THE BIOLOGY AND PEST STATUS OF OXYCANUS FUSCOM ACULATUS WALKER (LEPIDOPTERA: HEPIALIDAE) IN TASMANIA

Oxycanus fuscomaculatus , which has a life cycle of 2 years duration, inhabits south‐eastern Australia including Tasmania, and the south‐west comer of Western Australia. The adults emerge at night in late April and May particularly shortly after falls of rain. The females mate before flying and each lays about 1,800 eggs. It appears that in the field the eggs hatch in September or October. The larvae inhabit almost vertical tunnels in the soil and emerge at night to feed on the foliage of herbaceous plants, particularly grasses. Pupae are present from February to May. O. fuscomaculatus appears to have few insect parasites or predators in the pasture habitat. Since 1949 the larvae have caused sporadic but widespread serious damage to improved pastures, particularly in the autumn, winter and early spring on King Island and on the north‐west coast of Tasmania. Outbreaks of O. fuscomuculutus and 2 other pasture inhabiting hepialids, Oncopera intricata and O. rufobrunnea , appear to have occurred independently of each other, in spite of the concurrence of these 3 species in many pastures.