What Aphids Are and Why They Matter
Aphids are small, soft-bodied insects that feed by sucking the nutrient-rich liquids out of plants.1 In large numbers, they can weaken plants significantly, harming flowers and fruit.1 They multiply quickly, so acting early is essential.
Signs of an Aphid Problem
The most visible symptom is distorted or stunted growth on new shoots and leaves.2 Aphids also excrete a sticky substance called honeydew, on which sooty moulds can grow.2 Some species transmit plant viruses, adding another layer of damage.2
Aphids go by several common names — greenfly, blackfly, and plant lice — and most plants are susceptible.2 They are most active during spring and summer outdoors, but can persist year-round on indoor plants.2
How Infestations Start
Infestations generally result from small numbers of winged aphids that fly to the plant and find it to be a suitable host.1 They deposit several wingless young on the most tender tissue before moving on to find a new plant.1 Those immature aphids, or nymphs, then establish the colony.
Many generations can multiply in a single season.1 This rapid reproduction is why a minor infestation can escalate fast if left unchecked.
Where to Look on Your Plants
Check the softest, newest growth first — the most tender tissue is where the first arrivals deposit their young.1 Aphids cluster on the most tender tissue, which is where the first arrivals deposit their young.1 A careful look with good light is usually enough to spot them.
Getting Rid of Aphids
Physical Removal
A strong blast of water from a hose dislodges aphids from stems and leaves. Repeat as needed, since aphids multiply quickly and a single pass may not be enough.1 This works well on robust plants that can handle the pressure.
Working With Natural Predators
Aphids are the basis for many food chains and have many natural predators.2 Encouraging beneficial insects — such as ladybirds and lacewings — into the garden provides ongoing biological control without chemicals. Avoid broad-spectrum insecticides that kill these helpers alongside the pests.
Targeted Treatments
For persistent colonies, targeted sprays applied directly to affected growth can reduce numbers quickly. Focus on the undersides of leaves where aphids shelter. Reapply after rain to maintain coverage.
Preventing a Return
Sap-sucking damage causes a lack of plant vigour, which makes stressed plants more attractive to further infestation.2 Keeping plants well-watered and fed reduces vulnerability. Inspect new plants before introducing them to your garden — a single infested arrival can seed a wider problem.
Watch for sooty mould on leaf surfaces; its presence signals an active aphid colony nearby, even if the insects themselves are out of sight.2 Catching it early means less damage and faster recovery.
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