10 Simple Ways to Manage Aphids Naturally

Have you ever strolled through your garden and started to see some of your plants yellowing? Upon closer inspection and the simple turning of the leaves, you see hundreds of pear-shaped pests (Fig 1). 

You may have aphids and you may feel like your plant is lost. Managing aphids doesn't have to be the colossal headache that everyone makes it out to be.

Figure 1: Aphids on radishes.

Managing aphids takes an integrated approach. You often need to think about controlling aphids before you start putting plants in the ground. This blog will provide you 10 actionable ways you can control aphids before and during the season.

In this Article (click on link below to jump to section)

• What do you expect to see with aphids?
• What vegetables do aphids infest?
• Why is it important to manage aphids quickly?
• How to monitor for aphids?
• How do you manage aphids?
  • Add plants that repel aphids
  • Trap aphids with sacrificial plants
  • Use floating row covers to keep aphids out
  • Don't over-fertilize your plants
  • Make sure your plants are watered well
  • Remove the aphids physically
  • Attract or add beneficial insects
  • Use insecticidal soap and/or neem oil to kill aphids naturally
  • Dust with diatomaceous earth
  • Manage ants on plants

What do you expect to see with aphids?

Are your plants covered in tiny pear-shaped bugs? Aphids are common garden pests that can cause damage to a wide range of vegetable plants. It is said that there are 5000 species of aphids. They can be various colors - green, yellow, pink, or black (Fig. 2). If you look closely at them, you will see two tiny tailpipes out their rear ends. Most of them do not have wings but a few will, which allows them to spread to other plants in the garden.

Figure 2: Aphids can be an assortment of colors. Notice their pear-shade with two tiny tailpipes coming out.

These small, soft-bodied insects suck plant sap out of the plants like sucking soda with a straw. Their toxic spit mixes with the fluids of the plant, causing stunted growth, distorted leaves, and yellowing leaves. This spit can also transmit viruses that the plant can’t recover from. They prefer the younger leaves or flowers, but in time, the whole plant may be covered.

Aphids excrete a sugary substance called honeydew as they feed on the plant sap. This honeydew serves as a food source for sooty mold, a black fungus that can cover the leaves and stems of your vegetables. Sooty mold is ugly and can interfere with photosynthesis, reducing plant vigor (Fig. 3).

Figure 3: Sooty mold grows on the surface of honeydew excreted from soft-bodied insects like aphids.

What vegetables do aphids infest?

Aphids infest a variety of vegetables, including cabbage and other cruciferous crops, lettuce and salad greens, beans, peppers, tomatoes, cucumbers and squash, and peas. They will also attack sunflowers, roses, and fruit trees.

Why is it important to manage aphids quickly?

Once you have aphids, you need to begin managing them quickly because they reproduce quickly and spread to other vegetables. Most aphids are born pregnant and can give birth to live young. These baby aphids mature into adult aphids in a couple of weeks, continuing the cycle (Fig. 4). 

Figure 4: A single aphid can give birth to up to 12 nymphs per day.

How to monitor for aphids?

Scout early and often. Some aphids are green and blend in easily with the leaves. Aphids tend to hide under the leaves, so you may just see the symptoms until you start flipping over leaves. It is important to remember to turn your leaves over to find the population while it is still small (Fig. 5). Once it gets too big, you may struggle to control the population.

Figure 5: Aphids feed on the undersides of leaves and prefer younger growth.

You can also use yellow sticky traps near affected plants to catch aphids in flight and reduce their population, as well as monitor them (Fig. 6). You would hang them above your garden on strings or on posts. You can also make your own sticky trap by smearing Vaseline or Tanglefoot on a piece of wood painted yellow or a yellow plastic plate.

Figure 6: Yellow sticky cards can be used to monitor aphid populations. They should be positioned slightly above the foliage.

How do you manage aphids?

