After reviewing your site (having had searched through many bug books!), I think this is a Giant Ichneumon. Thought you’d like this picture for your website.
Thank you for sending in a textbook quality image of a female Megarhyssa atrata depositing an egg. This is the most commonly pictured of the Giant Ichneumon species. Your photo is glorious. We are thinking of redesigning our archive pages so that a classic image of the insect is prominently featured at the top of the page, and I think your image and letter will be at the top of the Ichneumon page for years to come. thank you so much.