It's a bug eat bug world
They've doubled in size since looking yesterday and the cluster of hatchlings is still there - maybe eating the remains of the eggs. But, who was also there but a monster larva eating the little hatchlings! I found him a leaf full of aphids instead. I knew our native ladybirds could get predated by the harlequins but I'm fairly certain this is a tree full of its own kind.
It was only a little while later (I sometimes get distracted from planning!) when I went to look and there was another, eating a batch of eggs! That one also found a new leaf pretty hastily.