What Are Aphids?

Aphids suck. Quite literally, they suck the sap from the leaves of your plants. But as far as garden pests go, aphids are super common and not anything to freak out about.

Aphids are small, soft-bodied insects that feed on the sugars in your plants. They like to hang out on the undersides of leaves or on tender new growth while quietly multiplying, and they cause the most harm when their numbers are left unchecked.

Simple things like watering regularly so your plants don't get stressed out and planting lots of flowers throughout your garden go a long way to prevent major aphid issues. If you do spot aphids, don't panic. They're pretty easy to get rid of.

Let’s dive into what aphids are, how to spot aphid damage on your plants, how to prevent aphid infestations, and simple organic ways to treat them — no harsh chemicals needed!

Key Characteristics of Aphids

Before diving into prevention and treatment strategies, let's get to know the pest we're dealing with.

Appearance

Aphids are pear-shaped and teeny-tiny (they range from 1/16 to 1/8 inch long). They come in various colors, including green, black, red, yellow, brown, gray, and even pink-ish. They shed their exoskeletons as they grow, leaving behind white skins on plants. Winged aphids are slightly darker but otherwise similar to their wingless counterparts.

Behavior

Aphids reproduce quickly, so they're typically found in large numbers. They cluster on new growth (young leaves are juicier than older leaves), flower buds, and the underside of leaves.

Feeding Habits

Aphids use needle-like mouthparts to suck sap from plants, targeting tender and nutrient-rich areas. After they've sucked all the juice from a leaf, it typically wrinkles and develops yellow or brown spots. If they feed on enough leaves, they can weaken the plants. But the most dangerous aspect of their feeding is they can potentially transmit plant diseases.

Aphids typically feed on plants like asparagus, beans, cabbage, calendula, cucumbers, corn, lettuce, melons, milkweed, nasturtiums, peas, spinach, tomatoes, and potatoes. I've also had issues with aphids on citrus trees in warmer climates.

Life Cycle

Aphids become active with the arrival of warmer weather in spring, and then they stay pesky throughout the remainder of the growing season. Female aphids give birth to live young during the growing season without the need for males. In fall, males appear so the females can lay eggs that overwinter in your garden. These eggs hatch in spring, starting the cycle again.

You've probably heard the expression "multiply like rabbits," but maybe it should be "multiply like aphids." Some types are capable of producing as many as 15 generations in one season. Yikes!

5 Quick Tips to Deal with Aphids on Plants Organically

Tip #1: Welcome beneficial insects like ladybugs and lacewings to control aphid populations naturally.

Tip #2: Use a strong stream of water to dislodge aphids from plants and reduce their numbers.

Tip #3: Add companion plants like marigolds, chives, and thyme to repel aphids from your vegetable garden.

Tip #4: Make your own homemade aphid spray using dish soap and water to effectively control aphid infestations.

Tip #5: Regularly inspect plants for early signs of aphids and take immediate action to prevent their spread.

How to Identify Aphid Damage on Plants

Your first sign that you have aphids might be the tiny little pests themselves. But if you study your plants, you may find some clues that these little sap-suckers have moved in uninvited. Here's what to look for in your plants.

Plant Symptoms

• Twisted, curled, or yellowing leaves
• Stunted shoots and poor growth
• Deformed flowers or fruit
• Sticky honeydew deposits on leaves

If you're wondering what honeydew is, it's basically aphid poop. Aphids can't metabolize all the plant sugars they feed on, so they send it right back out. The sugar in their honeydew can, unfortunately, attract ants. That's why you should probably check your plants over for aphids if you notice ants marching around. Honeydew from aphids can also foster something called sooty mold, a black fungus — gross!

Virus Transmission

Perhaps the worst symptom of an aphid infestation is your plant suddenly coming down with a disease. Aphids can carry plant viruses, like cucumber mosaic virus, which causes mottled or curled leaves, stunted growth, and misshapen fruit. (This virus, by the way, doesn't limit itself to cucumbers. It can infect anything in the squash family, plus beans, spinach, lettuce, tomatoes, and beets.) Aphids bring these viruses from plant to plant, like teeny tiny plague rats.

