Aphid Control in Your Garden (2024)

If treatment is required, spray withYates Baythroid Advanced Garden Pest Insect Killer Ready to Use Spray. It’s ready to use and perfect for use on vegies, such asBeans,Broccoli,CabbageandTomatoes, andornamental plants.

Aphids are common garden sap sucking pests. They can cause damage directly through their direct feeding or indirectly as vectors of plant viruses. Aphids excrete honeydew, which may cause a build up ofSooty mouldand attractAnts.

There are about 175 species of Aphids which occur in Australia and the vast majority are introduced (i.e., not native to Australia). Common pest Aphids include Black Citrus Aphids (Toxopteraspp.), Black Peach Aphid (Brachycaudus persicae), Cabbage Aphid (Brevicoryne brassicae), Green Peach Aphid (Myzus persicae) and Rose Aphid (Macrosiphum rosae). All these Aphids are introduced pests.

Aphids are small pear-shaped sap-sucking insects usually less than 3 mm long, which may be winged or wingless in the adult form. Nymphs are typically miniature versions of the adults but without wings.

• Adult Black Citrus Aphids are shiny dark brown to black Aphids about 2 mm long. They infest blossoms and young growth ofcitrus trees.
• Adult Black Peach Aphids are glossy black Aphids about 1.5 mm long. Black Peach Aphids nymphs are brown. These Aphids tend to cluster around blossoms and young growth ofPeach and Nectarinetrees.
• Adult Cabbage Aphids are about 2.5 mm long, are greyish to light green in colour, and covered with a mealy waxy substance. Cabbage Aphids typically form tight clusters on the upper surfaces of leaves and flower stems of brassica plants.
• Adult Green Peach Aphids are about 2.5 mm long and vary in colour from yellow to pale green to pinkish. Green Peach Aphids may form clusters of hundreds of individuals on a vast range of plants.
• Rose Aphids are about 2.5 mm long, and are green, pink or brownish orange in colour. All colour forms may be present at the same time. They typically form clusters onRosebuds.

Aphids typically develop through a life cycle of gradual metamorphosis. Depending on the species adult Aphids may lay eggs some of the time and lay live young at other times, or not lay eggs at all. Many Aphid species are capable of reproducing without males (i.e., they reproduce parthenogenetically). Aphid colonies can increase in size so rapidly because female Aphids mostly lay live young and can do so without having to mate.

Wingless adults are the norm when the colony is not overcrowded. Winged adult Aphids develop when a colony must migrate from an over-wintering site, or from drying plants, or when conditions become too crowded.

Aphids typically pass through 4 nymph stages (instars) before the adult stage. As they moult, they leave behind their old skin casts that are easily visible in Aphid colonies as white objects. Aphid life cycles can be completed in 10 to 14 days in warm weather, and there may be more than 20 generations per year depending on the climate and the species.

Some Aphid species feed on a specific plant, or groups of plants, while others feed on a wide variety of plants.

• Black Citrus Aphids mostly feed oncitrusbut may also attackCamelliaand Coffee plants.
• Black Peach Aphids feed on stone fruit includingPeaches,Nectarines,Plumsand Apricots. Black Peach Aphids avoid the heat of summer by moving down the tree and feeding on the roots. They move back into the canopy in autumn.
• Cabbage Aphids feed on brassicas, includingCabbage,Turnip,Broccoli,Brussels Sprouts,Cauliflower, commonStock, andweedssuch as Wild Turnip and Wild Mustard.
• Green Peach Aphids feed on a wide range of plants including stone fruit; vegetables such asBeans, Brassicas,Lettuce,Potato,SpinachandTomato;ornamental plantsincludingDahlias,Geraniums,PoppiesandRoses; andweedssuch asCapeweed, Dock and SowThistle.
• Rose Aphids feed onRoses.

• Distorted leaves and leaf drop.
• Wilting and stunting of seedlings.
• Wilting of shoots.
• Failure of fruit set. Fruit drop.
• Aphids excrete honeydew, which may promote the growth ofSooty Mouldand attractAnts.
• Leaves may be covered in unsightly white Aphid skin casts.
• Green Peach Aphids can transmit plant viruses such as potato leaf roll virus and several mosaic viruses.

Monitor

• Check susceptible plants while watering the garden or weeding. Look for clusters of small pear-shaped insects andSooty mouldorAntactivity.

Prevent

• Ants may protect Aphid colonies in return for a feed of honeydew. You can prevent Ants from climbing into trees by banding the trunks with horticultural glue.
• Trap Black Peach Aphids moving up and down the tree trunk by banding the trunk with horticultural glue.
• Some Aphid species breed in weeds. Controlweeds.

Natural Enemies

• Parasitic wasps (seeBeneficial Wasps) cause Aphids to turn into shell-like ‘mummies’. They may be bronze coloured or black depending on the wasp species.
• Hover fly larvae, lacewing larvae and ladybird beetles are the main predators of Aphids.
• Wasps and predators are very efficient at controlling Aphids. If you find Aphids on your plants, wait a week to see if the natural enemies control them for you. If they don’t control the Aphids, then you can take action.

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