Pests are a constant worry for us houseplant enthusiasts, and few pests fill us with as much dread as Aphids! These stubborn critters invade our homes quickly and, if left untreated, can cause chaos in our collections, traveling rapidly from plant to plant and leaving a trail of destruction in their wake. If that wasn’t fear-inducing enough, aphids are often immune to chemical pesticides, making them notoriously tricky to eradicate.
But don’t despair, there are plenty of alternative treatments and clever tricks you can use to protect your plants from an aphid invasion. Our ultimate guide to getting rid of Aphids will teach you everything you need to know to exterminate these pests for good!
What Are Aphids?
Aphids are tiny, oval-shaped insects belonging to the Aphidoidea family. There are around 5000 different species of aphid, most measuring less than 1/8 inch in length, and although most travel around by crawling, some species are winged and can fly between plants. You may commonly hear of aphids referred to as greenflies or blackflies, but they can actually range in color from green, black, brown, pink, or even translucent. They tend to live on the underside of leaves but can be found anywhere on the stems and foliage of host plants. They feed on the sap of plants, using their long mouthpieces to pierce the foliage and suck out the nutrients. Some species of aphids are monophagous, meaning they only feed on one specific plant, whilst other species will feed on many different types of plants.
Females can reach maturity in under a week and produce around 80 young during their lifespan, usually without the need for a male partner. Often, newborn aphids are already pregnant, so their population has the potential to increase exponentially over very short periods of time, which is one of the reasons they can be so troublesome to deal with.
What Causes Aphid Infestations?
Aphids prefer to feed on soft, new growth rather than older woody stems, so young plants are particularly susceptible to aphids. Unhealthy plants, particularly those suffering from root rot are also more vulnerable to aphids since the soft, rotting tissue entices them to feed. Aphid infestations on stressed or unhealthy plants are far more likely to be fatal, so try to meet the individual needs of each of your houseplants. After all, prevention is the best cure!
Aphids are common garden pests and are most likely to be found outdoors, but they are much easier to keep in check outside as their natural predators will keep their population to a minimum. Indoors, however, aphids have no natural predators so an infestation can quickly get out of hand. Bringing outdoors plants inside can introduce aphids to your houseplants, as can moving houseplants outside during summer. Wash home-grown vegetables thoroughly before bringing them indoors, and inspect cut flowers for any signs of aphids before bringing them inside. They can even be brought in on clothing, so be extra careful when coming inside after gardening that you don’t inadvertently introduce them to your houseplant collection.
How to Prevent Aphids
Keeping windows closed, especially during summer, is the best way to prevent aphids from invading your home since they usually migrate from the outside in.
As always, it’s good practice to thoroughly inspect new houseplants for any sign of illness or pests before you purchase. Even if it seems healthy, it’s always a good idea to keep it isolated from your wider collection for at least four weeks, giving any hidden nasties plenty of time to show themselves before you inadvertently introduce them to the whole plant gang!
Regularly inspecting all of your houseplants is so important for keeping pests at bay. Pay special attention to the undersides of the leaves. Aphids reproduce incredibly quickly, so catching an infestation early is the best way of treating it successfully. Its also beneficial to carry out preventative neem oil treatments on all of your houseplants periodically, even when there are no signs of infestation, as it offers residual protection against pests.
Symptoms of an Aphid Infestation
Luckily, aphids are generally big enough to spot with the naked eye. They often cluster together, making them easier to spot when they settle on the undersides of leaves. They prefer feeding on soft, new growth so keep a keen eye out for aphids on new plants in particular. You may also notice small white specks on the foliage or soil. These ‘casts’ are the exoskeletons that the aphid nymphs shed when they reach maturity.
As the aphids feed on your plant, they secrete a sticky substance known as honeydew, which is visible as shiny patches on the leaves around the areas where the aphids are feeding. This substance in itself is not harmful, but it can lead to the development of sooty mold on the leaves. Sooty mold appears as black fungus on the foliage, and whilst it isn’t particularly harmful to your plants, it can inhibit photosynthesis, and also attracts other fungus-loving pests like fungus gnats. The honeydew is sweet, so it may also attract ants!
Because the insects deplete your plant’s nutrients when they consume its sap, it will gradually become weaker, its growth will become stunted and its leaves will turn yellow, curl, wilt, and droop, before dropping. If left unchecked, the plant will become too weak to support itself and will eventually die. The good news is that aphids aren’t as catastrophic as some other pests, and healthy plants should be able to withstand a moderate infestation if treated promptly.
Aphids, apart from damaging the plant when they feed, are also vectors of secondary viruses like mosaic virus which they carry on their feet and can transmit to the host plant. Look out for yellow leaf mottling, patches, or streaks that are symptomatic of mosaic virus.
