First it was falling leaves and then falling stems.  Now it's falling branches.

Fortunately, the dropped branches are few in number and small in diameter.  In examining the breaks, they are suspicious looking.  Certainly there was a weakness at the point of separation that caused them to break.  Each fallen branch has a small cavity in the center and seemingly an exit hole on the side, as one might expect if an insect egg had been laid inside and hatched.  It's just a theory and I have not researched it, but it seems like a reasonable idea.

Besides, there's nothing I can do about — except pick up the branches.