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Hoverfly larvae feed on aphids and adult hoverflies are pollinators. These are good grubs, but they are often misidentified as diamondback moth larvae or other pest caterpillars
Hoverfly larva with tapering head region and no visible legs (left) and diamondback moth larva with a defined head capsule and six true legs (right) (Source: cesar)
Where have they been reported?
Green legless grubs have been found in sweep net catches within legume and canola crops within the Victorian Wimmera and Mallee, as well as the NSW Riverina. These have been identified as hoverfly larvae, a beneficial insect that feeds on aphids in it’s juvenile stage. They are often found in crops during spring in response to aphids colonising crops. In many instances people misidentify hoverfly larvae as pest grubs, often diamondback moth caterpillars.
About hoverflies
Hoverflies are flies from the family Syrphidae. The adults have large eyes and a flattened body with black and yellow/orange markings; hence they are easily confused with bees. Adults are pollinators; they feed on pollen and nectar. The larvae are maggot-like, legless grubs with a tapering head region and no eyes. Larvae can grow to up to 10 mm long and they vary in colour from cream to green or brown; many have a white stripe down the centre of their back.
For further information on hoverflies and other beneficial insects likely to be encountered in broadacre crops and pastures, view the GRDC Back Pocket Guide – Beneficial Insects.
Our advice
It is important that hoverflies are correctly identified before deciding on control strategies. Click here for images of hoverflies. Larvae are a very reliable form of control during the warmer days of spring when low to moderate numbers of aphids are present.
Source of field reports of hoverflies
Simon Craig – Agronomist, Agronomise Pty Ltd. (Victorian Mallee)
Andrew Reardon – Agronomist, AGnVET (NSW Riverina)
John Robertson – Agronomist, Agwise Services Pty Ltd. (Victorian Wimmera)
Justin Tidd – Agronomist, Landmark (NSW Riverina)
Nick Zordan – Agronomist, Western Ag (Victorian Wimmera)
What is PestFacts?
PestFacts south-eastern keeps growers and advisers informed about invertebrate pests and beneficials in broadacre crops and pastures during the winter-cropping season in Victoria and southern New South Wales.
PestFacts south-eastern is run through IPMforGrains: Best Practice Insect Pest Management, a project delivered by the National Pest Information Network (cesar, DPIRD, QDAF, NSW DPI, and SARDI). This project aims to provide grain growers and advisors with information on invertebrate grain pest occurrence and equip industry with the knowledge needed to implement integrated pest management practices. This initiative is a GRDC investment and includes in-kind contributions from all project partner organisations.
We need your reports
PestFacts is produced on an ʻas-needsʼ basis and relies upon pest observations and field reports from our subscribers. If you have recently observed invertebrate pests (or beneficial species) in broadacre crops, please contact us to report your observations.
Agricultural invertebrate identification
If you are a grower or agronomist in Victoria or NSW working with broadacre crops or pastures, we can assist you with identifying invertebrates found on farms at no cost. Please contact us for identification help.
PestFacts map
PestFacts map is an interactive tool that allows users to search and view historical pest reports across Victoria and NSW. The map is updated with each issue of PestFacts to include new reports.
How to acknowledge PestFacts?
With appropriate acknowledgement, cesar grants permission to reproduce information taken directly from PestFacts. To cite PestFacts: “PestFacts south-eastern (<<enter date published>>). cesar pty ltd.”
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