I see these everywhere and am yet to figure it out. Eggs, usually laid in a straight line, end to end, along a twig. Maybe 5-6mm long, 3mm tall, and 1mm wide. These look hatched so I didn't collect them. On acacia, eucalyptus, and other species. I mistook them at first of scale or hoppers, and they remind me of cockroach eggs but skinny.
@Hejor1 I’ve swapped it over from True Bugs to Katydids for you. I’m more than happy to be corrected, but that’s where I’d start with trying to get them identified. Fingers crossed for you😊