African black beetle

Heteronychus arator

Adult beetles are shiny black and cylindrical (not flattened), up to 12 mm long. Newly emerged they are brown, darkening to black as they mature. Occaisonally, large numbers fly into paddocks, but usually they walk slowly over the soil surface. Larvae live in the soil and are typical white "curl grubs", up to 25 mm long, with a brown head and three pairs of legs. The rear is swollen, baggy, and blue-grey, due to food and soil they have eaten.

Damage: African black beetle adults and larvae feed on many non-legume crops and plants, and are important pests of horticultural crops such as potatoes. Grasses with runners, such as kikuyu and couch, and tufted perennial grasses, such as perennial rye and paspalum may be damaged. Adult beetles chew stemsjust below ground level, leaving frayed edges. Plants or tillers may fall over. Small larvae feed on decaying organic matter, changing to root feeding as they mature. Brown or dead patches result, and the grass is easily pulled out. The extent of damage to perenial grass pastures in Western Australia is unknown, but serious damage has been measured in New Zealand, where such pastures are widely grown. The incidence of African black beetle may increase if a trend towards perenial grasses develops in coastal regions. Adults occaisonally feed in the crown of cereal plants. In spring, this results in tillers falling over, causing up to 10 per cent crop loss. In autumn, seedlings may be killed.