Trees, Shrubs and Conifers: ants, 2 by Weerobin

Weerobin wrote:
I was pruning a Japanese apricot (prunus mume) today.
One limb had a deep cleft in it where ants appeared to be entering & leaving frequently.
I cut the limb off as close to the trunk (pic #1) as I could.
But it appears there is a central rotted area where ants are still living (#2).
I realize prunus mume is prone to all sorts of pestilence,
but it's winter bloom is truly remarkable - pic #3 was taken on New Years Day!
If the tree is the only thing at risk, I'll take my chances.
But if my house is at risk (it's adjacent to the attached deck), I'll take the tree out.
The tree otherwise looks healthy - it grows like crazy, which is why it needs frequent pruning.
Suggestions?