How to Remove and Prevent Aphids on Trees

Have you recently noticed an excessive amount of sap dripping from your trees? What about a significant number of ants crawling around? These could be signs of a possible aphid infestation. Not only are aphids on trees a nuisance to your home and garden, but they also detract from the health and beauty of your trees. While the best course of action is to reach out to trained arborists, like those at Vernon Imel, you can also try to treat the infestation yourself.

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What Are Aphids and Why Should I Be Concerned?

Aphids are small, soft-bodied, oval- or pear-shaped insects and are usually 1/8 inch or smaller. With around 5,000 known species, they vary in color and can be green, yellow, brown, red, or black, depending on the species’ food source. In general, they’re wingless, but in certain circumstances can grow wings, most commonly when populations are high and their food source is limited.

Aphids are a concern for your trees because they are sapsuckers and like to feed on your trees’ foliage, especially leaf buds and tender new shoots. They use their sharp, piercing mouthparts, called stylets, to suck the sap out of leaves and new-growth branches, and then they secrete a sticky waste substance called honeydew. With a large infestation this secretion, which is sometimes yellow in color, drips off the trees onto the surface below; if you’ve noticed a sticky substance on your windshield after parking under a tree, it’s likely aphid honeydew.

Aphids on trees will weaken the plant and can also act as vectors for plant viruses or encourage the growth of sooty molds. Their honeydew secretion also attracts other pests, like ant colonies, leading to more issues. Because of the damage, they can cause it’s best to take steps early on to prevent an infestation if you don’t already have an active one.

Treating Active Infestations

While treating an active infestation is the least desirable of the options in relation to aphids, there are a few tactics you can employ. Some common methods for treating an aphid infestation include strong water blasts, pruning, insecticide soaps, and employing natural remedies like ladybugs.

Water

If you’ve noticed sticky residue or aphid colonies on your tree leaves, you can start by spraying down the leaves and foliage with a strong blast of water. As aphids tend to congregate on the underside of leaves, focus the water force there and repeat this step each day for up to two weeks until the aphids are no longer present. Once the aphids have fallen off the tree leaves, they are unlikely to return, due to their overall lack of mobility.

Pruning

For smaller infestations, homeowners can consider pruning away the sections of trees and plants containing the aphids. You can do this yourself or call in a professional tree service to address the issue. The key is making sure to get all the aphids and their egg clusters without pruning too much or causing harm to the trees.

Natural

A gardening favorite is to use natural methods to try to eradicate aphids. While ants may carry away some aphids to feed on their honeydew, they are also likely to use your trees to farm the aphids for a continuous supply of the sticky substance. To ensure the success of beneficial insects, like ladybugs and lacewings, you must also eradicate the secondary ant infestation—the ants will try to prevent natural predators from harming their food source.

One of the more voracious predators of aphids is the ladybug. Ladybugs can eat up to 60 aphids a day or up to 5,000 in a year. A loveliness (group) of ladybugs can significantly reduce an aphid infestation naturally. You can even purchase ladybugs and green lacewings, either alive or in their larval state, to release into your garden and trees.

Insecticide

If water and natural treatments are unsuccessful in removing the aphid infestation, consider more commercial treatments like neem oil or insecticidal soap. As these have various ingredients that may also be harmful to beneficial insects or even small pets, they should only be used as a last resort.

For maximum efficacy, these treatments should be sprayed until the tree is saturated and it’s dripping from the foliage. This ensures the spray has optimum chances to come into direct contact with the aphids. It can take several applications to eradicate the infestation. If you’re unsure about what may be best to use, consider reaching out to a trained arborist.

Preventative Measures You Can Take

The best-case scenario for aphid infestations is to prevent them altogether. There are a few ways you can go about doing this. To start, check your plants and trees before you purchase them. Look for live aphids or groupings of eggs on the underside of the leaves. If you find aphids on trees or plants during purchase, decide if you can successfully remove the infestation before bringing the tree into your yard or look for another non-infested tree.

When purchasing plants for your garden, you can also select plants aphids like and dislike. Place plants that repel aphids—oregano, chive, sage, leeks, garlic, onions, and more—nearer to your trees to deter the pests from coming around. You can also place more aphid-appealing plants, such as mustard or nasturtium, across your landscape, away from your trees. This will keep the trees safe and can possibly give you a more manageable treatment area, not so high off the ground. Consider, too, plants that attract aphids’ natural predators, like green lacewings and ladybugs. Some of these include dill, coriander, dandelions, and fennel. Just intersperse them throughout the garden to attract the “good-guy” insects.

Whether you’re trying to prevent aphids on trees or eradicate a current infestation, there are multiple tactics you can take. The best route will be dependent on your trees, the level of infestation, and how you prefer to garden. If you’re unsure what to do or where to start, contact trained professionals, like those at Vernon Imel, who are ready and available to assist.