Last summer this giant horntail or wood wasp landed on my wooden terrace, and I managed to take some pictures. The giant horntail is really giant, but it is not as frightful as it seems. The long projecting spike, that has given the horntail its name is not used for stinging. The female horntails lay their eggs in trees/wood. The larvae bore into the wood and live in the tree for up to 2 years, possibly more. They typically migrate to just under the bark before pupation. Actually, the ichneumon wasp shown elsewhere may be targeting a larvae of this giant horntail. The latin name Sirex gigas has also been used for this species.
I have made a blog entry in Danish on my Bruunshåb blog telling a little bit more about the images