Aphids seem to cause us problems both early and late in the growing season. We’ve found curling, yellowed leaves on chard within weeks of the plants emerging from the ground. Further examination revealed ants coursing up and down the stems. Looking carefully at the undersides of the forming leaves revealed why the ants were there: aphids! Clusters of the green and brown critters could be seen tucked away where the chard leaves created little pockets for them to hide.
Then comes August, when green tomatoes are usually swelling larger on the vine. Some years, we’ve found that fruit swelling coming to a stop and the leaves on our plants turning yellow. Again the problem is aphids, sucking the juice from our plants, denying it to the fruits that are still in the growing stage. This time — aphids on tomatoes were a particular problem when we lived in coastal California — the little critters were a translucent shade of pink and ants were again present.
Growing up, we learned about early aphids when they attacked Grandma’s peonies and late aphids when they appeared on her budding roses. Grandma’s strategy was to tolerate the little buggers. She didn’t think they hurt the blooms, except for the years the infestation was so bad that the flower buds on both peonies and roses, started to discolor and failed to open fully. At that point, when it was too late, Grandpa wanted to spray. Grandma, bless her heart, wouldn’t let him.
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Aphids are not only born hungry, they’re born pregnant. Those first aphids you discover in the spring were probably hatched from over-wintered eggs. That’s why garden cleanliness — keeping places where the eggs might survive the frozen months — is important to aphid control. On the other hand, once hatched, the young nymphs can be carried over great distances by the wind. You might keep a clean garden but your neighbor, even miles away, may not. Still, it’s a good idea to clean up in areas where you’ve previously had problems.
Though there are many types of aphids — some 4,000 species have been counted — most of those born from over-wintered eggs arrive already pregnant. This is one of the major divisions between aphid types. Many kinds of aphids give birth, amazingly, to live young. In warmer climates, aphids may go through as many as 12 generations before laying eggs to over winter. This explains why you might see a few aphids one day and a full-blown infestation the next.
Another difference in aphid types has to do with diet. Some aphids will feast on a host of different plants. Some prefer only one or two types. Rose aphids seem to prefer roses and nothing else. This is a non-scientific conclusion derived from my own experience. I’ve had aphids sucking the juice out of my roses but none in my vegetable garden. But then, maybe there are other factors involved, like the way I water my vegetables.
The Gardner’s Guide To Common-Sense Pest Control suggests that some aphids consume different plants in different seasons. This explains why you might find aphids all over your bok choy one day only to discover that they’ve disappeared a few days later. They’ve moved on to their second season crop. The Gardener’s Guide also gives the best advice when it comes to controlling these nuisances: “The first rule of aphid management is to conserve the many natural enemies of aphids present in most gardens.” I like to think that’s why Grandma, in her superior wisdom, wouldn’t take his rusting rose duster to the flower bed.
If you create a safe haven for beneficial insects, you’ll have much less problem with aphids. While ants always seem present when there are aphids — they harvest the honey dew excreted by aphids who are known to ingest more plant juice than they can process — they are not predators. In fact, you might even see an ant “milking” a particularly fat aphid with its feelers, a method used to coax more of the sweet, sticky dew from their bodies. Ants are even known to kill other insects that predate on their aphids.
Even with a safe haven for beneficial insects, you may notice aphids working a plant without a ladybeetle or lacewing in site. This is because there’s a lag between the aphid infestation and the beneficials finding out about it. This is where introducing predators comes in handy. You can purchase ladybeetles to release in affected areas within days instead of waiting for the local cavalry to arrive. Often a cold spring will allow aphids to flourish while their predators are waiting for warmer weather.
Another problem is that ladybeetles will leave an aphid infested plant before finishing off every last one of the little suckers. At a certain point, they’re not willing to work so hard to finish off the aphids when there are so many available elsewhere. This is good reason to develop an environment that includes a number of natural predators, or to introduce a predator that will work with the ladybeetles.
Detecting aphids early is crucial to combating them. Use sticky tape near plants that are susceptible (or with which you’ve had previous problems) to detect their presence. Check plants daily for signs of aphids. Nasturtiums are a favorite of aphids. Grow them in and around your garden and monitor them frequently for any aphids they might attract.
Available from Planet Natural, Green Lacewing feed on a large number of soft bodied pests, mites and insect eggs. A voracious predator, they can consume as many as 60 aphids an hour. Shipped as eggs packed in a carrier (rice hulls), larvae soon hatch out and will feed for 2-3 weeks before becoming adults.
We like to think of dealing with aphids as a hands-on project. Smashing the little blighters between your thumb and forefinger is not only effective, but satisfying (though a little messy). We like to get the kids to join us in this operation — some love to do it (some don’t). Spraying clusters of aphids off plant stems so that they fall to the ground where they can be devoured by spiders and other garden denizens can also be effective. But many aphids will survive by hiding on the bottoms or in the curls of leaves. This needs to be done every two-three days to have an effect.
Insecticidal soaps and oils which prevent the aphid from breathing can also be effective. But plants must be sprayed top to bottom with particular attention to the undersides of leaves. If you make your own soap-based solution, don’t use soaps that are heavy on detergent. Soaps based on coconut oils are the most environmentally friendly. Sprays made from garlic and chile peppers will also repel aphids to some extent. We’ve read that mixing coriander and anise oils, then spraying infested areas, will kill aphids.
