Observations on Rhopaea magnicornis Blackburn in sugarcane at Condong, NSW

Rhopaea magnicornis Blackburn has been recognised as a spasmodic pest of sugarcane in New South Wales since the early 1930s. Traditional canegrub control using benzene hexachloride 20% dust was not always effective, and in any case was unacceptable because of safe handling and environmental concerns, even before the phase-out of organochlorine products in the mid-1980s. As a prerequisite to investigation of possible control techniques, the life cycle and behaviour of the insect were studied. The findings are reported herein. The most significant finding was that the insect could complete its life cycle in 1 year, as opposed to the 2-year cycle previously postulated. The I-year cycle appears to be the more normal situation. Damage patterns are described. Chemical and non-chemical alternatives to the traditional chemical control methods are discussed. Suggestions are made as to future research needs.