The diet of sugar gliders (P. breviceps Waterhouse, Marsupialia, Petauridae) was determined by fecal analysis and direct observation of feeding animals in a strip of Eucalyptus spp. and Acacia mearnsii de Willdemann dominated roadside vegetation. Seasonal changes in glider diet were compared with seasonal changes in availability of different dietary items in the gliders habitat. During autumn and winter gliders fed predominantly upon the the plant exudates: wattle gum (from A. mearnsii), eucalypt sap (from E. bridgesiana R. T. Bak), and eucalypt nectar. During spring and summer gliders fed predominantly upon insects. The most important insects in the diet were species of pasture pest (various moths and scarabaeid beetles) that have larval stages which develop in pastures adjacent to the study area, and adult stages that are dependent upon eucalypts for food and shelter. Insects were taken in preference to plant exudates during spring and summer (possibly to meet protein requirements for reproduction) even though exudates were most abundant during these seasons. Glider population density is probably regulated by the abundance of plant exudates (particularly wattle gum) available during winter.