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Bronzed field beetles

Agronomist, Glen Sheppard (IMAG Consulting), has reported feeding damage to a wheat crop near Wellington, in the Central West Slopes and Plains district of NSW. Beetle larvae collected from the paddock have been identified by Senior Technical Officer, Ken Henry (SARDI), as the bronzed field beetle.

Bronzed field beetles (Adelium brevicorne) are up to 11 mm long and are shiny black in colour with a slight bronze appearance. The larvae are dark brown, up to 12 mm long and 3 mm wide. They have twelve body segments, the last one having two distinct upturned spines. The larvae are often confused with the grey false wireworm, which is a serious pest in Victoria and parts of southern NSW. The larvae of the grey false wireworm have a flatter appearance and the adults are dull brown in colour and smaller in size. For information on the grey false wireworm, refer to PestFacts Issue No. 3.

Bronze field beetle larvae are generally within the top 1 cm of the soil and can be found under plant material, clods of soil, rocks or wood. The larvae may be present in the soil with little or no damage to plant seedlings. This is because they primarily feed on dead organic matter and high numbers are required to cause serious crop damage. They mostly feed on plants at night but can sometimes be seen during the day. Glen reports the damage is similar to that caused by cutworms; chewing damage and ring barking to the above ground stem area with some plants eaten completely through, leaving only the stumps.

Bronzed field beetles are important pests of establishing canola. They typically do not affect cereal and pulse crops, although last year in South Australia, Ken received reports of feeding damage to lupins that was caused by bronzed field beetles. Glen is unaware of problems with bronzed field beetles in the past within this paddock and reports that the damage was confined within a small area.

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