Thank you for keeping us up to date. I'm glad you learned that they are springtail.
However, you might keep an eye on the tree and if you see it decline further notify one of the persons listed above to take a look at it. The springtail might not be the cause of the problem, but may be a symptom of it. There could be rot/moisture/damage issues that are attracting the springtail, but caused by another insect or disease.