Damage from aphids feeding on your plants is unlikely to kill mature, healthy plants. But virus transmission can be devastating for your vegetable garden.

How to Prevent Aphid Infestations

Let's look at 5 different ways you can prevent aphid infestations in your garden.

Check on Your Garden

Every day, when you step out to harvest something from your garden, give your plants a quick little inspection. Pay extra attention to new growth, like new leaves and flower buds. These are where aphids like to concentrate. Check the undersides of leaves and stems carefully for tiny bodies and sticky honeydew residue. Catching aphid populations while they're still small is the best way to prevent major infestations.

Follow Best Practices

Keeping the plants in your garden as healthy as possible is key to preventing all kinds of pest issues. When plants are stressed because they're thirsty or hungry for nutrients, they literally call out to pests. So make sure you're watering consistently and adding compost each quarter to ensure plants have the nutrients they need. Healthy plants are way less appealing to aphids.

Companion Plant

Companion planting has so many benefits for your garden, aphid prevention among them.

The first trick to companion planting is tucking in plants you know aphids don't like next to plants they do like. Garlic, onions, and chives all repel aphids with their smell, so I love to plant these guys next to my leafy greens to protect them.

Aromatic herbs like oregano, thyme, and marigolds also seem to deter aphids. I like to plant these herbs around the border of my raised garden beds to prevent pests from entering.

In general, avoid planting an entire raised bed with just one type of crop. If aphids were to make themselves cozy in this bed, it's way more likely to be bad news for you and your garden than if you had lots of different things planted there.

Plant Trap Crops

Trap crops are one of my favorite tools of organic gardening. A trap crop is something you plant to trap pests that would otherwise be attracted to your favorite vegetables. Think of them as garden decoys for plants like kale, lettuce, and spinach.

Trap cropping requires you to accept two things: one, pests are going to come to your garden no matter what, and two, it's better to have the pests concentrated on certain plants you don't care about.

The two most effective trap crops for aphids are calendula and nasturtiums. These flowering plants happen to grow best during the cool season, when aphids might start coming for your leafy greens. I've found calendula to be so effective in my garden that my calendula stems will be covered in aphids, while the tender lettuce plants right next to it will be pest-free.

Once you have a bunch of aphids on your trap crop, you can treat them following the steps below... or just leave them be. As long as the aphids don't start migrating from my calendula stems to my lettuce, I let them do their thing. Your calendula plants can handle some pest pressure.

Learn more about using trap crops.

Attract Beneficial Insects

Some bugs are natural predators of aphids. Take lacewings and ladybugs. The adult bugs are great because they pollinate your flowers. Their larvae are even better. That's because they're basically little aphid-eating machines. A single ladybug larva can eat 40 aphids per hour! (Ironically, these bugs feed on aphids the same way aphids feed on leaves: with a straw-like mouthpart that sucks out all the juice.)

Other beneficial insects that eat aphids include soldier beetles, minute pirate bugs, and hoverflies. To attract beneficial insects, plant nectar-rich flowering plants like sweet alyssum, dill, cilantro, daisies, asters, coreopsis, cosmos, yarrow, and zinnias. In one scientific study, alyssum was the most effective at attracting beneficial insects and decreasing aphid numbers compared to other flowers studied. (Their effect extended up to 50 feet!) Check out this list of 15 flowers to plant to attract ladybugs.

In addition to attracting these bugs, make sure you know what they look like so you don't confuse them with pests and try to remove them or squish them. You might think you have yellow jackets in your garden, for instance, when really you have hoverflies or parasitic wasps, both of which can help you take care of aphids. (Snap a picture and do a quick image search on Google before you squish anything!)

To emphasize my point, ladybug larvae look nothing like their adult counterparts (see picture below). Make sure you don't squish or spray these guys. They're your garden BFFs!

How to Get Rid of Aphids

Organic aphid control is pretty straight-forward and doesn't require you to run out and buy anything. If you spot aphids in your garden, follow these steps to get rid of them.

