Blackhead pasture cockchafers (Acrossidius tasmaniae) are a common pest.
They appear to be most problematic in areas where the annual rainfall exceeds 480 mm. The larvae are creamy-grey in colour with a hardened black head capsule. They have soft bodies and six legs. Fully-grown larvae are 15-20 mm long and tend to curl into a C-shape when exposed. Adult cockchafer beetles are approximately 10 mm long, dark brown to black in colour.
Blackheaded pasture cockchafers are the only cockchafer species that comes to the surface to feed. The larvae typically surface at night in response to rainfall and/or heavy dews. They feed on clovers, grasses and some weeds, chewing plant material in their tunnels during the day. Small mounds of dirt surrounding holes on the soil surface are often the first sign of their activity. Other indicators are bare patches that appear in pastures from mid-autumn to late winter. Most feeding damage occurs in May and June, when the rate of pasture growth is slowing down due to the cold weather.