Aphid (2024)

FAQs

Are aphids harmful? ›

Infestations of aphids have been known to occur, causing discoloration, spotting, or puckering of leaves. Most species of aphids suck up the cell contents of plants and are (relatively) harmlessly with their piercing mouthparts. A few, however, inject toxic substances with their saliva.

Aphids have a complex life cycle, with both winged and wingless forms of adults of the same species developing, depending on the conditions. Wingless adult aphids are known as apterous, and winged adults as alate. Alate aphids have two pairs of wings, one of which is much larger than the other.

As you note in your question, 1) aphids are often not a huge problem as long as their population is kept in check, and 2) once they reach a critical mass, they can be quite a nuisance. The most organic method of control, and often a quite effective one, is the spray of water.

Aphids are sap-sucking insects, they have many predators and are the basis for many food chains. The sap sucking can cause a lack of plant vigour, distorted growth and often excrete a sticky substance (honeydew) on which sooty moulds can grow. Some aphids transmit plant viruses.

Although large infestations of aphids have been reported to trigger allergic inhalant reactions in some people, these insects generally pose no threat to humans. It's largely due to the damage that aphids do to cultivated plants, especially in temperate areas, that they're regarded as pests.

While aphids are commonly regarded as pests, they are not harmful to humans. In fact, some people claim that when they are eaten, they have a sweet or bitter taste. Don't worry if you eat an aphid by accident; you will not be harmed.

In the case of aphids, it may be a combination of the spring drought and our gardening routines. We often apply fertilizers in the spring to give our plants a boost of nutrients. Aphids are attracted to young, tender, fast-growing plant parts rich in nitrogen. Aphids are also attracted to stressed plants.

Insecticidal soaps and horticultural oil will kill aphids but must be applied regularly during heavy infestations since aphids reproduce so quickly. These products only kill aphids when they come in direct contact, so you'll need to reapply frequently until the pests are completely gone.

Spray the plants with soapy water every few days, especially on the underside of the leaves. One tablespoon of dish soap or castile soap per gallon of water is enough. Spray with dish soap plus cayenne pepper and/or neem oil. Neem oil sprays are available at most garden centers.

Vinegar can kill aphids on contact but be cautious as it can also harm plants.

What do aphids hate the most? ›

Catnip, garlic, chives, onion, and allium are aphid repellers. Probably don't want catnip in your keyhole garden, which would be trading one nuisance for another.

Avoid over-fertilizing in the garden. Too much nitrogen encourages lots of new, tender growth that aphids love. Use rubbing alcohol to kill aphids. Dilute it heavily, with 20 parts water to 1 part rubbing alcohol and spray on foliage and stems.

This ubiquitous pest typically starts showing up in gardens mid summer and will linger through fall, often spreading and getting worse if left unaddressed. Read below to learn how to identify aphids and aphid damage, and how to manage them.

Neem (azadirachtin) is a plant based pesticide that discourages aphid feeding. Insects are not killed quickly, but it makes them stop feeding and they slowly die. Insecticidal soap, horticultural oil and pyrethrins can be effective at controlling aphids.