Step One: Remove Them Physically

You've got 3 different options for removing aphids. If there are just a few aphids present, you might consider handpicking them. Put on a pair of gloves, and then swipe them into a bowl of soapy water.

Another option is to prune heavily infested leaves or flower buds. Make sure these plant parts go into the trash, not the compost. While you have your pruners outs, prune any leaves that are showing signs of aphid damage.

Lastly, you can use a strong stream of water from your garden hose to dislodge aphids. Focus on the undersides of leaves and new growth, where aphids tend to congregate. This might seem like a temporary solution, but aphids are surprisingly bad at regrouping. Even a gentle rain can knock aphids off your plants. The spray also washes off any honeydew.

Step Two: Spray Soapy Water

Once you've removed as many aphids as possible, spray affected plants with a homemade aphid remedy. Mix a few drops of dish soap or Dr. Bronner's Castile soap with one quart of water. (Don't overdo the soap, or you'll gum up your spray bottle!)

Spray this solution thoroughly on the tops and bottoms of leaves, the stems, etc. Reapply every couple of days for about 2 weeks. Soap is all you need to treat soft-bodied pests like aphids because it penetrates their cell membranes.

Step Three: Remove Affected Plants, If Necessary

Most aphid problems can be taken care of by simply repeating steps one and two. Only in the cases of severe infestation or plant disease is it necessary to cut the plant at its base and remove it from your garden.

Even now, I wouldn't spray chemical solutions or use organic pesticides like Neem oil or diatomaceous earth in my garden. Remember those beneficial insects that help us keep aphid populations in check? Even organic and "safe" sprays can negatively impact those good guys. It's just not worth reaching for a pesticide, in my opinion. We want to work with nature, not against it.

What Happens if Aphids Are Left Untreated?

Most healthy and established plants can tolerate moderate infestations without any lasting damage. New or particularly stressed-out plants may experience stunted growth or die if aphids spread disease to them.

Any leaves that are twisted or curled because of aphid feeding will remain deformed. I recommend pruning them, which will help free up some of the plant's energy so it can fend off the aphid attack on its own.

If you were to leave aphids on your plants long enough, natural predators are sure to find them. It may take those ladybugs and lacewings some time to catch up (because aphids can multiply so fast), but they'll eventually reduce numbers for you.

FAQs About Aphids

How do I know if my plants have aphids?

Check for clusters of tiny pear-shaped insects on new growth, curled leaves, or sticky honeydew on plants.

Can aphids kill my plants?

While healthy plants can tolerate moderate infestations, young or stressed plants may suffer serious damage or die from aphid-transmitted viruses.

What is the best natural way to get rid of aphids?

A strong water spray or soapy water solution works well for small infestations. Attracting natural predators like ladybugs is also highly effective (and good for your whole garden).

Should I worry about honeydew and sooty mold?

Honeydew itself isn’t harmful (just gross!), but it can attract other pests and cause mold growth. Address the aphid problem to eliminate honeydew. Spraying your plants with soapy water will wash away the honeydew and eliminate the creatures that cause it, which will treat the sooty mold.

How often should I check my plants for aphids?

Regularly inspect your plants during the growing season to catch and control aphids early. I recommend growing lots of herbs and leafy greens in your garden so there's something you can harvest every single day. As you clip some rosemary or arugula leaves for dinner, check over your garden for signs of pest pressure.

Don't Stress About Aphids

Don't let a couple (hundred) aphids ruin your garden party. I'm more of a "let it be" kind of gardener, so I don't really stress about pests in general. Honestly, checking on your garden regularly, planting lots of fragrant herbs and flowers in each garden bed, and pruning go a long way toward preventing major pest issues.

Whatever you do, don't reach for the pesticides at the first sign of a tiny soft-bodied critter. Instead, see how you can welcome more life into your garden. If your garden is operating as its own little ecosystem the way only an organic garden free of pesticides can, then you'll have plenty of beneficial insects around to take care of pest issues for you. Nature sorts itself out.

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Sources

Scientific American, "Stressed Plants 'Cry'"

UCDavis, "Aphid Relief from Sweet Alyssum"

UCONN Integrated Pest Management, "Perimeter Trap Cropping Works"