Once you have identified aphids, you need to manage them. While spraying pesticides is a common approach, it is best if you use an integrated approach which is more proactive rather than reactive. Below is a list of integrated pest management (IPM) strategies that guide you from preventive strategies to non-chemical controls to chemical controls. You can use a mix of strategies to have long-term management of aphids.

#1. Add plants that repel aphids

Certain plants contain chemicals in them that repel aphids naturally. These are often strong-smelling plants such as marigolds (Fig. 7), catnip, dill, fennel, cilantro, peppermint, and chives. For aggressive plants like mint, you can plant them in containers near the susceptible plants. For others, you can plant them alongside the susceptible plants.

The added bonus is that many of these plants attract pollinators to the garden.

Figure 7: Marigolds are a great addition to any garden to help repel aphids and attract pollinators.

#2. Trap aphids with sacrificial plants

A trap crop is a plant that is more attractive to a pest. It is considered sacrificial because you need to remove the pest or in the case of aphids, you will likely remove the plant. Nasturtiums (Fig. 8), calendula, and nettles can serve as trap crops for aphids.

Plant these around the perimeter of your garden early in the season a couple of weeks before your other crops, so they can start blooming and attract the aphids before your main crops start producing.

Figure 8: This nasturtium has attracted the aphids to its leaves. Make sure you remove the aphids so they don't travel to your other plants.

#3. Use floating row covers to keep aphids out

To prevent aphids from ever attacking your plant, you can use floating row covers. You would cover vulnerable plants with a lightweight fabric to create a physical barrier that prevents aphids from reaching them. Make sure you use the insect netting rather than the frost cloth. You need to make sure that the row cover is anchored or weighed down so that pests can’t get underneath the cover (Fig. 9). This also prevents many other pests from infesting your plant.

Since these covers tend to hold humidity and heat in, this is more often done earlier in the season since it can increase the incidence of diseases.

Figure 9: Floating row covers are great for control earlier in the season.

#4. Don’t over-fertilize your plants

The life of an aphid is to suck plant sap and the tastiest plant sap are leaves with lush new growth. By providing more nutrients, especially nitrogen, in excess of what is needed, the plant will grow more leaves that are attractive to aphids.

Rather than applying all the fertilizer needed for the season at once, break up the application into smaller doses throughout the season. Another strategy is to use organic fertilizers which tend to be slow-release since microbes need to convert the fertilizer into a usable form.

#5. Make sure your plants are watered well

One thing I always say is when your plants are stressed, the pests will come. This is because stressed plants can’t produce the chemicals to ward off pests. Aphids are commonly a problem during the summer since it is hot and if you are going through a drought, then it is dry as well.

Droughts also cause the sugars to be more concentrated in the leaves, making the leaves particularly attractive to aphids. 

Make sure you stay on top of watering your garden. You can use an inexpensive moisture meter like this one to monitor the moisture. Drip irrigation on an automatic timer can also help keep your garden watered. 

Although don’t go the other direction and overwater your garden, because that can bring a whole different set of problems.

#6. Remove the aphids physically

You can use a strong stream of water from a garden hose to dislodge and remove the aphids from the plants. Focus the spray on the undersides of leaves and the stem, where the aphids tend to live. The reason this helps is because aphids have weak legs and can’t typically climb back up the plant. 

You can continue to do this to reduce the population. It will also rinse off the honeydew reducing the amount of sooty mold.

For smaller infestations or more delicate plants, you can use a small brush to remove the aphids and drop them into a bucket of soapy water.

#7. Attract or add beneficial insects

Aphids have a bunch of natural enemies, including ladybugs, lacewings, parasitic wasps, hoverflies, damsel bugs, big-eyed bugs, and others (Fig. 10). The adults, larvae, or both may eat or parasitize the aphids.

You can attract beneficial insects by planting flowers that adults may be attracted to like dill, Queen Anne’s lace, cosmos, black-eyed Susan, lantana, and basil. 

