SEASONAL HISTORY, HOSTS AND NATURAL ENEMIES OF MONISTRIA DISCREPANS (WALKER) (ORTHOPTERA: PYRGOMORPHIDAE) IN SOUTH‐WEST QUEENSLAND

Monistria discrepans (Walker) in south‐west Queensland is an obligate univoltine species. A temperature controlled diapause of the eggs confines hatching of eggs laid in the March‐May period to early October. Nymphs develop throughout the summer resulting in a population entirely of adults by April. The presence of nymphs coincides with the greatest growth of the host plant Eremophila gilesii F. Muell. In the Charleville area of south‐west Queensland, feeding is restricted to Eremophila and Myoporum (both Myoporaceae) but species of other families of plants are utilized in eastern areas of Queensland. In laboratory tests, nymphs failed to develop on species of Gramineae, Compositae and Leguminosae. Parasitism by the mites Leptus sp. and Podapolipus sp. nr. lahillei Naudo reached levels of 7.0% and 94.4% respectively during 1973–75. The non‐specific tachinid Ceracia fergusoni (Malloch) and sarcophagid Blaesoxipha pachytyli (Skuse) parasitised mainly adult females (up to 20.8% total parasitism) but also attacked final instar female nymphs and adult males. The hyperparasite Perilampus sp. nr. cairnsensis Girault was found in C. fergusoni larvae. The fungus, Aspergillus flavus Link, infected up to 40.9% of field‐collected adults but survival of infected individuals was high except after rain or in the high humidity of the laboratory. Although insectivorous birds are present in the area they exerted little control over the M. discrepans population.