Discouraging early season aphids is helped by controlling the nitrogen your plants are getting. Using soluble nitrogen fertilizer early in the growing stages (often just when you want to use it). Aphids are attracted by high levels of nitrogen in plants. That’s why you might find plants you’ve just pruned attacked. The aphids will seek out the high-nitrogen new growth that comes of pruning. Instead of highly soluble nitrogen fertilizers, including manures and fish emulsions, use something that’s slow-released. When fertilizing roses, peonies or other flowers, use a formula that’s higher in phosphorus than nitrogen. Keep pruning to a minimum if you’re having aphid trouble.
I can’t imagine any serious gardener who’s never had a problem with aphids. If that’s you, we’d like to hear about it. For the rest of us: what’s involved in your aphid management program? We’d like to know…
Eric Vinje founded Planet Natural with his father Wayne in 1991, originally running it as a grasshopper bait mail-order business out of a garage.
Eric is now retired, but is still a renowned gardener known for his expertise in composting, organic gardening and pest control, utilizing pesticide-free options, such as beneficial insects.
Eric believes when you do something good for the environment, the effects will benefit generations to come.
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11 Responses to “Organic Control of Aphids”
My heliopsis (false sunflower) has been infested since May with red aphids (it’s now mid-August). My reading has led me to believe this is called a ‘brown ambrosia’ aphid. No other aphids appear in my Midwestern perennial garden – though when I had goldenrod they were on it. Last year (their first) they prospered. This year is different. The flower buds have failed to produce a succeeding flush, turning black and knobby and one plant is dead. The others look healthy enough. Since this is a native plant that sometimes is found in open prairies I let them be together.
The population seems to have diminished some and the lower leaves seem to have a sort of ‘dandruff’. Is it possible that they have been set upon by a predatory wasp and these are the skeletons of vanquished aphids?
What is implied by “keeping the garden ‘clean’ over winter”? There is a heavy layer of composted wood chip mulch and I remove interplanted annuals at the end of the season, It seems counterintuative to remove the mulch.
Thank you for a very informative article.
A very good method is some instances is the use of Vick’s Vapo Rub or generic equivalent. I live in the tropics and ants carrying aphids were eating my cacao pods which grow directly from the branches and trunk. If you put a thick ring of Vick’s around the trunk the ants can’t climb in the first place. You can kill off the aphids with neem or orange oil. If you are concerned about the Vicks not being organic you can put it on tape and then remove it. I imagine there are other stcky things you can put at the base of a plant but with Vick’s they really hate the smell and just turn right around.
I have grown Nasturtiums many times, and have never seen a single aphid on them, however they have destroyed my Chard and other greens.
Then one time I noticed that Chard next to the Nasturtiums was being left alone. Now I suround my greens with Nasturtiums and have very little damage from aphids.
I live in Orange County California. It seems the aphids we get here are repeled by Nasturtiums!
I live in northern WI and until last year, had no knowledge of what was killing my false sunflowers in early August. Then, I saw what I learned to be, evil “aphids”. People that seem to have the answers to this problem all appear to live on the west coast. Does anyone have an answer to my location/problem? Today I discovered aphids (and I’ve been watching each day for them) aphids on the flowers…but only one plant out of the dozens in that flower bed. Should I remove the entire plant? I squeezed off as many as possible, then rinsed it down, including under leaves, plus all other plants. This evening, when it’s cooler and bees aren’t out (don’t want to kill bees) there’s an insecticide I could use. HELP! I don’t want to do that. Any advice for me in northern WI?
Aphids! No matter how diligent I clean the garden at the end, I get them every year somewhere. Ants farm them and take them to other locations. First, I control the ants with a line of 20 mule team borax along their path on the ground, they track it on their feet back to the nest and dries it up. (and they won’t cross it after that so watch for their trails) The most effective control I have used a continuous light coat application via an apparatus of diatomaceous earth after a rain and after watering. I use the “Gilmore” dry sprayer https://www.planetnatural.com/product/hand-duster-spray-doc/.
If I get an infestation overnight, I use soft soap in the evening, water early am and hose em off or sqwish ick! Must repeat per the directions (don’t forget to repeat). Homemade stuff wasn’t cutting it. And to reply to Karen yes I am on the west coast. These steps will work, but you MUST be diligent. Companion planting helps too. It doesn’t matter where you live, the treatment in this case is the same, trial and vigilant watch daily. They can suck the life out of a plant very fast!
Aphids come out like an army invasion beginning of spring and again in August. They are attracted right to the buds of plants where growth is highest and absorbtion of nitrogen the highest. If poss, (If I can remember or my hubs doenst put fert out too early)I try to hold off on HI nitrogen fertilizers for a couple weeks until June 1, after invasion danger has passed.
Don’t know about how organic (Spinosad) product is, supposed to be from abandoned rum still. I have had great results with this product if used on weekly basis for about three weeks. Must break the cycle.
Would like comments as to its organic properties.
The Garden Insect Spray (Spinosad) by Monterey will NOT persist in the environment and is classified as an organic substance by the USDA National Organic Program (NOP). It’s also OMRI Listed for use in organic production.
Interesting comment since on the label itself says to limit application of Spinosad up to 5x per season, and to limit its applicaion 3 weeks b.4 harvest. Not to mention, spinosad residue found on Marijuana plants will be rejected due to its harmful effects on humans. Organic products can still be dangerous if used improperly, Please read the directions. I use it also, but only in an extreme infestation, and no more than 2x
I have a heavy aphid infestation in a 2’x8′ raised wooden garden box. I have never seen this many! I was raising greens and they were on all of them, too many to squish. I pulled all of the plants and fed to the chickens. Now the bed is empty except for the soil. I am wondering if I should treat with something prior to planting something new in there?
In answer to your question about treating the soil, I read that aphids don’t overwinter in soil but in the bark of trees. You may want to check into it before you put the time and effort into treating the soil. Good luck