If you see puffed-up aphids (aphid mummies) on the leaves, it is a sign that you have parasitic wasps.

You can also release ladybugs, lacewing eggs, or parasitic wasps in your garden. You can purchase these beneficial insects from local nurseries or online suppliers. 

Make sure you follow the tips provided with the organisms. For example, instructions normally say to release ladybugs at sunset and to mist the leaves beforehand. This is so that they stick around on your plants rather than immediately flying off.

Figure 10: Learn to recognize various natural enemies so that you can protect them while managing aphids.

Pro Tip: If you have beneficial organisms actively on your plants with aphids, do not use pesticides, even soaps and neem oil, since many of them will kill your beneficial organisms.

#8. Use insecticidal soap and/or neem oil to kill aphids naturally

Due to their soft bodies, aphids can be killed easier than other insects. Natural pesticides like soaps and oils disrupt their membranes, suffocating them. You can use ready-to-use products or make your own such as this recipe: 2 ½ tablespoons of pure-castile liquid soap and 1 tablespoon vegetable oil (optional) in 1 gallon of water.

To boost the potency, I often will take a quart of the mixed solution and add 1 teaspoon of cold-pressed neem oil to use that day (Fig. 11). Neem oil’s active ingredient degrades quickly in water, so it is best to make the portion you will use that day.

Kind in mind that this solution is a contact solution so it must be sprayed on the pest. It can also kill beneficial organisms as well, so rely on tactics such as spraying water if you see beneficials. Soap and neem oil can burn plants in over 85°F weather, so spray early in the morning or after sunset on warm days.

Other organic pesticides include horticultural oils, pyrethrin, and sulfur.

Figure 11: Here is a DIY recipe you can use for manage soft-bodied pests.

#9. Dust with diatomaceous earth

Diatomaceous earth, also called DE, is made up of the fossilized remains of aquatic organisms called diatoms which contain silica. It looks like a fine powder, but to aphids and many other pests, it is like razors that cut through the waxy outer layer of pests, dehydrating them.

You can dust food-grade DE (not the pool-grade DE) on the leaves and stems of the plants. This dust easily washes away, so you will need to re-apply it if rain, irrigation, or high humidity removes it.

#10. Manage ants on plants

If you have aphids, you often will see ants. This is because ants “farm” the aphids for their honeydew, a sweet food source for ants. Sometimes, the ants will get the honeydew straight from the bum of the aphids. 

As good farmers, ants keep any predators away from their “cattle,” in this case, that is beneficial organisms such as predators and parasitic wasps. By getting rid of the ants, you can increase the number of beneficial organisms managing the aphid population naturally.

Many organic pesticides such as insecticidal soap, neem oil, and diatomaceous earth are also effective against ants, so you can reduce both populations. Another strategy is to wrap tape adhesive side out around the base of the stems of the affected plants. Then apply a layer of Tanglefoot or other sticky substance on the tape designed for catching insects (Fig 12). This will trap the ants on the tape since ants go up and down the plant multiple times a day.

Figure 12: This wrap covered in Tanglefoot was used to reduce the ants climbing on this trellised tomato to farm mealybugs in this case.

There you have it! 

By adding strategies that deter and prevent aphids combined with non-chemical, biological, and chemical control strategies, you can manage aphids in your vegetable garden.

Did you find these tips helpful? Share your top tip to stay motivated on the path to aphid management in the comments below!

If you still need help with your garden problems, join my free Facebook group where you can ask questions and get access to live training on your garden problems. There are no silly questions, and I am always happy to hear from vegetable gardeners. 

For more on organic pest management, including how to prevent pests and manage them with non-chemical or chemical controls, check out the posts below:

• Grow Sunflowers to Trap Stink Bugs
• Beginner's Guide to Watering your Home Vegetable Garden
• 8 Organic Pesticides for an Environmentally-Friendly Garden
• 5 Ways to Prevent Pests in the Garden

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