Pest

Aphids

What are Aphids?

Aphids are small insects which feed on plant sap using their needle-like mouthparts. They are sometimes called greenfly (green aphids) or blackfly (black aphids) . There are more than 500 aphid species in Britain. Some aphids feed on only one or two species of plant, but others can be found on a wide range of plants. Most types of plant can be affected.

In the aphid life cycle the insect looks similar at each stage, just getting larger as it reaches maturity. For most of the year aphids give birth to live young (aphid larvae) which during warmer weather develop into adult insects in as little as seven days. Although a small colony of aphids isn’t a threat to a healthy plant, when they multiply very rapidly a heavy aphid infestation can weaken a plant. Aphids lay overwintering eggs in the autumn so as to survive the colder months of the year.

Aphids eggs are often laid in a woody tree or shrub and when the eggs hatch in the spring, the aphids feed on the soft young leaves. When the leaves become older and tougher the aphid grows wings and moves to another plant for the summer, usually a non-woody plant with soft foliage.

How to get rid of aphids

The most effective way to get rid of aphids is to remove them early using a combination of water, natural sprays, and regular monitoring. Start by spraying plants with a strong jet of water to dislodge them, then follow up with treatments like insecticidal soap or neem oil to kill remaining aphids and prevent them returning.

How to identify aphids

Aphids are little bugs about 2mm long. They are usually green or black but some types of aphid are yellow, pink, white or mottled. Flightless when young, aphids develop wings in the later stages of their life cycle. You often see clusters of aphids feeding at the growing tip of young plants.

Key signs of aphids:

- Clusters of tiny insects (1–4mm)

- Sticky residue (honeydew) on leaves

- Curling or distorted new growth

- Presence of ants (attracted to honeydew)

Some common species of aphids include:

Green aphids

Green aphids are the most common type. They are small, soft-bodied, and blend easily with leaves, often found on new shoots and buds.

Black aphids

Black aphids are darker in colour and often appear in dense clusters on stems and flower buds. They are commonly seen on roses and ornamental plants.

White or grey aphids

These aphids may appear pale or dusty and are sometimes mistaken for other pests. They often leave behind sticky honeydew on leaves.

Red or brown aphids

Less common, these aphids can appear reddish or brown and may be found on a variety of plants, particularly in warm conditions.

Common Australian aphid species

Some of the aphids you’re most likely to see in Australian gardens include the green peach aphid (Myzus persicae), rose aphid (Macrosiphum rosae), cabbage aphid (grey and waxy, found on brassicas), black citrus aphid (Toxoptera citricida), oleander aphid (bright yellow), woolly apple aphid, and cotton or melon aphid.

Aphid damage & symptoms

Aphids feed by sucking the sap of plants, weakening them and reducing their growth. They can also transmit virus diseases to the plant. Affected plant leaves or stems can become curled or distorted in shape.

Aphid colonies usually gather underneath leaves, on flowers or at growth points. As they suck the sap, they excrete a sugary honeydew onto the leaves below, which develop a shiny glaze. Although ants do not eat aphids they sometimes collect the honeydew they secrete. In damp conditions, sooty moulds grow on the honeydew, forming a black or greyish green deposit on the leaves. This is not only unsightly, but will gradually deprive the leaf of light and might eventually kill the plant.

Aphids shed their skins as they grow larger. The skins gather on the leaf surfaces below where they are feeding and form a whitish dust, often the first sign of an aphid infestation.

How can you get rid of aphids? There are many methods of aphid control. Here we’ve listed a few different aphid pest controls, ranging from cultural and biological to chemical.

Natural treatments for aphid control

Tackle individual aphids on plants and small colonies by simply squashing them or wiping them off the plant with a damp cloth or small watercolour paint brush.

Biological treatments to combat aphids include midges, whose larvae eat aphids (Aphidoletes aphidimyza) or a type of parasitic wasp whose larvae develop inside the aphids’ bodies (Aphidius). Ladybirds and their larvae also eat aphids. You can attract them into your garden by planting calendula.

Chemical treatments for aphid control

If natural and biological controls aren't practical, aphids can be controlled with targeted insecticides. Contact insecticides, such as sprays containing pyrethrins, work by killing aphids on contact, so thorough coverage of leaves (especially the undersides) is essential for good results.

