Here is the overall picture.
Here is a closeup of the center. I'm interpreting the big round yellow things as 'aphid mummies'. When a parasitic wasp lays eggs in the aphids, they become big and round like these. The jumble of white is either 'molted aphid skin' or another aphid stage. I'm leaning towards the 'molted aphid skin'.
This is a closeup of the upper center. I'm interpreting the little black bugs as immature aphids. The white 'shards' look more like living aphids here.
During the winter, I've tried various things to control aphids. First, I tried neem oil with a little dishwashing soap. This seemed to kill tender new leaves. I'm not sure if it was the soap or the neem oil. Next, I tried dusting with Ortho Bug-B-Gone. The aphids didn't seem to mind the dust, regardless how thick I laid it on. It just made my trees ugly.
Over the last few weeks, I've started using a spray bottle and rainwater (my tap water has a PH over 8.2, so I try to stick with rainwater). This knocks a bunch of them off and immediately improves things. So far, I enjoy inspecting the trees and hunting aphids. It is getting a bit harder to find an infestation.
I'm interested in learning more about keeping beneficial insects around and was pleased to see the 'mummy aphids'. They didn't start showing up until I washed off the dust, so going to the water bottle has been helpful to the beneficials, too.
Based on my reading about beneficials, one needs to keep winter flowers in the greenhouse to provide a home for adult beneficials. The adults can live on nectar, but the nymphs need aphids. Thus, you keep the adults around on flowers until an aphid infestation pops up, then the adults lay eggs and everything stays in balance. At least that's the theory.
Mark
