Ex stalks my boyfriend

My boyfriend’s ex in which they only dated for less than 2 months continues to stalk his Instagram and watches his stories. He doesn’t talk to her or anything so I know that he’s not doing anything wrong and besides it’s been such a long time that they stopped talking. It’s just annoying how she knows that we’ve been together for a long time and that we’re happy, but still continues to stalk him and anonymously call him on the phone. I haven’t told him to block her or anything because that’s dumb but now that she’s doing it again, I feel very annoyed. Should he block this girl so that this can stop?