Order Hemiptera, Sub-order Auchenorrhyncha
Click on the thumbnails for a larger photo. Note that the size of the thumbnails and the size of the photos is not related to the size of the insect.
"Leafhopper" is not a very useful name because many species, including all those living on gumtrees, feed on stems or the trunk of trees rather than on leaves.
Species in this sub-family are all attended by ants. The nymphs and usually the adults are gregarious. The species shown here, with the possible exception of the last two, feed on the stems of Eucalypts and are often called "gumtree hoppers" although the subfamily does include species with other hosts. The nymphs cannot hop, and although the adults supposedly can I have never seen any of them do it - instead they just sidle around to the other side of the stem, or don't move at all if there are plenty of ants present.