Beneficial invertebrates

Several groups of beneficial invertebrates are prevalent during spring and can play a key role in control when low to moderate numbers of pests, such as aphids and lepidopteran larvae, are present. It is important to consider numbers of beneficials before deciding on a control strategy. Reports indicate that in many areas beneficial invertebrates have been slow to build-up in numbers this season, although there has been a sharp increase over the last week. Beneficial invertebrates likely to be encountered now include:

• Hoverflies (Family: Syrphidae) – larvae prey on aphids by spearing them with their mouth hooks and sucking out the body contents. They are grub or maggot-like, up to 10 mm long, blind, legless and transparent cream to green or brown in colour. Adults feed on pollen and honeydew, grow up to 10 mm long and have a flattened body with black and yellow markings. Adults can hover and fly swiftly, and may be confused with bees or wasps. Hoverfly larvae have been identified for agronomist, Mike Laidlaw (Harberger Farm Supplies), who reported finding them in low numbers in canola and pulse crops around Donald, in the Wimmera district of Victoria. Click here for images of hoverflies.

• Ladybird beetles (Family: Coccinellidae) – both adults and larvae consume prey including aphids, leafhoppers, thrips, moth eggs and small larvae. Adults are round or oval in shape, shiny and typically have patterns of black on a red, orange or yellow body. Larvae are generally elongated and mostly grey or black with orange markings and black legs.  Click here for images of the common spotted ladybird.

• Lacewings (Order: Neuroptera) – adults are 6-15 mm in length, have long antennae and wings with numerous veins giving a lacy appearance. Their wings are held over the abdomen in an inverted ‘V’ shape. Larvae vary in shape and size depending on species, but all have a tapered body and prominent, sickle-shaped mouthparts. Brown lacewings (Family: Hemerobidae) are predatory as both larvae and adults, whereas only the larvae of green lacewings (Family: Chrysopidae) are active predators.  Click here for images of brown lacewings and click here for images of green lacewings.

• Parasitic wasps (Order Hymenoptera) - adults vary in size (1-120mm long), and colour ranging from brightly coloured orange to completely shiny black. They have two sets of wings that are clear or dark coloured. Female wasps often lay their eggs into host larvae or eggs. The developing wasp larva feeds inside the host. Aphid ‘mummies’ (buff to bronze coloured, bloated enlarged aphids) indicates the activity of aphid parasitoid wasps that are small, usually dark in colour and difficult to detect. Females lay their eggs into the bodies of live aphids and the developing larva feeds inside, eventually killing it. The adult wasp then emerges through an exit hole in the body. Click here for images of aphid parasitoids.