Q.Bugs on blue hibiscus
I have a large blue hibiscus, but it looks like it is dying. I found on the trunk low on the ground big quantities of white stuff with ants all over. Is this scale, mealybugs, or what? I live on central coast of CA. What can I use to kill This? I really love this plant and don’t want to lose it. Thank you.

Sounds like you could have woolly aphids, mealy bugs or scale bugs. There are photos and additional links which may help you positively identify your unwanted visitors (and correct any damage they may have done) in these links:
https://www.gardeningknowhow.com/plant-problems/pests/insects/woolly-aphid-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/control-plant-scale.htm