19 Jan Aphids


Aphids have long been the gardener’s foe with them attacking a wide range of ornamental and edible crops. The pests themselves are typically bulbous in shape and around 2mm in length. They come in a variety of colours such as green, yellow, pink, brown and black. Plants attacked generally display limp, withered new growth with aphids typically present and visible to the naked eye as well as their discarded exoskeletons. Piercing and sucking insects such as aphids can also be credited with the spread of various plant viruses.

Damage Caused:

Aphids suck on the plants sap system that weakens the plant considerably. They can generally be found on the soft new growth of plants that is the softest part for them to pierce and draw sap, otherwise on the underside of leaves.

Ants can generally be found around aphids protecting them from natural predators such as ladybirds in return for a feed on the sugary substance (honey dew) they excrete on their backs.

It is also this honey dew that feeds a fungus called ‘sooty mould’ that blankets the leaves in a back, sooty film. Removal of the aphids will remove the source of the honey dew and thus diminish both of these.


Aphids are one of the easiest pests to kill but they are also one of the fastest to re-colonise as one quickly turns into hundreds.

Green: Horticultural soaps (eg. Natra Soap) and oils (eg. Eco-Oil) sprays are useful for both vegetable and ornamental gardeners. Soap sprays work by dissolving the exoskeleton of the pest killing it. Oils sprays work by smothering the pests, blocking their breathing (which they do through their body) and killing them. Application to the entire plant (including undersides of leaves is crucial when using these types of products, as they require you to get the spray onto every pest for successful control. Just a few sheltered pests can become hundreds in a matter of days.

NB Do not apply oil sprays in temperatures exceeding 25°C as this will likely burn foliage.

Orange: Generally only ornamentals are treated with systemic insecticides (eg. Confidor, Maxguard),which penetrate into the plants sap system that the pests feed on. They are highly efficient at killing these pests and last on average two weeks in the plants system. As they are systemic the spray does not have to make contact with the pest itself to work and insects can be killed in areas of the plant not reached by the spray (though thorough application is recommended)

NB Care should be taken when spraying these above chemicals is they harm foraging bees. As a rule I only use these on plants that are not currently in flower to avoid the risk to bees that are so vital in the garden. Saying that these sprays are invaluable for treating pests in situations such as hedging where contact with individual pests is not always possible.

Red: Not required for this pest.



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