Since October 2000, the commercial product Green Guard®, based on the entomopathogenic fungus Metarhizium anisopliae var. acridum produced by SGB Pty. Ltd. Wodonga, Victoria, has been used by the Australian Plague Locust Commission for operational control of the Australian plague locust, Chortoicetes terminifera. The production, formulation, storage, efficacy and non-target effects are reviewed. Between October 2000 and January 2001 over 23,000 ha were treated at doses of 12 - 25 g/ha in 500 ml of oil. Under most temperate or hot conditions, control of over 90% of Australian plague locusts was obtained by day 14 post spraying, but under less favorable conditions control could take up to 21 d. The factors which make Green Guard® attractive for locust control in Australia include low cost, the absence of environmental effects, especially on aquatic organisms, and its suitability for use in organic beef production areas and where the use of chemical pesticides is undesirable. Large-scale field trials against migratory locusts, Locusta migratoria, have shown that doses of 50–75 g/ha are effective. Spur-throated locusts, Austracris guttulosa, are very susceptible in the laboratory, but field trials have proved difficult to assess because of the high mobility of the adults and the absence of hopper bands at the nymphal stage. Results with the wingless grasshopper, Phaulacridium vittatum, have been variable, with the control being difficult to achieve during cool weather. Laboratory studies on Beauveria bassiana have shown that isolates of this fungus, derived from field-infected grasshoppers, are very virulent and will kill better under cool conditions.