Ants don't feed on plants, so it could be that there were or are aphids on
the new growth and that's why the ants are there, filling up on the
honeydew -- a nice name for the sticky excrement of the aphids --left by the
ants.

Suzy, Wisconsin, Zone 5
"HH" wrote in message
news
I have a Japanese maple that I have shaped as an outdoor bonsai that has
lots of ants in it. They are clustered at the extremities in the new
growth, much like aphids on new rose buds. Are they harmful to the plant? I
can detect no damage, but then I just noticed them yesterday.

HH