How to Get Rid of Aphids
Aphids are notorious for their immunity to synthetic and chemical pesticides, making them difficult to treat, particularly if the infestation is recurring, so it’s best to stick to natural remedies when dealing with aphids.
Remember to perform a test application of your chosen method on a small area of the plant first. Wait a couple of days to make sure the plant isn’t harmed before treating the whole plant.
Isolate and Prune
As with any infestation, isolate any affected plants at the first sign of trouble. This is particularly important with aphids, as they will quickly migrate to nearby plants if they become overcrowded, or when the nutrients of the original host are becoming depleted. Thoroughly clean the area where the plant stood to eradicate any lingering insects.
Prune the worst affected areas of the plant, and dispose of them carefully. Dunking the cuttings in a bucket of soapy water will kill the bugs.
If the infestation is in its very early stages, you may be able to deal with it by rinsing the plant under a steady stream of water, like a shower or hosepipe with enough force that it will remove the bugs without damaging the plant. The higher the water pressure, the more effective this technique will be, so it’s best used on tougher plants. This method won’t be effective on well-established infestations.
Neem oil is an organic, non-toxic pesticide and insect-repellant derived from the Azadirachta tree. It is mostly available as a concentrate, so follow the dilution instructions on the bottle. Spay the diluted neem oil over the entire plant, or use cotton buds or a soft cloth to wipe over each leaf and stem with the solution.
Neem oil is anti-fungal, so it will combat any sooty mold caused by the aphids, as well as offer residual protection against future infestations, so don’t wipe the oil off after treating your plant. You can give your plants a spray with the same neem oil treatment a couple of times a year even when no infestations are present, just as a preventative measure.
Insecticidal soap spray will kill aphids on contact by dissolving their protective outer layer and smothering them. You can purchase pre-made sprays or you can make your own at home by mixing one tablespoon of fragrance-free dish soap with one teaspoon of vegetable oil and one liter of water. Pour the mixture into a spray bottle and spray liberally over the entire plant, taking care to make contact with the underside of the leaves especially. Leave the spray to settle for a few hours or overnight before wiping over the foliage to remove any dead insects.
Unlike neem oil, insecticidal soap doesn’t offer any residual protection against future infestations. You may need to repeat this treatment a few times over several days or weeks to exterminate the whole aphid population.
Rubbing alcohol is another effective treatment that kills the bugs on contact, although it’s rather time-consuming. Using a soft cloth or cotton bud, thoroughly wipe over each leaf and stem, ensuring you make contact with all the bugs. To save time, you can dilute the alcohol with water at a ratio of 1:1 and spray it over the entire plant, but this method will probably need to be repeated a few times to be fully effective. Allow the alcohol to soak in for a few hours before rinsing the plant thoroughly under running water.
Sticky traps will help to keep an aphid infestation at bay, but only if yours are a winged species. Place the sticky traps in the vicinity of the affected plant. The bright yellow color of the traps will attract the flying aphids, and they will become caught on the sticky surface of the trap and eventually die.
Aside from insecticidal sprays, there are other natural, non-toxic sprays that you can make at home to treat aphids with varying degrees of success.
Garlic is a natural insect repellent, as it contains sulfur, and most insects are averse to strong smells. Garlic also has anti-fungal properties, so will help to prevent sooty mold from taking hold.
Make a garlic spray by finely chopping four or five cloves and mixing them with a teaspoon of vegetable oil, a tablespoon of dish soap, and a liter of water. The dish soap helps the mixture adhere to the foliage and the bugs. Mix well and let the mixture sit for 24 hours before straining out the garlic and pouring it into a spray bottle. Apply to the plant as you would with insecticidal soap.
A homemade chili pepper spray can be used in much the same way as a garlic spray, and you can use either fresh, chopped chillis or dried chili powder. The dish soap and water mixture will kill the insects it comes into contact with, whilst the capsaicin, which gives the chili its heat, will repel any lingering pests and prevent them from returning. You could even mix chili and garlic for a doubly effective super spray!
Frequently Asked Questions
Here are a few of the most frequently asked question that we get about getting rid of aphids:
How Long Do Aphids Live?
The lifespan and reproductive cycle of an aphid are very short and vigorous. Some species give birth to live young, who are already pregnant, others give birth to eggs, which can reach reproductive maturity in as little as a week! Females usually live for around a month, during which time she can produce up to 80 offspring, so it’s easy to see how infestations can get out of hand so quickly.
Are Aphids Harmful to Humans or Animals?
Thankfully, aphids aren’t harmful to any humans or animals in your home. Whilst their long mouthpiece is perfect for draining the sap from our plants, it’s nowhere near strong enough to bite on human skin.