These are egg masses on eucalyptus trunks, sometimes densely coating the entire trunk and branches, and bits of flaking bark. Each rectangular strip contains hundreds of oval orange eggs under a powdery fibrous cover. I hatched them at home. After about 5 days, thousands of fast walking minute flattish oval orange hatchlings swarmed out. I think they are probably sucking bug-like creatures with segmented abdomens. They have 2 forward facing widely spaced eyes. What might they be? (I viewed them under my microscope but can't photograph them).