Some species, such as woolly aphids, have a protective coating that contact sprays can’t easily penetrate. In these cases, a systemic insecticide may be more effective. These products are absorbed into the plant and kill aphids as they feed, while also providing ongoing protection against new infestations for several weeks.

Before you treat aphids on fruit and vegetables, always check that the insecticide is approved for use on edible crops. To protect bees and pollinating insects do not apply to plants when in flower. Do not use where bees are actively foraging. Do not apply when flowering weeds are present.

How to treat aphids on different plants

Aphid control can vary depending on the plant they’re affecting. Tailoring your approach helps manage infestations more effectively and reduces damage.

Aphids on roses

Roses commonly attract the rose aphid (Macrosiphum rosae), which is green or pink. Planting strongly scented herbs like thyme nearby can help deter them. For active infestations, use a rose-safe insecticide or wash them off with water.

Aphids on chilli and tomato plants

These plants are especially prone to aphids as soft new growth appears in spring, whether grown indoors or outdoors (most home gardens in Australia grow them outdoors). At the first sign of pests, wipe them off with a damp cloth or soft brush to prevent populations building up.

Aphids on trees

Aphids often overwinter as eggs on fruit trees such as cherries. Applying a dormant (winter) oil spray in mid-to-late winter, before bud burst (around July–August), can help control eggs before they hatch.

Aphids on runner beans and French beans

A useful companion planting method is to grow nasturtiums nearby, which attract aphids away from your crops and act as a trap plant.

Aphids on indoor plants

Indoor plants like basil are prone to aphids due to stable, warm conditions. Check plants regularly and remove aphids by hand or wipe them off to keep infestations under control.

Some plants require different aphid treatments:

Aphids on roses: try growing thyme near your roses because its strong scent deters black aphids, known as blackfly – one of the types of aphids that feed on roses. You can also get rid of aphids on roses with an insecticide designed for roses.

Aphids on chilli plants and tomato plants: these plants often attract aphids if they are grown indoors or in a greenhouse. As soon as you see them, wipe them off with a damp cloth or small paint brush.

Aphids on trees: aphids sometimes lay their eggs on fruit trees such as cherry trees over the winter. Aphid eggs can be destroyed by using a plant oil winter wash on a dry mild day from November until early February.

Aphids on runner beans and French beans: lure aphids away from your beans by planting nasturtiums nearby.

Aphids treatment for indoor plants: keep an eye out for signs of aphids on your indoor plants such as your basil plants and squash them between your finger and thumb or wipe them off as described before.

How to get rid of aphids (step-by-step)

Step 1: Identify the infestation

Look for clusters of tiny insects on new growth, sticky residue (honeydew), or curled leaves. These are signs of aphids.

Step 2: Remove aphids with water

Use a strong spray of water to knock aphids off leaves, especially the undersides where they gather. This is one of the quickest ways to reduce numbers.

Step 3: Apply a natural spray

Spray affected areas with insecticidal soap or neem oil. These treatments work by breaking down the aphids’ outer layer or disrupting their feeding and reproduction.

Step 4: Treat thoroughly

Cover all parts of the plant, including stems and leaf undersides, as sprays only work on direct contact.

Step 5: Repeat treatment

Reapply every few days until the infestation is under control, as aphids reproduce quickly.

Step 6: Remove heavily infested growth

Prune badly affected leaves or stems to reduce the population and help the plant recover.

Step 7: Monitor regularly

Check plants weekly to catch new infestations early and prevent spread.

How to prevent Aphids?

One way to prevent aphids damaging precious plants in your garden is to plant ‘companion’ plants which either put the aphids off completely or attract aphid predators which can keep down an aphid infestation. Here are some examples to try:

Lavender: the strong scent can deter aphids.

Wormwood (Artemisia absinthium): aphids appear to dislike the scent of this strongly smelling herb.

Fennel or herb fennel (Foeniculum vulgare): its attractive yellow blooms attract hoverflies, which prey on aphids.

FAQs

How do I identify aphids in my garden?

Aphids are tiny, soft-bodied insects found in clusters on new growth. Look for sticky residue, curled leaves, and visible bugs in green, black, or white.