN'T WORK to blend up the peel (tried it) eat your 'nana's and use the peels in the garden. (Oregon)
Do the peels need to be fresh and replaced often?
They're tiny, golden colored, and they are perfectly fitted inside each of the buds on my pansies. I want to either leave them be if they're good or dispose of them if theyre bad. Thanks
We've got some indoor pepper plants that get plagued by aphids all the time and pretty much nothing seems to work. However, i've also got a computer for which I decided to buy a small USB vacuum cleaner, so I decided to give it a try on my plants.
With a small brush attachment you can clean the leaves and in the corners of branches where aphids like to hide.
It's not a quick fix by anymeans, and it certainly isn't a 5 mintue job, but it definitely helps to see just how many of the little monsters you are getting before you watch them get washed down the drain. No doubt if you have a working insecticide then a little plant-cleaning beforehand can do wonders in destroying an infestation.
