Wildlife Spotting

Any help with an identification is much appreciated! These red ants were attending these plant/tree/leaf-hoppery? critters. There is one also underneath the ant on the LHS where the little yellow specks are on the leaf. I'm not sure if they are eggs or not, it was nearly 3 years ago now. These critters are on a Wattle tree (possibly Acacia elachantha, see spotting: https://www.projectnoah.org/spottings/468127327 ) The tree which they are on is along a walking trail amongst the grass and spinifex below a rocky cliff at Mornington Wildlife Sanctuary.