What are these white things?

[Avocado]

Aside from my pitiful plum tree leaves, what are these white things? (Circled in the picture)

 

[Oliver Buckle]

They look like pupae of some sort, I wouldn't let them live to find out of what. Your tree looks like it has enough problems and it might be the preceding larval stage that caused the damage, you don't want adults laying eggs.

 

[Avocado]

They look like pupae of some sort, I wouldn't let them live to find out of what. Your tree looks like it has enough problems and it might be the preceding larval stage that caused the damage, you don't want adults laying eggs.

I suspect you are right. The pitiful leaves are caused by sawfly larvae, which I am struggling to get rid of. So, the next day, I went to look for their pupae, but they were no longer there. Reading up on the sawfly lifecycle, the larvae turn into pupae and then drop to the ground. I should have checked the ground, but I didn’t.

 

[Oliver Buckle]

Cultivating the ground under the tree can help, it exposes them to frosts and predators like birds, wasps and ground beetles.