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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How much fungicide ? Please.
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;
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.
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.
It doesn't work. They come back the next day. We've tried everything but commercial pesticides
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.
50/50 isopropyl to distilled water
spray 2 times daily..
diatamaceous earth the soil and mix it in..
let dry so it can work properly, before even planting anything mix it in to the soil..
start spraying with alcohol and water before getting any bugs in the first place..
They are all over a plant ( house plant) that I want to bring in for the Winter.. what shall I do.
Treat the plant following the advice given above, specifically the dish soap spray solution. Before spraying, try to wipe off as many of the bugs as you can see. If temperatures allow, keep it outside for a while longer until you can get the aphids under control. When you bring it inside, keep it away from other plants until you aren’t seeing any more aphids show up.
help bringing in house plants...need control of aphids. last year they over whelmed our house help
