Once great Japanese Maple lookig very sad

Sharronk

Hi, my wife and I planted a Japanese Maple in our front yard over 25 years ago, and it has flourished and grown to about 3m tale. It has always been abundant in leaf. But over the past 6 months or so, it has been extremely sparse in leaf cover, although the leaves that are on it look reasonably healthy.
I have noticed very recently a hole high in the trunk of the tree approx 3/8 inch in diam, with spier web covering it.

Here in Melbourne Australia, our weather has always been from one end of the scale to the other. we will have Very cold winters, and then extreme heat in the summer. This has never seemed to worry our tree though in the past.
Does anyoned have any suggestions as to what we could use to maybe nourish the tree, and / or get rid of the spiders/bugs that maybe destroying it? We are desparate to try and save it. Thanks

dov

Are the possums eating it? Also if you can check if there seems to be any other signs of possible insect/fungus damage apart from that hole.