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Growth of larvae of the whitefringed weevil, Graphognathus leucoloma (Boheman), was studied in the laboratory and on various crops in pots in a shadehouse at Kairi, on the Atherton Tableland in north Queensland. In the laboratory at 25.5 ± 1°C there were 11 instars for which head capsule widths and weights were recorded. The first instar weighed 0.14 mg. This was a nonfeeding stage capable of prolonged survival, and after 10 weeks in soil without food 60% survived. When provided with carrot (Daucus carota) larvae grew to 2 or 3 mg after 6 to 7 weeks, then increased rapidly in weight reaching 140 mg after 120 days. At 25.5°C the average time from first instar to adult was 311 days, due in part to a long prepupal period. Larval growth was measured on the roots of peanut (Arachis hypogaea) plants in pots in summer and winter. Under summer conditions (mean soil temperature 23.3°C) larvae reached 140 mg in about 120 days, similar to that in the laboratory on carrot. These fully grown larvae remained in the pots over the mild winter without pupating. Larvae developing in autumn/winter grew more slowly, but the fully grown larvae were then exposed to high spring (early summer) temperatures and soon pupated, the average time from first instar to adult being 273 days. The indications are that temperatures above 25°C quickly precondition mature larvae from Tolga for pupation, thus explaining the broad timing of adult emergence in the field in north Queensland. On different plants common near Tolga, larvae grew most quickly on peanuts and on the pasture legumes dolichos (Lablab purpureus) and stylosanthes (Stylosanthes guianensis). Survival on maize equalled that on peanuts (46.5% in sterilized soil) but growth was less. Larval survival and growth on the grass crowsfoot (Eleusine indica), and (surprisingly) on the pasture legume glycine (Neonotonia wightii) was very poor.

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The influence of insect attack on bud fall and subsequent poor flowering in cultivated hibiscus (Hibiscus rosa-sinensis) was studied in cages and in the field in southern Queensland. Three species of Hemiptera (most importantly Aulacosternum nigrorubrum Dallas but also Nezara viridula (L.) and Tectocoris diophthalmus (Thunberg)) caused some bud fall in 2 plantations studied. Adult Macroura concolor (Macleay) suppressed flowering for long periods in spring and summer. Data from white funnel traps and counts in flowers showed that M. concolor beetles were most active in these seasons. Methiocarb (0.75 g/L a.i.) reduced beetle numbers and increased flowering. When 15 or more adult M. concolor occurred per bud (or flower) most buds fell and few flowers were produced, but when beetles declined to 10 or fewer many buds survived and widespread flowering occurred. Larvae fed in fallen buds and flowers and the mean duration of development of the combined immature stages was 14 days at 26°C. The preference of adult M. concolor for pale coloured flowers was examined. Hibiscus plants produced most buds from December to June with lower numbers in winter and spring (July to November). Bud production in spring and early summer (September to December) vaned greatly and probably contributed to poor flowering, however, even when large numbers of buds occurred very few flowers were produced because of the activities M. concolor.