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Beneficial insects

Several groups of beneficial insects are prevalent during spring and can play a key role in pest control when low to moderate numbers of pests, such as aphids and caterpillars, are present. It is important to consider numbers of beneficials before deciding on a control strategy. Some beneficial insects likely to be encountered include:

  • Damsel bugs (Family: Nabidae) – adults are 8-12 mm long and move quickly when disturbed. They have a slender light-brown body with long antennae and large protruding eyes. Juveniles are similar but smaller in size. Damsel bugs feed on a range of soft-bodied prey including moth eggs, aphids, small caterpillars and mites. They have a long curved ‘snout’ that is carried under the body when not feeding. Click here for images of damsel bugs.
  • Hoverflies (Family: Syrphidae) – adults are 4-10 mm long and have dark-coloured flattened bodies with black and yellow markings. As the name suggests they ‘hover’ over objects and look similar to bees and wasps. The larvae are legless, green in colour, 8-10 mm long and appear grub-like. They are often mistaken for pest caterpillars such as diamondback moth. Hoverflies attack a range of soft-bodied insects, but prefer aphids. They are quite common in flowering crops such as canola. Click here for images of hoverflies.
  • Parasitic wasps (Order: Hymenoptera) – adults vary in size (1-80 mm 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, usually aphids or pest caterpillars. Aphid ‘mummies’ (bronze-coloured, bloated/enlarged aphids) indicate the activity of aphid parasitic wasps, which are small and difficult to detect. Click here for images of aphid parasitic wasps.
  • Ladybird beetles (Family: Coccinellidae) – both adults and larvae consume prey including aphids, leafhoppers, thrips, moth eggs and small caterpillars. 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. They are found in most crops. Click here for images of the common spotted ladybird.
  • Lacewings (Order: Neuroptera) – adults are 6-20 mm in length, have long antennae and wings with numerous veins giving them 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 are predatory as both larvae and adults, whereas only the larvae of green lacewings are active predators. They attack aphids, thrips, caterpillars and moth eggs. Click here for images of brown lacewings and click here for images of green lacewings.

For further information on beneficial insects likely to be encountered in broadacre crops and pastures, view the GRDC Back Pocket Guide – Beneficial Insects.

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