Giant (yellow headed) Ichneumon wasp – Megarhyssa atrata - Female.
This huge wasp, 6inch+ body, is drilling to deposit her eggs in a live grub or larva in the tree. The eggs hatch and their wasp larva eat the host insect in the tree for the nutrients before they chew their way out of the tree. The female’s Ovipositor or tail is approx. 1.5 feet and she can hardly fly because its so long.
This one is missing it’s Ovipositor’s case or sheath.