They look like the eggs of moths. They could also be the eggs of butterflies. Many species lay their eggs on twigs. Exactly what species is hard to say but it does not really matter. Whatever they are they will emerge and consume your leaves.

You should scrape them off to kill them. Once they hatch they are much harder to control as the caterpillars move away. Check as much as you can throughout the orchard and destroy the egg patches.